Lysinoalanine in foods

Abstract

The formation of lysinoalanine has been primarily associated with the alkaline treatment or heat processing of proteins. The chemistry, food occurrences, nutritional significance, and methods available for the analysis of this phenomenon, relative to the literature, are discussed.Lysinoalanine (LAL) [JV'-(DL-2-amino-2-carboxyethyl)-L-lysine] represents a unique amino acid that apparently has been present in our food supply for centuries, especially in products that undergo alkaline processing and/or heating of a protein-containing food. In addition, Gross et al. (1975) report that LAL is a natural constituent of cinnamycin and duramycin, which are two peptides present in certain species of Streptomyces.However, it was not until the mid 1960s that LAL was actually identified (Patchornik and Sokolovsky, 1964b;Bohak, 1964). Since that time numerous studies have been reported in an attempt to more completely understand its formation mechanism(s), ways of minimizing its formation, and levels present in foods and, most importantly, to identify its specific nutritional and potential toxicological significance relative to food processing and preparation. Several reviews have appeared that discuss certain aspects of the above (Sternberg and Kim, 1977;de Groot et al., 1977;Struthers, 1981), but no review has attempted to provide an inclusive overview of the entire subject. Thus, the primary objective of this review is to more extensively discuss the literature to date in an effort to summarize our knowledge of LAL in food and to point out areas that need further investigation or clarification.

Formation of lysinoalanine following alkaline processing of soya bean meal in relation to the degradability of protein in the rumen

“…The reduction of threonine, serine, cystine, lysine and arginine following alkali treatment was in agreement with the results of Friedman et a1 (1984). A Belimination reaction of threonine, serine, cystine and cysteine residues produces dehydroalanine, which has the double bond reacting with lysine to form LAL (Maga 1984). Arginine is known to be degraded to form ornithine under alkaline conditions (Ziegler et a1 1967).…”

Functionality of oilseed protein products: A review

“…Alkaline processing can alter protein quality due to undesirable reactions involving (i) racemization of amino acids, (ii) formation of lysinoalanine by reactions of lysine with dehydroalanine, produced by degradation of cysteine and serine, and (iii) reduction of digestibility and loss of essential amino acids (Liener, 1994;Maga, 1984). The solubilized protein can be recovered at isoelectric pH and further separated by centrifugation.…”

Comparative study of gelation and cross-link formation during enzymatic texturisation of leguminous proteins

“…However, heat-induced formation of protein cross-links, such as those based on ε-(γ-glutamyl) lysine (Otterburn, 1983;Sakamoto et al, 1995), lysinoalanine (Friedman, 1999;Schwass & Finley, 1984), histidinoalanine (Lauber, Klostermeyer, & Henle, 2001), and further cross-linked amino acids (Maga, 1984), may occur under the given thermal conditions (90°C, 5 min). Furthermore, gelling of proteins through the formation of disulphide bridges has been described (Ma & Harwalker, 1992;Boye, Ma, & Harwalker, 1997;Oakenfull, Pearce, & Burley, 1997;Acton & Dick, 1989).…”