Application of steam explosion for preparing high value-added antioxidants from eggshell membrane waste

Eggshell membrane (ESM) is primary considered as food industry discard due to its highly insoluble structure. In this study, steam explosion was exploited to improve the utilization of ESM and convert it into high-valued antioxidants. An increase in dissolution rate of ESM to 66.67%-219.05% was detected, along with decrease in disulfide bonds and cysteine/cystine level induced by the steam explosion. After steam explosion pretreatment, DPPH radical scavenging rate and total antioxidant capacity of ESM hydrolysate (ESMH) were maximally increased by 87.48% and 103.09%, respectively, indicating an overwhelming advantage than unpretreated hydrolysate. Furthermore, ESMH exerted strong synergistic antioxidant activity with gallic acid (GA). Importantly, ESMH-GA mixture protected UVB-injured L929 cells by reducing reactive oxygen species and could be potentially used as antioxidant ingredients in cosmeceutical foods. This finding provided an efficient recycling strategy and direction for ESM utilization. Industrial relevance: Steam explosion is a new green and efficient processing technology. ESM with low solubility is an underutilized byproduct. This study applied steam explosion to ESM and significantly improved antioxidant activity of its hydrolysates (ESMH). ESMH protected UVB-injured L929 cells by reducing reactive oxygen species and could be potentially used as antioxidant ingredients in cosmeceutical foods. Steam explosion has the potential to be used to high-value utilization of ESM.