Screening Of Soybean Varieties Lacking Subunits And The Effect Of β-Subunit On Properties Of Soybean Products

Soybean is a good dietary protein resource.11S (glycinin) and 7S (p-conglycinin) are major components in soybean. Glycinin is consisted of acidic subunits (A) and basic subunits (B), Acidic and basic subunits formed five complexes: group I (A1aB2, A1bB1b,A2B1a) and II(A5A4B3, A3B4), P-conglycinin is consisted of a', a, and p subunits.The soybean protein subunit compositions of more than 1624 varieties were analyzed by SDS-PAGE and western-blotting methods in this study, and the lacking extent of the p subunits was analyzed and identified. The effect of p subunits on soybean process properties were used the low or lacking p subunits soybean as materials.The results, showed that there were many native aberrant materials which having low content of or lacking A3, A, γ,β subunits among the soybean varieties in China, and the special soy variety lacking p subunits was found for the first time. The results of the western-blotting analysis confirmed this result. The result of amino acid analysis of the variety lacking the p subunits showed that the suit-ammo acid content was high in this variety.The extraction states of protein in soymilk prepared with the varieties of different p subunit content were investigated. The results showed that the relative content of the protein particles in soymilks prepared with lacking p subunit was higher than the common obviously, and the protein particles were more sensitive to the coagulate. Reaction caused by the calciulmion and hydrogenion. However, as the increase of the content of p subunit, the protein particles in soymilk decreased gradually. The constitutes of protein particles in soymilks prepared with varieties containing different p subunit content were analyzed by SDS-PAGE, the results showed that the more p subunit in soymilks, the more p subunit content in protein particles, and the less basic subunit content. Keeping the protein concentration constantly, the p subunit content in soymilk was adjusted by soy protein riched p subunit, and the textural characteristics of tofu gel prepared with adjusted soymilk were analyzed, the results showed that the hardness and springiness of tofu gel decreased with p subunit content increasing, the whole texture characteristics such as the hardness and the flexibility of the tofu gel decrease. The functional properties of various SPI were investigated, the results indicated that the variety lacking p subunits showed the lower gel textural propeties and emulsified stability. As the results above, the p subunits have important effect on exist state of the protein and the gel network during the soybean process.