Sensory evaluation of fish sauces

Food QuaSty and Pnfermce 5 ( 1994) 179-184 0 1994 ElswierScienceLimited

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SENSORYEVALUATIONOFFISHSAUCES Norlita G. Sanceda,a*

Marieta F. Sanceda,bVelma

S. Encanto,CTadao

Kurata%

Nobuhiko

Arakawaa

“Department of Food Science and Nutrition, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo, Japan ‘Department of Home Economics, Oton National High School, Oton, Iloilo, Philippines ‘Department of Agriculture, Regional Information Office, Region VI, Iloilo, Philippines ‘Institute of Environmental Science for Human Life, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo, Japan

(Receìved 18 March 1993; acct$ted 20 December 1993)

for some social classes and in specific areas in the region. Lafont (1955) reported that Patis (Philippine fish sauce) and other fish sauces should not be considered as condiments only. Those with 1% nitrogen or more could be considered as rather better than condiments. Fish sauces contain about 20 g/liter of nitrogen, of which 16 g/liter are in the form of amino acids, and thus they may be considered significant sources of amino acids. Personal observations have revealed that, in specific areas and among certain social groups in the Philippines, the daily meals are composed of only rite and fermented fish products, and so the latter are an important source of protein. The traditional way of producing fish sauce is by mixing fish and salt in the ratio of 2 : 1 or 3 : 1 (the fish/salt ratio depends on the quality of fish and the kind of salt used) and plating the fish in layers in a loosely covered container (aerobic). The fish is allowed to ferment for between six and twelve months at 30-35%. It has a high salt content, which inhibits a large intake, and thus the nutritive importante is considered limited. However, in spite of its limited nutritive importante, demand for the product far exceeds the supply (Vicente, 1980), which indicates that the viability of its production remains and wil1 presumably continue with the increasing population (Mabesa, 1987). The aroma of fish sauce is often used as a measure of product quality, since the very salty taste tends to overpower other flavouring constituents. Several studies on the aroma quality of fish sauces have been reported (van Veen, 1941; Vialard-Goudou, 1941, 1942; Truongvan Chom, 1957; Sanceda et al., 1986a,b), but they were mostly carried out by using traditionally produced fish sauces. In previous papers (Sanceda et al., 1983, 1984), we reported that volatile acids were quantitatively predominant in the sauce, with n-butanoic acid as the most abundant compound. It thus appeared that volatile acids contributed to the aroma of fish sauce. Dougan and Howard (1975) described the following as contributory factors in the aroma of Thai fish sauce; (i) a cheesy note, (ii) an ammoniacal note, and (iii) a meaty note. The authors, using a subjective comparison, found Budu less meaty than Nampla. These results were also obtained by using traditionally produced

ABSTRACT Sensory evaluation

of anaerobically and aerobically fm-

mented commercìalfih

sauces was carried out. The results

of the evaluation by two groups of Filipinos (A and B) and one group

of Japanese

(0)

revealed a diffmence

in the smell and taste of the jsh

sauces. Howeoe7; after

several exposures

in smell became sig-

nijìcantly smal& changed.

the diffmence

hut the taste rernained

Groups A and B (familiar

fermented jîsh sauce) peferred

almost un-

with aer-obìcally

the smell of the aerobìc

over that of the anaerobìc sauce but acct@ed the taste of the anaerobic sauce. Group D, who had never known or heard of either of the sauces, had a reverse reaction and preferred

the anaerobic over that of the aerobic sauce.

Group C (Filipino children) did not like the sauces. In general, fermatation

under anaerobic conditions brought

about changes in the aroma quality of jïsh sauce during the manufactuting

process, to yield an acceptable

p-oduct. Keywords: sensory evaluation; jîsh sauce; aerobic, anaerobic fermentation;

volutile acids.

INTRODUCTION Fish sauce is a clear brown liquid-hydrolysis product of salted fish and possesses a characteristic odor. It is one of the most popular fermented fish products in Southeast Asia and is known by various names according to the country of origin (for example, Patis in the Philip pines; Nampla in Thailand and Laos; Ngampi-pya-ye in Burma; Shottsuru in Japan; Ketjap-ikan in Indonesia; or Nuocmam in Vietnam). It is generally used as a condiment, but it is an important source of amino acids * To whom correspondence should addressed. Note: Part of this paper was presented in the Symposium on Advances on Sensory Food Science, Jarvenpaa, Finland, on 2-6 August 1992. 179

180

N. G. Sunceduet al.

sauces. Several studies were undertaken on the modification of the quality of fish sauces by using the traditional method of production (Chayovan et aL, 1983; Sanceda et d, 1989,199O). This study is intended to evaluate the sensory properties of a new fish-sauce product and determine its acceptability. Sensory evaluation was carried out on aerobically and anaerobically fermented fish sauces by using a similarity rating test and an hedonic-rating test. An analytical study of the volatile acids of the sauces was also carried out by using gas chromatography and gas chromatography-mass spectrometry.

never heard or seen either the fish sauces before, and the test was their first opportunity to smell and taste them. Groups A, B, and C were Filipinos, and the sensory evaluation was conducted in the Philippines. Group D were Japanese, and the evaluation was conducted in Japan. The same subjects were used throughout the tests, except that a few were not available for the fourth test.

Preferente Test No.--______

MATERIALS

AND

METHODS

Please smell and taste the samples and write your degree of preferente using the rating scale found at the bottom of the sheet.

Patis, an aerobically fermented Philippine fish sauce (made by the traditional method of production and used as control) and an anaerobically fermented sauce (made by a new method of production), were supplied as test samples by the Fisheries Processing and Promotion Center, Municipal Office, Nemuro City, Hokkaido, Japan. Fermented fish sauces were used in this study. In this paper, aerobically fermented fish sauce refers to Patis.

Fish sauce anaerobically

Sample

Rating smell

B Rating scale 1 = like very much 2 = like a lot 3 = like

4 = dislike 5 = dislike a lot 6 = dislike very much

L

Ï

Similarity

Rating Test

Date _~~____

No.________

Please compare sample B with sample A and rate the differente or similarity using the rating scale found at the bottom of the test sheet. Write your answer on line B under the rating column. Rating

Sample

Sensory evaluation evaluation of fish-sauce samples was done by using a similarity-rating test and an hedonic-rating test. Subjects were untrained panelists aged 5-55 divided into groups according to age and familiarity with the product (Patis, aerobic). Group A, aged 25-55, staff members of Oton National High School, Philippines, and Group B, aged 12-18, students of the same school, have known the product (Patis) and usually include it in their diet. Group C was composed of children aged 5-7 who were familiar with the product (included in their families’ meals) but had never tasted it. Group D, aged 25-55, residents of one community in Japan, had

taste

A

fermented

The preparation and fermentation conditions of this fish sauce were the following: Iwashi fish (Surdinops melunostictus sardine) was soaked in a 20% brine solution for 2 h, drained, and mixed with salt in the ratio of 1: 0.08 to 1.0. The mixture was placed in a nylon bag and air removed by rotary pump. The bag was then sealed and stored at room temperature (lO-30°C) for one year. After that time, the liquid (fish sauce) was boiled for about 20 min, and fat on the surface was separated by using a separatory funnel and discarded. The liquid was then filtered by using filter paper No. 2 and refrigerated at 5°C for one week to prevent precipitation. Finally, the liquid was again filtered, bottled, and pasteurized at 85°C for 40 min.

Date ~~___~~

smell

taste

Sensoty

A (control) B Rating scale 1 = very different 2 = different 3 = not so different

4 = not so similar 5 = similar 6 = very similar

FIG. 1. Example of test sheet for the hedonic-rating larity-rating tests.

and simi-

Sen.sq Eztaluationof Fish Sauces Figure 1 shows an example of the test sheet for the similarity-rating and hedonic-rating tests. The subjects used the same numbers for their identity throughout the test.

Similarity-rating test The samples in their original form, in glass beakers, were presented with the same appearance, at the same temperature, and in equal amounts. They were lettercoded, and the subjects were asked to compare sample B (anaerobic) with sample A (aerobic) and rate the degree of differente or similarity by using a six-point rating scale where 1 = ‘very different’ and 6 = ‘very similar’.

Hedonic-rating test The lettercoded samples were presented to the sub jects separately. With a six-point rating-scale test, where 1 = ‘very much like’ and 6 = ‘dislike’, provided on the test sheets, the subjects were asked to rate the samples individually with the aerobic sample presented first and the anaerobic next, both in codes. This testing pattern was used consistently throughout al1 the tests. In both tests, the assessment of aroma was carried out in the following manner: each sauce was absorbed into half a strip (1 cm X 5 cm) of filter paper, and the subjects sniffed the samples. For taste, half a teaspoon of each sample was given to the subjects, one after the other, and they rinsed their mouths between samples. Re-smelling and retasting were allowed. Three observations were made in one test, with an interval of about 5 min between observations, and the subjects were given a separate sheet for each observation. The standard error of the average of three observations was calculated.

Analytical study The volatile acids in the two samples were analyzed by using gas chromatography (CC) and gas chromatography-mass spectrometry (GC-MS). An internal standard hexacosane solid mp 57°C C,,H,, was first added to the samples before distillation was carried out. Volatile compounds were collected by steam distillation under reduced pressure, where the distillation flask was chilled on ice throughout the process, and the distillates were fractionated into an acid fraction with 5% HCl, saturated with NaCl, and extracted with ether. Anhydrous sodium sulfate was added to the extracts, which were then allowed to stand overnight. The fractions were concentrated in the usual manner to a volume of 0.5 ml and analyzed. Separation of volatile acids was achieved on a 50-m X 0.25mm (i.d.) high-resolution fusedsilica column coated with PEG 20 M with a phase thickness of 0.15 Pm

181

(Gasukuro Kogyo Inc., Japan) attached to a Shimadzu 9A microcomputer gas chromatograph equipped with a flame-ionization detector (FID). The oven temperature was programmed at 6O”C, held for 4 min, and then increased at 2”C/min to 180°C and held for 25 min. The carrier gas was nitrogen, with a split ratio of 1: 40. The injection temperature was 2OO”C, and the detector was at 230°C. Relative concentrations of the acids were calculated by using a multifunctional data processor (Shimadzu CR4A Chromatopac) connected to the GC. The volatile acids were identified by using gas chromatography and mass spectrometry (GC-MS). A Hewlett Packard model 5790 gas chromatograph with fused-silica capillary column coated with PEG 20 M (50 X 0.25 mm (id.)) was used. A JEOL model JMXDX mass spectrometer attached to the Hewlett Packard gas chromatograph was used. Analysis was done by using the electron-impact-ionization method at 70 eV, and the interface temperature was 200°C. Concrete identification of the compounds was made by comparing the retention time, Kovat’s index, and mass-spectra pattern with the corresponding values of the authentic compounds.

RESULTS

AND

DISCUSSION

In our preliminary work on the effect of oxygen on the formation of volatile acids during the fermentation process of fish sauce, we reported that Patis, an aerobically produced fish sauce, had a strenger acid odor, which was more rancid, cheesy, and a little more pungent; the anaerobically produced fish sauce had a milder odor that was a little more sweet and a little more burnt (Sanceda et aZ.,1992). Table 1 shows the results of the similarity-rating test on the smell and taste of the sauces. Four tests were conducted at different times, with an interval of two weeks between tests. In the first and second tests, groups A, B, and D gave a rating of between 1 and 2 for the differente in smell of the two products. In the third and fourth tests, the rating for the differente in the smell was smaller (between 2 and 3) except in group A, where the rating was a little above 3. The evaluating groups (except group C) gave a 2-3 rating for the differente in taste in the first test, but, in contrast to the smell test, the rating remained almost unchanged to the fourth test. It seemed that the changes occurred at higher rates in smell than in taste. The children did the test only once and did not want to participate in any further tests, since they did not like the product. The hedonic-rating results showed that groups A and B, who were familiar with Patis, preferred the smell and taste of the aerobically fermented sauce over that of the anaerobically fermented product, although they did not show a dislike for the latter (Table 2). The mean

182

N. G. Sanceda et al.

TAE%E 1. Sensory Evaluation of Fish Sauces by Using Similarity-Rating Test Panelists

Anaerobic

Group A

Group B

1st test mean f S.E.

2nd test mesn f S.E.

3rd test mean + S.E.

4th test mesn f S.E.

Staff-Filipinos Smell Taste

1.28 tr 0.05 2.70 f 0.07

1.42 +0.06 2.72 f 0.07

2.67 f 0.07 2.74 f 0.07

3.01* 0.09 2.74 i 0.08

Students-Filipinos Smell Taste

1.35 f 0.05 2.89 f 0.08

1.58kO.06 2.87 f 0.07

2.59 f 0.10 2.90 f 0.07

2.98 i 0.06 2.90 f 0.07

2.00 + 0.05 2.87 f 0.06

2.73 f 0.06 2.87 f 0.07

Group C

Children-Filipinos Did not like the sauce and refused to participate in the test

Group D

Aged 23-55 years-Japanese Smell Taste

1.69 f0.07 2.87 f 0.06

1.70 f 0.05 2.89 If:0.06

Group A, B: aged 25-55 and 12-18, respectively, are familiar with Patis, which is often included in their diet. Group C: children aged 5-7, are familiar with Patis but do not include it in their diet. Group D: aged 25-55, tasting both sauces for the first time. Mean: average of three observations of 25 panelists. S.E.: standard error of the mean. Mean scores in the lst, 2nd, and 3rd tests were averages of three observations of 25 panelists. Mean scores in the 4th test were averages of three observations of 80% of the 25 panelists. The other panelists were not available during the last test. Aerobic: commercial Philippine fish sauce (Patis) fermented in the presence of air and used as control. Anaerobic: commercial fish sauce (new product) fermented in the absente of air. Rating scale: 1 = very different, 2 = different, 3= not much different, 4 = not so similar, 5 = similar, 6 = very similar.

scores of the entire observations A and B remained tests. The

almost

children’s

with the product, pate further

of the smell by groups

unchanged

group,

though

throughout

mented almost

the

included

they were familiar of group

in the second

in the table) . However,

smell and taste changed

disliked it and did not want to partici-

in any of the tests. Members

sauce in the first test, and the ratings remained unchanged

and third the degree

in the fourth

tests (not of liking in

test.

in the quality and quantity of the volatile acids in the two samples and showed that the aerobically fermented sauce had a Analytical

D,

who were not familiar with the product previously, preferred the smell and the taste of the anaerobically fer-

results revealed

a differente

TABLE 2. Sensory Evaluation of Fish Sauce by Using Hedonic Rating Aerobic

Anaerobic 1st test mean + S.E.

Panelists

Aerobic

Anaerobic 4th test* mean * S.E.

Group A

Staff-Filipinos Smell Taste

1.33 f0.06 1.80 * 0.06

2.01 rt 0.09 2.03 + 0.08

1.36 f 0.08 1.83f0.09

1.40 + 0.08 1.90+0.08

Group B

Students-Filipinos Smell Taste

2.00 f 0.08 2.01 t 0.08

2.42 f 0.05 2.j7 f. 0.05

2.02 * 0.08 2.00 f 0.07

1.90 i 0.05 1.89 f 0.05

Group C

Children-Filipinos Smell Taste

dislike dislike

dislike dislike

Group D

Aged 25-55 years-Japanese Smell Taste

3.51 f 0.06 3.31 f 0.05

1.50 f 0.05 1.40f0.06

did not want to participate 2.50 f 0.07 2.91 f 0.05

1.45 f 0.05 1.42 f 0.05

Mean: Average of three observations of 25 panelists. SE.: Standard error of the mean. *: Mean scores in the 4th test were averages of 80% of the 25 panelists. Results of the 2nd and the 3rd tests were not significantly different from the 1st test and are not included in the table. Rating scale: 1 = like vety much, 2 = like a lot, 3 = like, 4 = dislike, 5 = dislike a lot, 6 = dislike very much.

Sensory Evaluation

of Fish Sauces

study on these two kinds of commercial fish sauce and also on the model samples (Sanceda et aL, 1992). In the anaerobic sauce, al1 the acids had concentrations of less than 1% of the acid fraction. is&Butanoic, iscFhexanoic, and n-heptanoic acids were not detected in this sample. iso-Octanoic acid was not detected in either of the samples, though we found it in traces in our previous

greater number and higher concentrations of volatile acids than the anaerobically fermented sauce as shown in Table 3 and graphically presented in Figs 2 and 3. nButanoic acid was the most abundant (20.74%) among the acids in the aerobic sauce and was followed by propionic (8.69%) and is+pentanoic acid (5.00%). These findings agree with the results of our preliminary

nidentified ,ompound 3HT

4 2

1

I

1

I

16

15

12

I

h I

2:

32

13

lA

I

I

+

40

48

56

I

16

I

64

I

72

min

FIG. 2. GC profile of the volatile acids in anaerobically fermented fish sauce. 2

4

5

BHT

6

1

16

-l 24

I 32

I 40

183

10

I

48

FIG. 3. GC profile of the volatile acids in aerobically fermented fish sauce.

I

56

I

64

I 72

min

184

N. G. Sancedaet al.

TABLE 3. Relative Concentrations of Volatile Acids in the Acid Fraction of Commercial Fish Sauces Peak No.

Volatile ad.5

1 2 3 4 5 6 7 8 9 10 12 13 14 15 16

Acetic Propionic is&Butanoic n-Butanoic is~Pentanoic n-Pentanoic &Hexanoic n-Hexanoic &Heptanoic n-Heptanoic is&Nonanoic n-Octanoic n-Nonanoic iso_Decanoic Decanoic Total Hexacosane

Aerobic

Anaerobic

Mean area ratio f S.E.” 6)

Mean area ratio f S.E.” (%)

2.72 f 0-020 8.69 f 0.073 0.56 f 0,001 20.74 f 0.204 5.00 f 0.740 0.23 f 0.004 0.20 f 0.006 0.09 f 0.001 0.02 f 0908 0.01 f 0.004 1.48 + 0.095 0.70 * 0.006 tr 0.20 f 0.002 tr

0-20 f 0.004 0.09 f 0*002 nd 0.27 f 0.006 0.20 f 0.011 0.01 f 0.001 nd 0.03 f 0*002* tr nd tr tr tr 0~18*0*002” tr

(IS.)

40.64 1.00

0.98 1.00

%: GC peak area. ‘: Mean area ratio = acid peak area/total acids area/I.S. peak area: average of three replicates. S.E.: Standard error of mean ratio. I.S.: InternaI standard, hexacosane. tr: Trace: value is less than O*Ol%. nd: Not detected. Values in the same line without superscripts are significandy different at p < 0.001 level. b: Significantly different at p < 0.01 level. c: Not significantly different. Test of significante was made by using Student’s t-Test and Cochran-Cox Test. Peak numbers correspond to the peak numbers in the CC profile. study

et aL, 1992).

(Sanceda

quantity

and quality of volatile

samples may explain

This

differente

in the

acids between

the two

the differente

in smell as revealed

in the sensory evaluation.

CONCLUSIONS The volatile-acids was higher There

were differences

the aerobically sauces.

However,

mentation

in the aerobic

in smell and taste between fish

especially

in

smaller after several tests. Fer-

under anaerobic

to the aroma

fermented

the rate of differente, became

sauce

sauce.

(Patis) and anaerobically

smell, gradually

seemed

concentration

than that of the anaerobic

conditions

brought

changes

quality of the sauce, and the end-product

to be more

acceptable.

Results

of the study

suggest that it is possible to modify the aroma quality of fish sauce under controlled-fermentation conditions dwing the manufacture of fish sauce.

REFERENCES Chayovan, S., Liuzzo, A. J. 8c Rhan, A. M. (1983). Fatty acids and sensory acceptance of dietary sodium-potassium fish sauce. J. Agric. Food Ckem., 31, 14. Dougan, J. & Howard, G. E. (1975). Some flavoring constituents of fermented fish sauces.J. Sn’. Food Agric., 46,887. Lafont, R. (1955). Valeur alimentaire des sauces de poisson. In Proczedings of IndwPaci$c Fish Cmmcil, 15th Meeting, Bangkok, Thailand, Sections 11 and 111,p. 163. Mabesa, R. (1987). Patis: Fish sauce, Bagoong: Fish paste. Processing industty in the Philippines. Prospects and Problems. Traditional Foods and their Processing in Asia. Nodai Research Institute, Tokyo University of Agriculture, p. 156. Sanceda, N., Kurata, T. 8c Arakawa, N. (1983). Volatile acids in the steam distillate of Patis, a Philippine fish sauce. Phil. Agric., 66, 176. Sanceda, N., Kurata, T. & Arakawa, N. (1984). Fractionation and identification of volatile compounds in Patis, a Philip pine fish sauce. Agn’c. Biel. Gem., 46,3047. Sanceda, N., Kurata, T. & Arakawa, N. (1986a). Formation of volatile acids in various stages of fermentation. Nippon Shokuhin Kogyo Gakkaishi, 33,285. Sanceda, N., Kurata, T. 8c Arakawa, N. (19866). Study on the volatile compounds of fish sauces-Shottsuru, Nampla and Nuoc Mam. Agric. Biel. Chm., 50,lZOl. Sanceda, N., Kurata, T. & Arakawa, N. (1989). Effect of addition of animal and plant protein sources on the aroma of fish sauce. Addition of chicken liver or soybean protein. Nippon Shokuhin Kogyo Cakkaishi, 36, 152. Sanceda, N., Kurata, T. & Arakawa, N. (1990). Overall quality and sensory acceptance of a lysine-fortified fish sauce. J. Food Sci., 55,983. Sanceda, N., Kurata, T., Suzuki, Y. & Arakawa, N. (1992). Oxygen may affect formation of volatile acids during fermentation-manufacture of fish sauce. J Food Sci., 57, 1120. Truong-van Chom. (1957). The volatile fatty acids of nuoc mam. In Proceedings of 9th Pac@ Science Congress, Paczjîc Scimce Association, Bangkok, Thailand. 5: 135. van Veen, A. G. (1941). Chemischonderzock over pedah. Communication No. 6, Institute of Fisheries, Batavia, Java, p. 1. Vialard-Goudou, A. (1941). Teneur en volatiles et en acides volatiles de la saumure indochinoise ‘nuoc mam’. Rev. Med. Frac. d ExtrerwOnent (Hanoi), 19,106l. Vialard-Goudou, A. (1942). Etude chimeque de la saumure indochinoise ‘nuoc mam’. Reu. Med. Frac. d’Extrenu+íhient (Hanoi), 20,960. Vicente, T. (1980). Feasibility of establishing a Patis plant. Matrix Inc.-Lopez Sugar Corporation Liberty Bldg. Makati, Metro Manila, Philippines.