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【答案】应助回帖
ljzm(金币+90, 翻译EPI+1): 2011-10-28 09:35:06
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When pH is deviated from the isoelectric point of potato protein, which is that pI equals to 7, the charge on protein itself and static electricity repulsion increase. So it resulted in decrease in amount of attached protein on unit area of gas-liquid boundary, increase in repulsion force between bubbles, increase in interspace of bubbles, and increase in thickness of liquid membrane. Also the static electric repulsion between charged molecules as well as ions in interspace liquid and protein attached on gas-liquid boundary, which makes liquid in membrane hard to drain into Plateau boundary layer and liquid hold of foam increases, so the enrichment ratio decreases and recycling ratio increases. On the other hand, when pH is on the isoelectric point of potato protein, the static charge on protein is zero and repulsion between molecules decreases and attached amount of protein on gas-liquid boundary increases. Meanwhile, the repulsion between bubbles decreases and liquid in membrane can drain into Plateau boundary layer quickly. Moreover, the liquid could drain quickly to wall of inner spinal structure under force of gravity and centrifuge. Therefore, the liquid hold of foam is lower while enrichment ratio increases, and volume of collected bubble-free liquid decreases and recycling ratio of protein decreases. |
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