Antioxidative Activity of Barley Hordein and Its Loss by Deamidation

Hiroko CHIUE, Takanori KUSANO, Kimikazu IWAMI
1997 Journal of Nutritional Science and Vitaminology  
Barley hordein was comparable to maize zein in antioxida tion under a powder model system. Various deamidated "hordein" preparations were obtained and examined for their molecular-size distri bution (by Sephacryl S-100 gel filtration), hydrophobicity (by fluores cence measurement using fluorescent probes) and antioxidative activity (by the ferric thiocyanate method). Deamidation caused fragmentation of the hordein molecule and simultaneously lowered its fatty acid-binding capacity rather than
more » ... s surface hydrophobicity. Then, the antioxidative activity diminished with increasing deamidation. When the fatty acid binding capacity was plotted against the antioxidative activity, a high correlation (r2=0.92) was observed between these two events. Oxidative deterioration of unsaturated lipid-rich foods doesn't only lessen their tasty or nutritive value but also brings about toxicity in extreme cases. Food manufacturers make use of antioxidants and often package their goods under anaerobic conditions for prevention of possible trouble. The use of synthetic antioxidants such as butylhydroxyanisole and butylhydroxytoluene tends to be recently avoided because of a doubt upon their safety for health (1, 2). Instead, much interest has been directed toward the development of natural and more safe antioxidants; for example, amino acids (3, 4), peptides (5), proteins (6) and so on (7, 8). Among such promising foodstuffs are cereal prolamins represented by wheat gliadin (9) and maize zein (10). It is generally accepted that deamidation of these proteins leads to an increase in their solubility or emulsification, and thereby to an extention of use for food materials. There are, however, only a few investigations on the possible role of amide bonds in antioxidation. This paper deals with the antioxidative activity of barley hordein as a member of these prolamins and its related significance to amide bonds.
doi:10.3177/jnsv.43.145 fatcat:yq7cweg765bgzoo6mkgbzxemqq