MICROBIOLOGICAL RESEARCH ON SOME DAIRY PRODUCTS

Abd Elaal S.f.a

doi:10.21608/avmj.2008.176196

Abstract

One hundred samples of dairy products (25 each) of UHT milk, plain yoghurt, fruit yoghurt and white soft cheese samples were examined for total viable count, and the presence of foodborne pathogenic microorganisms. The results declared that the mean total bacterial counts/ml or gm were 2.9 x104 and 7.8 x104 in examined UHT milk and white soft cheese samples, respectively. Staphylococci, Enterococci, E. coli, and Clostridium perfringens were detected in (0.0, 28.0, 40.0 and 64.0 %) & (16.0, 20.0, 36.0 and 48.0 %) & (0.0, 20.0, 28.0 and 28.0 %) and (8.0, 0.0, 0.0 and 12.0 %) of examined samples, respectively. The mean values of isolated organisms/mL or gm were (0, 1.2 x103, 1.3 x103 and 3.4 x103) & (1 x103, 1.4 x103, 1.98 x103 and 1.95 x103) & (0, 7.6 x102, 2.2 x103 and 2.1 x103) and (0.9 x103, 0, 0 and 3.3 x103), respectively. The predominant isolated bacterial stains were Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, E. coli, and Clostridium perfringens by frequency distribution of (0.0, 21.7, 12.9 and 20.4 %) & (0.0, 26.2, 29.0 and 26.5 %) & (28.6, 21.7, 19.4 and 10.2 %) & (42.8, 8.7, 12.9 and 14.3 %) & (0.0, 0.0, 3.2 and 8.2 %) & (0.0, 21.7, 22.6 and 14.3 %) and (28.6, 0.0, 0.0 and 6.1 %) of total isolates, respectively. Meanwhile, Campylobacter jejuni and Salmonellae failed to be detected in all examined samples. The sanitary and public health importance of these organisms as well as control measures to improve the quality of dairy products and to safeguard the consumers from infection were discussed

Highlights

Dairy products have generally been considered an excellent source of high-quality protein, calcium, potassium, phosphorus, magnesium, zinc, and the B vitamins riboflavin, niacin, vitamin B-6, and vitamin B-12 (Buttriss, 1997).Many methods of food preservation are used for ensuring microbiological safety, among which UHT
Lower prevalence in UHT milk was reported by Schaal and Noecker, 1977
The higher total count was observed in examined white soft cheese samples due to several factors as the extent of handling in its production (Seligman, 1976), post pasteurization contamination, usually through contact with equipment surfaces or from the air and biofilms residing on surfaces which are one potential source of contamination (Austin and Bergeron, 1995)

Summary

Introduction

Dairy products have generally been considered an excellent source of high-quality protein, calcium, potassium, phosphorus, magnesium, zinc, and the B vitamins riboflavin, niacin, vitamin B-6, and vitamin B-12 (Buttriss, 1997).Many methods of food preservation are used for ensuring microbiological safety, among which UHT. Dairy products have generally been considered an excellent source of high-quality protein, calcium, potassium, phosphorus, magnesium, zinc, and the B vitamins riboflavin, niacin, vitamin B-6, and vitamin B-12 (Buttriss, 1997). In UHT processing, the milk is heated before its packaging and sealed into sterilized containers in a sterile environment. The use of higher temperature 135-142°C for few seconds will increase the microbial death rate more than the loss of milk quality associated with thermal reactions (Adams and Moss, 1995). UHT seems a very promising technique as it offers numerous opportunities for developing new stable milk with extended shelf life, high nutritional value and excellent organoleptic characteristics. UHT milk minimally processed but safe for consumers and the product requires no refrigeration (Fonberg–Broczek et al, 1999)

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Results

Conclusion