Effect of lipoxygenase‐induced oxidation on molecular structure and digestive properties of arachin and conarachin

Abstract

Lipid oxidation products can affect the molecular structure and digestibility of peanut protein isolates. Lipid-oxidizing systems (LOS) is a simulation system which uses oxygen-free radicals generated by the reaction of linoleic acid and lipoxygenase as oxidants.The simulation system was established to mediate oxidation of arachin or conarachin. Degree of oxidation (DOX) of peanut protein isolates (PPIs) was measured as quantity of LA to generate LOS. This study analyzed the effect of lipid oxidation-derived free radicals on the molecular structure and digestive properties of arachin and conarachin and observed substantial changes in carbonyl content, total sulfhydryl content, and number of disulfide bonds as quantities of LA increased, thus indicating significant oxidation of two proteins. Further, it was found that arachin was more stable than conarachin in a LOX-catalyzed oxidizing system. When the amount of LA was 3 and 5 ml, the maximum surface hydrophobic characteristic values of arachin and conarachin reached the maximum, which were 235 ± 10 and 349 ± 13, respectively. This study laid a theoretical foundation for the application of peanut protein in food products.

The Impact of AAPH-Induced Oxidation on the Functional and Structural Properties, and Proteomics of Arachin

“…This impact is specifically observed as follows: As the degree of oxidation deepens, the carbonyl content of arachin gradually increases (from 3.629 to 9.894 nmol/mg), while the levels of both total sulfhydryl and free sulfhydryl show a corresponding gradual decrease (23.665 and 5.534 nmol/mg, respectively). The reason may be that the high activity of free radicals enables proteins to be oxidized directly, which causes the breakage of polypeptide chains and the formation of carbon based cross-links via covalent bonding with side-chain free radicals [17]. Therefore, these indicators can serve as important markers in reflecting the degree of protein oxidation [19,38,39].…”

“…The modified method of Li et al [17] was used for the oxidation experiment. A protein solution with a concentration of 10 mg/mL was prepared using a 0.01 mol/L pH 7.4 phosphate buffer.…”

“…Peanut (Arachis hypogaea L.) is recognized as a high-quality food ingredient due to its protein content of up to 22-30%, lack of anti-nutritional factors, and complete amino acid profile, as well as its distinctive flavor [15]. Arachin, which accounts for about 44.3-62.7% of the total content of peanut protein, plays a crucial role in the thermal, immune, allergenic, and physicochemical properties of peanut protein while functioning as an essential storage protein during seed development and germination [16][17][18]. The high unsaturated fatty acid content in peanut kernels makes peanut protein highly susceptible to oxidation.…”