• Applied Biological Chemistry
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• v.35 no.6
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• pp.490-494
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• 1992

The effect of heat treatments (boiling or microwave heating) on packaged Tofu was investigated by microbial and physicochemical changes during its storage in order to improve the shelf-life. The shelf-life of the packaged Tofu prepared by acetic acid was found better than that prepared by calcium chloride. As the spoilage of Tofu developed, titratable acidity, amino and ammonia nitrogen contents, and optical density of packaged Tofu suspension were increased. Heat treatment of fresh Tofu in package was effective in lowering the bacterial counts, and extending shelf-life, but there was no significant difference between heating methods. Packaged Tofu prepared from acetic acid and pretreated by heating for 3 minutes kept the shelf-life of 4 days at $30^{\circ}C$, but that without heat treatment spoiled at one day.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.3
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• pp.455-459
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• 2001

Tofu (soybean curd) was made with whole soybean flour (WSF, 420 mesh) by various processing conditions of water addition ratio, heating time, coagulation temperature, molding pressure and 0.3% of mixed coagulant (CaSO₄:GDL=50:50(w/w)). Yield content of WSF-tofu was the highest in processing condition of 85℃ coagulation temperature, 10 times water addition, 5min. heating time and 25.00 g/㎠ molding pressure. As the increase of the water addition ratio from 8 to 14 times (water:WSF, v/w), Hunter's L and a values were increased. Raising of heating time (100℃, 1, 5, 10 and 15 min), a and b value were increased. Textural properties of WSF-tofu were significantly affected by coagulation temperature (75, 80, 85 and 90℃). Hardness was increased, but adhesiveness and cohesiveness were decreased. heating time was influenced on harness of WSF-tofu, but water addition ratio was not affected on hardness of WSF-tofu. Increasing of molding pressure (16.83, 25.00, 33.22 and 41.67 g/㎠, 1 hr) was resulted from a increased hardness, gumminess and chewingss of tofu, but adhesiveness was addition ratio, 5 min heating time and 25.00 g/㎠ molding pressure recorded the highest score in sensory evaluation test.

• The Korean Journal of Food And Nutrition
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• v.27 no.2
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• pp.302-309
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• 2014

In this study, the characteristics of soybeans with different cultivation methods depending on their origins and the properties of tofu made from these soybeans were studied. The isoflavone content was higher in the general Korean soybeans compared to the organic American soybeans. There were no significant differences among the Chinese soybean samples, so the cultivar method was considered to have a greater effect on the isoflavone contents rather than the cultivation method. The protein contents were higher in the tofu made from the general Chinese soybeans and the organic Korean soybeans. Furthermore, the tofu made from the organic Chinese soybeans contained the least amount of proteins. Isoflavone contents were not significantly different among the samples. Texture profile analyses consisting of hardness, cohesiveness, adhesiveness, springiness, and gumminess were all shown to be higher in the organic tofu than in general tofu, with the exception of adhesiveness. In sensory evaluation, color and texture were significantly different according to the samples, and the differences were found to be affected more by the origin of soybeans rather than the cultivation methods. According to this study, the physicochemical properties of the soybeans and tofu seemed to be influenced by the cultivation region rather than the methods.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.158-163
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• 2007

The compositions of tofus made with Baktae and Huktae were compared to those made with other respective types of soybeans. The lipid and protein contents of Baktae were 20.8% and 39.7%, while those of Huktae were 15.8% and 41.1%, respectively. In both soybean types, linoleic acid(18:2), oleic acid(18:1), and palmitic acid(16:0) accounted for more than 80% of the total fatty acids. The tofu made from Baktae was whiter than the tofu made from Huktae, as exhibited by a higher Hunter's L-value. The lipid content of the Baktae tofu(4.41%) was higher than that of the Huktae tofu(3.26%). The amino acid compositions of the Huktae and Baktae tofus were similar, with glutamic acid and aspartic acid being the most abundant amino acids in both tofus. However, the content of the limiting amino acid, methionine, increased 2.5-fold in the tofus as compared to the soybeans, on a per gram protein basis. Isoflavones were lost during tofu making as contents for the tofu were 20${\sim}$25% of those for the soybeans.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.1
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• pp.161-166
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• 1999

CaCl2 and water soluble degraded chitosan mixtures were used as coagulants for extending the shelf life of tofu. Microbial counts, pH, and turbidity in tofu immersion solution were analyzed during the periods of storage at 4oC and physico chemical properties of tofu were determined by rheological properties, color and yield. There was no significant difference in moisture content and yield between tofu made with and without chitosan. Failure stress and stress relaxation values were reduced when chitosan was added to CaCl2, but there was no significant change among contents of chitosan added to tofu. The pH values were decreased at the beginning and then slowly increased after 14 days storage. The changes in turbidity were increased during storage, but the change in 2.0g degraded chitosan mixture with 7.0g CaCl2 coagulant(2.0:7.0 ratio) was lower than others and initial turbidity was lower as much as chitosan added to coagulant. These data showed that the water soluble degraded chitosan had a good anti microbial effect and increases the shelf life of tofu.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.833-839
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• 1998

Hwangkeum Kong was stored at 5$^{\circ}C$, $25^{\circ}C$ and 35$^{\circ}C$ for 8 months to investigate the changes of the suitability for Tofu processing. The properties of Tofu prepared with the soybeans stored at 5$^{\circ}C$ for 8 months showed no significant differences from the non-stored control soybeans. However, soybeans stored under high temperatures showed low yield, water holding capacity and Sag value of Tofu Compared with the soybeans stored at 5$^{\circ}C$ for 8 months, fracturability in the texture of Tofu significantly increased when the soybeans had been stored at $25^{\circ}C$ and 35$^{\circ}C$ for 8 months, while hardness, cohesiveness, adhesiveness, elasticity, gumminess and chewiness decreased. The color of Tofu changed from pale yellow to brown depending on high temperature and long-term of storage. The Tofu prepared with the soybeans stored under high temperatures was significantly different in sensory evaluations from the non-stored soybeans as well as from the soybeans stored at 5$^{\circ}C$ for 8 months in color(p<0.01), texture(p<0.05) and taste(p<0.05).

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.116-122
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• 1990

In order to improve the shelf life of Tofu, the effect of calcium chloride or acetic acid as coagulants were investigated for microbial and physicochemical changes during the storage in different kinds of soaking solution. The soaking water of Tofu prepared from calcium chloride was found to be spoiled after 15-17 hours of storage at $30^{\circ}C$, by reaching the bacteria count to 10million per ml. The shelf life of the Tofu prepared from acetic acid was better than those prepared by calcium chloride. For the effect of soaking solution on storage life, soaking Tofu in 0.1% acetic acid was found to be more effective than soaking in other solutions of 3% NaCl or 0.1% K-sorbate. The optical density of soaking solution of Tofu increased in proportion to spoilage, and in case of soaked Tofu in 3% sodium chloride and 0.1% K-sorbate solution, it greatly increased. Titratable acidity, and amino nitrogen contents in soaking solution increased as spoilage of Tofu progressed, but pH decreased the early period, one or two days, of stored Tofu and then increased.

• Food Science and Preservation
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• v.10 no.1
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• pp.41-46
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• 2003

To prove the extension of shelflife of soybean curd(Tofu) steeped in the diluted solution of botanical antimicrobial agent and stored at 20$^{\circ}C$, such chemical ＆ microbial properties as the contents of moisture, crude protein and crude fat, colony count and surface color of Tofu were investigated in comparison with the control. Tofu treated with botanical antimicrobial agents showed higher contents of moisture, crude protein and crude fat compared to those of the control Tofu through all the storage period. After 7 days of the storage period, cell count of coliform bacteria reach 75 x 103CFU/m1 in the control Tofu, whereas 13∼39 CFU/ml in Tofu treated with botanical antimicrobial agent Treatment of Tofu with botanical antimicrobial agent seemed to be a potential method to prolong the shelflife of processed Tofu.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.77-83
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• 2008

This study investigated the quality of tofu prepared by treating soybean milk with deep seawater as a coagulant. The quality and shelf-life of the tofu prepared using the deep seawater coagulant were determined and compared to those using $CaSO_4$, surface seawater, and intermediate seawater coagulant. The tofu made with the deep seawater coagulant was firmest. In addition, the deep seawater tofu product had more, smaller particles in the microscopic view, compared to the tofu made from surface and intermediate seawater coagulants. The deep seawater tofu product had the lowest viable cell counts and turbidity. In addition, the deep seawater tofu product had a longer extended shelf-life. From these results, deep seawater appears to improve the texture, taste, and shelf-life of tofu when used as a coagulant.

• Journal of Dairy Science and Biotechnology
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• v.38 no.4
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• pp.222-229
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• 2020

This study was conducted to develop a novel cheese tofu hybrid product by increasing the calcium content of cheese, an animal protein source, and tofu, a vegetable protein source. Both pH and moisture were lower in the cheese tofu hybrid than those values in the control group (6.03% and 72%, respectively). Protein and fat were slightly higher than in the control (15.43% and 9.91%, respectively). Total bacteria count increased at the end of the product's shelf life, but did not affect its texture. The cheese tofu hybrid displayed stronger a) red, and b) yellow coloration than the control, and its lightness (L) was lower than that of the control. The cheese tofu hybrid possessed high hardness, and displayed high values for gumminess and brittleness. Sensory evaluation by a specialized agency examined consumer preferences, purchase intentions, strengths, and weaknesses of the developed product line. A panel of 30 female volunteers in their 20s and 40s recorded an overall preference for cheese tofu of 5.40 points, fairly good. Cheese tofu was found to be better than the control tofu, with appealing differences in appearance, color, nutty aroma, chewiness, and cheese flavor.