Abstract: This study investigated the impact of storage on protein quality in infant formulas and milk products through measurement of available lysine and formation of protein carbonyls. The samples manufactured by dietetic company were collected from open market as displayed on the shelves, these consists of four brands of powdered milk, three of evaporated tin milk and two of infant cereal products.. Available lysine and protein carbonyls were measured after derivatization with 1-fluoro-2-4- dinitrobenzene (FDNB) and 2, 4-dinitro-phenylhydrazine (DNPH) respectively, using spectrophotometer. The results showed that moisture content, protein, available lysine and protein carbonyl ranged from 2.04-37.81%, 9.23-29.07%, 7.24-24.57 g1 100 g protein and 0.45-18.96 nmol/mg proteins, correspondingly. Protein carbonyl increases whereas available lysine decreases as storage period is prolonged. The study concluded that though infant formulas and milk products was said to a have prolonged shelf-life, the products in the open markets especially in the tropics should be periodically analyzed to ensure that the protein quality did not deteriorate before the product is consumed.
Israel Olusegun Otemuyiwa and Olalekan Olabisi Yahya, 2016. Spectrophotometric Measurement of Available Lysine and Protein Carbonyls in Commercial Infant Formulas and Milk Products. Journal of Food Technology, 14: 9-13.