Effect of microbial contamination with fungi, Aflatoxin mi and Enteric gram negative bacteria on milk and some dairy products [electronic resource]

Includes bibliographic reference

Milk and milk products are excellent high quality foods,
providing nutritional values through important elements in
the healthy human diet. In this study, 75 samples of dried
milk, raw milk, butter, cream and cooked (processed) cheese (15
of each) were collected randomly from various dairy shops and
supermarkets in Giza Governorate, and tested microbiologically for
fungal and enteric gram negative bacterial contamination;
detection of AFM1 residues using ELISA technique as well as
detection of lipolytic and proteolytic activities of the most isolated
fungi and bacteria. Six genera of moulds were recovered from the
examined samples and three genera of yeasts. The most isolated
moulds were species of genera Penicillium followed by Aspergillus,
Cladosporium, Geotrichum, Mucor and Scopulariopsis, while the
most isolated yeasts were species of genera Candida followed by
Rhodotorula and Saccharomyces. AFM1 levels were detected in all
analyzed samples of raw milk and milk products. AFM1 levels
exceed EU legal limits (50 ppt) (0.05 ?g/L/kg) while the detected
limits were below the international legal limits of USA (FDA) (500
ppt) (0.50 ?g/L/kg) in raw milk and dairy products for human
consumption. The highest lipolytic and proteolytic activities were
detected in A. niger and Mucor spp. (100%) while Cladosporium
spp. possessed the lowest activities (50%), Candida albicans had
activities (80%) and Rhodotorula had activities (62.5% and 75%).
Pseudomonas spp. isolates were examined for proteolytic and
lipolytic activities; three isolates had lipolytic activity (27.27%), also
three isolates had proteolytic activity (27.27%). On the other hand,
the most isolated enteric gram negative bacteria from the
examined samples were identified as E. coli followed by species of
Psudomonas, Klebsiella, Shigella and Salmonella. Moreover, no any
bacteria were isolated from butter and dry milk samples. The
economic importance and public health significance to the present
results as well as apply the proposed sanitary measures to reduce
microbial contamination and food safety for human health were
discussed.

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