Tofu Moisture Content

Table 2 shows the pH, °Brix value, moisture and ash content of the unfried and fried tofu. From the results, we can see that the pH of all fried and unfried tofu was around 6. This is in expectation as tofu is categorized as low acid food (Ryan, 2015). The pH of tofu is in the range of 5.8 to 6.2 (Kim, Son, & Han, 2004). Therefore, tofu is highly perishable and easily spoiled as this pH range is very suitable for the growth of pathogens. Besides, this indicates the tofu we made is in fresh and edible condition. Tofu contained siako and GDL (formulation 2) had the highest pH, followed by formulation 1, formulation 3 while tofu contains only GDL (formulation 4) had the lowest pH value before and after fried. Siako is a type of salt coagulant

The standard moisture content of fresh soft tofu is about 89% (Hou et al., 1997). The moisture content of regular tofu should be less than 88% (Shurtleff & Aoyagi, 2001). All tofu we made had less moisture content than standard value due to different processing method, ingredients used and the variety source of soya bean. According to Table 2, for both unfried and fried tofu, formulation 1 had the lowest moisture content while formulation 2 had highest moisture content. Coagulants used in making tofu can bring variation in moisture content due to different coagulating properties and gelling network formed resulting different water holding capacity in tofu (Shokunbi et al., 2011). The results show that tofu with siako (formulation 1) had weaker ability to trap moisture while combination of siako and GDL (formulation 2) had a great ability to trap moisture. Moisture content of all formulations tofu dropped after deep fried. This is due to moisture evaporated from the tofu to atmosphere during heating. Loss of moisture is correlated with the water holding capacity of tofu. From the results, formulation 1 tofu lost greatest amount of moisture while formulation 4 lost least moisture after fried. Hence, we can say that tofu with siako has weaker water holding capacity while tofu with GDL has higher ability to hold water during

For unfried tofu, formulation 1 tofu had highest ash content, followed by formulation 2, 4 and lastly formulation 3. For fried tofu, formulation 1 tofu had highest ash content, followed by formulation 2, 3 and lastly formulation 4. Results show that addition of siako to tofu (formulation 1) increases the ash content more than addition of GDL (formulation 3 and 4). This might be due to siako contains more micronutrients than GDL (Shokunbi et al., 2011). Siako is a salt which contains mineral ions such as calcium thus increase the ash content (Sidar et al., 2012). Frying the tofu increase the ash content of tofu for all formulations as the ash value in all formulations fried tofu is higher than their respective unfried tofu. This might due to the absorption of mineral ions by the tofu from the surrounding frying oil during frying