Incorporation of fatty acid into food protein: palmitoyl soybean glycinin

Application Potential of Food Protein Modification

“…Increased exposed hydrophobicity of proteins has for example been related to an improved capacity to form and stabilize emulsions and foams which is the result of improved potential to interact with hydrophobic surfaces, both the air-water and oil-water interface, and including (model)membranes (Nakai, 1983;Wierenga et al, 2003;reviewed in Wilde, 2000;Wilde et al, 2004). Various saturated and unsaturated fatty acids have been employed to induce lipophilization of proteins including caproic acid (Liu et al, 2000), capric acid (Aewsiri et al, 2010;Liu et al, 2000), lauric acid (Aewsiri et al, 2010), myristic acid (Aewsiri et al, 2010;Ibrahim et al, 1993;Liu et al, 2000), palmitic acid (Haque et al, 1982;Haque & Kito, 1983a, 1983bIbrahim et al, 1991), stearic acid (Djagny et al, 2001;Ibrahim et al, 1993), and oxidized forms of linoleic acid (Aewsiri et al, 2011a(Aewsiri et al, , 2011b, and the efficiency of the lipophilization reaction was found to be inversely proportional to the length of the lipid chains used (Liu et al, 2000). Reaction of 28% of the available free amino groups of ovalbumin with activated capric acid was shown to result in retained secondary structure while inducing oligomerization and destabilization of the protein structure as a result of lowering the enthalpy for unfolding .…”

“…Even though increasing extents of covalent linkage with palmitoyl residues lead to insoluble protein, as spectrophotometrically determined by solution turbidity at 500 nm, foaming stability and emulsifying activity were progressively improved by linkage of palmitic acid to the protein molecule. More groups showed that the foaming or emulsifying activities of a wide range of proteins could be improved upon lipophilization, including soybean glycinin (Haque et al, 1982),  s1 -casein (Haque & Kito, 1983b), and cuttlefish skin gelatin (Awesiri et al, 2011a(Awesiri et al, , 2011b. A further effect resulting from the incorporation of myristic and stearic acids into lysozyme was related to antimicrobial activity and stearic and palmitic acid conjugation resulted in more effective antimicrobial agents against E. coli, than the attachment of myristic acid or the unmodified protein (Ibrahim, 1993).…”

“…The type of assays developed can be categorized by the type of aimed conjugated chemical group of the protein they probe, such as amine groups, thiol groups or carboxyl groups. Some other researchers use methods which rather probe for the attached molecule, such as the use of gas liquid chromatography (GLC) to determine the degree of lipid incorporation (Haque et al, 1982).…”

“…The peak intensities at these wavelengths could be directly converted to obtain information on the degree of modification. Degrees of palmitoylation of soybean glycinin (Haque et al, 1982) and  s1 -casein (Haque & Kito, 1983a) have been determined using gas liquid chromatography.…”

“…In vitro digestibility of modified proteins is often assayed through exposure of the proteins to a single or a mixture of enzymes including trypsin and pancreatin (Salgó et al, 1984), a combination of trypsin, chymotrypsin and peptidase (Hsu et al, 1977), or pepsin-pancreatin mixtures (Haque et al, 1982) to simulate (post)gastrointestinal digestion of food proteins. The small increase in digestibility of acylated mung bean protein isolate reported by ElAdawy (2000) was primarily correlated to the concurrent loss of tannin; tannins have been shown to play an important role in the reduction of protein digestibility (Barroga et al, 1985).…”