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Application of Gypsum (Calcium Sulfate) in Soybean Products
The difference between gypsum and other coagulants
The hardness and chewiness of tofu made with gypsum are lower than the tofu made with brine, but the yield of the tofu made with brine is lower and the water retention is poor.
The salt coagulant such as gypsum and brine is poor on the preserved effect of the isoflavones in soybeans than gluconolactone. But the gypsum is better than brine.
Gypsum is a late-setting coagulant and the solidification time is long. The tofu made with gypsum has more delicate tissue structure.
Application of gypsum in soy products
The concentration of coagulant is mainly determined by the reaction rate of coagulant and soya milk, the amount of coagulant and the quality of tofu.
When the calcium sulfate’s concentration is 0.25mol / l, the tofu’s bean curd tissue is good, coagulant and soy milk’s reaction is easier to control than brine and the mixing is relatively uniform. When the brine’s concentration is 1.9mol / l, the tofu’s bean curd tissue is good, coagulant and soy milk’s reaction is relatively easy to control and the mixing is relatively uniform. When the calcium sulfate and brine’s mixed coagulant ratio is 4: 6, the tofu will get better quality and taste.
There is no significant difference in the quality and taste of the tofu produced using the coagulant after the sterilization, but it contributes to the improvement of tofu’s quality and shelf life.
Gypsum is a late-setting coagulant and the solidification time is long. Excessive use of gypsum will remain calcium sulfate in tofu and affect tofu’s aroma and taste.
Calcium, magnesium and hydrogen can promote tofu solidification; sodium and potassium ions postpone solidification and improve pH at the same time. The calcium or magnesium salts in organic acids also improve tofu flavor.
石膏（硫酸鈣）在豆制品中的應用綜述
石膏和其它凝固劑的區別
以石膏為凝固劑制得的豆腐的硬度與咀嚼性明顯低于用鹵水制得的豆腐，用鹵水制得的豆腐出品率偏低，保水性較差[4]。
以石膏和鹵水為代表的鹽類凝固劑對大豆內異黃酮的含量保存效果沒有葡糖糖酸-內酯好，其中石膏對大豆內異黃酮的含量保存效果比鹵水好[5]。
石膏為遲效性凝固劑，它與大豆漿液中的蛋白質作用速度慢，蹲腦時間（凝固時間）長[6]，其形成的豆腐組織結構細膩[7]。
石膏在豆制品中應用注意事項
凝固劑濃度的確定主要從凝固劑與豆漿反應的速度、凝固劑的用量以及制成豆腐的質量三個因素考慮。
單獨成分的凝固劑鹵水濃度為1.9mol/l時，制成豆腐的豆花組織較好，凝固劑與豆漿反應相對容易控制，混合相對均勻。單獨成分的凝固劑硫酸鈣濃度為0.25mol/l時，制成的豆腐豆花組織較好，凝固劑懸濁液添加前需攪拌、混勻、反應相對容易控制，混合相對均勻。硫酸鈣和鹵水兩者的混合凝固劑比例在4:6時，可以制得質量和口感都比較好的豆腐[4]。
使用滅菌后的的凝固劑制作的豆腐的質量和口感沒有明顯差別，但有助于豆腐在衛生質量上的提高，相對延長豆腐的保質期[4]。
石膏是遲效性凝固劑，凝固時間長，石膏過量使用會在豆腐中殘存硫酸鈣，產品帶有苦澀味，影響豆腐的香氣、口感[6]。
鈣、鎂和氫離子可促進豆腐凝固，鈉和鉀離子推遲凝固，提高pH值可推遲凝固。有機酸的鈣或鎂鹽還能改善豆腐風味。
