• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.637-645
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• 2016

This study was conducted to investigate the characteristics of fermentation and quality of Cheongju prepared by mashing using rice Nuruk inoculated with Aspergillus oryzae. Mashes were prepared by fermentation for 30-50 days using different amounts of fermenting agent, brewing water, milling ratios and fermenting temperatures. Adding fermenting agent at 15% resulted in slow fermentation, but a final alcohol content of 17% (v/v), similar to other samples tested. Addition of higher amounts of Nuruk resulted in increased amounts of citric acid, tartaric acid and malic acid, but low levels of succinic acid. Incomplete fermentation occurred when the ratio of brewing water was low, but the alcohol content (17%) of all samples was similar. When the amount of brewing water was high, the organic acid was levels were high. The speed of saccharification and fermentation was low when fermentation was conducted at $10^{\circ}C$, but the final alcohol content was the highest at this temperature. However, the content of n-propanol, isobutanol, isoamyl alcohol and organic acid was low at low temperature. At this time, the content of citric acid and malic acid was low, but the content of succinic acid was high. A higher milling degree resulted in a lower content of alcohol, organic acid and higher alcohols, with 10% milling resulting in a significantly higher content than the other samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.492-501
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• 2016

This study was conducted to investigate the physiochemical characteristics of Cheongju prepared using different types of rice (rice and glutinous rice) according to addition rate of Nuruk during low temperature fermentation. The characteristics of Cheongju prepared using three different temperatures ($10^{\circ}C$, $18^{\circ}C$, $25^{\circ}C$) were compared. After fermentation for 30-50 days, the pH of mash prepared at lower temperature was lower, as was that of mash made from rice relative to that prepared using glutinous rice. The total acidity was formed at lower temperature and generated in mashing prepared by glutinous rice. The organic acid content of mash made from rice at $18^{\circ}C$ was lowest, while that of mash prepared from glutinous rice was lowest at $10^{\circ}C$. The fermentation speed was lowest at $10^{\circ}C$; however, low temperature fermentation resulted in the highest alcohol content. The mash prepared from glutinous rice showed faster fermentation than that made from rice. In addition, the pH was lower when lower levels of Nuruk were added and higher in mash made from glutinous rice than that prepared from rice. The lower addition rate of Nuruk also showed a lower sugar content and final alcohol content. The levels of citric acid and lactic acid were higher, while those of succinic acid, acetic acid, and ethyl acetate were lower when lower levels of Nuruk were added. The mash prepared from glutinous rice showed a higher alcohol content than that made from rice.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.10
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• pp.1528-1539
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• 2019

Objective: To evaluate the effects on microbial diversity and biochemical parameters of gradually increasing temperatures, from $5^{\circ}C$ to $25^{\circ}C$ on corn silage which was previously fermented at ambient or low temperature. Methods: Whole-plant corn silage was fermented in vacuum bag mini-silos at either $10^{\circ}C$ or $20^{\circ}C$ for two months and stored at $5^{\circ}C$ for two months. The mini-silos were then subjected to additional incubation from $5^{\circ}C$ to $25^{\circ}C$ in $5^{\circ}C$ increments. Bacterial and fungal diversity was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiling and biochemical analysis from mini-silos collected at each temperature. Results: A temperature of $10^{\circ}C$ during fermentation restricted silage fermentation compared to fermentation temperature of $20^{\circ}C$. As storage temperature increased from $5^{\circ}C$ to $25^{\circ}C$, little changes occurred in silages fermented at $20^{\circ}C$, in terms of most biochemical parameters as well as bacterial and fungal populations. However, a high number of enterobacteria and yeasts (4 to $5\;log_{10}$ colony forming unit/g fresh materials) were detected at $15^{\circ}C$ and above. PCR-DGGE profile showed that Candida humilis predominated the fungi flora. For silage fermented at $10^{\circ}C$, no significant changes were observed in most silage characteristics when temperature was increased from $5^{\circ}C$ to $20^{\circ}C$. However, above $20^{\circ}C$, silage fermentation resumed as observed from the significantly increased number of lactic acid bacteria colonies, acetic acid content, and the rapid decline in pH and water-soluble carbohydrates concentration. DGGE results showed that Lactobacillus buchneri started to dominate the bacterial flora as temperature increased from $20^{\circ}C$ to $25^{\circ}C$. Conclusion: Temperature during fermentation as well as temperature during storage modulates microorganism population development and fermentation patterns. Silage fermented at $20^{\circ}C$ indicated that these silages should have lower aerobic stability at opening because of better survival of yeasts and enterobacteria.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.2
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• pp.125-140
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• 2016

We analyzed the cultural characteristics of isolated brewing fungi for developing fermentation starters. In a previous study, we collected 87 domestic nuruk, from which 481 fungi strains were isolated and 11 were selected showing improved productivity. After culturing these 11 fungi strains in several types of media, temperatures, carbon and nitrogen sources, Rhizopus sp. grew well in MEA, ME20S, PDA medium while Aspergillus sp. grew well in ME20S and YES. Both Rhizopus sp. and Aspergillus sp. survived well at optimal growth temperatures of 30 and $37^{\circ}C$. Rhizopus sp. utilized lactose, glucose and peptone sources while Aspergillus sp. utilized glucose, mannose, fructose and yeast extract sources. ${\alpha}-Amylase$ activity was excellent in L. ramosa CN044, R. oryzae 82-7(MEB), R. oryzae CN174 and A. oryzae 58-11(WEB) culture extracts. This study suggests that R. delemar 26-4, 58-8 and A. oryzae 78-5, 37-7 might be appropriate fungi strains for fermentation starters based on development of large fungi bodies and their good enzyme activities.

• Food Science and Preservation
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• v.22 no.6
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• pp.920-925
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• 2015

The microbial composition in Nuruk, a Korean cereal fermentation starter, is a critical factor for the quality and organoleptic properties of traditional alcoholic beverages. This study was aimed at monitoring the compositional change and enzyme activity of culturable lactic acid bacteria (LAB) in two types of Nuruk fermented at different temperatures. All culturable LAB were isolated at various time points (0, 3, 6, 10, 20, and 30 days) and identified by 16S rRNA sequencing. In traditional Nuruk type A (TN-A), which was fermented at $36^{\circ}C$, the population of total culturable LAB during the fermentation period was between $10^4$ and $10^5$ log CFU/mL. On the other hand, the LAB population in traditional Nuruk type B (TN-B) fermented at $45^{\circ}C$ (primary fermentation for 10 days) and $35^{\circ}C$ (secondary fermentation for 20 days) was $10^2$ log CFU/mL; however, these bacteria could not be detected after 6 days. Major LAB strains were identified in both Nuruk types: (1) from the MRS-culture of TN-A, Pediococcus pentosaceus at 3-30 days; (2) from MRS-culture of TN-B, P. pentosaceus at 3 days and Enterococcus hirae at 6 days. The protease activities of the dominant LAB isolated from the TN-A and TN-B cultures were within the ranges of 0.64~1.03 mg/mL and 0.74~0.81 mg/mL (tyrosine content), respectively, whereas the ${\alpha}$-amylase activities were 0.75~0.98 mg/mL and 0.78~0.79 mg/mL (amylose content), respectively.

• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.151-156
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• 2009

Samhaeju is a traditional Korean noble rice wine, in which its processing is performed at low temperatures for an extended fermentation time and with three brewing steps. In this study, Samhaeju was prepared by different brewing methods that were modified from the method in the literature. Chemical composition of samples were determined to evaluate the quality of the Samhaeju. The Samhaeju was analyzed for pH, total acids, amino nitrogen, Hunter color values, free sugars, organic acids, and volatile components. Before the addition of the second and third mashing, pH values had decreased slightly and total acids had rapidly increased. Free sugar and amino nitrogen contents were high in final product. After addition of the third mashing as the advanced step, a dilution effect was shown. Glucose (A: 0.77-7.0%, B: 0.77-3.81%) was a major free sugar, and lactic acid (A: 0-2,840mg%, B: 0-3,375mg%) was a major organic acid during the entire period of fermentation. Based on principal component analysis of electronic nose data for the components, the stages of Samhaeju fermentation were primarily separated along the first principal component (PC, proportion : 98.67%). The first PC component (PC1) was moved from negative value(-6.16) to positive value(9.00) with increasing fermentation time. The change patterns for pH and total acid during the fermentation period were similar to those of PC1 from the data obtained by electronic nose based on mass spectrometry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1120-1128
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• 2001

This study was to investigate the flour quality and bread making condition required for Korean-style steamed bread, using 5 commercial wheat flours (protein content from 8.2 to 12.5%), They were compared in making steamed bread (SB) and baked roll bread (BRB). Straight dough method was used and the temperatures of dough and fermentation were controlled at 26$^{\circ}C$ and 32$^{\circ}C$, respectively. The first fermentation was conducted at various times (0, 20, 40 and 60 min) and then forty min of proofing (2nd fermentation) was used for all bread dough. As the 1st fermentation time increased, volumes of both SB and BRB increased 4.3 ~8.7% and 27~40%, respectively, but the SB flattened and the total bread scores of SB decreased due to the lack of smoothness and shininess of the bread surface and poor grain. Contrary to that, the total bread scores of BRB increased. SB made from the flour containing 10.5% of protein, was of its highest quality: relatively high volume, smooth, semiglossy and white surface, good texture, followed by SB made from flours containing 10.9%, 9.5%, 12.5%, and 8.2% of protein content, respectively These results suggest that the 1st fermentation process was not needed for SB making. Total bread scores of SB were better correlated with farinograph dough stability than protein contents and volumes of SB were correlated with farinograph development time. Therefore, in steamed bread making, flour dough rheology is important as well as protein content.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.175-181
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• 2011

Kimchi is a group of traditional fermented vegetable foods in Korea and known to be the product of a natural mixed-fermentation process carried out principally by lactic acid bacteria (LAB). According to microbial results based on conventional identification, Leuconostoc mesenteroides and Lactobacillus plantarum were considered to be responsible for the good taste and over-ripening of kimchi, respectively. However, with the application of phylogenetic identification, based on 16S ribosomal RNA gene similarities, a variety of Leuconostoc and Lactobacillus species not detected in the previous studies have been isolated, together with a species in the genus Weissella. Additionally, Lactobacillus sakei has been accepted as the most populous LAB in over-ripened kimchi. In this study, Leuconostoc and Weissella species inhibiting the growth of Lb. sakei were isolated from kimchi for future applications to do with kimchi fermentation. From 25 kimchi samples, 378 strains in the genera Leuconostoc and Weissella were isolated and 68 strains identified as Lc. mesenteroides, Lc. citreum, Lc. lactis, W. cibaria, W. confusa, and W. paramesenteroides exhibited growth inhibition against Lb. sakei. Most of the strains also had antagonistic activities against Lb. brevis, Lb. curvatus, Lb. paraplantarum, Lb. pentosus, and Lb. plantarum. Their antagonistic activities against Lb. sakei were more remarkable at lower temperatures of incubation.

• Preventive Nutrition and Food Science
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• v.6 no.2
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• pp.117-121
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• 2001

Changes in antioxidative activity and Angiotensin converting enzyme(ACE) inhibitory activity in juice prepared from Dolsan leaf mustard kimchi (DLMK) ar various fermentation temperatures were investigated. Antioxidative activity of juice from optimally ripened DLMK at 20 and 3$0^{\circ}C$ showed 80 and 83%, respectively. Juice from 10-day fermented DLMK at 3$0^{\circ}C$ showed 62% inhibitory activity against the ACE. In the juice fermented DLMK at 2$0^{\circ}C$~3$0^{\circ}C$, physiological activity was higher than that of the 4~1$0^{\circ}C$. In particular, optimally ripened DLMK at 3$0^{\circ}C$ showed the highest physiological activity. The physiological activity in DLMK juice at the fermentation period increased significantly with an increase in the growth of microbes. Consequently, a maximum physiological activity was shown at the maximum cell number. These results suggest that the microorganisms in DLMK juice would play an important role in the physiological activity.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.136-140
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• 1985

Optimal quality retentions of cooked rice packed in retort pouch were simulated by computer using various thicknesses of retort pouch (5 to 24mm) and process temperatures (110 to $150^{\circ}C$). Optimal conditions were chosen by the minimal c-values and maximal thiamine retention when good bacteriological lethality (12D processing) was obtained. From the results of calculations, it were shown that the better quality retentions of high tharmal processing can be obtained below pouch thickness of l0mm and that the thickness of pouch is critical factor at higher processing temperature.