Effect of protein treatment on the enzymatic hydrolysis of lysinoalanine and other amino acids.

Lysinoalanine (LAL) release from alkali-treated proteins by proteolytic enzymes could be measured on a large scale using an in vitro digestion method based on a two-step hydrolysis with pepsin and pancreatin. The hydrolysis was carried out in a dialysis bag, and the digestion products collected and analyzed. Applying this procedure to alkali-treated soybean and rapeseed protein showed that the release of LAL was not related to its concentration in the protein. Instead, LAL release depended on the nature of the protein, the length of the treatment, and the presence of untreated protein. The enzymatic procedure was also used to measure the release of other amino acids in treated and untreated proteins. This in vitro method could directly measure beneficial and adverse effects of processing on amino acid digestibility.