Abstract:

During storage and transport, the functional characteristics of soy protein isolate (SPI) may deteriorate, which impacts its industrial applications. In the present study, different packaging ways: packaging in aluminium foil bag vacuumed or filled with 100% nitrogen gas or a mixture of nitrogen gas and carbon dioxide (4:1 or 3:2, V/V), practical industrial packaging (packaging with white paper/plastic/high density polyethylene, HDPE) and polyethylene (PE) packaging were used to package SPI, followed by 5-month storage in high temperature (30 ℃) and humidity (80%) environment in order to address the effects of storage environment and period and packaging conditions on the 7S/11S ratio, sulfhydryl group content, disulfide bond content and solubility of SPI. Nigtrogen-filled packaging promptly increased the solubility of SPI and was beneficial to better maintenance of the functional characteristics of SPI. Comparatively, aluminium foil packaging was the best barrier to humidity, followed by practical industrial packaging and PE packaging. The 7S/11S ratio of PE packaged SPI had no significant correlation with its solubility, but there was a significant positive correlation between its sulfhydryl group content and solubility.

Key words: soy protein isolate (SPI), storage, solubility, packaging