Extraction optimization and antioxidant activity evaluation of se‐enriched walnut proteins

Abstract

In this study, the proteins of selenium‐enriched walnuts produced in three seleniferous areas of Enshi (Yesanguan (YS), Lichuan (LC), and Sancha (SC)) were extracted by the alkaline method. Response surface methodology (RSM) was used for the optimization of protein extraction. The total selenium (Se) content of walnut proteins was 1.3345 mg/kg in YS, 0.6219 mg/kg in LC, and 0.4219 mg/kg in SC, and about 82–85% was organic Se. The major Se speciation was selenocystine and selenomethionine. All walnut proteins showed antioxidant activities in a Se‐concentration‐dependent manner. The antioxidant activity of YS walnut was stronger than that of other proteins, which exhibited high DPPH radical (69.5%) and moderate hydroxyl radical (46.5%) scavenging activities at 1.0 mg/ml. After enzymatic hydrolysis, protein hydrolysates displayed significantly higher antioxidant capacities than undigested proteins at all tested concentrations. The overall results indicated that Se‐enriched walnuts have great potential as functional food additives for a dietary supplement. Novelty impact statement Organic selenium accounts for more than 82% of the total Se in walnut proteins, in which SeCys2 and SeMet are major organic forms of selenium. The Se content in walnut proteins is positively correlated with the antioxidant ability. Walnut protein hydrolysates exhibit better antioxidant activities than proteins.

Modulation of cecal microbiota and fecal metabolism in mice by walnut protein

“…Plant proteins are nutritionally similar to animal proteins but are more easily digestible. 35 WP is a natural plant protein with edible and medicinal value, often used in sports food, nutritional food, oral cosmetic food, food formulated for special medical purposes and health care products, with a variety of biological functions, 36 including antioxidant, 37 lipid-lowering, 38 and blood pressure lowering to prevent cardiovascular diseases, 39 and hypoglycemia. 40 In the present study, WP was extracted in large quantities from the remaining walnut meal from supercritical extraction, and its structure and its effects on cecal flora and fecal metabolic profiles in C57/BL6 mice were investigated.…”

“…4 As a high-quality protein, the utilization rate of walnut protein is extremely low in China, and the protein content of walnut meal is up to 40% or more, from which the extraction of walnut protein can significantly increase the added value of the walnut industry. 5 Numerous studies have shown that walnut protein has significant antioxidant, 6 anti-inflammatory, 7 blood pressure-lowering, 8 and sleep-improvement 9 effects. In addition, according to Elouafy et al , 10 pyruvic acid, which is present in walnuts, has the ability to perform functions of dissolution, abatement and excretion, which has a good curative effect on gallstones; walnuts are rich in vitamin E, which has a function in cosmetology.…”

Research Progress on the Preparation and Function of Antioxidant Peptides from Walnuts

“…This peptide has good application prospects in functional foods and in preventing oxidative reactions during food processing [36]. Similarly, Zhang et al showed that the DPPH and hydroxyl radical scavenging capacity of protein hydrolysates hydrolyzed by alkaline protease exceeds 60%, and the obtained hydrolysates show significantly higher antioxidant activity than the original protein [37].…”