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Tofu containing both low and high viscosity chitosan was prepared and changes in the microbiological, physicochemical and sensory properties of the tofu during storage were investigated. The colony forming units of mesophilic and psychrotrophic microorganisms in tofu containing high viscosity chitosan were markedly lower during storage than those in the control tofu as well as the tofu containing low viscosity chitosan. The pH of the tofu samples increased during storage. The L and a values of the tofu, especially the control tofu, increased during storage. In the sensory test, the roasted nutty and beany aromas of the tofu decreased during storage. Instrumental analysis of hardness and chewiness of the tofu decreased during storage. Overall preference for the tofu gradually decreased during storage, but overall preference for the tofu containing high viscosity chitosan scored higher than the other tofu samples.

The sensory characteristics of tofu made from soybeans (var. TaeKwang) heat treated at 60C for 60, 120 and 180 min were investigated to determine the effects of heat shock on the texture and flavor of tofu, which play an important role in consumer preference. Hardness and chewiness increased with heat treatment, reaching maxima at 120 min, while cohesiveness decreased significantly with heat treatment in the 120 min sample. Sensory evaluation showed that the smoothness and homogeneity of the surface of the tofu increased with heat treatment from those of the control. Grassy aroma, which is one of the main undesirable flavors of tofu, was decreased by the heat treatment. Firmness and elasticity both had a maximum value of 8.4 by the 15‐cm line‐scale evaluation in the 120 min treated samples, showing the practical possibility of using mild heat treatment to produce firm and elastic tofu. Increases in the 7S globulin due to heat treatment are thought to be responsible for the textural changes observed. PRACTICAL APPLICATIONS Texture and flavor are major factors in determining the quality of tofu. Tofu has become popular as a healthy food and its consumption is increasing, hence the necessity of producing tofu with various kinds of texture. We found that heat treatment on soybean used in tofu preparation can be one of the methods to control the texture of tofu. The grassy flavor of soy products is the limiting factor that seriously affects their consumption. According to our sensory evaluation, the grassy aroma was decreased significantly by heat treatment, showing that controlled heat treatment has a positive effect on the overall quality of tofu. This study suggests that heat treatment of soybeans can be applied to produce tofu with less grassy flavor and firmer texture.

Tofu, containing high viscosity chitosan dissolved in a δ‐gluconolactone solution, was prepared and physico‐chemical properties, microstructure, textural properties and sensory characteristics were investigated. Moisture content and pH of the chitosan tofu were slightly lower than those of the control tofu. The textural properties of tofu such as hardness, cohesiveness, gumminess and chewiness measured by an instrumental method were not significantly changed by the addition of chitosan to tofu. Springiness of chitosan tofu, however, was significantly higher than that of the control tofu. All characteristics except the roasted nutty aroma and yellowness in the sensory evaluation, did not exhibit significant differences between the chitosan tofu and control tofu. Therefore, the quality of tofu was little affected by the addition of the chitosan content employed in this experiment.

This study analyzed the antibacterial activity of a Rubus coreanum (Bokbunja) ethanol extract. The antimicrobial activity was determined by disc diffusion, minimum inhibitory concentration (MIC), and growth inhibition methods with seven kinds of bacteria related to foodborne illness (Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhimurium). In the results, disc diffusions of the ethanol extract from R. coreanum (9.8-17.5 mm at 4,000 μg/disc) clearly showed the antimicrobial activity of the extract against all tested microorganisms. Rubus coreanum promoted an inhibitory effect as follows: E. coli O157:H7 ˃ P. aeruginosa ˃ L. monocytogenes ˃ E. coli ˃ S. aureus ˃ B. cereus ≥ S. typhimurium. In the MIC test, R. coreanum showed high antimicrobial effect against L. monocytogenes at 500 ppm. Moreover, the R. coreanum ethanol extract showed strong growth inhibition against microorganisms, similar to the MIC results. These results show that a R. coreanum ethanol extract has powerful antimicrobial activity against all tested microorganisms, suggesting that R. coreanum will be useful as a potential natural preservative.

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This study investigated consumers’ awareness and information need about food hygiene especially focused on pesticide residues and food borne illness in Korea. The data were collected from 350 adults living in Daegu and Busan, Korea by a self‐administered questionnaire. Frequency and chi‐square tests were conducted by SPSS. The results of the survey were as follows: Firstly the consumers’ concerns about food hygiene were high. About three‐fourths of the respondents answered that they were ‘somewhat’ or ‘highly’ concerned about pesticide residues and food borne illness. Especially women and the older showed more concerns than men and the younger. Secondly, the respondents worried about eating vegetables, fruits and grains in turn because of pesticide residues, and did not trust the results from food hygiene tests by the Government. Thirdly, three‐fourths of the respondents used the way to wash food stuffs with water several times to clean pesticide residues. Fourth, about four‐fifths of the subjects worried about food borne illness caused by fish to the extreme and about two‐thirds answered that un‐fresh or contaminated food stuffs were the major factor of food borne illness in cooking. Finally, the respondents primarily wanted to get the information about harmfulness of pesticide residues in foods, and methods to choose fresh food regarding food borne illness. Under the situation of the lack of educational programs for food hygiene in Korea, the educational contents for food hygiene to improve public health can be developed on the basis of this study.