• Food Science and Biotechnology
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• v.17 no.3
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• pp.655-658
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• 2008

Although arabinose isomerase (E.C. 5.3.1.4), a commercial enzyme for edible tagatose bioconversion, can be expressed in an Escherichia coli system, this expression system might leave noxious by-products in food. To develop an eligible tagatose bioconversion with food-safe system, we compared the tagatose production activity of immobilized arabinose isomerase expressed in Bacillus subtilis (a host generally recognized as safe) with that of the enzyme expressed in E. coli. A 48% increase in tagatose production (4.3 g tagatose/L at $69.4\;mg/L{\cdot}hr$) was found using the B. subtilis-expressed immobilized enzyme system, compared to the E. coli-expressed enzyme system (2.9 g tagatose/L). The increased productivity with safety of the B. subtilis-expressed arabinose isomerase suggests that it is a more eligible candidate for commercial tagatose production.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.463-468
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• 2004

This study was conducted to determine the antimicrobial effect of leaf, bark and xylem of 6 kinds of Quercus spp. against food borne disease bacteria. All of the samples tested showed the antimicrobial effect against food borne disease bacteria. Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus was more sensitive than gram negative bacteria such as Salmonella typhimurium and Escerichia coli O157:H7, but no antimicrobial activity was observed against yeast and molds. Based on antimicrobial activity for kinds of Quercus spp., the antimicrobial activities of Quercus aliena Blume, Quercus mongolica Fisch, and Quercus dentata Thunb were stronger than those of Quercus variebilis Blume, Quercus serrata Thunb, and Quercus acutissima Carruth. In the meantime, the ethanol extract of Quercus spp. leaves showed the strongest antimicrobial activity compared to that of bark and xylem. Especially, the ethanol extract of Quercus aliena Blume leaf showed the strongest antimicrobial effect against foodborne disease bacteria among 6 kinds of Quercus spp.

• Culinary science and hospitality research
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• v.17 no.1
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• pp.226-237
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• 2011

This study investigates the effects of chajogi (perilla frutescens) extracts on quality of vinaigrette dressing during storage. Vinaigrette dressing(VD) samples prepared with chajogi(perilla frutescens) extracts were divided into control(0% chajogi extracts) and the groups added chajogi extracts. VD samples prepared with chajogi extracts were divided into $T_1$(VD with 0.4% chajogi extracts), $T_2$(VD with 0.8% chajogi extracts) and $T_1$(VD with 1.2% chajogi extracts). The pH values during storage at 25 and $50^{\circ}C$ for 120 days in all samples ranged from 2.38 to 2.83 and form 3.21 to 3.36, respectively. As for total acidity, it decreased in all samples during storage while there wasn't significant difference in the samples of different storage temperature(25 and $50^{\circ}C$). L(lightness) value scores of all samples added with chajogi extracts during storage went higher and a(redness) and b(yellowness) value scores became lower. Escerichia coli forms were not detected in all samples. Antioxidant capacity by peroxide value of T1, T2 and T3 sample showed higher than that of the control sample. Crude Fat contents of the control sample during storage at $25^{\circ}C$ were the highest as compared to those of the other samples.