| Summary: | 碩士 === 國立嘉義大學 === 食品科學系研究所 === 104 === The study aimed to investigate the effect of different mixture ratio and amount of compound coagulants added on the quality characteristics of black soybean tofu. In pre-testing, properties of tofu prepared from green-cotyledon (TN3) and yellow-cotyledon (TN5) were compared. Tofu made from TN5 had higher yield, higher water content and better structure. Therefore, TN5 was chosen as the raw material for tofu preparation in the study. In the first part of the study, five black soybean tofu experts were phone-interviewed and six commercial black soybean tofu products were analyzed for physical properties, textural and sensory characteristics, in order to find out the properties of commercial black soybean tofu products and sensory preferences of consumers. One of the shortcomings of black soybean tofu is poor in taste and which was improved in the follow-up studies. In the second part of the study, tofu prepared by three kinds of commercial coagulants, i.e. magnesium chloride (MgCl2), calcium sulfate (CaSO4) and glucono-δ-lactone (GDL), and the optimal amount added and the mixture ratio of compound coagulants was determined by investigating on the physical properties, ABTS+∙ free radical scavenging ability, texture and sensory properties as well as the microstructure of black soybean tofu prepared. The results showed that, as compare to the rapid-acting coagulant (MgCl2), the water content and yield of tofu became higher, and the whey loss was lower when increasing the added ratio of the slow-acting coagulants (CaSO4 and GDL). Moreover, the scores of most sensory properties including appearance, springiness, hardness, chewiness and overall preference were higher as well. In addition, amount of coagulants added up to 0.4% with mixing ratio of the slow-acting coagulants raised would led to higher textural properties, such as hardness, cohesiveness, gumminess and chewiness. However, the springiness and resilience were higher as mixing ratio of rapid-acting coagulant increased. Furthermore, the microstructure of tofu made by slow-acting coagulants had uniform pores and finer structure, while opposite result was obtained by using rapid-acting coagulants. Thus, this study suggested that mixing ratio and amount of compound coagulants added had significant effect on the quality of black soybean tofu.
|
|---|
