Potential uses of jojoba oil and meal — a review

INDUSTRIAL CROPS ANDPRODUCTS ANINTERNATIONALJOURNAL

ELSEVIER

Industrial Crops and Products 3 (1994) 43-68

Potential uses of jojoba oil and meal -

a review

Jaime Wisniak Department of Chemical Engineering, Ben-Gution University of the Negev, Beer-Sheva 84105, Israel

Received 7 October 1993; accepted 8 March 1994

Abstract The chemical composition of jojoba oil is unique in that it contains little or no glycerin and that most of its components fall in the chain-length range of C49-C 42. Linearity and close-range composition are probably the two outstanding properties that give jojoba oil its unique characteristics. Jojoba oil molecules contain two double bonds separated by an ester bond. These three active centers have been proven to be the source of a very large number of intermediates or final products. This paper describes the applications of natural jojoba oil and reviews

in particular the reactions that lead to derivatives with potential industrial application: (1) production of semisoft waxes by geometrical isomerization; (2) production of hard waxes by hydrogenation; (3) additives for high-pressure high-temperature applications; (4) extractants for mercury cations; and (5) selective extractants for the nuclear industry. In addition, a general view of the potential uses of jojoba meal as animal feed is presented. Keywords:

Jojoba oil; Non-glycerides

1. Introduction

Jojoba is known in botanical literature as Simmondsia chinensis (Link) of the family Buxaceae and as Simmondsia culifomica Nutall. The first

name is the correct one, although it perpetuates a geographical misnomer. In late 1970 sperm whale was included by the US Government in the list of endangered species and imports of oil, meal and other products derived from whales banned. At that time, sperm oil consumption in the United States was about 40-50 million pounds per year, with half that figure used in lubricant applications. No single natural, or synthetic replacement with the unique qualities of sperm whale oil has yet been found, but enough experimental evidence * Fax (972)-57-236446,

E-mail [email protected].

0926-6690/94/$07.00 0 1994 SSDZ 0926-6690(94)00018-T

has accumulated in the last 25 years that jojoba oil is not only an excellent substitute of sperm oil but its potential industrial uses go beyond those of sperm oil. Most of the initial development work on jojoba was based on the promise that its main application is as a straight substitute of sperm whale oil. This stage has been surpassed. Jojoba is a desert shrub that grows wild in southern Arizona, north-western Mexico and is being cultivated in many semi-arid lands around the world. Extensive efforts are being made to domesticate the shrub. Jojoba is a woody evergreen shrub that is commonly 2-3 feet high, easily recognized by its thick, leathery, bluish-green leaves and dark-brown nutlike fruit. Interest in jojoba stems from the unusual properties of the oil that can be extracted from its seeds. Jojoba is unique among plants in that the nuts it produces contain about 50% by weight of a

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44

J. Wwniak / Industrial Crops and Products 3 (1994) 43-68

practically odorless, colorless oil composed mainly of the straight chain monoesters of the monounsaturated Cza and Czz alcohols and acids, with one double bond at each side of the ester bond. The almost complete absence of glycerin indicates that jojoba differs radically from all known seed oil, it is not a fat but a liquid wax. Jojoba possesses several advantages over sperm oil: (1) it has no fishy odor; (2) the crude oil contains no stearins and requires little or no treatment for many industrial purposes; (3) it can take larger amounts of sulfur; (4) it does not darken on sulfurization; and (5) the highly sulfurized oil is liquid, whereas sperm oil when highly sulfurized requires addition of mineral oil in order to remain liquid. The growing enthusiasm for the commercial future of jojoba oil and its derivatives has been generated by its many potential uses. The oil has been evaluated with respect to its suitability for sulfurization to produce lubricants, lubricant additives, and rubber-like factices for use in the manufacture of linoleum and printing inks. It offers excellent possibilities as a lubricant at high temperatures and pressures. The oil has a high dielectric constant, which may make it suitable for electrical applications. It may also be useful as an ingredient in the manufacture of carbon paper, stencils, pharmaceuticals, cosmetics, insecticide carrier, thermosetting compositions for use in the formation of a magnetizable film, dental prosthetic materials, and hypocaloric foods. The oil can be easily hydrogenated to form an extremely hard white wax with a high melting point and properties competitive with beeswax and candelilla, carnauba, and spermaceti waxes. Jojoba oil is unique as a source of C20 and C22 straightchain alcohols, which could prove valuable in the manufacture of detergents, wetting agents, dibasic acids, long-chain ethers, hydroxy ethers, and sulfated products. A monograph by Wisniak (1987) summarizes the chemistry and technology of jojoba oil and jojoba meal. 2. Extraction Enough experimental evidence is available to affirm that extraction of the oil from jojoba seeds can be achieved with standard equipment, mainly

by the pressing or solvent extraction methods used commercially to isolate vegetable oils. No special difficulties have been experienced in obtaining a satisfactory yield by either crushing or solvent rendering, if attention is paid to the fact that the seeds have a relatively high oil content. Even after the most efficient pressing, jojoba meal will retain an appreciable amount of absorbed oil, usually amounting to 3 to 8% by weight. Liquid solvent extraction is usually used to recover the larger part of this oil. Knoepfler et al. (1959) and Spadaro et al. (1960) have reported on the methods and solvents applicable for industrial operation. Wisniak et al. (1987) have conducted experiments to determine the holdup and drainage curves of jojoba meal for oil dissolved in several solvents. Their results for commercial hexane are reported in Fig. 1. An interesting alternative to solvent extraction should be supercritical gas extraction. Stahl and Quirin (1983) have patented a general process for the extractive recovery of high-grade natural waxes, using supercritical gas extraction, and in a patent by Olberg et al. (1982) it is claimed that jojoba oil can be extracted easily from crushed seeds by CO2 under supercritical conditions. The phase behavior of mixtures of jojoba oil and carbon dioxide between 100 and 2600 bar is given in

%JOJOBA

OIL IN HEXANE

1.3

MEAL

0

5

10

15

20

DRAINING TIME,

SOLUTION

1

25

30

35

MIN

Fig. 1. Draining times of jojoba solutions in hexane (Wisniak et al., 1987).

45

J. WBniak / Industrial Crops and Products 3 (1994) 43-68

Table 1 Properties of jojoba oil (Wisniak, 1987)

100

500

1000

1500

2000

PRESSURE,BAR Fig. 2. Solubility isotherms of jojoba oil in CO2 (Stahl et al., 1983). STP = standard pressure and temperature (1 atm and 273.15 K).

Fig. 2 (Stahl et al., 1983). While the solubility in liquid CO2 at 20°C is only slightly influenced by pressure, a great increase in solubility with pressure, and thus gas density, can be observed in the higher temperature isotherms. The extrapolation of the solubility isotherm at 80°C allows the presumption of a very high solvent power of CO2 in the pressure range between 700 and 1400 bar. 3. Physical properties of the oil The oil obtained from the jojoba nuts is usually a low-acidity (<2%), light-golden fluid that requires little or no refining. It is non-volatile and free from rancidity. Even after repeated heating to temperatures above 285°C or after heating to 370°C for 4 days it is essentially unchanged (Daugherty et al., 1953). Its boiling point (at a pressure of 757 mmHg, under nitrogen) rises to 418°C but drops rapidly to a steady 398°C (Miwa, 1973). Neutralization of the oil is not usually required and bleaching to a water-clear fluid can be done with common commercial techniques. According to Banigan and Verbiscar (1981) treatment with 2-5% of Filtrol 105 for 15-30 min at 100°C reduces the color from 7 to 3 in the Gard-

Freezing point, “C Melting points, “C Boiling point at 757 mm under N2, “C Heat of fusion by DSC, Cal/g Refractive index at 25°C Dielectric constant (27°C) Specific conductivity, mho cm-’ (27°C) Specific gravity, 25”/25”C Surface tension, dyne cm-r (235°C) Viscosity Saybolt, lOo”C, SLJS Saybolt, 21O”C, SUS Smoke point (AOCS Cc 9a-48), “C Flash point (AOCS Cc 9a-48), “C Fire point (COC), “C Iodine value Saponification value Acid value Acetyl value Unsaponifiable matter, % Total acids, % Iodine value of alcohols Iodine value of acids Average molecular weight of wax esters

10.6-7.0 6.8-7.0 389 21 1.4650 2.680 8.86 X 10-13 0.863 34 127 48 195 295 338 82 92 <2 2 51 52 77 <76 606

ner scale. The bleaching earth selected should be one that does not remove the natural antioxidants present in the oil. Some properties of the oil are listed in Table 1 (Wisniak, 1987). Wisniak and Liberman (1975) measured the refractive index (n), density (d, g ml-‘), and viscosity (11, cP) of jojoba oil at various temperatures and developed the following relationships:

n = 1.47391 - 0.000360t

(1)

d = 0.88208-

(2)

0.000655t

q = 0.004995 exp(2646/ T)

(3)

with t in degrees C and T in degrees K. From Eq. 3 we get that the viscosity index of jojoba oil is 225. Kuss et al. (1983) have made extensive measurements of the density, compressibility, and viscosity of jojoba oil in the temperature range of 25-120°C and the pressure range l-2000 bar. The specific conductivity values for jojoba oil in the temperature range 34-140°C are similar to those of oleic acid. However, an advantage of jojoba oil is its neutrality. Wisniak and Stein (1974) and

.I. WisniakI IndustrialCrops and Products3 (1994) 43-68

46

oil encapsulated. Landis and Craver (1984) have measured the solubility of jojoba oil in water, 19 organic solvents, and mixtures of toluene with either methanol or dimethylformamide. Jojoba oil is soluble in common solvents such as benzene, petroleum ether, chloroform, carbon tetrachloride, and carbon disulfide, and is essentially immiscible in methanol, ethanol, acetone, and acetic acid. 4. Molecular structure

0

0.4

0

MASS

FRACTION

Q6

Jojoba oil is a liquid wax that contains two double bonds and one ester group in each constituent molecule. NMR spectroscopy of the raw material shows that the hydrogen atoms next to the double bond and the allylic hydrogen appear with shifts of 5.5 ppm and 2.1 ppm, respectively. The hydrogen atoms in (Yposition to the oxygen and a carboxylic group appear with shifts of 4 ppm and 2.15 ppm. The aliphatic hydrogen and those in the methylene groups appear with shifts of 1.1 ppm and 0.8 ppm, respectively.

0.8

FREON 22

Fig. 3. Solubility of refrigerant gas R-22 in jojoba oil expressed as mass fraction of the gas in the liquid phase (Wisniak and Touvia, 1989).

Wisniak and Touvia (1989) measured the solubility of hydrogen and refrigerant gases R-22 and R-l 14 in jojoba oil in a wide range of temperatures and pressures. mica1 results for R-22 appear in Fig. 3. Wisniak and Touvia concluded that solutions of R-22 in jojoba oil may find use in absorption refrigeration cycles. Gonzilez et al. (1979) studied the crystallization of jojoba oil and measured its specific heat by differential scanning calorimetry. Dependence of the specific heat capacity CP (cal g-’ K-*) on temperature (K) was expressed by the following equation: cp = 9.51 x 10-4T + 0.129

(4)

Miwa and Hagemann (1978) also reported that low-density polyethylene dissolved readily in hot jojoba oil and that on cooling, the plastic solidified with the liquid oil encapsulated inside. The rate of diffusion of jojoba oil to the surface depended on the porosity of the encapsulating polymer, which in turn depended on the amount of

5. Composition Greene and Foster (1933) were the first to report that jojoba nuts contain about 46% of a liquid oil that resembles sperm whale oil in its analytical characteristics and which they therefore concluded to be a liquid wax. Miwa (1971, 1973) developed an analytical process based on HClcatalyzed ethanolysis followed by saponification. The GLC technique developed by Miwa was improved by Duncan et al. (1974) to decrease the time required by the HCl-hydrolysis step. A more refined analysis using GLC coupled with highpressure liquid chromatography, mass spectrometry, and ozonolysis was later reported by Spencer et al. (1977) and Miwa (1980) (‘Ihbles 2 and 3). Wiesend (1989) has suggested a high-performance liquid chromatography method analysis based on the use of 3-phenoxybenzyl alcohol as a derivatizing agent. Ozonolysis was used to determine that the double bonds are in the o-9 position. Routine analysis techniques for jojoba oil have already been developed by Tonnet et al. (1984), Graille et al. (1986) and Pioch et al. (1986). Jojoba oil is unusually stable towards oxidation especially at high

41

.I. Wisniak / Industrial Crops and Products 3 (1994) 43-68

Table 2 Composition and structure of fatty alcohols and fatty acids derived from jojoba oil - Analysis by GLC, ozonolysis - GC and GC-MS (Miwa, 1980) Alcohols

%

Acids

%

Tetradecanol Hexadecanol Heptadec-8-enol Octadecanol Octadec-9-enol Octadec-11-enol Eicosanol Eicos-11-enol Hecos-12-enol Docosanol Docos-13-enol Tetracos-U-en01 Hexacosenol

trace 0.1 trace 0.2 0.1 0.4 trace 43.8 trace 1.0 44.9 8.9 trace

Dodecanoic Tetradecanoic Pentadecanoic Hexadecanoic Hexadec-7-enoic Hexadec-9-enoic Heptadecenoic Octadecanoic Octadec-9-enoic Octadec-11-enoic Octadecadienoic Octadecatrienoic Nonadecenoic Eicosanoic Eicos-11-enoic Eicosadienoic Docosanoic Docos-13-enoic Tkicosenoic Tetracosenoic Tetracos-15-enoic

trace trace trace 1.2 0.1 0.2 trace 0.1 10.1 1.1 0.1 trace trace 0.1 71.3 trace 0.2 13.6 trace trace 1.3

temperatures. Kono et al. (1981) separated and identified some of the antioxidants by molecular distillation of the oil and analysis of the distillate by gas chromatography/mass spectrometry. The o, y, and S isomers of tocopherol are present, in varying quantities depending on the origin of the oil, the y-isomer being most abundant. 6. Jojoba oil replacements The small amount of jojoba oil available on the market in the past and today, and its relatively high price, have prompted a search for substitutes. The approach has been in two directions: chemical synthesis and development of other natural products of similar composition. 6.1. Synthetic jojoba oil Inspection of the ester composition of natural jojoba oil suggests as possible substitutes the esterification products of C& and Ci; acids and alcohols. The four possible esters possess the following

Table 3 Jojoba oil wax ester composition (Spencer et al., 1977; Miwa, 1980) Wax ester chain length

Alcohol/acid combination

Percentage by GLC and GC-MS

34 36

18/16 18/18 20/16 16122 18/20 20/18 22116 16124 18/22 20120 22118 24116 18/24 20122 22120 24118 20124 22122 24120 24120 24124 26124

0.1 0.1 1.8 0.2 1.0 5.4 0.2 0.6 1.5 24.3 3.6 0.3 1.5 10.5 37.0 1.0 0.9 2.1 7.0 0.8 0.1 0.02

38

40

42

44

46 48 50

important characteristics similar to those of jojoba oil: (a) straight chain esters, (b) one double bond on each side of the ester group, (c) no glycerides, (d) chain length 36-44 carbons, and (e) physicochemical properties most probably close to those of jojoba oil. The four esters can be manufactured by known technologies from readily available fatty materials. Oleic acid is a major component of all commercial oil seeds and erucic acid can be obtained from rapeseed oil. An important obvious disadvantage is that they are synthetic compounds, so that their use in the food, pharmaceutical, and cosmetic industries may require extensive and expensive testing. Aracil et al. (1992) and Sanchez et al. (1992a, b) have studied the kinetics and process characterization and modeling of the esterification of oleic acid and oleyl alcohol using zeolites or cobalt chloride as catalysts and concluded that this synthetic path offers attractive commercial incentives. Rae and Philpott (1990) have suggested preparing synthetic jojoba oil by esterification of erucic acid with 2-octyldecanol.

48

J. Wisniak/ IndustrialCrops and Products3 (1994) 43-68

Perlstein et al. (1974) have used a BouveaultBlanc sodium reduction of glycerides followed by esterification to synthesize ester mixtures with a composition similar to that of sperm whale oil. Miwa and Wolff (1962, 1963, 1965) applied the same experimental techniques to oils derived from the herbs Crambe abyssinica,Lunaria annua, and Limnanthes douglasii specifically as jojoba substitutes. Lipase-catalyzed reactions such as hydrolysis and esterification of lipids, have received considerable attention during the past few years in view of their potential biotechnological applications in the oil and fat industries. Mukherjee and Kiewitt (1988) and Trani et al. (1991) have shown that esters composed of long-chain (t&j, Cts) and/or very long-chain (> Czs) acyl and alkyl moieties, which resemble some naturally occurring waxes of commercial importance, can be prepared conveniently in high yield by alcoholysis or esterification reactions catalyzed by Lipozyme and Lipase G. 4.2. Natural replacements Buisson et al. (1982) have discussed the possibility of using tropical fish oils such as orange roughy (Hoplosthetus atlanticus), black Oreo (AZlocyttus sp.) and small spined Oreo (Pseudocythus maculatus) as replacements for jojoba oil. The levels of wax esters found in the fish oils are close to that of jojoba oil (97%) and considerably higher than that of sperm whale oil (66%). The principal components of the esters from roughy and the Oreo SpeCieS are Of chain length C34-C42. This contrasts with the shorter chain length (c2S-c36) found in sperm whale oil and the longer chains found in jojoba oil. Hydrogenated roughy oil is a pure white, crystalline wax with no detectable odor, and its characteristics compare favorably with those of both sperm whale oil and hydrogenated jojoba oil. Orange roughy oil can be easily sulfurized and may have considerable potential as additive for high pressure lubricants. 7. Applications The particular properties and composition of jojoba oil suggest the following framework of applications.

A. No change in chemical composition A.1 Natural oil (Food, medical, pharmaceutical and cosmetics use; electrical insulator, lubrication) B. Attack at the double bonds B.l Cis-trans isomerization B-2 Hydrogenation B.3 Sulfurization B.4 Halogenation B.5 Sulfurhalogenation B.6 Phosphosulfurization B.7 Phosphonation B.8 Oxidation-ozonolysis B.9 Epoxidation B.10 Alkylation (Friedel-Craft) C. Attack at the ester bond C. 1 Hydrolysis C.2 Amidation C.3 Ammonolysis All of these possibilities have been reported in the literature and their characteristics will now be reviewed. 7.1. Direct utilizationof jojoba oil Jojoba oil may be considered a low-energy replacement for conventional fats and oils. The nutritional properties of jojoba oil have been evaluated by several investigators (Bracco, 1982; Heise et al., 1982; Yaron et al., 1982; Decombaz and Anantharaman, 1985; Ranhotra et al., 1986; Stalder et al., 1985; Verschuren, 1989; Verschuren and Nugteren, 1989). Jojoba oil was found to be highly resistant to rancidity and was poorly digestible, characteristics that suggest that it may have potential benefits in reducing fat-related energy intake. Reduced-calorie foods represent one of the fastest growing segments of the food industry in the U.S. Ingredients that permit this are being sought and developed vigorously. Ranhotra et al. (1986) evaluated jojoba oil for its usable energy value by feeding weanling rats with diets containing 24% of soybean oil and increasingly replacing the latter with jojoba oil. At levels up to 9% jojoba oil in the diet, the lean body

49

J. Wmniak IIndustrialCropsand Products3 (1994) 43-68

mass of the rats was little affected, while their body fat content declined substantially. Based on these and other response parameters, Ranhotra et al. concluded that jojoba oil contains very little usable energy. Verschuren (1989) examined the nutritional properties of jojoba oil by feeding rats a diet with jojoba oil al levels 2.2, 4.5 and 9%, supplemented with a conventional fat up to 18%. General health, survival and food intake were not adversely affected, but body-weight gain showed a dose-related decline. Clinical chemistry revealed significantly increased levels of several enzymes, particularly transaminase, indicating cell damage. There was also an increase in white blood cells. On the basis of the significant adverse clinical and histopathologic effects, Verschuren concluded that jojoba oil cannot be considered as a promising alternative dietary fat with a low digestibility. In a following study, Verschuren and Nugteren (1989) demonstrated that jojoba oil does not affect the intestinal transit time nor the absorption of conventional fat. One of the most useful oils for foam control during production of antibiotics by fermentation has been sperm whale oil, its advantages being excellent antifoam characteristics, low cost (formerly) and low rate of metabolism by the microbial cultures. Pathak et al. (1978) made comparative tests on jojoba and sperm whale oils as antifoaming agents in the production of penicillin and cephalosporin C and found that the antibiotic yields were at least equivalent to those obtained with sperm oil. With a high-yielding penicillium strain, jojoba oil increased the penicillin yield. In cephalosporium fermentation, jojoba oil showed no deleterious effects in the shaken-flask experiments, while in the 14-liter fermentors it enhanced the yields of cephalosporin C. Thus, jojoba oil seems to be a highly promising antifoam agent in antibiotic production and to have some physicochemical properties needed to enhance the yield. M. Mandels (pers. commun., 1983) evaluated jojoba oil as an antifoam agent in cellulose production by Ttichodemza reesei and found that growth of the microorganism and cellulose production were slowed. Other experiments with detergent foam, and in fermentation with Aspergillus niger have shown that jojoba oil does not offer advan-

tages over the standard antifoaming agents. On the basis of this information and the fact that the results of Pathak have not been reproduced, we should conclude that jojoba oil may act as an antifoam agent only on specific systems. The Cosmetic Ingredient Review Panel of the Cosmetic, Toiletry and Fragrance Association, Inc., has recently concluded (1992) that jojoba oil and jojoba wax are safe as cosmetic ingredients in the present practices of use and concentration. Bhatia et al. (1990) studied the possibility of using natural jojoba oil as a replacement of mineral oils in lubrication and concluded that the pour point, acid value, and oxidative stability were the limiting factors in the use of jojoba oil for this purpose. 8. Chemical transformation

of the oil

Jojoba molecules contain two double bonds and one ester group. These two active sites can give place to a large number of intermediates or final products (Knoepfler and Vix, 1958; Wisniak, 1977, 1987). 8.1. Basic chemistry Shani has published five basic works (1981, 1982, 1983, 1986, 1988) describing many possible reaction schemes at the double bond. One of these is shown in Fig. 4. The reader is referred to the original publications for detailed information on the chemical synthesis of the different derivatives described in this figure. Galun and Kampf (1981) and Galun et al. (1985) have studied the allylic bromination, chloroesterification and oxidation with hydrogen peroxide and permanganate, of the olefinic bonds of jojoba oil. Barlas et al. (1989) have studied the cyclic addition of nitrile oxides to jojoba oil; most of the double bonds were converted to cis isoxazolines. Landis et al. (1992) have studied the pyrolysis of jojoba oil to produce dienes and fatty acids in the Cl&24 range. 8.2. Cis-trans isomerization It is a well-known fact of the chemistry of unsaturated fatty materials that they can be converted

50

J. WuniakI IndustrialCrops and Products3 (1994) 43-68 JOJOBA

OIL

HN02 c

I

TRANS-JOJOBA

OIL

b

I

Br2

17. CH3(CH2)7$H$H(CH2$,,COtCH2&~tt$HCH2),CH3

9

CHB(CH2),C1H~H(C~))IIICO(CH2)n~H~H(CH2)7CHg Br Br

E

BrBr

Br Br

(Br)?

I BASE

(Br)H

II

1

CH,(CH2),C=~(CH2,,CO(CH2)n~=~(CH2)7C~3 (H)Br

(H)Br VI

CH3(CH2),C:C

+

f7

(CH2),,,CO(CH2),C:C(CH2),CH3

?

CH3’CH2’,C;=$‘CH2’m

CO(Ctt#=~(CH2),CH3-

H Br (Brw)

CH,(C~)i

+

CH=C=CH(CH2)j

(Hklr

+ CH&H2),

IX

CH30t&C~~CH2~,~OH

~O(CHZ)I

CH=CECH’CH~~CH~

VII

0

CH3(CH2)7C=$kH2),,,tOH

H Br (BrXH)

v’a

VII (Br)!

Br0r

PO

BASE

H(B0 C=&12)nOH X E&H)

+ CH$H&

CZ(CH2),0ti

CH,(CH2t2’,~=f’CH2’,COH

‘?

+CH3[CH2+~=$(CH2),0H

H Br (BrXH) IXa CH,@12)iCH=C=CH(Ct12,)j

*

Br H XdHbr) P COH +Ct$kH2)kCH=C=CH(C~),

XIII

OH

XIV

i = 6,

j = 7,9,11,13

k= 6,

I = 6Jl,12,14

i = 7,

j=6,6,10,12

k= 7,

I- 7,9,11,l3

Fig. 4. Some possible chemical reaction (Shani, 1981).

into solid materials by geometrical isomerization of the double bonds. The truns isomer is thermodynamically more stable than the cis form, has a higher melting point and its soaps have superior wetting and detergency properties. The reaction has never had any commercial significance probably because the same results can be achieved by partial hydrogenation with the additional advantage of higher oxidation stability. The unusual properties of jojoba oil have suggested that this phenomenon could be used to enhance the uses of this material. The pharmaceutical characteristics of the oil could be advantageously used if the wax had a natural creamy structure. A large number of catalysts have been proposed and tested for the geometrical isomerization of a double bond. Among them, mention can be made of the oxides of nitrogen, selenium, tellurium, sulfur dioxide, various phosphorus compounds, catalytic hydrogenation, mercaptans, silicates, iodine, ultraviolet light and electron radiation. Selenium and oxides of nitrogen have been the most widely used of these catalysts (Litchfield, 1966). The maximum

content of tram isomer and the conditions of isomerization of fatty materials with selenium and NO2 have been investigated by Litchfield et al. (1963, 1965) and Litchfield (1966). They have determined that in the equilibrium state about 7580% of the bonds are in the tram form. The cistruns isomerization of jojoba oil with selenium and NO2 catalysts has been reported by Wisniak and Alfandary (1975), under a wide range of conditions. The NO2 was generated by decomposition of HN02. Wisniak and Alfandary found that the reaction was reversible, of order 1 and had an activation energy of 35 kcal/mol. Typical curves appear in Fig. 5 for several catalyst and temperature levels. It is seen that the reaction was very fast and that the rate increased with increased temperature and catalyst concentration. Melting points of the reaction product varied between 36 and 40°C with selenium catalyst and from 38 to 42°C with NO2 catalyst. Proper adjustment of the operating conditions could then allow the production of a material with a melting point temperature close to that of the human body. The thermal and pho-

J. Wisniak I Industrial Crops and Products 3 (1994) 43-68

r

51

Table 4 Melting points of jojoba oil isomerized with different catalysts (Wisniak, 1987) Catalyst

60

ir

9 HN02 /lOOQ

0 60°C

A .

Clays Selenium NOz NO2 (purified product) Chemical route

Oil

0.91 1.83 2.74

% TYans bonds 25 40-50 65-75 >95 >95

Melting point (“C) 29-31 36-40 36-40 52-54 52-54

A 3.66

0.919 HNO#lOOQoil

k

a

t

10

A

60 90

I

,

I

20

30

40

60

TIME MINUTES Fig. 5. Isomerization with HNOz. Influence of temperature and catalyst concentration (Wisniak and Alfandary, 1975).

tosensitized isomerization of jojoba oil has been studied by Galun and Shaubi (1984) and Galun et al. (1984). Since the cis isomer has generally a lower heat of combustion and a higher thermal stability than the fruns form, it can be transformed into the trans form if heated to a temperature sufficiently high to cause the rotation of the double bond. The double bonds present in jojoba oil absorb light of wave length below 200 nm (short wave length UV) so that sensitizers are required to allow the absorption at wave lengths of 366 nm or more (visible light). Photosensitized reactions may be important as sensitizing substances may be part of cosmetic formulations for the skin based on jojoba oil. Brown and Olenberg (1982a, b) have shown that isomerization can be induced by heating jojoba oil to temperatures above 150°C in the presence of acidic bentonite clays. Brown and Olenberg describe the preparation and uses of isomorphous compositions based on mixtures of jojoba isomerates with hydrogenated jojoba oil.

These are solid solutions that have a melting point dependent on the relative proportion of the two components. Mixtures of jojoba oil and its trans isomer have been shown to be non-mutagenic using Salmonella typhirium strains TA 97, TA 98, TA 100, and TA 102 (Marshall et al., 1983). Shani (1986) has developed a procedure for obtaining all-truns jojoba oil by a straight chemical route; all-trans jojoba has a melting point of 52-54°C. Table 4 compares the results of the different methods. 8.3. Hydrogenation Hydrogenation is a standard technique for improving the properties of vegetable and animal oils. In addition to increasing the softening and melting points of the fats, the hydrogenation process also improves their color, odor and stability. During catalytic hydrogenation of an unsaturated fat, the double bonds are not only saturated but they can also undergo geometrical isomerization from the cis to the trans form and migrate along the chain, forming positional isomers. Warth (1956) reported that jojoba oil could be easily hydrogenated by a process similar to hydrogenation of cottonseed oil and that the resultant product consisted of highly lustrous, very hard pearlywhite crystalline laminae that melted at 70°C. The solid wax has been recommended as ingredient in polish waxes, carbon paper and penicillin drugs, for the waxing of fruit and the impregnation of heat-resistant paper containers, and as an exterior coating for candles. It is said that candles made from it burn with a brilliant flame and do not smoke. Wisniak and Holin (1975) have studied the hydrogenation of jojoba oil with several nickel and

52

.I. Wisniak / Industrial Crops and Products 3 (1994) 43-68

25 Catalyst

.-

E

A

100°C 920 R.P.M.

5

G 70

lOg/lOCCl mL oil

5g/lOOO mLoil A 100 P.S.I.G. A 200 P.S.I.G. 0 300 P.S.1 G. o 600 P.S.I.G.

80

0

100 200

300

400

500

600

700

800

60

40

0

20

IODINE VALUE (WIJS) Fig. 7. Pressure effect on isomerization (Wisniak and Holin, 1975). Iodine number measured by the Wijs method.

HYDROGEN PRESSURE P.S.I.A. Fig. 6. Pressure effect on hydrogenation rate at 900 rev/ min. G-70 is a nickel on kieselgur catalyst with a nominal composition of 25% nickel (Wisniak and Holin, 1975). 60

copper chromite catalysts in the range 100-800 psig and lOO-140°C. The reaction was found to follow pseudo first-order kinetics in the double bonds. Cis-tram isomerization was not affected significantly by catalyst concentration and rate of agitation, although at lower agitation rates, somewhat more tram isomers were formed. The effect of pressure on the overall reaction rate constant and geometrical isomerization is shown in Figs. 6 and 7. Mapstone (1982) has reported the variation of the melting point of partially hydrogenated jojoba oil with its iodine value (Fig. 8), this is an indicative curve only since the same iodine value may correspond to a wide range of tram isomer content, with the corresponding variation in melting points. Simpson and Miwa (1976, 1977) have studied the X-ray diffraction of hydrogenated jojoba oil and shown that both compounds have nearly identical powder patterns and that they are isomorphic. Miwa (1974) has studied the compatibility of polyethylene and paraffin wax with hydrogenated jojoba oil and found that the binary systems are miscible in all proportions; addition of hydrogenated jojoba oil to polyethylene facilitates the processing of the plastic by using lower temperatures than normal. A comparison between

10 :

01 0

RAW OIL---Z_ \

’

’

’

30

’

’

’ 60

’

’

1

90

IODINE VALUE Fig. 8. Melting points of hydrogenated jojoba oil (Mapstone, 1982).

hydrogenated jojoba wax, prepared from bleached and unbleached oil, and beeswax and carnauba wax is reported in Table 5 (Wisniak and Holin, 1975). It is seen that jojoba wax is substantially better than beeswax and compares extremely well with carnauba wax. The melting point of the jo-

J. WisniaklIndustrialCrops and Products3 (1994) 43-68

53

Table 5 Comparison between jojoba wax, beeswax and carnauba wax (Wisniak and Holin, 1975) Property

Melting point Congealing point Penetration at 77°F at 100°F Refractive index at 80°C Total acid number Iodine value Ash Color

Method

ASTM D-127 ASTM D-938 ASTM D-1321

Units

“C

“C 0.1 mm

ASTM D-1747

no 80°C

ASTM D-664 1.P. 84 ASTM D-482 ASTM D-1500

mg KOH/g

g iodine/100 g wt%

joba wax is lower than that of carnauba, but this fact does not influence the penetration comparison. The comparison between carnauba and jojoba given in Table 5 should not be considered definite because carnauba is sold in several grades of quality and purity. Some miscellaneous uses for hydrogenated jojoba oil appear in the patent literature: Kubie (1960) claims that the material is suitable as a component in cold forming lubricants; Sano and Yoshida (1978) describe the preparation of liquid shortenings by combining hydrogenated jojoba oil, an emulsifier, and a liquid vegetable oil, while Devitt and Rossell (1979) claim that improved coating compositions for foodstuffs, like chocolate and dried fruit, can be obtained using partially or totally hydrogenated jojoba oil. Hirano et al. (1977) describe bath preparations that contain jojoba oil or hydrogenated jojoba oil, and Murase et al. (1985) claim that cocoa fat substitutes with high mold release rates can be prepared by isomerization hydrogenation of mixtures of cottonseed oil and jojoba oils. 8.4. Halogenation Halogenated fatty materials find extensive use in the preparation of quaternary compounds, antirotting, flame proofing, and fungicide additives, as well as lubricant additives. Brominated vegetable oils have long been used as a weighting oil in carbonated drinks. Wisniak and Alfandary (1979) have described the kinetics and influence

Jojoba Wax

Beeswax

Carnauba wax

64.0 62.0

75.5 68.9

4 7

20 41

9 13

1.4391 2.5

1.4400 18.4

1.4361 3.3

0.01 1.0

0.001 L1.5

0.02 1.0

White

Yellow

67.0 66.5

67.5 67.0

6

1.4380 1.9 0.02 LO.5

of operating variables on the chlorination and bromination of jojoba oil. Their results indicate that the chlorination reaction is first order in the concentration of the double bonds and that of bromination has variable-order kinetics. In both cases the rate is strongly affected by the polarity of the solvent; larger dielectric constants induce faster reactions. An additional observation has possible analytical consequences: NMR tracking of the reaction in solvents of high dielectric constant (methylene chloride and methylene bromide) showed complete disappearance of the double bonds within 20 s. This suggests that in the Wijs method for iodine number part or all of the carbon tetrachloride employed may be substituted by methylene chloride or methylene bromide, shortening the overall analysis time. Trial runs with jojoba oil effectively indicated that titration with potassium iodide/sodium thiosulfate within 1 min of addition yielded an excellent estimate of the iodine value. The Falex-load carrying capacity of chlorinated jojoba oil varies significantly with chlorine content, reaching 3700 lb for tetrachlorojojoba (21% chlorine by weight). Tetrabromojojoba, the bromine saturated product of jojoba oil, is a low-viscosity liquid that contains about 34 wt% bromine. This relatively high percentage suggests immediately its possible industrial uses since bromine is known to communicate flame-retarding properties to chemical compositions. This derivative presents the following characteristics (Wisniak, 1987): autogenous ignition point 34O’C; flash

54

J. Wisniak I Industrial Crops and Products 3 (1994) 43-68

point 230°C; pour point 2°C; electric strength >30 kV; specific heat (25°C) 0.404 Cal/g “C; viscosity (195°C) 1.42 CP The compound can be heated repeatedly and held for days at 230°C without any change in its physical appearance and composition. Boiling will start above 23O”C, HBr is liberated and heavy smoking begins above 305°C. From the above picture it would seem that tetrabromojojoba could find use as a heating fluid, as an oil for electrical apparatus, as a flame-retarding additive for plastics, and perhaps as a carrier for pest control chemicals containing halogen. 8.5. Sulfurization and sulfur halogenation Sperm oil has many uses. It is widely used for many types of lubrication as refined, for the oiliness and metal wetting properties that it imparts, as well as for its non-drying characteristic that prevents gumming and tacking in end-use formulations. It is more important as a chemical intermediate since it is sulfonated, oxidized, sulfurized, sulfur-chlorinated and chlorinated to give industrial products that have uses primarily as wetting agents and extreme pressure (EP) additives. Conventional EP additives based on sperm oil include sulfurized sperm oils containing 10, 12 and 18% sulfur, sulfur-chlorinated products with 6% and 8% each of sulfur and chlorine, and a chlorinated sperm oil having 12% chlorine. The total annual volume of all sperm-oil-based extreme pressure additives that were produced in the U.S. is not known but the annual production of sulfurized sperm oil was reported as 23 million pounds in 1966 (Thompson, 1972). The solubility characteristics of sulfurized sperm oils are better than with other sulfurized fats. Also, they are more polar and thus have better metal wetting properties that give reduced wear rates in gear oils and greases. Sulfurized sperm oil was used in many lubricants because it had a combination of properties not matched by other available additives: solubility in high-viscosity paraffinic oils, low tendency to form sludge on oxidation, good antiwear, friction, and extreme pressure properties, as well as compatibility with other additives such as lead naphthenate. It was also available in large quantities and at

low cost, a fact that eliminated significant research over the years on synthetic replacements (Peeler and Hartman, 1972). The ban on the use of sperm oil prompted an intensive search for substitutes. Many synthetic compositions have already appeared in the market that match or surpass sperm oil in some laboratory tests, but not all in one product or from the same source. Three patents issued to Smith (1939a, b, c) describe one of the most important discoveries in the history of lubricant additives. Smith found that sulfurized sperm whale oil (SSWO) was more soluble in paraffinic oils and much more stable than the sulfurized lard oil (SLO) previously used as an EP agent for gear lubrication, and that the improved stability of SSWO resulted from its monoester structure compared with triester structure of SLO. The results of Smith were promptly applied to jojoba oil by Ellis (1936), Flaxman (1940) and Wells (1948). Ellis’ work was intended primarily to the manufacture of a factice that was readily soluble in various aromatic and aliphatic solvents and could be incorporated in rubber, linoleum, paints and varnishes, plastics, and the like. Whitner (1940) suggested using the factice as a modifier for quick-drying printing inks because it gave place to non-tacky, nonsmudging, flexible ink films. Flaxman (1940) and Wells (1948) reported the sulfurization of jojoba oil for use as lubricants and extreme pressure additives. Kuss et al. (1983) measured the influence of pressure and temperature on the viscosity and density of refined and sulfurized jojoba oil, and a number of monoester oils intended as substitutes. Wisniak and Benajahu (1975, 1976a, b, 1978a, b, 1979) studied the kinetics and parameter effect on the sulfur halogenation of jojoba oil with sulfur monochloride and sulfur monobromide (&X2). Cryoscopic measurements showed that for S contents between 0 and 6.6% the average molecular weight of the sulfur-brominated oil varied between 600 and 2850, indicating that the average molecule was produced by the polymerization of 3-4 molecules of jojoba oil. Their results indicated that there is a clear relation between the rate of disappearance of the double bonds and the polarity of the solvent; larger dielectric constants produced faster rates of reaction.

55

.I. WisniakIIndusttialCrops and Products3 (1994) 43-68 Table 6 Repetitive extractions with sulfurized jojoba oil (Wisniak et al., 1990) Stage

eem Hg(ff) a

Extraction efficiency b

Distribution coefficient

1 2 3 4 5

146.4 19.6 2.0 0.090 0.005

86.6 98.2 99.8 99.99 99.999

6.4 54.6 555 12499 100000

a After extraction; b % of original Hg(II)

s a s Cn ,400 4

I i

I

ii + .200! 0

Wisniak et al. (1990) tested sulfurized jojoba oil containing 12 wt% sulfur as an extractant for Hg(I1) from aqueous solutions. The experiments were performed with the extractant dissolved in a solvent (liquid-liquid mode) or adsorbed in Amberlites XAD-4 and XAD-8 resin matrix (solidliquid mode). In all cases, polar chlorinated solvents gave the best results. Both modes of operation showed that sulfurized jojoba oil had very good potential as an extractant; liquid-liquid extraction easily reduced the level of Hg(I1) ions below the level required for liquid wastes (5 ppb) (Table 6). Wisniak et al. estimated that there are about 2 mol of S active sites per kg of resin. 9. Lubricating halogenated

properties derivatives

of sulfur and sulfur-

9.1. Suljiuized oil Sulfurized products based on hog fat and its derivatives have extensive commercial use as additives for metal working and industrial oil. Kammann and Phillips (1985) have shown that sulfurized jojoba oil has the best solubility of the vegetable products in paraffinic base oils. Gisser et al. (1975) have compared the mechanical properties of the jojoba oil and sperm oil sulfurized with sulfur by standard procedures. The diluted oils were evaluated on the Four-Ball EP and Falex Testers, and Four-Ball Wear Testers ‘. Results of 1 The corresponding apparatus consists of three metal balls, fixed on a table, and a rotating shaft carrying a fourth ball; load is applied on the shaft until motion is stopped by friction. Friction of the rotating ball on the fixed balls produces wear

NAPHTHENIC

o-

Jojobo

0 ---

Sperm

I __

i!u

I .^ 4”

OIL

oil+ oil

lO%S + lO%S

, _^ 0”

I ^^ (1”

i do .I

PERCENT SULFURIZED OIL Fig. 9. Comparison between sulfurized sperm oil and sulfurized jojoba oil Four-ball scar diameter (Gisser, 1975).

the experimental work showed that sulfurized jojoba and sulfurized sperm oils were essentially equivalent in improving the load-carrying capacity under extreme pressure conditions of both naphthenic and bright stock base oils (Fig. 9). Both undiluted sulfurized oils exhibited approximately equivalent EP properties. Small amounts of sulfurized jojoba and sulfurized sperm oil were also equally effective anti-wear additives to the naphthenic and bright stock oils. Additional testing on shop drilling and tapping operations led Gisser et al. (1975) to conclude that sulfurized jojoba oil will perform as well as sulfurized sperm oil in practical operations. The results of Giesser et al. have been confirmed and extended by Bhatia et al. (1988) who concluded that in order to develop jojoba oil-based EP additives it is necessary to cause a certain amount of cross-linking and polymerization of the sulfurized oil. The most exhaustive testing of sulfurized jojoba oil as EP additives have been conducted at Southwest Research Institute in San Antonio, Texas (Miwa and Rothfus, 1978). The purposes of the study were to measure the basic characteristics of the additive as well as simulated in-use performance tests. Results of all these tests showed unequivocally that sulfurized jojoba oil outperforms or performs as well as sulfurized sperm whale oil. in the form of a circular scar. The load and scar diameter will depend on the properties of the lubricant used.

56

J. Wisniak/ IndustrialCrops and Products3 (1994) 43-68

9.2. Sulfur-halogenated

oil

Organosulfur compounds and sulfur-halogenated compounds have been used as additives in lubricants for many years. Wisniak and Benajahu (1978a) reported on the lubricating properties of sulfur-chlorinated and sulfur-brominated jojoba oil, as well as a comparison with similar products based on either sperm whale oil or other vegetable oils. Four-Ball Scar diameter measurements for additive diluted in the base oil to give %S up to 2.5% appear in Fig. 10. It is seen that both derivatives are good antiwear agents but the SzCl2 is superior to S2Br2. The sulfur-brominated derivative functions better at very low concentrations (about 0.1%). In Fig. 11 the sulfur-halogenated compounds are compared with some standard products such as sulfurized lard oil (SLO), sulfurized sperm whale oil (SSWO), and sulfurized jojoba oil (SJ). It is seen again that for this property SzC12 is better, except perhaps at very low concen-

m 10 %S 0

0.4

0.3

7.1 % Cl

q

J.J%S

6.4% S 14 % Br

0

5.5% s

l

0.9 -

0.3 ’ 0

’ a2

LARD OIL (SLO)

lO%S

SPERM WHALE OIL

0 lO%S m 7.7% S-86%CI

JOJOBA (SJ) JOJOBA (SCJ)

A

JOJOBA (SBJ)

6.4% s- 17% B

’

I 1

I

I 2

I

SSWO

1 3

DILUTION WT. PERCENT SULFUR Fig. 11. Scar diameter, comparison of different oils (Wisniak and Benajahu, 1978a).

trations. Both sulfur-halogenated derivatives are good replacements of SSWO. Load-carrying capacity (Falex tester) measurements indicated that both sulfur-halogenated derivatives have excellent properties for EP lubrication. When added to either naphthenic or bright stock oil bases, the sulfur-chlorinated derivative is a better load carrier than the sulfur-brominated one; it reaches the maximum load at very low concentrations. On the other hand, the sulfur-brominated additive has a substantially higher weld point. Fig. 12 shows a comparison with SLO, SSWD and SJ and brings out the synergistic combination of S and halogen for lubricating purposes. Fig. 13 reports the extreme pressure capacity of the different derivatives (Four-Ball weld point) and shows that the sulfur-brominated oil allows loads that exceed the measuring capacity of the apparatus.

6.5% s 8.61% Cl

,j

0 5 %S

17 96 Br

SCAR DIAMETER OF BLANK: 0.800MM

1

I

I

I

D2

1

2

3

DILUTION WT. PERCENT SULFUR Fig. 10. Four-Ball scar diameter, sulfur-halogenated jojoba oil (Wisniak and Benajahu, 1978a). Dilution wt. percent sulfur expresses the sulfur concentration in the solution of additive and base oil.

9.3. Phosphonation

Dialkyl alkylphosphonates are a group of stable organic phosphorus esters that have been recommended for use as plasticizers, synthetic lubricants, additives to improve the extreme pressure

J. Wuniak / Industrial Crops and Products 3 (1994) 43-68

5000

I_

::--)/ q

5001

’

0

’

’

71%

S Z49%CI

JOJOBA

I

I

I

’ 1

OILtSCJ)

I

2

I

3

DILUTION WT. PERCENT

SULFUR

Fig. 12. Load test, comparison of different oils (Wisniak and Benajahu, 1978a).

800

c

700

600 z ii -

500

B

400

O

I-

WELD

POINT

6> r

OF

BLANK

I

: 170 kg

A

5

300

L

A

200

I J

A

10

00

5.5 6.4 % %S S 14 17

%Br %Br

n

6.4%

%CI

A

7.1 %s

z49%Ci

0

5.6 %S

148%Br

s

S 6.6

100

i DILUTION

WT. PERCENT SULFUR

Fig. 13. Weld point, sulfur-halogenated and Benajahu, 1978a).

jojoba oil (Wisniak

properties of lubricants, functional fluids, oil or fuel additives, deicers and pour-point depressants, pesticides, synergists or carriers for pesticides and fertilizers, intermediates for the synthesis of cor-

57

rosion inhibitors, and metal extractants. Several dialkyl alkylphosphonates have been found to be useful as flame retardants, softeners, textile treating agents, and heat transfer media. Extreme pressure and antiwear additives are used in lubricants industrially to prevent galling, scoring and seizure, and to reduce or minimize wear. Compounds containing elements such as sulfur, chlorine or phosphorus have been used as antiwear and extreme pressure agents for many years. Wisniak (1978, 1982) has reported preliminary experimental data on the phosphonation of jojoba oil with different dialkylphosphites. The average ester chain in jojoba oil contains two double bonds so that the product may contain up to two atoms of phosphorus per chain. Main purpose of the work was to determine the kinetics of the reaction, the influence of operating variables, and to evaluate the lubrication properties of the derivatives. Jojoba dibutyl phosphonate was tested as a lubricant additive; with a bright stock base oil the additive effect was similar to that of tricresyl phosphate, and with a parafhn stock base oil the jojoba derivative gave a better performance than tricresyl phosphate. The dialkylphosphonates have been shown to be suitable as extraction agents and to exhibit superior properties as extraction agents for separating actinide metal ions (Wisniak, 1986, 1987). Extensive studies on the extraction of hexavalent uranium U(V1) from highly acidic solutions like those present in the phosphoric acid industry were conducted, as was the separation of U(V1) from thorium(IV) and plutonium(IV). It was found that at maximum concentration for thorium extraction there is a difference of approximately 500 in the extraction constants for thorium and uranium. Thus the jojoba phosphonates provide an excellent medium for separating thorium(IV) from uranium(V1). Standard techniques of solvent extraction were followed using trace level concentrations 233U (as UOi+), 230Th (as Th4+), 241Am (as Am3+), and 23gPu (as Pu4+). The extraction of Th4+ and Pu4+ was so great under these conditions that it was not possible to define a dependency on the oil concentration. Table 7 compares the extraction coefficients for jojoba diphosphonates with those of the solvent used in the standard Purex process used in the

58

J. WisniaklIndustrialCrops and Products3 (1994) 43-68

Talbe 7 Values of extraction coefficients for 4.0 M nitric acid/10e3 or 19% TBP (Wisniak, 1986, 1987) Cation

Ants+ uo;+ Th4f PU4+

Distribution coefficient Jojoba

TBP

4 x 10-S 2.2 250 900

0.2 30 1.9 12

Table 8 Separation factors for jojoba diphosphonates tion (Wisniak, 1986, 1987) Cation

Pu4+/uo; Pu4+/Am3+ UOF/Am3+

and TBP extrac-

Separation factor Jojoba

TBP

400 2.3x 10-S 550

0.4 60 150

nuclear industry (a solution of 4 molar nitric acid containing 19% of tributyl phosphate, TBP) while Table 8 compares the separation factors that can be achieved under the same conditions. Both tables show clearly the advantages of using jojoba oil phosphonates. Wisniak and Benajahu (unpublished results) have reacted jojoba oil with PzSs in order to produce a derivative suitable as a lubricant additive. Analysis of the amounts of sulfur and phosphor present in the product showed that their ratio was the same as in the P2S5 reagent indicating that one full molecule was added for each mole of oil. Typical Four-Ball results in a paraffinic base oil are as follows: The jojoba PzS5 derivative seems to have promising applications if one considers that for a good EP additive the minimum incipient seizure should be 60 kg, the minimum weld point 200 kg and the wear index as high as possible. 10. Oxidation and ozonolysis

It has already been mentioned that jojoba oil shows good thermal stability up to relatively high temperatures. Libby (1981) has shown that

cosmetic formulations containing jojoba oil have superior oxidation stability than those based on other lipids used for this purpose. Kampf (1979) has conducted an in-depth study of the accelerated oxidation of crude jojoba oil, as well as bleached and stripped oils. In spite of its high initial peroxide value (17 meq/kg) the crude wax has a long induction period of 45-50 h as compared to the bleached and stripped waxes that have short induction periods of 12 and 2 h, respectively, in spite of their initial zero peroxide values. Experiments were also conducted to test the possibility of protecting the oil with antioxidants BHT and BHA (butylated hydroxyanisole). Both antioxidants were found to be highly compatible with wax. The experimental results indicate that BHT and BHA are effective antioxidants that prolong the induction period of bleached jojoba oil to 50 and 80 h, respectively. BHT has an activity comparable to the natural antioxidant, whereas BHA seems to be superior under the conditions mentioned. Zabicky (1985) and ZabicQ and Mhasalkar (1986) have studied the ozonolysis of jojoba oil using ozone as a reagent, to attain intermediates for synthesis. De Villez and Brown (1984) claim that acne can be treated by application of compositions containing ozonized jojoba oil. The ozonized material has the ability to penetrate the comedone and deliver nascent oxygen directly to the acne microorganism. 11. Epoxidation

Epoxides of unsaturated glycerides and of simply fatty acid esters are currently being employed as plasticizers and stabilizers for vinyl chloride containing plastics. Since jojoba oil contains monounsaturation in both its acid and alcohol moieties, epoxidation of the oil would result in the formation of a unique product. Fore et al. (1958) have reported on this possibility and evaluated the epoxide as a light and heat stabilizer in PVC polymers. The epoxidized oil was found to contain 4.1% oxirane oxygen (theoretical 5.0%). Preliminary results showed that the epoxides of jojoba oil cannot be used as primary plasticizers because of their poor compatibility characteristics with vinyl copolymer. The experimental results

.I. Wisniakllndustrial

Crops and Products 3 (1994) 43-68

obtained showed that epoxidized jojoba oil was a satisfactory thermal and ultraviolet stabilizer for both TCP and DOP plasticized stocks and had no adverse effects on the plasticizer properties of these materials. In general, epoxidized jojoba oil was found to be equivalent to or superior to the other epoxides tested for this purpose. 12. Ester reduction Molaison et al. (1959) have applied the sodium reduction method to jojoba oil and showed that it yields a quantitative mixture of unsaturated longchain alcohols. 13. Ammonolysis and quaternary salts

ammonium

Primary fatty amides are a unique group of solid compounds of high surface activity. They have high melting points, great stability, and extremely low solubility in all common solvents. They are used primarily as additives for lowdensity polyethylene and propylene to whom they impart improved slip and antiblock properties. Small quantities often give striking improvements in the properties of the polymers. The special alcohol composition of jojoba oil may be of interest to manufacture amides not available before. Shani et al. (1980) have reported the synthesis of jojobamide and homojojobamide by transesterification of jojoba oil to its methyl esters and alcohols, and amidation with aqueous ammonium hydroxide. Shani and Horowitz (1980) have synthetized a large number of quaternary ammonium salts based on jojoba oil. These salts may have potential as germicides, surfactants, emulsifiers, and phase transfer reagents. Madgassi and Shani (1990) used jojoba oil as the starting point in the synthesis of various quaternary ammonium and pyridinium salts that were tested as surface active agents. In general, it was found that all cationic derivatives had surface activity and reduced the surface tension to about 35 dyne cm-‘. The critical micelle concentration (CMC) of the various derivatives decreased with an increase in the total number of carbon atoms in the molecule. In comparison with other cationic surfactants, the CMC values of the

59

compounds prepared were extremely low due to the very long hydrophobic jojobyl chain. The effect of the configuration (cis or truns) on the surface activity was also evaluated. The results indicated that the truns cationic surfactants generally had larger CMC values and a larger area per molecule than the cis derivatives. According to Madgassi and Shani, the cis isomer is more hydrophobic than the truns isomer. 14. Miscellaneous For& et al. (1960) prepared a number of maleinized derivatives of jojoba oil and tested their applicability to the plasticizer field. Marvel et al. (1960), Paisley (1961) and Gonzdlez (1980) investigated the possibility of converting the acrylate and methacrylate esters of the alcohols from jojoba oil into a high molecular weight homopolymer of copolymer. While most of these polymers and copolymers seemed to have adhesive properties and did readily cross-link on air-drying, not one of them has yet been developed into a useful adhesive. Shani (1979) has synthesized muscalure, a component of the pheromone of the housefly, using a form-step process based on jojoba oil. The method suggested by Wayo (1967) has been used by Wisniak (unpublished results) to produce diphenyljojoba and dinaphthyljojoba by reacting one mole of jojoba oil with two moles of benzene or one mole of naphthalene at temperatures between 75 and 100°C and using 1.3 moles of AK& as catalyst. Diphenyljojoba is a very dark non-viscous liquid while mononaphthyljojoba is a dark semi-solid material. Wells (1954) has reported data on the sulfation of jojoba oil with concentrated sulfuric acid at o”C, and compared its rate of hydrolysis with that of similar derivatives based on castor, cottonseed, rapeseed and sperm oils. Sperm oil has been an important raw material in the leather industry as the fat liquors based on it allow production of medium, light soft, non-greasy leathers with waxy feel and special surface effects such as sheen on suede leathers and gloss on full grain leathers. Vijayalakshmi et al. (1984) prepared different sulfited and sulfated jojoba oils and tested them in the fatliquoring of chrome leather. The leathers treated with jojoba

60

.I. WisniakI IndustrialCrops and Products3 (1994) 43-68

oil based fatliquors were much softer than the leathers fatliquored with commercial sulfited vegetable oils. In addition to the softness, the grain was more smooth with slippery and silky feel. The experimental leathers were whiter without any rancid odor. 15. Jojoba meal A byproduct of jojoba seeds is the meal remaining after the oil has been pressed and extracted. This material constitutes about 50% of the seed and plans for commercial processing must take into account the handling of large amounts of meal and its potential uses. The meal contains 25-30% crude protein, is high in dietary fiber and could serve as an animal feed supplement. Much effort has been devoted lately to the possibility of using jojoba meal as an ingredient in feeds for domestic animals.

Table 10 Amino acid composition (%) of deoiled meal of two varieties of jojoba meal (Verbiscar and Banigan, 1978a) Amino acid

Apache 377

SCJP 977

Lysine Histidine Arginine Aspartic acid Threonine Serine Glutamic acid Proline Glycine Alanine Valine Methionine Isoleucine Leucine Tyrosine Phenylalanine Cystine+cysteine Tkyptophan

1.05 0.486 1.56 2.18 1.14 1.04 2.40 0.958 1.50 0.832 1.10 0.186 0.777 1.46 1.04 0.919 0.791 0.492

1.11 0.493 1.81 3.11 1.22 1.11 2.79 1.10 1.41 0.953 1.19 0.210 0.866 1.57 1.05 1.07 0.519 0.559

15.1. Composition

Tables 9-11 present some basic information on the composition of the meal, as well as its amino acid and carbohydrate contents. Protein represents the most important nutrient in jojoba meal with respect to its potential as a livestock feed. Jojoba meal contains between 28% and 30% protein (Table 9), somewhat less than major feeds like soybean and cottonseed meals (40-50% protein). Analysis of the amino acid composition (Table 10)

shows an imbalance in the thioaminoacids: the cystine content is high while that of methionine is below the accepted dose. About 50% of the sugars are in the form of pentoses (Table 11) which are unsuitable for monogastric animals like chicken. 15.2. Simmondsin and its derivatives Booth (1972) found that rats died within two weeks when offered a meal containing either

Table 9 Percent composition of jojoba materials (Cotgageorge et al., 1978; Verbiscar and Banigan, 1978a; Verbiscar et al., 1978; Watanabe et al., 1978) Component

Moisture Crude protein (N x 6.25) Crude oil (ether extract) Crude fiber Ash N.P.E. Total sugars Polysaccharides a Two different samples.

Type of jojoba material Whole seed a

Dehulled whole seed

Hulls

Dehulled meal (10% hulls)

Partially dehulled meal (17% hulls)

Undehulled meal

0.8 15.1 50.2 4.2 1.6 28.1 29.3 20.3

4.3 14.9 53.8 3.5 1.4 22.1 3.7 17.4

10.7 7.0 0.7 15.6 4.4 61.6 3.3

8.9 28.9 3.0 8.1 3.1 47.8 8.7

5.8 24.1 1.6 11.0 4.9 52.6

5.7 20.1 0.9 14.3 3.6 55.4 -

4.4 13.7 49.9 1.4 16.6 -

61

J. Wisniak I Industrial Crops and Products 3 (1994) 43-68

Table 11 Sugars in jojoba carbohydrates (Watanabe et al., 1978) Sugar

Glucose Galactose Mannose Xylose Arabinose Unidentified Other

CHCN

after complete acid hydrolysis

8-GLUC

OH

OH

0CH3

OCH3

OCH3

Jojoba material Defatted seed

Hulls

22.3 15.4 1.9 10.9 38.2 8.2 3.1

9.3 24.6 1.6 15.3 38.4 3.6 1.2

22% of the whole bean or 30% of the meal. The probable cause of death was starvation, since very little of the diet was consumed. Rats also died when fed a diet containing 15% jojoba meal. No deaths occurred at dietary levels of 10% meal or lower, but growth was clearly inhibited. Histopathologic examination revealed severe testicular atrophy with cessation of spermatogenesis, large cytoplasmic vacuoles in the acinar cells of the pancreas, and fatty infiltration of the liver. From these results, Booth concluded that toxic constituents were present in jojoba meal. Elliger et al. (1973, 1974b, c) isolated and determined the structure of the toxic material that they called simmondsin. Simmondsin was found to inhibit feeding, although its acute toxicity was extremely low (LDsa >4 g/kg). Its structure was determined to be 2-(cyanomethylene)-3hydroxy-4,5dimethoxycyclohexyl #I-D-glucoside, with an empirical formula CieH2sNOs. Verbiscar and Banigan (1982) found that at least three other minor toxicants are present (simmondsin 2’-ferulate, 5desmethylsimmondsin and 4,5didesmethylsimmondsin), as well as pinitol, ogalactosylpinitol, sucrose, galactose, and unidentified alkaloids (Fig. 14). Verbiscar and Banigan (1982) found also that simmondsin could not be hydrolyzed by commercial glycosidic enzymes but that jojoba seeds contain enzymes that do split simmondsin and related compounds. These enzymes are deactivated by heat. Verbiscar and Banigan (1978a, b) determined also the composition of jojoba seeds and hulls, as well as the presence of simmondsin in different parts of the plant. The

1 SI~~~I~NOSIN

lClS

AND

TRANS

SIMMONDSIN

CH$N

CHCN B-GLUC

Z’-FERULATE

0

6-GLUC

OH OCH3

0

OH OH

0 OH

OH P5-DESMETHYL

SIMMONDSIN

OH

&74,5-MDESMETHYL

SIMMONDSIN

OH

0 HO

h

OH HO CH30

OH

0

w OH OH

A P

GALACTOSYL

PINITOL

2-Oa-O-GALACTOPYRANOSYL-4-0-METHYL-D-CHIRO-lNOSlTOL

Fig. 14. Structure of the main components of simmondsin.

high level of toxicants in the leaves, twigs, and seeds may explain why jojoba is unsuitable as a grazing material. 15.3. Simmondsin toxicity Several studies have been made to determine the toxicity of the components of jojoba meal and their possible use as biological agents. Verbiscar and Banigan (1982) found that oral administration of simmondsin to starved rats had no adverse effects, but chronic oral doses induced weight loss. Pathological examination showed no particular damage in the males but anovulatory ovaries were observed in the female rats. These effects contrast with those reported by Booth et al. (1974) for male rats fed whole jojoba meal, indicating that the physiological damage is due to factors present in the whole jojoba meal other than simmondsinbased toxicants. When simmondsin was administered by routes other than oral, toxic symptoms were generally absent, indicating that the compound itself is relatively non-toxic to mammals,

62

J. WuniakIIndustrialCrops and Products3 (1994) 43-68

and that a toxic metabolite might be generated in the gut prior to absorption. Williams (1980) reported that mice dosed with purified simmondsin showed elevated blood concentrations of cyanide and thiocyanate, the former apparently resulting from release of cyanide during metabolism of simmondsin. 15.4. Animal feeding Many publications have reported on the use of jojoba meal (as such or detoxified) for animal feed (Wells, 1955; Booth, 1972; Booth et al., 1974; Weber and Reid, 1975; Cook, 1977; Verbiscar and Banigan, 1977, 1978a, b, 1982; Verbiscar et al., 1978; Cotgageorge et al., 1978; Williams, 1980; Lisk and Brown, 1984). Only four of these studies dealt with the toxicity of purified simmondsin (Booth et al., 1974; Cook, 1977; Williams, 1980; Verbiscar and Banigan, 1982). Feeding studies with diets supplemented with jojoba meal have been conducted with broiler chicks (Ngoupayou, 1985), rabbits (Ngoupayou et al., 1985), and lambs (Verbiscar et al., 1980, 1981; Manos et al. 1986). They have addressed ration palatability, feed efficiency, growth, and toxicology. Practically, it has been found that the meal cannot be fed directly to animals because of the antinutritional factors (ANF) it contains. In monogastric animals the ANF apparently cause death by cyanide poisoning. Ruminants are more tolerant of the ANF but do not use the protein efficiently or gain weight well (Manos et al., 1986). 15.5. Detoxification Detoxification of jojoba meal has been attained by physical, chemical, biological, and microbiological methods. The problem in itself is not a new one, since seed meals from colza, carthamus, crambe, and other cruciferae (VanElten and Wolff, 1973; Baker et al., 1977) contain glucosinolates, cyanogenic glucosides, and thioglucosides, which do not allow their direct alimentary use. Elliger et al. (1974a) established that the toxicity of jojoba meal could be reduced by exposing the meal to NH3 for 5-30 days, and that the resultant product was a valuable feed for ruminants and other ani-

mals. A patent to Sodini et al. (1979) describes a method for extracting toxic glucosidic compounds (such as simmondsin) under conditions that do not cause degradation of proteins. The method uses one or more organic solvents in a mixture that contains at least one polar group; such a solvent or solvent mixture must contain, in addition, an aqueous solution of an acidic electrolyte. Cotgageorge et al. (1978) investigated the detoxification of jojoba meal by germination, enzymatic hydrolysis, and solvent extraction. The choice of these techniques was based on the theoretical properties of jojoba and the thought that simmondsin may be an allelophathic agent, that is, a compound secreted in order to prevent the germination of the seeds of competitive plants. Their most successful treatment in terms of both disappearance of simmondsin and the acceptability of the product to mice was extraction with water. The first comprehensive study on the detoxification of jojoba meal and its use as an animal feed was conducted by Verbiscar et al. (1978, 1980, 1981). Removal of the toxicants with water was deemed impractical unless the water-soluble proteins were first denatured by brief boiling or by acidification to pH 3-4 with acids. Heat-treated meals lost their bitter taste but retained their toxicity, in spite of a decrease in simmondsin level. Apparently, heat decomposes simmondsin and related compounds, but does not destroy the toxic cyano group. The meal was treated chemically with ammonia or by spraying mixtures of hydrogen peroxide and ammonium hydroxide over the meal. Banigan and Verbiscar (1980) claim that their method is successful for other foodstuff like peaches, bitter almonds, cassava, sorghum, lima beans, etc., all known to contain cyanogenic glycosides. A different approach to detoxification has been microbial treatment. Verbiscar et al. (1981) screened fifteen strains of microorganisms for their ability to grow on jojoba meal and modify the toxicants. These included Saccharomyces cerevisiae and several strains of Lactobacillus acidophillus bulgaricus. The advantages of using lactic acid bacteria are that these microorganisms are notably nontoxic themselves and can be the basis for an ensilage process. The microorganisms substantially reduced the toxicant levels by 95-98%, partic-

J. Wisniak I Industrial Crops and Products 3 (1994) 43-68

ularly in the presence of ammonium hydroxide. Meals treated with Lactobacilli and ammonium hydroxide showed a significant increase in protein, from 25.5% to above 30% on a dry basis. According to Abbott et al. (1991) deoiled jojoba meal can be converted to animal feed by extraction with water, by ensilage with endogenous enzymes, or by fermentation with microorganisms that degrade ANE The method of choice depends on the economics of each process, the stability of the endogenous enzymes, and the solubility of the proteins after the deoiling process. They point out that because the jojoba industry uses 45-min steam desolventizing after the oil is extracted, the enzymatic process cannot be used on that type of meal. Also, water-extraction of the meal yields an undesirable byproduct-contaminated water stream. Thus, the choice of fermentation for currently produced defatted meal seems inevitable. Abbott et al. recommended that a non-toxigenic Fz~~arium or other organism that degrades monofilifome ANF in the meal should be used; the meal should be tested for the absence of toxins and retention of nutritional value. On the other hand, Lanzani et al. (1991) claim that simultaneous extraction of the oil and detoxification of the meal can be achieved in a one-stage process where the seeds are broken, homogenized with water at a suitable pH and temperature, followed by centrifugation. Oil is obtained with a yield of 70-75% and requires no additional refining, the meal is detoxified and its protein content remains unchanged. According to Medina and Trejo (1990), washing jojoba meal with 70% isopropanol removes 86% of the total phenolic compounds and 99% of all the simmondsins. They claimed that simmondsin 2’-ferulate is the major bitter principle and that the detoxified meal had improved palatability and caused no deaths of experimental rats. Ngoupayou (1985) suggested that condensed tannins or tannic acid could be the main ANF of jojoba meal because of the general unavailability of the amino acids even after trypsin inhibitor inactivation. Sanchez Lucero and Price (1988) have shown that trypsin and chymotrypsin are completely inactivated by jojoba tannins at 5.8 pg/ml tannins and 36.44 &ml tannins, respectively. Due to the activation of chymotrypsin by trypsin in the

63

digestive tract, a small concentration of tannins in jojoba seeds may reduce the amount of active chymotrypsin and the activity of both enzymes. 15.6. Jojoba proteins

Cardoso and Price (1980) studied the properties of defatted jojoba meal to develop a suitable fractionation procedure and to determine properties of the proteins. The separation methods yielded albumin, globulin, prolamine, and glutelin fractions. Seed coat removal did no affect the amount of protein recovered. Amino acid analysis indicated that the amount of cysteine in albumins and glutelins was lower than that in the globulin and prolamine fractions. Methionine was the limiting amino acid, as also reported by others (Verbiscar and Banigan, 1978a). Comparison between whole egg protein and jojoba meal albumin indicated that the latter had lower levels of lysine, leucine, methionine, phenylalanine, and isoleucine. The prolamines from jojoba meal were lower in methionine and isoleucine. Minimum solubility of all four protein concentrates occurred in the pH range 3.0-4.0. The nitrogen solubility of the protein concentrates varied between 76 and 98%, which is higher than that reported for soy and alfalfa protein concentrates. The emulsifying activity and stability of the jojoba albumin and globulin fractions were in the same range as in alfalfa leaf proteins, soybean isolates, and oat isolates. On the basis of these measurements Cardoso and Price (1980) concluded that only the albumin and globulin fractions appear to have applications in the food and feed industries. These two fractions behaved similarly to or better than the proteins systems that are already used by the food industry, such as soybean, sunflower and oat protein concentrates. Particularly suitable applications seem to be in the production of drinks or structured products such as cheese, meat, and sausages homologues and in bakery goods like whipped toppings, desserts, and cakes. Shah and Stegemann (1983) and Shah (1984) have studied the protein components of jojoba beans and characterized their molecular weights and isoelectric points by gel chromatography. About 80% of the total protein was found to be water-soluble

64

J. WisniakI IndustrialCrops and Products3 (1994) 43-68

(compared with the 65% reported by Cardoso and Price, 1980). Wiseman (1983) improved the commercial means of protein extraction by washing the protein concentrate with methanol, acetone and acidic methanol, to remove sugars, polyphenolic components and simmondsin. Concentrates with 85% protein, less than 0.3% polyphenolic compounds and less than 1% simmondsin resulted and these were tested for their functional properties. The results indicated that all but the globulin ones had good gelation properties. It was also concluded that jojoba meal concentrates could be used in whipped food products. 15.7. Proteolytic and trypsin inhibitors Samac et al. (1980) and Samac and Storey (1981) studied the changes in proteolytic activity (amino peptidase, carbovpeptidase, and endopeptidase) that occur during germination, in extracts from jojoba cotyledons and from buffered extracts of jojoba meals and found that a seed cotyledon extract inhibits the activity of trypsin, chymotrypsin and pepsin, but not that of a protease from Aspergillus saotoi. According to Samac et al., the presence of inhibitors of bovine protease in jojoba meal may have practical implications for its use as an animal feed. References Abbott, TP., Nakamura, L.K., Buchholz, G., Wolf, W.J., Palmer, D.M., Gasdorf, H.J., Nelson, TC. and Kleiman, R., 1991. Process for making animal feed and protein isolates from jojoba meal. J. Agric. Food Chem., 39: 1488-1493. Aracil, J., Martinez, M., Sanchez, N. and Corma, A., 1992. Formation of a jojoba analog by esterification of oleic acid using zeolites as catalyst. Zeolites, 12: 233-236. Baker, EC., Mustakas, G.C. and Sohns, V.E., 1977. Crambe processing: glucosinolate removal by water washing on a continuous filter. J. Am. Oil Chem. Sot., 54: 387-391. Banigan, TF. and Verbiscar, A.J., 1980. Detoxification of Botanical Foodstuffs. U.S. Patent 4,209,539. Banigan, TE and Verbiscar, A.J., 1981. Jojoba Happenings, 35: 2. Barlas, J., Crook, S., Leslie, M.G., Paton, R.M. and Webb, N., 1989. Cycloaddition of nitrile oxides to jojoba oil. Chem. Ind. (London), 534-535. Bhatia, VK., Chaudhry, A., Masohan, A., Bisht, R.P.S. and Sivasankaran, G.A., 1988. Sulfurization of jojoba oil for application as extreme pressure additive. J. Am. Oil

Chem. Sot., 65: 1502-1507. Bhatia, V.K., Chaudhry, A., Sivasankaran, G.A., Bisht, R.P.S. and Kashyap, M., 1990. Modification of jojoba oil for lubricant formulation. J. Am. Oil Chem. Sot., 67: l-7. Booth, A.N., 1972. Jojoba oil and meal: subacute toxicity study with rats. In: E.F. Haase and W.G. McGinnes (Editors), Proceedings of the First International Conference on Jojoba and Its Uses, University of Arizona, Tucson, A&., pp. 73-74. Booth, A.N., Elliger, C.A. and Waiss, AC., 1974. Isolation of a toxic factor from jojoba meal. Life Sci., 15: 1115-1120. Bracco, U., 1982. Hypo Caloric Food Composition. European Patent EP 067,358. Brown, J.H. and Olenberg, H., 1982a. Isomerization of Jojoba Oil and Products Thereof. U.S. Patent 4,329,298. Brown, J.H. and Olenberg, H., 1982b. Isomorphous Jojoba Oil Compositions Containing X&rs-Isomerized Jojoba Oil. U.S. Patent 4,360,387. Buisson, D.H., Body, D.R., Dougherty, G.J., Eyres, L. and Vlieg, P., 1982. Oil from deep fish species as a substitute for sperm whale and jojoba oils. J. Am. Oil Chem. Sot., 59: 390-39s. Cardoso, EA. and Price, R.L., 1980. Extraction, characterization and functional properties of jojoba proteins. In: M. Puebla (Editor), Proceedings of the Fourth International Conference on Jojoba and Its Uses, Hermosillo, pp. 305316. Cook, E.M., 1977. Toxic Effects of Jojoba Meal Fed to Weanling Mice. M.Sc. Thesis, University of Arizona, ‘Ibcson, Ariz. Cosmetic Ingredient Review Panel, 1992. Final report on the safety assessment of jojoba oil and jojoba wax. J. Am. Coll. Toxicol., 11: 57-74. Cotgageorge, A.G., Weber, C.W., Reid, B.L. and Price, R.L., 1978. Detoxification of jojoba seed meal. In: D.M. Yermanos (Editor), Proceedings of the Third International Conference on Jojoba and Its Uses, Riverside, Calif., pp. 171-184. Daugherty, PM., Sineath, H.H. and Wastler, TA., 1953. Industrial raw materials of plant origin, IV A survey of Sitnmondsia chinensis. Bull. Eng. Exp. Sta., Georgia Inst. Technol., 15(13). Decombaz, J., Heise, C. and Anantharaman, K., 1985. Nutritional investigations on jojoba oil. In: J. Wisniak and J. Zabicky (Editors), Proceedings of the Sixth International Conference on Jojoba and Its Uses, Beer-Sheva, 1984, pp. 323-331. De Villez, R.L. and Brown J.H., 1984. Method of ‘Beating Acne Using Ozonized Materials. U.S. Patent 4,451,480. Devitt, M.T and Rossell, J.B., 1979. Edible Oil for Coating Foods. UK Pat. Appl., 2,0160,042. Duncan, C.C., Yermanos, D.M., Kumamoto, J. and Levesque, C.S., 1974. Rapid ethanolysis procedure for jojoba wax analysis by gas liquid chromatography. J. Am. Oil Chem. Sot., 51: 534-536. Elliger, CA., Waiss, A.C. and Lundin, R.E., 1973. Simmondsin, an unusual 2cyanomethylene glucoside from

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calijornica. J. Chem. Sot., Perkin ‘Bans., I( 19): 2209-2212. Elliger, C.A., Waiss, A.C. and Booth, A.N., 1974a. Detoxification of Jojoba Meal. U.S. Patent 3,9919,432). Elliger, C.A., Waiss, A.C. and Lundin, R.E., 1974b. Structure and stereochemistry of simmondsin. J. Org. Chem., 39: 2930-2931. Elliger, C.A., Waiss, A.C. and Lundin, R.E., 1974c. Cyanomethylenecyclohexyl glucosides from Simmondsia California. Phytochemistry, 13: 2319-2320. Ellis, C.A., 1936. Factis and Process of Making Same. U.S. Patent 2,054,283. Flaxman, M.T, 1940. Sulphurized Lubricating Oil. U.S. Patent 2,212,899. Fore, S.P., Magne, EC. and Bickford, W.G., 1958. Epoxidized jojoba oil as a stabilizer for vinyl chloride containing plastics. J. Am. Oil Chem. Sot., 35: 469-472. Fore, S.P., Pastor, HP, Hughes, J.P. and Bickford, W.G., 1960. Derivatives of jojoba oil as plasticizers for vinyl polymers and Buna-n rubber. J. Am. Oil Chem. Sot., 37: 387-390. Galun, A.B. and Kampf, A., 1981. Hydroxylation and direct halogenation of jojoba wax. Internal Rep. No. BGUNRDA-299-81, Div. of Chemistry, Research and Development Authority, Ben-Gurion University of the Negev, Beer-Sheva. Galun, A.B. and Shaubi, E., 1984. Thermal Isomerization of Jojoba Wax. J. Am. Oil Chem. Sot., 61: 564-569. Galun, A.B., Shaubi, E., Markus, A., Grinberg, S. and Zabicky, J., 1984. Photosensitized cis-trans isomerization of jojoba wax. J. Am. Oil Chem. Sot., 61: 102-103. Galun, A.B., Grinberg, S. Kampf, A. and Shaubi, E., 1985. Oxidation and halogenation of jojoba oil. In: J. Wisniak and .I. Zabicky (Editors), Proceedings of the Sixth International Conference on Jojoba and Its Uses, 1984, pp. 355-358. Gisser, H., Messina, J. and Chasan, D., 1975. Jojoba oil as a sperm oil substitute. Wear, 34: 53-63. Gonzalez, V., 1980. Obtencion de1 polimetacrilato de 10s alcoholes derivados de la cera de jojoba. Rev. Pl&sticos Modernos, 294 (Dec.): 721-723. Gonzalez Gonzalez, V, Valero Cross, R.D. and Campos Lopez, E., 1979. Thermal properties of jojoba wax, I. Crystallization behavior. J. Therm. Anal., 15: 315-323 Graille, J., Pina, M. and Pioch, D., 1986. Routine analysis of jojoba wax fatty acids and alcohols by single column capillary Gc. J. Am. Oil Chem. Sot., 63: 111-116. Greene, R.A. and Foster, E.D., 1933. The liquid wax of seeds of Simmondsia califomica. Bot. Gaz., 94: 826-828. Heise, C., Decombaz, J. and Anantharaman, K., 1982. Int. J. Vitam. Nutr. Res., 52: 216. Hirano, S., Tsumura, J., Imazeki, I., Amano, K., Kawamura, H. and Kawasaki, Y., 1977. Bath Preparations Containing Jojoba Oil or Hydrogenated Jojoba Oil. Japan Kokai 77 64,615. Kammann, K.P and Phillips, A.I., 1985. Sulfurized vegetable oil products as lubricant additives. J. Am. Oil Chem. Sot., 62: 917-923.

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Kampf, A., 1979. The accelerated oxidation of jojoba wax. Internal Report No. BGUN-RDA-243-79, Division of Chemistry, Research and Development Authority, Ben-Gurion University of the Negev, Beer-Sheva. Knoepfler, N.B. and Vix, H.L.E., 1959. Review of chemistry and research potential of Simmondsia chine&s (jojoba) oil. J. Agric. Food Chem., 6: 118-121. Knoepfler, N.B., McCourtney, E.J., Molaison, L.J. and Spadaro, J.J., 1958. A comparison of six solvents for the extraction of jojoba seed. J. Am. Oil Chem. Sot., 36: 644648. Kono, Y., Tomita, K., Katsura, H. and Ohta, S., 1981. Antioxidant in jojoba crude oil. In: M. Puebla (Editor), Proceedings of the Fourth International Conference on Jojoba, Hermosillo, pp. 239-256. Kubie, W.I., 1960. Cold Forming Lubricant and Method of Applying Same. U.S. Patent 2,921,874. Kuss, E.W., Vogel, W. and Deymann, H., 1983. Pressure dependence of the viscosity of various ester oils. Ttibol. Schmirungstech, 30: 283-290. Landis, P.S. and Craver, R.H., 1984. Solubility of jojoba oil in organic solvents. J. Am. Oil Chem. Sot., 61: 1879-1880. Landis, P.S., Cra-qer, R.H. and Barton, D.E., 1992. Pyrolysis studies with jojoba oil. J. Agric. Food Chem., 40: 456-457. Lanzani, A., Bondioli, P, Brillo, A., Cardillo, M., Fedeli, E., Ponzetti, A. and Pieralisi, G., 1991. A wet process technology applied to jojoba seed to obtain oil and detoxified protein meal. J. Am. Oil Chem. Sot., 68: 772-774. Libby, H., 1981. Jojoba oil - a component in cosmetic formulation technology. In: M. Puebla (Editor), Proceedings of the Fourth International Conference on Jojoba, Hermosillo, pp. 266-271. Lisk, D.J. and Brown, J.H., 1984. Utilization of defatted jojoba meal. In: J. Wisniak and J Zabicky (Editors), Proceedings of the Sixth International Conference on Jojoba, Beer-Sheva, 1984, pp. 343-353. Litchfield, C., 1966. Analysis of Fatty Acid Geometric Isomers by Gas-Liquid Chromatography. Applications to the Study of Cis-‘Bans Isomerization Reactions. Ph.D. Thesis, Texas A&M University, College Station, Texas. Litchfield, C., Isbell, A.F. and Deisen, R.J., 1963. Cis-trans isomerization of oleic, Iinoleic and linolenic acids. J. Am. Oil Chem. Sot., 40: 553-557. Litchfield, C., Harlow, R.T.D., Isbell, A.F. and Reiser, R., 1965. Cis-Trans isomerization of oleic acid by nitrous acid. J. Am. Oil Chem. Sot., 42: 73-78. Madgassi, S. and Shani, A., 1990. Surface activity of quaternary ammonium salts derived from jojoba oil. J. Am. Oil Chem. Sot., 67: 605-606. Manos, C.G., Schrynemeeckers, P.J., Hogue, D.E., Telford, J.N., Stoewsand, G.S., Beerman, D.H., Babish, J.G., Blue, J.T, Shane, B.S. and Lisk, D.J., 1986. Toxicologic studies with lambs fed jojoba meal supplemented rations. J. Agric. Food Chem., 34: 801-805. Mapstone, G.E., 1982. A note on hydrogenated jojoba oil. Chem. Aust., 49: 386. Marshall, M.V., Noyola, A.J. and Brown, J.H., 1983. ‘lbst-

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