Dynamic Changes Of Rapeseed Protein During Seed Germination, Development, Aging And Its Variation Of Physical, Chemical,Functional Properties

Rapeseed is one of the important oilseed crops Its protein has a well-balanced amino acid composition and is a potential protein source with excellent quality.The rapeseed quality and seed aging have close effects on the development and utilization of the seed protein.In this study,with the purpose of providing a theoretical basis for improvement and comprehensive utilization of rapeseed protein,sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE) condition of rapeseed major storage protein subunits was optimized with the variety of Xiangzayouyihao,Xiangzayouerhao and so on,and protein dynamic changes during seed germination,development and aging were investigated with the variety of Qinyouqihao.The experimentation results were as follows:1.Under the condition of crosslinking degree and separating gel concentrations of this research,the resolving effect ofα₁,α_2/3,α₄ could not be greatly affected by change of gel diameter.Under 13%resolving gel concentration and the crosslinking degree of 3%,4%, 5%and 6%,although all fraction subunits of 12S could be resolved clearly,the subunits of 2S run over separation gel when bromophenol blue reached the platinum gold wire. Under 17%resolving gel concentration and the crosslinking degree of 3%,4%,5%and 6%,the subunits of 2S appeared the 'pull-tail'.Comprehensive consideration,the crosslinking degree of 3%,4%,5%and resolving gel concentration of 15%should be the best choice to obtain the good resolving effect of subunits of 12S and 2S fractions.2.The major storage protein subunits of rapeseed rapidly degraded after germination of two days,but did not degraded completely until death of the seedling at the germination of 7th days.3.During seed development,the water content decreased from 81.61%to 23.22%.The content of oil,protein,soluble protein increased from 0.26%to 31.38%,1.1%to 21.36%, and 0.63%to 12.21%,respectively.The accumulation of 12S fraction started earlier than that of 2S fraction.The correlations between the activity of PEPCase and the protein content,oil content were found during different stages of seed development,the negative correlations between the activity of PEPCase and oil content/protein content ratio,12S content,α_2-3 content,α₄ content,β₂ content,β₃ content,andβ₄ content were found;no correlation between the activity of PEPCase and 2S fraction content and its subunits was found.4.Under the treatment of two aging method,the decrease of surface hydrophobicity, sulphydryl content,water holding capacity,oil holding capacity,gel texture properties were distinctly found after dealing of 1 d or 5 min;the nitrogen solubility index changed with change of pH;Foaming capacity decreased dramatically after dealing of 2 d or 10 min. Significance analysis showed that the effects of treatment time of both methods on protein properties were found significant except for free sulphydryl content.The effects of two methods on protein properties were found significant except for foaming capacity and foaming stability under some concentrations of pH.The effect of pH on protein properties was also found significant.