Fluid Milk Industry in the Central Province of Saudi Arabia

OUR INDUSTRY TODAY Fluid Milk Industry in the Central Province of Saudi Arabia JOSEPH P. SALJI, WAJIH N. SAWAYA, and M U H A M M A D A Y A Z Regional Agriculture and Water Research Centre Food Science and Nutrition Section Ministry of Agriculture and Water P.O. Box 17285 Riyadh, Saudi Arabia 11484

ABSTRACT

INTRODUCTION

Production, processing, and quality aspects of fluid milk were investigated. Annual production of 36,046, 9,360, and 4,207 metric tons were obtained for raw milk, sterilized milk, and pasteurized milk, respectively. Sterilized milk was made exclusively from reeombined milk and constituted 70% of the total processed fluid milk. Only one-third of raw milk was used for manufacture of pasteurized milk and two-thirds for yogurt products. Pasteurized milk was made exclusively from fresh milk. Heat treatment included batch, high-temperature short-time, and ultrahigh temperature. The high-temperature short-time pasteurization was predominant. Compositional aspects of raw milk indicated means of 3.09% fat, 3.07% protein, .71% ash, 4.49% lactose, 11.59% total solids, and 8.51% solids-not-fat. The physicoehemical analysis of processed fluid milk indicated means of 3.24% fat, 3.30% protein, .73% ash, 4.56% lactose, 11.94% total solids, 8.69% solidsnot-fat, 6.59 pH, .14% titratable acidity, .95 acid degree value, 1.3493 refractive index, and 1.0327 specific gravity. Bacteriological analysis showed coliform, Salmonella spp., and Stapbylococcus aureus as main contaminants of raw milk. Bacillus cereus and Clostridiurn perfringens were also detectable but in smaller numbers. Pasteurized milk was of good bacteriological quality and free from detectable antibiotics.

Judged by its growth rate and development, the dairy industry may be viewed as one of the most progressive food industries in Saudi Arabia. The rapid growth of this highly subsidized industry is manifested by the remarkable increase in production of dairy products as a result of proliferation of both dairy farms and processing plants (1, 2, 15). During the past 5 yr in the central province of Saudi Arabia, increases of 371 and 182% were obtained for the annual production of raw milk and total dairy products, respectively. Locally manufactured dairy products in the central province of Saudi Arabia consist of pasteurized and sterilized fluid milk, cultured dairy products predominantly yogurt, white cheeses, ice cream, and whipping cream. Yogurt products constitute the major dairy products followed by sterilized milk, pasteurized milk, white cheese, ice cream, and whipping cream (10, 11). The latter product, however, is produced in nominal quantities only. Production figures show that 82% of the total processed dairy products in the central province of Saudi Arabia is yogurt, 16% processed fluid milk (pasteurized and sterilized), and only 2% is cheese and ice cream (11). The qualitative and quantitative aspects of the yogurt industry have been investigated in the central province of Saudi Arabia (11). However, information is still lacking, scarce, or inaccurate (4) concerning production and quality aspects of the fluid milk industry. The objective of this study, therefore, was to investigate and document production and quality aspects of locally produced raw and processed fluid milk as they prevail in the central province of Saudi Arabia. MATERIALS AND METHODS

Received May 11, 1983. 1984 J Dairy Sci 67:1054-1060

A total of 14 plants representing all dairy plants in operation in the central province of 1054

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TABLE 1. Dairy processing plants in the central province of Saudi Arabia.

a

,

Plant code

Date of initial production

Plant processing pasteurized/ sterilized milk

A B C D E F G H I J K

1978 1980 1980 1976 1979 1977 1980 1975 1982 1978 1980

+a + + _b --+ + + + +

Powder Fresh Fresh Fresh Fresh

L M

1979 1979

-

... ...

N

1980

--

...

.

Type of milk used Fresh Fresh Fresh .., ...

,

+, Processing fluxd milk. b - , Not processing fluid milk.

Saudi Arabia were visited between December 1981 and May 1982 (Table 1). Information was obtained through direct contact with plant management. Production figures were obtained from production managers, but manufacturing practices and quality control measures were both observed and inspected. Six representative samples of each product per processing plant were collected randomly for physicochemical and microbiological analyses. These samples were collected from the production line (pasteurized or sterilized milk) or from the cold storage tank (raw milk) of the plant and within 24 h of production. All samples were refrigerated at 4 to 6°C and analyzed within 24 h of collection. The physicochemical tests of raw milk included fat, protein, ash, lactose, total solids (TS), and milk solids-not-fat (MSNF). Pasteurized and sterilized milk were analyzed for fat, protein, ash, lactose, TS, MSNF, pH, titratable acidity (TA), phosphatase, hydrolytic rancidity (ADV), specific gravity, and refractive index. Fat was determined by the Gerber method (8). Total protein was analyzed by Kjel-Foss Automatic (Foss Electric). Total solids, ash, and TA were determined according to methods of Association of Official Analytical Chemists (AOAC) (3). Solids-not-fat was obtained by difference

(TS-fat). The pH was measured on a digital pHmeter (Orion Model 701A). Lactose was determined gravimetrically (3), and the lactometer method was used to determine specific gravity (8). Refractive index (RI) was measured in a temperature-compensated Abbe Refractometer (American Optical, Model 10450). Phosphatase (Ph-ase) was determined by the Scharer modified Ph-ase test (Applied Research Institute), and hydrolytic rancidity was measured by determining the acid degree value (ADV) of the product (16). Microbiological analyses included standard plate count (SPC), coliform (VRB method), S t a p h y l o c o c c u s aureus, C l o s t r i d i u m perfringens, Bacillus cereus, Salmonella, and Shigella.

Milk samples also were tested for antibiotics (disc assay). The SPC, coliform, and antibiotics were determined according to the S t a n d a r d M e t h o d s f o r t b e E x a m i n a t i o n o f Dairy P r o d u c t s

(7). Salmonella and Shigella were detected according to AOAC methods and confirmed by biochemical and serological methods (3). The procedures of the Bacteriological A n a l y t i c a l M a n u a l of the Food and Drug Administration (5) were used for detection of S. aureus, C. perfringens, and B. cereus except Shahidi Ferguson Perfringens (SFP) agar base (Difco) was used for C. perfringens. Journal of Dairy Science Vol. 67, No. 5, 1984

SALJI ET AL.

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The dairy processing industry in the central province of Saudi Arabia is a young, dynamic, and rapidly growing industry. Table 1 shows that most of the dairy plants (11 out of 14) became operational during the last 5 yr. It is also indicated that 57% of the plants are involved in fluid milk processing. This figure is almost double what it was in 1978 for all the kingdom (15); nevertheless, the amount of milk channeled into pasteurized or sterilized milk remains far behind the amount of milk used in the manufacture of yogurt products (t 1). Production Aspects

Production aspects of raw milk, pasteurized milk, and total processed dairy products are shown in Table 2. As indicated, all processed milk in the central province is made from fresh milk (raw) except in one plant where sterilized UHT (ultra-high temperature) milk is made from recombined milk (recombined skim powder and milk fat). Although all pasteurized milk is made from fresh milk, the production figure of raw milk is almost 2.7 times the production of pasteurized milk. This is a clear indication that

TABLE 2. Annual production of fluid milk in the central province of Saudi Arabia (metric tons). Pasteurized milk

Total dairy products

624 2,184 218 None None None

4,113 390

281 138 728 34 None None None

4, 524 11,575 1,310 2,912 3,240 4,368 12,761 311 1,711 8,044 237 619 32,843 390

36,046

13,567

84,845

Plant code

Raw milk

A B C D E F Ga H

4,446 11,606 1,310 2,912 None None None 330 1,711 8,372 237

I

J K L

Mb N Total

619

9,360

aSterilized recombined milk. bRaw milk and reconstituted milk are used in making dairy products. Journal of Dairy Science Vol. 67, No. 5, 1984

only a minor portion of the raw milk is utilized in the manufacture of pasteurized milk. Approximately one-third (37.6%) of the raw milk produced in the central province is used in the manufacture of pasteurized milk and twothirds (62.4%) is used in the manufacture of other dairy products, mainly plain liquid yogurt (11). Processed fluid milk in the central province of Saudi Arabia consists of sterilized and pasteurized milk. The sterilized milk constitutes about 70% of the total output of processed fluid milk. Fresh milk production and utilization have been significantly increased. The remarkable increase of fresh milk production becomes evident when comparison is made between past and present. In 1978, annual production figures for dairy products in Saudi Arabia were 7,650 and 30,046 tons for fresh milk and total processed dairy products (15). However, present data (Table 2) indicate 36,046 tons for fresh milk and 84,845 for total processed dairy products in the central province only. Manufacturing Practices

Modern technology and fairly well-equipped plants are used in the manufacture of processed fluid milk. It is rather unusual to find a dairy farm without a processing plant in the immediate vicinity. Raw milk from the milking parlor is either pumped or transferred into the processing plant. Cooling of the raw milk is either in bulk coolers or, more efficiently, in plate coolers. On the average, raw milk is processed within 24 h of milking. When powder milk is used, a recombination process is carried on whereby melted butter is fed into a liquid phase made of skim powder, stabilizer, and water to yield the final recombination of c o n s t i t u e n t s prior to heat treatment. Heat treatment of milk involves the three most commonly practiced methods, namely, vat pasteurization, high-temperature-short-time (HTST) pasteurization, and ultra-high temperature (UHT) treatment (Table 3). The HTST method is predominant and is used in six out of seven plants in manufacture of pasteurized fluid milk. Only one plant uses the batch pasteurization method. Also, UHT treatment is only used by one plant in the manufacture of sterilized recombined milk. A wide range of temperaturetime application is used in plants with the HTST method. The range varies between 72 to 94°C

OUR INDUSTRY TODAY TABLE 3. Heat treatment of fluid milk in the central province of Saudi Arabia.

Plant code

Treatment type

Temperature and time

A B C G H I J K

Batch HTST a HTST UHTb HTST HTST HTST HTST

85°C; 10 min 72°C; 15 s 85°C; 3 s 145°C; 5 s 82°C; 15 s 94°C; 15 s 73°C; 15 s 75°C; 30 s

aHTST, High-temperature, short time. bUHT, Ultra-high temperature.

and 3 to 30 s f o r t e m p e r a t u r e a n d h o l d i n g time. T h e r e seems t o b e a t e n d e n c y f o r o v e r h e a t i n g t h e p r o d u c t in b o t h b a t c h a n d H T S T s y s t e m s ( T a b l e 3). After homogenization and pasteurization, t h e p r o d u c t is filled in Pure-Pack c a r t o n s or in form-and-fill plastic c o n t a i n e r s a n d r e f r i g e r a t e d b e t w e e n 4 a n d 8°C. Fast delivery a n d q u i c k retail d i s t r i b u t i o n are p r a c t i c e d b e c a u s e pasteu-

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rized m i l k c a n n o t b e legally sold a f t e r 3 d a y s f r o m p r o d u c t i o n t i m e (12). S t a n d a r d i z a t i o n o f p a s t e u r i z e d m i l k is lacking in five o f t h e seven p l a n t s visited, and, t h e r e f o r e , f a t o f t h e p r o d u c t is s u b j e c t to f l u c t u a t i o n s t h a t m a y a f f e c t cons u m e r a c c e p t a n c e adversely. It is n o t i c e a b l e f r o m T a b l e 5, h o w e v e r , t h a t fat was n e v e r b e l o w 3% in all processed fluid milk.

Composition C o m p o s i t i o n o f b o t h raw a n d p r o c e s s e d fluid milk is s h o w n in T a b l e s 4 a n d 5. T h e average c o n t e n t s o f fat a n d solids-not-fat in raw m i l k were 3.09 a n d 8.51% (Table 4). T h e s e averages c o n f o r m e d to t h e m i n i m u m r e q u i r e m e n t s set b y t h e Saudi A r a b i a n S t a n d a r d O r g a n i z a t i o n ( S A S O ) for raw m i l k (13). Also, t h e legal req u i r e m e n t s f o r fat a n d solids-not-fat were m e t for p a s t e u r i z e d a n d sterilized m i l k (12, 14). In a d d i t i o n , all r e p o r t e d m e a s u r e s (Table 5) fell w i t h i n t h e n o r m a l range o f a c c e p t a b l e m i l k (6, 7, 8, 16). It was observed, however, t h a t in r e l a t i o n t o h y d r o l y t i c rancidity, t h e A D V w e r e on the higher end of the spectrum reported for a c c e p t a b l e m i l k (7, 16). R a n c i d flavor in p a s t e u r ized m i l k has b e e n d e t e c t e d o n m a n y o c c a s i o n s by the authors.

TABLE 4. Composition of raw milk in the central province of Saudi Arabia. Plant code

Fat

Protein

Ash

Lactose

TS a

MSNF b

4.84 4.96 4.46 4.55 4.59 4.14 4.56 4.04 4.62 4.01

11.65 12.01 11.66 11.89 10.87 12.41 12.16 12.17 10.39 12.02 10.31

8.65 9.01 8.23 8.89 8.27 8.90 8.81 8.87 7.38 9.00 7.56

4.49 4.01--4.96 .311

11.59 10.31--12.41 .734

8.51 7.38--9.01 .578

(%) A B C H I J K Dc Lc Mc Nc

3.00 3.00 3.43 3.00 2.60 3.51 3.35 3.30 3.01 3.02 2.75

3.22 3.02 3.33 2.95 3.50 3.25 3.30 2.18 3.15 2.59

.75 .74 .70 .75 .71 .74 .74 .75 .63 .71 .62

Mean Range SD

3.09 2.60--3.51 .282

3.07 2.18-3.50 .383

.71 .62--.75 .040

3.32

4.67

aTS, Total solids. bMSNF, Milk solids-not-fat. Cplants D, L, M, and N do not process raw milk into pasteurized fluid milk. Journal of Dairy Science Vol. 67, No. 5, 1984

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TABLE 5. Physicochemical analysis of processed fluid milk in the central province of Saudi Arabia. Plant code

Fat

Protein

Ash

Lactose

Total solids

Milk solidsnot-fat

A B C Ga H I J K

3.00 3.00 3.75 3.55 3.00 3.27 3.08 3.30

3.25 3.23 3.25 3.47 3.46 3.06 3.35 3.37

.74 .73 .72 .75 .76 .70 .69 .72

4.66 4.85 4.48 4.62 4.56 4.47 4.34 4.51

11.49 11.87 12.53 12.38 11.95 11.52 11.73 12.03

8.49 8.87 8.78 8.83 8.95 8.25 8.65 8.73

Mean Range SD

3.24 3.00-3.75 .284

3.30 3.06-3.47 .135

.73 .69-.76 .025

4.56 4.34-4.85 .153

11.94 11.49-12.53 .374

8.69 8.25-8.95 .228

pH

Titrable acidity

Phosphatase

Acid degree value

Refractive index

Specific gravity

A B C Ga H I J K

6.55 6.57 6.52 6.59 6.69 6.61 6.62 6.61

.13 .15 .16 .13 .13 .14 .13 .14

Neg Neg Neg Neg Neg Neg Neg Neg

1.07 1.32 .84 1.42 1.02 .68 .57 .72

1.3472 1.3496 1.3484 1.3519 1.3520 1.3500 1.3475 1.3477

1.0327 1.0338 1.0328 1.0319 1.0338 1.0314 1.0328 1.0323

Mean Range SD

6.59 6.52-6.69 .052

.14 .13-.15 .011

. . .

1.3493 1.3472-1.3520 .00260

1.0327 1.0314-1.0338 .00084

(%)

. . .

. . .

. . .

95 57--1.42 307

asterilized recombined milk.

TABLE 6. Bacteriological analysis of raw milk in the central province of Saudi Arabia (bacteria/ml). Plant code

Standard plate count

Coliform

monella

Shigella

S. aureus

C. perfringens

B. cereus

A B C H I J K Db Lb Mb Nb

3,400 58,000 40,000 83,000 10,000 550,000 57,000 120,000 169,000 190,000 5,200

20 500 2,600 12,500 1,500 37,000 4,400 2,600 1,300 3,000 190

+ ND ND ND + ND + ND + + +

ND a ND ND ND ND ND ND ND ND ND ND

450 30 90 150 480 235 800 50 2,000 3,000 500

<10 <10 <10 <10 10 470 15 <10 < 10 10 <10

<10 600 <10 1,700 < 10 365 <10 <10 1,200 <10 <10

Sal-

aND, Not detected. bplants D, L. M, and N do not process raw milk into pasteurized fluid milk. Journal of Dairy Science Vol. 67, No. 5, 1984

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TABLE 7. Bacteriological analysis of processed fluid milk in the central province of Saudi Arabia (bacteria/ml).

Plant code

Standard plate count

Coliform

Salmonella

Shigella

S. aureus

C. perfringens

B. cereus

Antibiotic

A B C Gb H

1,500 2,000 600 <10 350

<10 < 10 30 <10 < 10

4,000

< 10

< 10

<10

7,600 500

< 10 10

<10 <10 <10 <10 <10 20 <10 <10

<10 <10 <10 <10 65

I

ND ND ND ND ND ND ND ND

<10 <10 <10 <10 <10

J K

ND a ND ND ND ND ND ND ND

<10 <10

<10
ND ND ND ND ND ND ND ND

aND, Not detected. bsterilized recombined milk.

Microbiological Analyses

Microbiological analyses of raw and processed fluid milk are shown in Tables 6 and 7. Coliform, Salmonella, and S. a u r e u s were among the m a j o r c o n t a m i n a n t s o f raw milk. The presence o f B. c e r e u s and C. p e r f r i n g e n s also was detectable b u t in small numbers. It is obligatory for raw milk i n t e n d e d for public c o n s u m p t i o n to undergo pasteurization in Saudi Arabia. With the e x c e p t i o n of B. c e r e u s and C. p e r f r i n g e n s , which can survive pasteurization because of their ability to sporulate, all o t h e r f o o d pathogens r e p o r t e d in raw milk (Table 6) are destroyed by pasteurization. It also is i m p r o b a b l e that spores of B, c e r e u s will germinate and propagate in pasteurzied milk to cause f o o d poisoning u n d e r the c o m m o n cold storage conditions of the product. F u r t h e r m o r e , off-flavor and undesirable appearance due to the growth of this bacteria discourage consumption and can hardly pass u n d e t e c t e d (9). Pasteurized milk in the central province of Saudi Arabia (Table 7) can be classified microbiologically as Grade A pasteurized milk according to the 1965 r e c o m m e n d a t i o n s of the United States Public Health Service (17). As stated in these standards, Grade A pasteurized milk should have m a x i m u m bacterial limit of 2 0 , 0 0 0 / m l and coliform limit not exceeding 10/ml. Table 7 shows that pasteurized milk in all plants c o n f o r m e d to these standards e x c e p t plant C where coliform c o u n t was 30/ml. Furt h e r m o r e , no antibiotics were d e t e c t e d in the

product, and f o o d pathogens, with two m i n o r exceptions, were absent (Table 7). The high standard of microbial quality of pasteurized milk in the central province indicates proper sanitation and g o o d m a n u f a c t u r i n g practices at the plant. ACKNOWLEDGMENTS A c k n o w l e d g m e n t is due to Fahed O t h m a n , Tarek V. Bahareth, and Ali M. A1-Sogair for technical assistance and to Hossein M. A1M o h a m m e d , Anwar A. Ismail, and M a h m o u d M. A1-Mohammad for conducting the physicochemical analyses of the products. A special a c k n o w l e d g m e n t is due to the dairy plant m a n a g e m e n t w h o showed active interest in the project and generously provided us with the needed i n f o r m a t i o n . REFERENCES

1 Anonymous. 1976. A commercial study of dairy products in the Kingdom of Saudi Arabia. Ind. Stud. Dev. Ctr., Riyadh. 2 Anonymous. 1981. Annu. Rep., Dep. Anita. Res., Min. Agric. Water, Riyadh. 3 Association of Official Analytical Chemists. 1980. Official Methods of Analysis 13th ed. Assoc. Offic. Anal. Chem., Washington, DC. 4 E1-Erian, A. F., and J. S. A1-Shaikhli. 1980. A physico-chemical and microbiological study of market milk in Riyadh area. Proc. Saudi Biol. Soc. 4:1980. 5 Food and Drug Administration. 1978. Bacteriological Analytical Manual. 5th ed. Food Drug Admin., Bur. Foods, Assoc. Offic. Anal. Chem., Arlington, VA. Journal of Dairy Science Vot. 67, No. 5, 1984

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6 Lampert, L. M. 1965. Modern dairy products. Chem. Publ. Co., Inc., New York, NY. 7 Marth, H. E., ed. 1978. Standard methods for the examination of dairy products. 14th ed. Am. Publ. Health Assoc., Washington, DC. 8 Milk Industry Foundation. 1959. Laboratory manual. Methods of analysis of milk and its products. Milk Ind. Found., Washington, DC. 9 Robinson, R. K. 1981. The microbiology of raw milk. Dairy microbiology. Vol. 1. Appl. Sci. Publ., London and New Jersey. 10 Salji, J. P., A. A. Ismail, and A. F. A1-Shalhat. 1982. Consumption trends of dairy products in the Kingdom of Saudi Arabia. Unpublished data. Reg. Agric. Water Res. Ctr., Riyadh. 11 Salji, J. P., W. N. Sawaya, and M. Ayaz. 1983. The yogurt industry in the central province of Saudi Arabia. Cult. Dairy Prod. J. 18(4):14.

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12 Saudi Arabian Standards Organization. 1977. Pasteurized milk. Standard No. 40, Riyadh. 13 Saudi Arabian Standards Organization. 1978. Raw milk. Standard No. 98, Riyadh. 14 Saudi Arabian Standards Organization. 1978. Sterilized milk. Standard No. 97, Riyadh. 15 Sawaya, W., A. Mashhadi, H. Khatchadourian, and W. Sail. 1978. Food industry survey for the year 1978 in the Kingdom of Saudi Arabia. Reg. Agric. Water Res. Ctr., Riyadh. 16 Thomas, E. L., A. J. Nielsen, and J. C. Olson, Jr. 1955. Hydrolytic rancidity in m i l k - A simplified method for estimating the extent of its development. Am. Milk Rev. 17(1):50. 17 US Public Health. 1965. Grade "A" Pasteurized Milk Ordinance, 1965. Recommendations US Publ. Health Serv., US Dep. Health, Educ. Welfare, Publ. Health Serv., Washington, DC.