Objectives This study aimed to show that ingesting egg white hydrolyzate (EWH) could improve antioxidant capacity and reduce mental fatigue. Two clinical trials were conducted to examine the antioxidant capacity and the fatigue reduction function of EWH. In Study 1, 19 athlete students were received a single dose of EWH (5 g/day) or placebo. In Study 2, 74 athlete students ingested EWH (5 g/day) or placebo before training for 2 weeks. Results Single dose of EWH significantly increased the antioxidant ability compared with the placebo group (p < 0.05), and there was no significant difference between the groups in the oxidative stress test results on Study 1. Two-week intake of EWH significantly decreased mental fatigue compared with the placebo (p < 0.05). This study showed that ingesting EWH improved antioxidant capacity with a single dose and reduced mental fatigue after 2 weeks of ingestion. Trial Registration Japan Medical Association Center for Clinical Trials identifier; JMA-IIA00395 (Study1) and JMA-IIA00396 (Study2), both trials were retrospectively registered on 26 October, 2018.

Objective Eggshell membranes, the thin film lining the insides of eggshells, are constituted mostly from protein (eggshell membrane protein, ESM-P). The digestibility and dietary net protein utility of ESM-P are not known. ESM-P functions as a barrier to prevent foreign matter from reaching the egg white and yolk, so it would be expected not to decompose easily by digestion when ingested. We therefore prepared a hydrolysate of the membrane (ESM-H). In this study, we assessed the digestibility and net protein utility of ESM-P and ESM-H in rats. Results The digestibility of ESM-P and ESM-H were 87.0% and 94.8%, respectively, significantly lower than that of casein (98.5%). The net protein utility values were 84.7% and 84.6%, respectively, significantly higher than that of casein (75.1%). Digestibility was significantly higher for ESM-H than for ESM-P, but there was no significant difference in net protein utility between ESM-P and ESM-H. These results demonstrated that more than 80% of ESM-P or ESM-H is absorbed and utilised in the bodies of rats.

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The flavor deterioration of mayonnaise is induced by iron, which is released from egg yolk phosvitin under acidic conditions and promotes lipid oxidation. To prevent oxidative deterioration, natural components, rather than synthetic chemicals such as ethylenediaminetetraacetic acid have been required by consumers. In the present study, we evaluated the inhibitory effects of three egg white components with the same amino acid composition, namely egg white protein, hydrolysate, and the amino acid mixture, on lipid oxidation in mayonnaise and an acidic egg yolk solution as a model system. We found that the hydrolysate had the strongest inhibitory effect on lipid oxidation among the three components. The mechanism underlying the antioxidant effect was associated with Fe-chelating activity. Thus, egg white hydrolysate may have the potential as natural inhibitors of lipid oxidation in mayonnaise.