Effect of Methods of Extraction on Physicochemical Properties of Soy Proteins (Tofu)
Soy proteins can be extracted using different protein coagulants. This study focused on the modifications of soy proteins from soymilk brought about by using citric acid, alkalined citric acid and the salt magnesium sulphate. The objective of this investigation was to determine the suitable levels of the extractive coagulants for production of a soy protein food (tofu); thus three different types of tofu were produced. Tofu properties evaluated were: yield, protein concentration, moisture, texture and colour with respect to the levels of coagulants. The main results showed that the yield of fresh tofu from magnesium sulphate at 10.4% produced the highest yield followed by citric acid and alkaline treated citric acid at concentration of 3% with no significant difference between the two acidic methods. On dry weight basis there were no significant variations in the protein yield of tofu with respect to the coagulants. The moisture content of the various coagulates varied significantly. Tofu from magnesium sulphate coagulation had the highest moisture content. The texture of tofu varied with the method of protein isolation. The salt precipitated proteins showed the highest textural indices such as softness, chewiness and springiness as compared to the acidic methods which also produced lighter tofu in colour. It can be seen that the three methods produced tofu with different physicochemical properties.
Soy Protein, Magnesium Sulphate, Citric Acid, Tofu and Texture
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