Physicochemical and functional properties of egg white peptide powders under different storage conditions

This study aims to evaluate the effects of different storage conditions (temperature and relative humidity) on the physicochemical and functional properties of egg white peptide powders (EWPPs). The samples (EWPPs) were stored for 28 d under four conditions (4 °C, 50% RH; 4 °C, 75% RH; 25 °C, 50% RH; 25 °C, 75% RH). Results showed that storage temperature and relative humidity had a significant effect on the physicochemical and functional properties of EWPPs. The contents of antioxidant amino acids such as histidine, tyrosine, tryptophan, and lysine were reduced significantly under different storage conditions, which resulted in the decrease of the antioxidant activity of EWPPs. Circular dichroism spectroscopy analysis indicated that the secondary structure of EWPPs changed from the regular structure to the irregular coiled structure during the storage. Additionally, the hydrophobic groups of the EWPPs originally embedded inside the molecules were exposed to the surface of the molecules during the storage, which led to an aggregation of EWPPs molecule and a decrease in solubility of EWPPs. The aggregation of EWPPs molecules resulted in a decrease in emulsification, emulsification stability, foaming ability and foaming stability of the EWPPs. Therefore, different storage conditions do have an impact on the physicochemical and functional properties of EWPPs. Lower temperature and humidity storing conditions were beneficial to retain the functional property of the EWPPs.