• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.150-155
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• 2016

This study investigated the effects of combined treatments of immersion liquid and high hydrostatic pressure (HHP, 100−400 MPa) on the quality of mackerel. In this study, we measured viable cell counts, pH level, color value, texture properties, and sensory evaluation of mackerel. Viable cell counts of mackerel treated with combined HHP were decreased by 2 log cycles at 300 MPa and 400 MPa compared to the control. The pH values of mackerel treated with HHP at 300 MPa and 400 MPa were higher than that of other samples. Hardness, gumminess, and chewiness decreased when treated with combined HHP and increased with increase in HHP. Lightness and whiteness of mackerel increased, but redness decreased, with increase in HHP. In case of sensory evaluation, texture of mackerel treated with HHP at 300 MPa and 400 MPa showed higher scores than that of other samples. These results suggest that immersion liquid and HHP treatments can increase microbiological safety and improve textural properties of mackerel.

• The Korean Journal of Food And Nutrition
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• v.36 no.1
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• pp.17-24
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• 2023

To apply UV-C as a non-heating sterilization method to increase the microbiological safety of fresh seedless watermelon products, reductions in E. coli and quality changes by treatment dose (0, 2, 4, 8, 14, 20 kJ/m²) were investigated. The pH, sugar content, and hardness of watermelon inoculated with E. coli were not significantly different according to the UV-C treatment dose, but the polyphenol content was significantly decreased compared to the controls (425.4 GAE ㎍/g F.W.). When treated with 2 and 4 kJ/m², the lycopene content was 31.6 and 30.9 ㎍/g F.W., respectively, which was increased compared to the controls (28.5 ㎍/g F.W.). The arginine and citrulline content was also significantly increased compared to the controls. The number of E. coli was significantly decreased compared to the controls following UV-C treatment. Considering the degree of E. coli reduction, lycopene content, arginine content, citrulline content, and UV-C irradiation time, subsequent experiments were conducted by selecting a UV-C treatment dose of 2 kJ/m². The results of confirming the degree of reduction in the number of E. coli colonies by a single treatment and combined treatment with UV-C 2 kJ/m² and 70% ethanol showed that the combined treatment was most effective as colonies were decreased by 2.3 log CFU/g compared to the controls. Therefore, it is judged that UV-C 2 kJ/m² radiation and combined treatment with 70% ethanol could be applied as a non-heating sterilization method for fresh watermelon slices.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.1
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• pp.83-88
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• 2013

To improve kimchi qualities, Ecklonia (E.) cava of 5%, 15% or 25% were added and the qualities investigated by measuring changes in physicochemical, microbiological, and sensory characteristics during fermentation at $5^{\circ}C$. The pH of kimchi with E. cava added decreased and acidity increased. The number of Leuconostoc sp. in kimchi reached its maximum at the optimum fermenting stage, the $16^{th}$ day in control kimchi and the $20^{th}$ day in the kimchi added E. cava. The optimum fermenting stage of the kimchi was retarded due to adding the E. cava. The reducing sugar contents was highest in kimchi with 25% E. cava during the early stage of fermentation. According to Hunter's color values, the lightness of the kimchi with E. cava added decreased during fermentation, while the redness increased as fermentation proceeded. The sensory scores for overall acceptance, taste, texture and appearance were highest in kimchi with 15% E. cava.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.120-127
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• 2005

Electron beam irradiation was applied to examine the microbial growth and qualities of vacuum-packaged chicken breasts. Chicken breast samples were irradiated at dose of 2, 4, 8, 12, and 16 kGy, respectively. After irradiation, chicken breast samples were individually vacuum-packaged and stored at $4^{\circ}C$. Microbiological change of irradiated vacuum-packaged chicken breasts showed that populations of total bacteria, yeast and mold, total coliform, and salmonella spp. in chicken breasts were significantly reduced with increasing irradiation dose. The pH values of vacuum-packaged chicken breasts were not significantly changed among treatments. Lipid oxidation measurements showed that TBARS values of vacuum-packaged chicken breasts increased with increase of irradiation dose, and gradually increased during storage. Color measurements showed that irradiation reduced Hunter a value of vacuum-packaged chicken breasts with increasing irradiation dose. However, Hunter L and b values of vacuum-packaged chicken breasts were not significantly altered among treatments. Sensory quality results of vacuum-packaged chicken breasts showed that there were no significant changes among the samples irradiated. These results indicate that irradiation can be used to improve the microbial safety and qualities of poultry products.

• Korean Journal of Microbiology
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• v.51 no.3
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• pp.300-307
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• 2015

For selecting Bacillus strains producing high-quality Cheonggukjang, 8 strains were isolated from the different Cheonggukjang samples. Seven of them exhibited the highest 16S rRNA gene sequence similarity value of over 99.9% to Bacillus subtilis subsp. subtilis and one of them showed the similarity to B. licheniformis. All the strains showed positive activities for amylase, cellulase, protease and lipase, and 6 strains are positive for fibrinolytic activity. To confirm the safety of the strains isolated from the samples of Cheonggukjang which are manufactured by traditional method, strains were analyzed for the presence of seven toxin genes of Bacillus cereus and results were found negative. And 7 strains did not produce at all or merely produce both histamine and tyramine, the representative biogenic amines. Biogenic amine degradation analysis by HPLC revealed that, most of them exhibited tyramine degradation activity. For Cheonggukjang fermented by artificial inoculation of selected strains, fermentation property, sensory test, volatile basic nitrogen production and metabolic profiles by $^1H-NMR$ were tested. Seven strains were confirmed to make high-quality Cheonggukjang.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.241-248
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• 2011

The use of synthetic additives for preservation and enhancement of the market quality of food products has been emerging as a societal issue in terms of safety as well as changes in consumption patterns. Various research related to natural additives is being conducted to address these issues. This study examined the antibacterial effects of 79 types of medicinal herbs used as oriental remedies on bacteria isolated from beverages of damaged marketable quality. The antibacterial effects of methanol extracts on 13 Bacillus sp. and three Paenibacillus sp. were evaluated. We found that 43 of the herbal medicines analyzed had antibacterial effects on the isolated bacteria. Of those, eight were selected, and their antibacterial effects were further examined using water, ethanol, methanol, and ethyl acetate as solvents. The results revealed that Prunus mume, Rhus javanica, and Coptis japonica had excellent antibacterial effects against the isolated bacteria. In particular, they exerted greater antibacterial effects when water and ethanol were used as solvents. This result indicates the possibility of developing natural additives using these substances. Since P. mume in particular, has not been sufficiently studied compared to other herbal medicines, it presents an opportunity for additional investigation and the possibility for development as a new product in the future.

• Korean journal of food and cookery science
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• v.31 no.4
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• pp.387-394
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• 2015

The red snow crab lives at a depth 200-2,000 m in the east coast. It has a smooth taste with a rich texture. However mostly red snow crab are only utilized materials. For seafood development, research is needed on using red snow crab in various products. In this study, quality changes in fried rice prepared with red snow crab meat, red snow crab emulsion sauce and red snow crab effluent were investigated. Physicochemical, microbiological and sensory characteristics were determined during storage at -20, 4 and $25^{\circ}C$ for 5 weeks to assess changes in the quality of the fried rice. The pH and acidity values did not show any significant differences at $-20^{\circ}C$. The VBN and TBA values of fried rice stored at 4 and $25^{\circ}C$ were significantly higher than those of fried rice stored at $-20^{\circ}C$ during the same storage period. The viable cell count of the fried rice stored at $-20^{\circ}C$ changed little during the storage period. During storage at $25^{\circ}C$, the overall quality was initially 8.0, but rapidly decreased to 1.0 after 5 weeks. In conclusion, the best storage temperature for both quality and safety was $-20^{\circ}C$. The storage condition for instant rice containing red snow crab affects the quality and we confirmed the applicability of using materials from red snow crab.

• Food Science and Preservation
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• v.20 no.3
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• pp.424-428
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• 2013

Microbiological contamination of 4 vegetables (garlic, red pepper, perilla leaf and lettuce) collected from 10 restaurants around university was examined. The vegetables were evaluated for total plate count, coliforms, psychrophiles, yeast, and Staphylococcus aureus. The results of total plate count showed the highest value as $5.4{\pm}0.69$ log CFU/g in lettuce, following by $4.8{\pm}1.53$ log CFU/g in red pepper, $4.5{\pm}1.65$ log CFU/g in perilla leaf and $3.4{\pm}1.27$ log CFU/g in garlic. The contamination level of coliforms and psychrophiles were highest in red pepper with maximum as 4.7 log CFU/g and 8.2 log CFU/g, respectively. Red pepper of psychrophiles showed the highest average value as $5.0{\pm}1.82$ log CFU/g followed by $4.2{\pm}1.91$ log CFU/g in lettuce, $4.7{\pm}1.55$ log CFU/g in perilla leaf and $2.4{\pm}2.10$ log CFU/g in garlic. The average number of yeasts were highest in perilla leaf with $4.4{\pm}1.41$ log CFU/g and were lowest in garlic with $0.9{\pm}1.41$ log CFU/g. The contamination level of S. aureus was detected in 27 samples among the total 40 samples with the range of 0.5-5.2 log CFU/g. In conclusion, the microbial quality of the fresh vegetables evaluated in this study was not very good. Therefore, it needs to be enhanced through the good sanitation management and production and distribution methods to improve the safety of fresh vegetables.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.319-331
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• 1998

The purposes of this study were to develop Hazard Analysis Critical Control Point plan applicable to cook/chilled Pork Bulkogi (broiled sliced pork with sauces) in school foodservice operations and to establish reasonable shelf-life limits by assessing food quality during chilled storage period of 5 days. During the product flow, time-temperature profile was recorded and microbiological analyses including mesophilic and psychrotrophic total plate counts, coliform, and fecal coliform and qualitative analyses of Salmonella and Listeria monocytogenes were done. Chemical analyses (pH, acid value, total volatile basic nitrogen), sensory evaluation, and quantitative analysis of thiamin were conducted for 5 days of chilled storage. The number of mesophiles in raw pork ($4.26{\pm}0.11\;Log\;CFU/g$), seasoning mixture ($5.97{\pm}O.04\;Log\;CFU/g$) and marinated pork ($5.56{\pm}0.21\;Log\;CFU/g$) were below the microbial standards for "requires further cooking" food items. Listeria monocytogenes was detected in seasoning mixture. After heating, the number of mesophiles ($5.17{\pm}0.04\;Log\;CFU/g$) were slightly reduced but it did not meet the microbial guidelines of $5\;Log\;CFU/g$ for "ready-to-eat" foods. No other microbes including pathogens were detected. By reheating the menu item after chilled storage, the number of mesophiles were reduced in every phase of 1st day ($4.62{\pm}0.22\;Log\;CFU/g$), 3rd day ($4.55{\pm}0.20\;Log\;CFU/g$) and 5th day ($4.25{\pm}0.16\;Log\;CFU/g$) of chilled storage, and the number of microbes was below the standard limits for "ready-to-eat" foods. At the fifth day of chilled storage, pH (p<0.05), acid value (p<0.01) and TVBN (p<0.05) showed significant increases. Sensory evaluation results did not show any significant change for 5 days of chilled storage. Thiamin content showed a decrease for 5 days of chilled storage. Consequently, the ideal shelflife recommended for Pork Bulkogi was within 3 days of chilled storage. CCPs for Pork Bulkogi were purchasing and receiving of raw meat and some seasoning ingredients, heating, chilling, chilled storage, reheating, and distribution.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.477-484
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• 2017

This study was conducted to investigate the content of sulfur dioxide, carotenoids and the degree of contamination of Bacillus cereus in 33 kinds of dried sweet potato from domestic mainly dried agricultural products in Korea. According to the characteristics of dried sweet potato samples, it was classified into four clusters and as a result of analyzing the contents of sulfur dioxide, carotenoids and the degree of contamination B. cereus was no significant difference among the clusters. The detection ranges of residual sulfur dioxide from 33 dried sweet potatoes ranged from 0.38 to 28.16 mg/kg, three cases (9.09%) were detected at the reference level of 10 mg/kg or more. But no samples exceeding 30 mg/kg, the tolerance level of sulfur dioxide in dried sweet potatoes were detected. Since dried sweet potato does not have a standard for carotenoids, when comparing the national and international standards of carotenoids, the range of detection of carotenoids in dried sweet potato was $46{\sim}2,663{\mu}g$/100 g, which was within the reference range of $0{\sim}9,826{\mu}g$/100 g. In principle colonies suspected to be B. cereus in dried sweet potato were not detected. In 7 cases (21.21%), there were detected in the range of 0.05~1.59 log CFU/g but not more than 3 log CFU/g as the reference value. The results of this study are expected to be used as basic data to establish quality standard for dried sweet potatoes. In order to control the quality of dried sweet potatoes in domestic market, raw materials, drying method and packaging after distribution, it is necessary to maintain and maintain the process steadily.