Properties Of Tofu Research Articles

Properties of soya milk and tofu prepared with γ‐irradiated soya beans

AbstractSoya beans (Glycine max) ‘hwang keum’ were γ‐irradiated at dose levels of 0, 2.5, 5, 10 and 20 kGy and the effects of the irradiated soya beans on soya milk and tofu properties were studied. An irradiation dose of 5 kGy caused an increase in yield of soya milk and tofu while having very little effect on their quality. The properties of tofu prepared with the soya beans irradiated at 2.5–5 kGy showed no significant difference from the non‐irradiated control. However, at higher doses (10–20 kGy), decreases in yield, water holding capacity and sag value of tofu were observed. Compared with the non‐irradiated control, hardness and fracturability in the texture of tofu were both significantly increased when the soya bean had been irradiated at 10–20 kGy, while cohesiveness and adhesiveness decreased. The changes in color values of soya milk and tofu were pronounced at 20 kGy.

Micronization Effects on Composition and Properties of Tofu

ABSTRACTThe effect of infra‐red heating (micronization) was investigated on the composition and textural, biochemical and nutritional properties of soymilk and tofu. The yield, protein content and textural properties of tofu made from micronized beans using the common procedures (70°C as coagulating temperature and CaSO42H 2O as coagulating agent) were lower than those of tofu from unprocessed beans; tofu prepared from micronized beans and coagulated at 90°C using a mixture of citric acid (0.01M) and calcium sulfate (0.03M) showed improved characteristics. The microstructure of tofu prepared from micronized beans lacked the regularity of the honeycomb‐like structure shown by tofu from unprocessed beans. The heat treatment by micronization had little effect on the protein components of soymilk and tofu as determined by polyacrylamide disc gel electrophoresis.

Studies on Coagulation Process of Soymilk in "Tofu" and "Kori-tofu" Manufacture. Part 6. Relationships of Coagulation Characteristics and Properties of "Kori-tofu" in a Controlled Soymilk Coagulation System.

A controlled coagulation system applying torque measurement was developed in order to investigate the related factors. From the characteristic rise of torque curve, proper amounts of coagulant could be determined automatically. The coagulated soymilk reacted with steadily added calcium chloride by this system, molded to intermediate and then frozen and dried to final product kori tofu. The optimum coagulation conditions were precisely examined at the various reaction conditions of concentration of soymilk, reaction temperature, and concentration of coagulant. The relationships between the torque changes and the properties of tofu and kori-tofu were also investigated.Through a series of coagulation and pressing experiments with this new system, following results were obtained. (1) Determination of the required amount of coagulant as well as the on-off control of stirring of soymilk are performed automatically. (2) The optimum initial concentration of soymilk was around 5% from the view point of water holding capacity of the dried kori-tofu. (3) The higher temperature, between 54 and 70°C, shortened the pressing time, hardened the tofu curd in one hand and decreased the water holding capacity of kori-tofu in the other. The optimum temperature was 60 to 65°C. (4) The optimum concentration of calcium chloride was around 10mM in the present experimental conditions.These findings contributed to the semi-automated processing and the products of fine properties.

Soymilk and tofu properties as influenced by soybean storage conditions

AbstractSoybeans were stored at two temperatures, 20°C and 30°C, and two relative humidities, 65% and 85%. The amount of protein extracted into soymilk decreased by about 14% of the initial extractability in all cases after eight months of storage. The decline in protein extract‐ability could not be explained by decreases in pH, nor by loss of solubility of certain protein components. Tofu made from beans that were stored at 85% relative humidity became less uniform in microstructure toward the end of the storage period. The volume of whey produced increased with bean storage time.

Optimization of yield and properties of silken tofu from soybeans.

SummaryThe extraction phase of the preparation of silken tofu was investigated and the ratio of beans:water was shown to be very critical in terms of the amount of protein extracted and the properties of the tofu. In the range 9–14:1, 10:1 gave the best result. Extraction at 8:1 and making up to 10:1 gave much poorer results, but maceration at 8:1 followed by a further extraction at 2:1 gave a better quality tofu. The time of maceration was shown to have a pronounced effect on the amount of protein extracted.

Effect of Boiling Treatment of Soymilk on the Composition, Yield, Texture and Sensory Properties of Tofu

Soymilk was boiled for 0, 12, 30 and 60min before coagulation with CaSO4 to make tofu, and a texture profile analysis was performed on the product obtained. Hardness and gumminess increased slightly up to 12min of boiling but decreased significantly after 30min and 60min of boiling the soymilk. Chewiness decreased significantly after 30min and 60min of boiling. Springiness was not affected by boiling. Cohesiveness increased slightly after 12min boiling and then decreased slightly but not significantly after 30min and 60min of boiling. Composition and sensory qualities of tofu were not significantly affected by the length of time soymilk was boiled prior to coagulation.

Effect of Coconut Cream Addition to Soymilk on the Composition, Texture, and Sensory Properties of Tofu

ABSTRACTCoconut cream was added to soymilk at 0, 4.7, 9.0, 16.6, 33.3, and 50% levels prior to coagulation with calcium sulfate. The protein and moisture content of the tofu decreased while fat increased with increasing levels of added coconut cream. The percent yield of tofu did not increase up to 4.7% added coconut cream but increased significantly when 9.0% or more coconut cream was added to soymilk. Hardness, springiness, cohesiveness and gumminess were increased by low levels of added coconut cream and decreased with high levels of coconut cream. This simple technology of coconut cream enrichment increased the caloric density of the tofu without affecting its acceptability.

Effects of Heat and Ionic Strength Upon Dissociation‐Association of Soybean Protein Fractions

ABSTRACTThe effects of heat and ionic strength upon dissociation or association of soybean proteins were characterized by an immunoelectrophoresis. Among thermal products of both glycinin and β‐conglycinin, the dissociated subunits of β‐conglycinin retained their antigenic reactivities, while the thermal products of glycinin lost their antigenic reactivities. Appearance of immunoprecipitin arcs was dependent on the ionic strength of the solutions. This is based on the conformational changes at the ionic strengths below 0.1 where the thermal denaturation of β‐conglycinin transforms from association to dissociation. The immunoelectrophoretic results can be used to determine the ionic strength of the solution in complex systems including whole soybean extracts and soybean milk. Relationship between the differences in textural properties of tofu and conformational changes of soybean protein is discussed.

Food Processing Characteristics of Soybean Proteins

Relation between sulfhydryl groups in soybean proteins and the physical properties of tofu was studied. Changes in the amount of sulfhydryl groups by heating or treatment with urea were more rapid in 11S protein as compared with 7S protein. Moreover, by changing the amount of sulfhydryl groups in proteins by N-ethylmaleimide, 2-mercapto-ethanol and dithiothreitol, the physical properties of tofu from 11S protein were more significantly effected than that from 7S protein. Namely, tofu-gel from I1S. protein got harder and stronger as the amount of sulfhydryl groups increased. The results may suggest that tofu prepared from 11S protein has more disulfide bonds in its gel than that from 7S protein.

Statistical Observation on Physical Properties of Tofu

Statistical Observation on Physical Properties of Tofu