The aim of this research is to study the most important physical, chemical and
microbial changes in several kinds of infant milk available in local markets. The milk
samples were studied in conditions similar to those used by mothers when they prep
are
infant milk bottles at their houses. The results showed that moisture content increased in all
samples from approximately 1% to 3.2-4.4% after storage for 9 days. Acidity increased
considerably from 0.14% to 0.2%.
The results showed that peroxide value passed the allowable limits (0.25) and
reached about (0.47) in samples stored for 9 days at room temperature. However, the value
for samples stored in the refrigerator ranged between (0.25-0.29). The free acidity number
of fat for all samples specially the refrigerated ones was within the natural limits (<0.5).
Chromatographic analyses showed apparent differences in fatty acid percentages between
the kinds of milk. The rate of lenoleic acid (C 18-2 ) decreased during storage in all samples
and in all conditions.
Soluble nitrogen increased in all samples at the end of storage and the highest value
was 0.49% in Nido milk samples. The solubility of milk samples was checked during
storage and was found to decrease very little ( 1%).
The total count of aerobic bacteria showed that all samples conform to the Syrian
standards (No. 197, 1996) during the first six days of storage, but they passed the upper
limits at the end of storage. However, all samples were free of pathogenic microbes .
Vitamin C concentration was studied in samples of infant formula from 5 companies
(referenced A-E) using the 2,6-Dichlorophenolindophenol titration (AOAC, 2006) method.
Results revealed that ascorbic acid content in formulas D and C was the closest
to its
recommended daily intake (RDI) and to the concentrations which are mentioned on the
label of the samples. Storage conditions at room temperature or in the refrigerator did not
affect ascorbic acid levels. In comparison to vitamin C concentrations in milk dissolved in
tap water, its levels decreased when water was warm (40°C) or hot (100°C), and its
concentrations further declined in dissolved form kept for two hours after preparation.
