低温等离子快速提高糖基化花生分离蛋白溶解性及乳化性.

Peanuts known as important oil crops are widely planting for a high yield in China. As an energy dense food, peanut contains a large amount of fat, proteins, carbohydrate, vitamins, minerals, and phytochemicals. Peanut protein is one of valuable byproducts from the oil extraction due to its excellent nutritional source of high-quality protein, while a low dose of anti-nutritive factors. However, low aqueous solubility and emulsification occurred in peanut protein compared with soybean protein. It is necessary to improve the functional properties of peanut protein for the better applications in food industry. Recently, protein glycation has become a safe method most commonly used to produce non-health-hazardous byproducts during protein modification. Protein glycation involves the formation of covalent bonds between proteins (free amine groups, i.e., terminal or side chain) and polysaccharides (reducing terminal carbonyl group) via the Maillard reaction. This study aims to improve the solubility of Peanut Protein Isolate (PPI) using Non-Thermal Plasma (NTP) treatment for glycation of peanut protein isolate–dextran. NTP has become an emerging technique to treat many high energy radicals, such as atomic oxygen (O), superoxide (O2 ·-), nitric oxide (·NO), and hydroxyl radicals (·OH), while the treatment can be fast, nonthermal, operationally flexible, and nonhazardous. During treatment, these obtained particles can break the covalent bonds to trigger various chemical reactions. Therefore, an experiment has been conducted to investigate the effect of NTP treatment time (0、0.5、1.5、2.0、 3.0 min) on the glycation of PPI and Dextran (Dex). Under the NTP power of 70 W and solution temperature of 60 ℃, the Degree of Grafting (DG) of PPI-Dex increased with the extension of NTP treatment time, where the maximum DG of PPI-Dex was 21.62% at 1.5 min. The grafting time of PPI-Dex was greatly reduced, when compared with ultrasonic grafting of 40 min, and the traditional wet grafting of 24 h. After PPI-Dex grafting, there was a remarkable increase in the solubility and emulsification of PPI-Dex conjugates, where the solubility increased by 22.28% compared with that of untreated. A systematic analysis has been carried out to measure molecular weight, amino acid content, infrared spectrum and protein surface hydrophobicity index (Ho), in order to evaluate the effects of NTP treatment on the structure and functional properties of peanut protein. Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis confirmed the coupling of PPI with dextran to form conjugates. The amino acid content analysis revealed a decrease in the content of lysine and phenylalanine, indicating that lysine and phenylalanine can be involved in glycosylation during NTP treatment. Fourier Transform Infrared (FTIR) showed an increase in the absorption of the characteristic hydroxyl peaks at 3 000-3 500 cm-1 and 1 000-1 260 cm-1 of PPI-Dex grafts, when NTP treatment time at 1.5 min, compared with that of untreated, and a decrease in the content of α-helix and β-sheets, while an increase in the content of β-turns. A significant decrease in Ho of PPI indicated the increase of hydrophilicity of PPI surface. This variation in the reaction can attribute to the alteration of PPI structure from compact/hydrophobic to dense/hydrophilic during NTP treatment. When PPI was glycosylated with Dex, the reaction sites can be lysine and phenylalanine. The finding demonstrated that the NTP method can be successfully applied to accelerate the graft reactions of peanut protein isolate for the peanut food production. [ABSTRACT FROM AUTHOR]