Chemical Modification of Food Proteins

Abstract

During the past decade, a number of non-conventional proteins have been identified as human food ingredients, e.g., single-cell proteins, fish, leaf, and cereal concentrates, and soybeans, cottonseeds, and rapeseeds. Successful utilization of these new proteinaceous materials depends on their digestibility, nutritive value, and overall functional and organoleptic properties as related to processed food formulations. Many of them, although to varying degrees, fail to meet one or more such utilization criteria.Although the science, much less the art and technology, of chemical modification of food proteins is in its infancy, there exists a potential for the use of existing fundamental knowledge on protein derivatization -modification, replacement, and remov al of amino acid residues, and protein-lipid, protein-carbohy drate, and protein-ligand interactions for commercially viable food products and process research. Such research programs may lead to the development of modified food-grade proteins of improved functionality, nutritive value, and organoleptic quality and of reduced propensity to deterioration by physicochemical agents. This chapter is a review of 1) theory and known mecha nisms of modification, 2) applied and basic research on chemical modification of food proteins, 3) interaction of modified proteins with other food ingredients and 4) legal, regulatory, public health, and consumer acceptance implications of modified food protein products. In general, future research must address three major objectives: 1) selecting a structure-function specific modification scheme; 2) developing a process and product control strategy from commercial standpoints; and 3) testing the efficacy and safety of the product for human consumption. Chemistry of Food Protein ModificationFood protein structure. The knowledge of food protein struc ture, its capacity for covalent and non-covalent interactions, and structure-function relationships in the native state must be 0097-6156/82/0206-0275$07.75/0

Effect of Acetylation on Physicochemical and Functional Properties of Commercial Pumpkin Protein Concentrate

“…The cleavage specificity of porcine pepsin includes peptides with an aromatic amino acid, preferentially at carboxylic groups of the amino acid, especially if the other residue is also an aromatic or a dicarboxylic amino acid and does not destroy bonds containing valine, alanine or glycine linkages [ 34 ], while trypsin cleaves the peptide chain on the C-terminal side of lysine and arginine amino acid residues. Similar findings were reported by Shukla [ 35 ]. However, the applied method is definitely more precise than the method proposed by Salgó et al [ 36 ] because that determines only peptides, not protein, extracted from the studied material.…”

Effect of acetylation on emulsifying properties of glycinin

“…At the interface of oil and water, the protein orients hydrophobic residues to the oil phase and hydrophilic residues to the aqueous phase, reducing surface tension at the interface. Emulsifying activity is dependent upon various intrinsic physical properties of the protein such as shape, hydrophobicity, flexibility, and surface charge (Shukla, 1982). Our previous experiment on surface hydrophobicity indicated an increase in surface hydrophobicity from less than 90 to more than 190 upon excessive acetylation of lysine residues.…”

Chemical and Enzymatic Protein Modifications and Functionality Enhancement

“…The ε-amino group of lysine residue is most readily acylated (Kinsella and Shetty 1979;Shukla 1982). The phenolic hydroxyl group of tyrosine residue is less reactive because of its high pK.…”