Is there microbial health hazard from plain and flavored UHT milk ?

ABSTRACT

This study was conducted to answer the question about the probability of incidence of microbial public health hazard that may arise from consumption of UHT milk either plain or flavored types. To answer this question, we examined microbiologically UHT milk samples in 3 lines aerobically, anaerobically and fungal. Therefore, 100 UHT milk samples were collected randomly from different supermarkets and retails distributed in Assuit city during summer season of 2011. Plain type was represented by 14 samples, while chocolate flavored by 31 samples, strawberry flavored by 30 samples and banana flavored by 25 samples. All samples were examined for the incidence of aerobic, anaerobic and fungal contamination. The revealed results showed that neither anaerobes nor fungi could be detected, while the aerobic microorganisms were detected in 11 samples [11%], in which Staphylococci species were isolated from 7 samples and Gram-negative bacilli werw isolated from 4 samples. It was also noticed that none of the contaminated samples was from the plain type, but they were from flavored types as 8 chocolate and 3 strawberry. Moreover, 6 samples out of the 11 contaminated were of the same production date [29/5/2011], indicating that the line of production in such day may be faced to unhygienic conditions. Latex agglutination test, SDS-PAGE and PCR were used for identification and toxigenicity detection of Staph. aureus strains, in which, 4 samples out of the 7 with Staphylococci species had enterotoxigenic Staph. aureus as 3 samples contaminated with strains harboring classical superantigen genes [2 with SEA + 1 with SED gene] and 4th sample contaminated with strain harboring new superantigen gene [SEG gene]. The Gram-negative bacilli were E. coli, Klebsiella species and Proteus species. Because of the isolated microorganisms were heat-sensitive, their presence in UHT milk means the sterilization temperature was inefficient and/or post-sterilization contamination that are referring to the answer of the present study