• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.411-416
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• 1994

The research is concerned with optimization of growth medium composition in an attempt to improve the product yield of Bacillus licheniformis amylase (BLMA) in recombinant E. coli containing the BLMA gene. BLMA has the catalytic activity of producing branched oligosaccharides from starch. The medium optimization was performed in flask cultures based on the Box and Wilson method. The optimized medium is composed of tryptone 18.0 g/l, yeast extract 22.4 g/l, NaCl 5.3 g/l and glucose 2.1 g/l. In a jar fermenter culture with the conventional LB medium, the recombinant E. coli yielded 1.39 g/l of final dry cell mass and 5.11 U/ml of enzyme activity. In the optimized medium, however, the final cell mass was increased to 6.01 g/l and the enzyme activity to 23.2 U/ml. Medium optimization improved cell mass by 4.3 times and enzyme activity by 4.5 times. Such an increase in enzyme activity is mainly due to an enhancement of cell mass.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.8
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• pp.1031-1037
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• 2007

Changes in red ginseng fusion cheonggukjang properties under various hydrolytic conditions were investigated for its possible application to different types of food products. Among the four types of protease that were analyzed, protease (KMF -G) produced the highest hydrolysis rate, calcium binding capacity, and total phenolic compound content. In addition, the highest fibrinolytic activity and ACE inhibitory activity were also exhibited at 87.10 units and 67.17%, respectively. Among a number of different protease concentrations, a 0.02% concentration of protease (KMF-G) was found to be appropriate for the purposes of the study. The best results for red ginseng cheonggukjang hydrolysis were observed at the 60 and 90 min intervals. However, there was not a significant difference between the results at the two time points. The unpleasant odor and bitter taste associated with red ginseng fusion cheonggukjang improved with hydrolytic activity exceeding 60 min. Thus, the optimal hydrolysis time was determined to be 60 min. The total ginsenoside content of red ginseng cheonggukjang was 9.197 mg/g and the hydrolysate content was 11.707 mg/g. Based on the results, it was determined that the addition of 0.02% protease (KMF -G) and treatment for 60 min are the optimal hydrolytic conditions for red ginseng cheonggukjang to improve its biochemical characteristics, including fibronolytic activity and ACE inhibitory activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.2
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• pp.190-194
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• 2008

Physicochemical properties of the green tea component enriched mushroom (Flammulina velutipes) were investigated. The yield of mushroom was highest with green tea powder untreated sample and the yield was decreased by the addition of green tea powder. However, hardness was increased by the addition of green tea powder. Analysis of catechins and caffeine in mushrooms showed that catechins were not transferred into mushrooms, whereas caffeine content was increased. The content of total polyphenol in mushroom was not affected by the addition of green tea powder and crude catechins. Analyses of aroma patterns using the electronic nose based on GC with SAW sensor showed that new peaks occurred from 3 to 6 sec in green tea added mushroom. This study showed that functional components and quality of mushroom were possibly improved by incorporating green tea powder in growth medium.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.8
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• pp.1195-1199
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• 2011

Inactivation of foodborne pathogenic bacteria in corn silk tea was evaluated using a microwave plasma sterilization system (MPSS). Corn silk tea was inoculated with Escherichia coli and Listeria monocytogenes, treated with an MPSS treatment, and stored at 25$^{\circ}C$ for 12 days. The one, two, and three cycles of treatment with MPSS reduced the population of E. coli by 1.14, 2.49, and 5.72 log CFU/mL, respectively, compared to that of the control. In the case of L. monocytogenes, one, two, and three cycles of MPSS treatment reduced the population by 1.93, 4.49, and 6.62 log CFU/mL, respectively. Both E. coli and L. monocytogenes were eliminated within four cycles of treatment with MPSS, and even after 12 days of storage, the bacteria were not detected. Total polyphenol content in the corn silk tea did not change much among treatments, and turbidity of the corn silk tea improved following four cycles of MPSS treatment. These results suggest that MPSS treatment can be useful for improving the microbial safety and quality of corn silk tea during storage.

• Food Science and Preservation
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• v.16 no.1
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• pp.68-74
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• 2009

This study investigated the quality characteristics of breads made with addition of lotus(Nelumbo nucifera) seeds powder. Breads were prepared with 0, 5, 10, 15 and 20%(w/w) lotus seed powder instead of wheat flour. The moisture, crude protein, crude fat, crude ash and crude fiber contents of the breads increased as the proportion of lotus seed powder increased. The pH of the breads increased as lotus seed powder levels increased. The weight of breads increased with increasing lotus seed powder levels, whereas volume decreased. The specific volumes of breads with lotus seed powder were in the range of $3.59{\sim}4.68\;mL/g$, whereas the control value was 5.12 mL/g. The baking loss rates of breads prepared with 5%, 15% and 20% lotus seed powder were 8.95%, 8.17% and 7.67%, respectively. Lightness (L value) of breads was decreased by addition of lotus seed powder, whereas redness (a value) and yellowness (b value) increased in crumb and crust. Texture measurements showed that hardness and gumminess increased with increased lotus seed powder levels, but springiness decreased. In sensory evaluation, the highest scores for flavor, taste and overall preference were obtained when lotus seed powder content was 10%, and color and texture were the best when 5% of lotus seed powder was added. Thus, addition of $5{\sim}10%$ lotus seed powder may have a role in functional bread preparation, resulting in improved quality.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.321-328
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• 2004

Raw mulberry (Morus spp.) juice was prepared by minimal processing using several filter aids, fining agents, and clarifying enzymes, followed by filtration, centrifugation, and membrane filtration. Control of browning in minimally processed mulberry juices by anti-browning agents, sodium hydrosulfite, L-ascorbic acid, citric acid, and NaCl, was investigated using quantitative measurements of color changes during storage. Clarification of mulberry juice was improved by adding several filter aids, fining agents, and enzymes, followed by filtration and centrifugation. Several fining agents, including chitosan, chitin, PVPP, gelatin, and casein at a concentration of 1%, and combination of ultrafiltration and centrifugation at 8,000 rpm were not suitable for clarification of juice owing to strong adsorption of anthocyanin pigment. Combination of $0.01\;{\mu}m$ membrane filtration and centrifugation at 8,000 rpm was effective for clarification of mulberry juice. Browning of minimally processed mulberry juice was inhibited significantly by adding 200 ppm sodium hydrosulfite, and 0.1% L-ascorbic acid (L-AsA) and 0,1% citric acid (CA) also showed considerable browning inhibition. Combination of L-AsA and CA, which was moderately effective for browning inhibition of juice, may be useful as a sulfite alternative for mulberry juice. Optimum sugar ($^{\circ}Brix$)/acid ratio and commercial sterilization of minimally processed mulberry juice were approximately 40 and 10 min at $85-90^{\circ}C$, respectively.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.339-343
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• 2018

Effects of different drying processes, such as hot air drying (HA), superheated steam with hot air drying (SHS/HA), and superheated steam with far infrared radiation (SHS/FIR), on the properties of cherry tomatoes (Solanum lycopersicum var. cerasiforme) were studied. Characteristics of dried cherry tomatoes were determined by examining the water content, internal microstructure, and rehydration capacity under different drying processes. Moreover, ascorbic acid (AA) and lycopene levels were also measured to evaluate thermal damage caused by drying. Cherry tomatoes dried using both SHS/HA and SHS/FIR had water content and water activity similar to those of intermediate moisture food, indicating partial dehydration after combined drying processes. Although AA and lycopene levels decreased drastically after drying, tomatoes dried using SHS/FIR showed the lowest losses of AA and lycopene among samples. Cherry tomatoes dried using SHS/FIR showed a less compact internal cell structure than that of cherry tomatoes dried using HA and SHS/HA, resulting in the highest rehydration capacity. These results suggest that a combined drying process such as SHS/FIR is more effective than conventional hot air drying for the production of partially dried cherry tomatoes with improved quality attributes.

• Food Engineering Progress
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• v.13 no.2
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• pp.147-153
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• 2009

Quercetin is one of the main flavonoids from onion. To use quercetin as a functional component for onion food products, the effects of various extraction assisting methods such as juicing methods, microwave, ultrasound and enzyme treatments on the yield of quercetin and its glucosides were investigated. For conventional solvent extraction, the highest yield of quercetin and its glycosides was achieved with 0.8 mL/g of 60% methanol at 50$^{\circ}C$ for 15 min. The juicing methods using mixer and screw showed no influence on the yield. Microwave and ultrasound treatments showed 2.14 times and 2.06 times more quercetin yields than non-treated extraction, respectively. For cellulase and viscozyme treatments, the highest yields of quercetin were achieved with 0.5 mL/g of 1% enzyme-0.1M sodium acetate (pH 5.2) buffer solution. Cellulase and viscozyme treatment improved quercetin yield 1.65 times and 2.29 times more than non-treated one, respectively.

• Food Science and Preservation
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• v.14 no.2
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• pp.136-141
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• 2007

The effects of various concentrations (0.01% 0.02% both v/v) of a Turmeric (Curcuma aromatica Salab.) ethanol extract (CE) on the shelf life of tofu were investigated during tofu storage for 12 d at $25^{\circ}C$. The total number of bacteria in tofu containing 0.02% CE was ca. 100 1,000-fold lower than that of the control after this period Tofu containing CE had a lower pH then did control curd, but was higherin titratable acidity, during the storage period. Measurement of hardness, cohesiveness, and springiness of tofu containing CE were higher than those of control during storage. Each of these parameters of texture value improved (increased) with an increase in the concentration of CE in tofu The degree of whiteness of tofu did not differ between samples with or without CE. The yellowness of tofu increased after addition of CE. The overall acceptability of tofu containing CE was lower than that of control.

• Food Science and Preservation
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• v.18 no.3
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• pp.319-327
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• 2011

This study was conducted to monitor the quality characteristics of mate (Ilex paraguarensis) ethanolic extracts via the response surface methodology. In the extraction conditions that were based on the central composite design with variations in the ethanol concentration (0-100%), extraction temperature($35-95^{\circ}C$), and the ratio of the solvent to the sample (10~30 mL/g). The extraction yield and total polyphenol content improved with the increase in the ethanol concentration than in the extraction temperature. The caffeic acid content increased with the decrease in the solvent ratio. The coefficients of determinations ($R^2$) were 0.8842 (p<0.05), 0.8729 (p<0.05), and 0.9205 (p<0.05) in terms of the electron donating ability, nitrite scavenging effect (pH 3.0), and SOD-like ability, respectively. The estimated conditions for the maximized extraction, including in terms of the yield, total polyphenol content, caffeic acid content, and electron donating ability, were a 21-48% ethanol concentration, a $76.4^{\circ}C$ extraction temperature, and 10-14mL/g solvent-to-sample ratio.