• The Korean Journal of Food And Nutrition
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• v.35 no.6
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• pp.521-530
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• 2022

This study was conducted to compare the quality characteristics of commercial tofu products from the market in Korea. Seventeen types of commercial tofu samples were taken and their physicochemical properties, including soluble solid contents, salinity, pH, total acidity and moisture (total solid contents), were analyzed. The hardness of tofu was negatively correlated with the moisture contents of tofu (r=-0.667^**). The commercial tofu showed pH 5.80~6.24, total acidity of 0.016~0.034%, soluble solids of 1.50~3.45°Brix, salinity of 1.20~2.30%, and moisture content of 79.91~87.57%, respectively. All 17 tofu samples sold in the Korean market were prepared using crude MgCl₂ and sea water as a coagulant. The quality characteristics vary depending on the constituent's of soybeans, and the ratio and amount of coagulants of tofu used. The origin of soybean seeds affected the yellowness of tofu; tofu made from imported soybean showed a higher b value than domestic soybean. These results are expected to be useful for understanding trends in the domestic tofu industry.

• The Korean Journal of Food And Nutrition
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• v.33 no.5
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• pp.576-583
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• 2020

The purpose of this study was to compare the quality characteristics of silken tofu products from the commercial market in Korea. Seven types of commercial silken tofu were sampled and their physicochemical properties, including soluble solid contents, salinity, pH, total acidity, moisture contents (total solid contents), crude protein and fat contents were evaluated. The TPA results suggest that the texture of silken tofu was very different from one another according to the type of and the amount of coagulant. The commercial silken tofu showed a range of pH 5.53~6.48, total acidity of 0.12~0.32%, soluble solid contents of 2.62~5.07 °Brix, salinity of 2.28~4.30%, and moisture contents of 87.10~92.24%, respectively. In terms of the coagulant of tofu, besides the GDL (glucono-δ- lactone), other coagulants such as MgCl₂ for making 'silken tofu' in the Korean tofu market. The quality characteristics differed depending on the constituents of sample and the coagulants of tofu used. These results are expected to be useful in identifying new trends in the domestic silken tofu industry.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.580-584
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• 2009

The effect of freshwater crab meat additive on protein quality of tofu was studied. Tofu containing freshwater crab meat(TCM) prepared by the formulation for the best sensory qualities had about 20% more lipid and ash content than those of commercial tofu. TCM showed a higher content of lysine, methionine, cysteine and tyrosine compared with those in commercial tofu. TCM was comparable to commercial tofu(CT) regarding the in vitro protein digestibility(95%). A considerable difference in computed protein efficiency ratio(C-PER) resulted between CT(1.76-1.81) and TCM(2.61). Therefore, crab meat has potential as an ingredient for enriching essential amino acid and improving protein quality of CT.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.3
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• pp.190-196
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• 2009

To optimize the mixing ratio of ingredients for optimal sensory qualities of seasoned tofu, a response surface methodology with a central composite design was performed on tofu containing freshwater crab meat (TCM). Using the desirability function technique, the optimal formulation was determined to be 3.67 g of freeze dried meat, 5.54 g of garlic powder, and 2,120 mL of soymilk. In the texture profile analysis, tofu prepared using the optimal ingredient ratio had a higher hardness, cohesiveness and gumminess than commercial tofu but TCM value for adhesiveness, springiness and chewiness were lower. However, the texture properties of TCM were not significantly different than those of commercial tofu.

• Korean journal of food and cookery science
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• v.24 no.2
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• pp.258-265
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• 2008

This study investigated the quality characteristics of tofu(soybean curd) samples prepared with differing amounts of commercial chungkukjang powder(0, 1, 2, 3, 4%). According to the results the 3% chungkukjang tofu 3%(C3) had the highest yield, and the tofus containing chungkukjang powder had higher pH and acidity levels than the control. Turbidity increased and moisture content decreased with increasing chungkukjang powder concentration. And pH, acidity, and turbidity were negatively correlated with moisture content. In terms of color, the L value decreased, and a and b values increased with increasing chungkukjang concentration. For texture, the 1% chungkukjang tofu(C1) had higher hardness, springiness, and cohesiveness values than the other samples. C1 also had the highest overall acceptability score. Finally, sensory properties of taste, texture, and overall quality were positively correlated with the mechanical properties of moisture content, hardness, springiness, cohesiveness, chewiness, and brittleness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.1
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• pp.74-80
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• 1999

Growth and bacteriocin production by Lactobacillus sp. GM7311 in tofu residue treated with two commercial amylases were investigated. The optimal condition of amylase Ⅰ(liquefied enzyme for sauce) and Ⅱ(multienzyme 2,000) for the enzyme reaction was showed at pH 6.0 and 4.0, respectively. The optimal temperature was 40oC both. At the enzyme dosage 4% and 3% and reaction time 1hr, about 2% of reduced sugar needed bacteriocin production was obtained. The enzymatic treatment of tofu residue enhanced bacteriocin production by lactic acid bacteria, particularly in the tofu residues added 2.0% yeast extract. But, we couldn't see the increment of bacteriocin activity in the tofu residues added other nitrogen sources such as proteose peptone No. 3 and lab lemco powder. Also, in the comparision of amylase I and Ⅱ, bacteriocin activity in the tofu residue treated with amylase Ⅰ was better than that of amylase Ⅱ.

• Food Science and Preservation
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• v.20 no.5
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• pp.636-642
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• 2013

Quality and sensory characteristics of tofu prepared with concentrated to 8 $^{\circ}Brix$ deep ground sea-like water (SW) were investigated to check the availability for coagulants. The tofu was coagulated with three kinds of commercially coagulant, such as $MgCl_2$, $CaSO_4$ and glucono-${\delta}$-lactone. Different amounts of SW and soybean milk were added: SW-20 g/L, SW-25 g/L and SW-30 g/L. The moisture content and pH were significantly lower in which preparation with glucono-${\delta}$-lactone coagulated tofu, and others has not significantly difference each other. The mineral contents in the coagulant influenced the mineral content of the tofu, which contained larger quantities of major minerals. However, the mineral content of the tofu was not affected of the mineral concentration in the coagulant. The L and b values of the tofu prepared with SW were not significantly different. The hardness of the tofu prepared with the commercial coagulants was significantly lower than that of the tofu produced with the SW. The sensory property was lower when the hardness was lower and higher. In conclusion, the quality characteristics of SW-prepared tofu were not significantly different from those of the tofu prepared with the commercial coagulants, but the texture and the taste of the SW-prepared tofu were excellent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.603-608
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• 2004

Traditional Jeju tofu with a hard texture was manufactured by traditional method with a compounded coagulant. The processing condition for industrial production was optimized by determining soaking of soybean, extraction and heat treatment of soymilk as well as concentration and composition of coagulant. Maximum yield of soymilk was obtained by grinding one part of soaked soybean with eight parts of water, and the soluble solid of soymilk was about 8$^{\circ}$Brix. The free thiol group in soymilk was maximally exposed by heating at 10$0^{\circ}C$ for 2 min. A vacuum cooker for heating soymilk was effective for the improvement of yield and texture properties of tofu. The hardness of traditional Jeju tofu was obtained by increasing pressing time and drying by a fan instead of soaking in cold water. Optimization of a traditional tofu production resulted in the increase of total yield and improvement of quality control. Texture of traditional Jeju tofu prepared in industrial production scale was analyzed by instrumental analysis and sensory evaluation. Traditional Jeju tofu showed higher score in the hardness, roasting taste and overall preference compared with a commercial tofu, showing significant difference in 5% significant level..

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.4
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• pp.458-463
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• 2007

This study was carried out to investigate potential use of Scutellaria bicalensis Georgi (SBG) as an ingredient for extending the shelf life of tofu. The spore of Bacillus sp. KN-4 was isolated from commercial tofu and inoculated to soybean milk to prepare artificially contaminated tofu. The contaminated tofu was stored in the presence of 0.05 and 1% of SBG extract at $25^{\circ}C$ for 72 hrs. The pH changes of contaminated tofu with SBG extract was slower than those of control during storage. The degree of pH change decreased as the concentration of SBG extract was increased from 0.05% to 0.1%. The change of titratable acidity of the tofu showed the same tendency as pH change during storage. Total cell number of the SBG extract added tofu was lower about $1{\sim}2$ log cycle (0.05% SBG extract) or $2{\sim}3$ log cycle (0.1% SBG extract) than that of control after storage for 12 hrs at $25^{\circ}C$. The color changes of the tofu did not show any difference with and without SBG during storage at $25^{\circ}C$. The strength and hardness of the tofu was improved by the addition of SBG extract. Especially, the strength and hardness of tofu in the Presence of 0.1% SBG extract did not change during storage time. The sensory Qualify of SBG extract added tofu was better than control in texture, but not in taste and color. The overall acceptability of the SBG extract added tofu was similar to control.

• The Korean Journal of Community Living Science
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• v.26 no.3
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• pp.489-498
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• 2015

This study investigates the effects of a China root (Smilax china L.) extract on the chemical and microbiological characteristics and antioxidant activity of the sausage stew sauce and the soft-tofu stew sauce over a 5-week storage period. Commercial sauces were obtained from the market, and samples were prepared using four different concentrations of the China root extract (0% (control), 0.5%, 1.0%, and 1.5%) and stored at $5^{\circ}C$ and $20^{\circ}C$. Over the 5-week storage period, pH and salinity showed slight changes in both the sausage and soft-tofu stew sauces, but there was no significant difference (p<0.05) regardless of the extract amount and temperature. At 5 weeks, there were significant decreases in the total microbial count in groups with the China root extract (p<0.05) for both the sausage and soft-tofu stew sauces at $5^{\circ}C$. Over the whole storage period, no coliform, yeast, and mold were detected in any sample. S. aureus counts were not detected in 1.0% and 1.5% China root groups at $5^{\circ}C$, but 1.00-1.60 log CFU/g was found in the control and 0.5% groups. DPPH radical scavenging activity at 5 weeks showed an increase with an increase in the amount of the China root extract in both sauces. These results indicate that the China root extract inhibited microbial growth during storage as well as scavenging activity and thus that it can be considered to prolong the shelf life of commercial sauces.