Analysis of amino acid composition of skim milk and buttermilk for the production of dairy drink when introducing whey protein hydrolysate

Abstract

The imbalance of macronutrient composition of people's diets determines the relevance of the functional foods development - sources of protein and essential amino acids. The aim of the work was to analyze the amino acid composition and determine the functional significance of the product based on skim milk and buttermilk byadding whey protein hydrolysate. Material and methods. The control options were samples of skimmed milk, buttermilk and their mixtures in a 1:1 ratio. From 1 to 3% of the whey protein hydrolysate with a degree of hydrolysis of about 60% of peptide bonds were added to the same milk base samplesin the experimental options. The amino acid composition was analyzed by high performance liquid chromatography using a cation exchange analyzer and subsequent post-column derivatization with ninhydrin. Results and discussion. The content of essential amino acids per 100 g of whey protein hydrolysate (WPH) is 50.6-168.0% from the adequate level of their daily intake, while there are only 3.0-22.3 and 2.6-19.9% in skimmed milk and buttermilk, respectively. Despite the practically equal protein content in skimmed milk and buttermilk 3.36±0.02 and 3.09±0.01%, respectively, the absolute content of all essential amino acids in buttermilk is lower than in skimmed milk. This can be explained by differences in the qualitative composition of proteins in these types of dairy raw materials. Conclusion. The amino acid composition of the milk base, consisting of buttermilk and skimmed milk mixture in a 1:1 ratio, can be presented as «functional» product in relation to Val, Ile, Leu, Lis, Trp and Tyr, due to the addition of 3% WPH, because the product portion of 200 g provides 15% of adequate daily intake of these essential amino acids. There is the reason to include additional information: low-fat, low-calorie, contains only natural sugars and a source of protein for people whose protein requirement does not exceed 99 grams per day in the labeling of the developed product, in addition to its nutritional and energy value.