Development of Novel Functional Properties by Biological, Chemical and Physical Modification of Food Proteins

Abstract

With a view to develope novel functional properties of food proteins, biological, chemical and physical modification was carried out. Differences of nucleotide sequence found in cDNA of soybean glycinin A_1aB_1b subunit prepared from Glycin max var. Shirotsurunoko and Bonminori suggest that oligonucleotide site-directed mutagenesis is useful to develope novel functional properties. Formation of n-hexanal, undesirable flavor, was depressed in soybean by the deletion of lipoxygenase 2. In addition, n-hexanal was proved to be produced enzymatically from 13-hydroperoxy-linoleic acid by hydroperoxidelyase. Soy glycinin and α_s1-casein were lipophilized by chemically attaching naturally occurring fatty acids to them. The covalent attachment of fatty acid residues to these proteins caused an increase in their emulsification activity. The binding of orthophosphate to soy proteins increased gel forming and emulsification activities even at acidic environment. Soy proteins and maize protein, zein, were associated with soy lecithin and phosphatidate by sonication, respectively. The emulsiffication activity of phospholipid-protein complex was highly increased after they were treated with 50% alcohol or pro tease digestion.