The Influences Of Storage Conditions On Functionalities Of SPI

The SPI was applied in food industry widely, but the functionalities of it may change during storage. The effect of store temperature, time, RH and package material on SPI functionalities such as solution, emulsification, oil absorption, water absorption and gelation property were studied, when SPI was packaged in 100% N2 and Al,80%N2:20%CO2 and Al, 60%N2:40% CO2 and Al, vacuum and Al, white paper/plastic/HDPE, and PE and then stored for 5 months in the conditions of RH 80%,30℃, RH 65%,25℃,4℃,-20℃～-18℃and naturally.It was shown that the 7S/11S of SPI only packaged in PE and stored in high temperature and RH for 4 months decreased significantly(p<0.05), while the subunit of SPI would lost in different levels and obviously in PE. It was observed by SDS-PAGE that in all storage, the subunit of SPI disaggregated and molecules aggregated.Focus on the sulfhydryln group and disulfide bond, it was found that the content of sulfydryl decreases while disulfide bond increased. They both changed slightly in inflatable and vacuum packaging but sharp in PE packaging. The lower was the temperature, the slighter decreased the content of-SH and sharper increased the-S-S-. The content of-S-S-increased slower in the freezing condition than in the cool temperature.The N2 in the inflatable packaging could enhance the solubility, emulsibility and gelation property of SPI rapidly and delay the decreasing of water absorption in the condition of high, ambient temperature and RH and natural with short storage. In the storage, the lower was the N2 percent and the temperature and RH, the more stable was the functionalities. Comparing the functionalities of SPI with different packaging material, it was shown that the sequence of the barrier property of material to T and RH was Al packaging>factory packaging>PE packaging.The solubility, emulsibility and gelation property of SPI improved in the cool and frozen condition. The decreasing of water absorption was delayed. The functionalities of SPI with PE packaging enhanced obviously. But with the time going, they decreased, except for the SPI in 60%N2:40%CO2 and Al packaging.It has been showed that N2 could improve the oil absorption of SPI significantly and then keep it stable even as the time, ambient temperature and RH, content etc.. The oil absorption of SPI with PE packaging and 3 months storage of high temperature and RH decreased significantly, and other four storage conditions, packaging material and ambient condition had little relationship with it.Analysis by relatedness, it was shown that the 7S/11S of SPI with PE packaging storage only in high T and RH was significantly positive correlation with oil absorption, but not with solution, emulsification, water property and gelation property. In the five storage pattern, the content of-SH with PE was significantly positive correlation with emulsion stability and water absorption, but the content of-S-S-was significantly negative correlation with them. The-SH of SPI in 60%N2:40%CO2 inflatable Al packaging was significantly positive correlation with water absorption and negative correlation with oil absorption, the-S-S-was negative correlation with water absorption but positive with oil absorption.