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Abstract
Summary
A total of two hundred and fifty random samples of infants milk powder for babies after birth (70 samples), milk-cereal based weaning food (90 samples) and dried milk powder (90 samples) were purchased from different shops and pharmacies in Assiut city and villages around the city. These samples were still valid for consumption as shelf life is at least to be more than one year from production time and they were transferred to the laboratory in their packages to be examined microbiologically to evaluate their quality.
The mean value of total colony count /g were 9.2x10; 6.1x10 and 1.3x102 of examined infant milk formulae, milk-cereal based weaning food and dried milk powder samples, respectively. Most of the examined samples 71.7, 84.9 and 70.1 % had counts ranged from 10 to < 102 / g, respectively. Our current results indicated that the psychrotrophic count ranged from <100 to 1.2x104 with an average count of 2.9x102/ g of infant milk formulae samples and it is worth to notice that most of positive samples (11) in a percentage of 73.3 % contained psychrotrophs within the range of 102 to < 103. While, in milk-cereal based weaning food and dried milk powder, the psychrotrophic count ranged from <100 to 7.8x103 and <100 to 1x104 with average counts of 2.9x103 and 2.8x102 cfu/g, respectively, and the highest frequency distribution (52.9 and 92.4 %) lies in between 103 to < 104 and 102 to < 104. In addition, coliforms, fecal coliforms and E. coli failed to be detected. Moreover, Enterococci could not be enumerated in any one of the examined samples, however, they were isolated from 20, 1.1 and 13.3 % of samples, respectively.
On the other hand, statistical analytical results of B. cereus count in the examined baby foods samples showed that the pathogen could be counted in 32 (54.3); 17 (18.9) and 35 (38.9 %) of the concerning samples with average count of 0.3x10; 0.56x10 and 7.2x10 cfu/g, respectively. 17 (43.1%) and 3 (17.6 %) of positive samples of infant milk formulae and milk-cereal based baby food had counts of B. cereus ranged from 102 to < 103/ ml, while, the majority of positive samples of dried milk powder (97.2%) had counts ranged from <102 to < 103/ g. Moreover, B. cereus could be isolated in percentages of 54.3; 18.9 and 38.9 % from the examined samples, respectively.
About the anaerobes by using stormy fermentation, they were detected in a percentage of 44.3% for infant milk formulae; 54.4% for milk cereal-based baby food and 38.9 % for dried milk powder. Regarding the total yeasts and molds count, the results revealed that 77.1; 60 and 83.3% of the examined samples of infant milk formulae, milk-cereal based weaning food and dried milk powder were contaminated with these microorganisms in average counts /g of 3x10; 8x10 and 5.1x10 cfu/g. Most of positive samples (90.7, 83.3 and 73.3%) lies within the range of 10 to < 102 / g , respectively.
Furthermore, Enterobacteriaceae existed in the examined samples at percentages of 10, 40 and 15.6 %, respectively. E. cloaca, Serratia marcescens and Klebsiella oxytoca were isolated from infant milk formulae in a percentags of 42.9, 42.9 and 14.2%, respectively. Concerning milk-cereal based baby food, E. cloaca, E. sakazakii; Serratia marcescens; Serratia liquefaciens; E. aerogenes; K. oxytoca; Citrobacter freundii; Hafnia alvei; Proteus spp.; Salmonella spp. and Chryseomonas luteola were found in 13, 6, 1, 2, 1, 4, 1, 5, 5, 1, 1 and 1 of the examined samples, respectively. While, E. cloaca; E. sakazakii; Serratia marcescens; Hafnia alvei; Yersinia pestis and Yersinia pseudotuberculosis were demonstrated in dried milk powder samples in incidences of 42.9, 7.1, 7.1, 21.4, 14.3 and 7.1 %, respectively.
Regarding the ubiquitousness of E. sakazakii in inanimate (water, soil, plants) and animate environment (animals, man) it is not surprising, that E. sakazakii was detected in a wide spectrum of food and food products of animal and vegetable origin. Altogether, E. sakazakii is not very frequent in food. Hygiene mismanagement due to incorrect temperature and time factors as well as due to the contact transmission of microorganisms via hands, insects, small vertebrates and equipment should be avoided during production, preparation and storage of food and drink. E. sakazakii represents a significant risk to the health of neonates where it could be isolated from 6/90 milk-cereal based baby food samples and from 1/ 90 dried milk powder samples, however, failed to be detected in infant milk formulae which considered as non a sterile product.
The survival and growth of E. sakazakii in milk-based cereal weaning food using different reconstituted liquids (apple juice and water) stored at different temperature (room temperature 16 ± 2°C and refrigerated temperature 4±1°C) were done. The results revealed that the growth did not occur in cereal reconstituted with apple juice, regardless of storage temperature, or in cereal reconstituted with water stored at 4 °C. Upon reaching maximum populations of 4 log10 cfu/ g, in some instances populations decreased to nondetectable levels during subsequent storage which was concurrent with decreases in pH. E. sakazakii initially at very low populations can rapidly grow in infant cereal reconstituted with water. Reconstituted infant cereal can support luxuriant growth of E. sakazakii. Therefore, reconstituted cereal that is not immediately consumed should be discarded or stored at a temperature at which E. sakazakii and other food-borne pathogens cannot grow.
These results declared the presence of E. sakazakii and other species of Enterobacteriaceae in the examined baby food before and after weaning. This may be belongs to its resistant to heat treatment processes and neglected sanitary control measures during handling, manufacturing, distribution and storage of the different products.
The public health importance of E. sakazakii as well as the recommended sanitary measures were discussed.