• Korean journal of food and cookery science
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• v.29 no.3
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• pp.267-274
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• 2013

Demand for a rice cake, a popular traditional food in Korea, is rising, but its industrial-scale production is extremely difficult due to its short shelf-life caused by starch retrogradation and microbial spoilage. By means of the sourdough fermentation technique, we attempt to develop rice cakes with a longer shelf-life. Heterofermentative lactic acid bacteria (Weissella koreensis HO20, Weissella kimchii HO22) isolated from kimchi were used to ferment wet-milled rice flour for their abilities to produce exopolysaccharides and to inhibit the microbial spoilage of rice cakes. After 24 hr of fermentation at $25^{\circ}C$, viable cell counts in rice dough increased from $10^6$ CFU/g to $10^8$ CFU/g and total titratable acidity increased from 0.05% to 0.20%, whereas pH decreased from 6.5 to 5.1. Fermented rice flour showed significantly lower peak, trough, and final viscosities as well as breakdown and setback viscosities measured by rapid viscoanalyzer. Both lactic acid bacteria showed in vitro antifungal activity against Penicillium crustosum isolated from rice cakes. The antifungal activity remained constant after the treatments with heat, proteinase K and trypsin, but fell significantly by increase of pH. Rice cakes made of fermented rice flour were found to retard mycelial growth of P. crustosum. The degree of retrogradation as measured by the hardness of the rice cake was significantly reduced by the use of fermented rice flour. The results suggest that use of fermented rice flour has a beneficial role in retarding starch retrogradation and in preventing fungal growth, hence extending the shelf-life of rice cakes.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.404-409
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• 1999

The studies were carried out to investigate antimicrobial activity of mixture of Caesalpina sappan L. and Lithospermum erythrorhizon extracts against lactic acid bacteria isolated from Kimchi. The effects of the mixture and crab shell extracts on the shelf-life of Kimchi were also investigated. The growth of heterofermentative lactic acid bacteria and homofermentative lactic acid bacteria was inhibited by 98% ethanol extracts of Caesalpina sappan L. and Lithospermum erythrorhizon. The pH of Kimchi containing mixed extracts of Caesalpina sappan L. and Lithospermum erythrorhizon extracts (1 : 1) and crab shell was lower than that of control during fermentation for 25 days of $10^{\circ}C$. The viable cells of Lactic acid bacteria of the mixed extracts and crab shell added Kimchi were lower than that of control during fermentation. The sensory quality of the mixed extracts and Crab shell added Kimchi was a little inferior to control for during fermentation of Kimchi.

• Journal of Microbiology and Biotechnology
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• v.17 no.5
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• pp.822-829
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• 2007

A gene coding for phosphoketolase, a key enzyme of carbohydrate catabolism in heterofermentative lactic acid bacteria(LAB), was cloned from a Lactobacillus paraplantarum C7 and expressed in Escherichia coli. The gene is 2,502 bp long and codes for a 788-amino-acids polypeptide with a molecular mass of 88.7 kDa. A Shine-Dalgarno sequence(aaggag) and an inverted-repeat terminator sequence are located upstream and downstream of the phosphoketolase gene, respectively. The gene exhibits an identity of >52% with phosphoketolases of other LAB. The phosphoketolase of Lb. paraplantarum C7(LBPK) contains several highly conserved phosphoketolase signature regions and typical thiamine pyrophosphate(TPP) binding sites, as reported for other TPP-dependent enzymes. The phosphoketolase gene was fused to a glutathione S-transferase(GST::LBPK) gene for purification. The GST::LBPK fusion protein was detected in the soluble fraction of a recombinant Escherichia coli BL21. The GST::LBPK fusion protein was purified with a yield of 4.32mg/400ml by GSTrap HP affinity column chromatography and analyzed by N-terminal sequencing. LBPK was obtained by factor Xa treatment of fusion protein and the final yield was 3.78mg/400ml. LBPK was examined for its N-terminal sequence and phosphoketolase activity. The $K_M\;and\;V_{max}$ values for fructose-6-phosphate were $5.08{\pm}0.057mM(mean{\pm}SD)$ and $499.21{\pm}4.33{\mu}mol/min/mg$, respectively, and the optimum temperature and pH for the production of acetyl phosphate were $45^{\circ}C$ and 7.0, respectively.

• Journal of Microbiology and Biotechnology
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• v.33 no.11
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• pp.1448-1456
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• 2023

A Gram-positive, non-motile, and non-spore-forming lactic acid bacterium, designated as BK2^T, was isolated from kimchi, a Korean traditional fermented vegetable food, and the taxonomic characteristics of strain BK2^T, along with strain LMG 11983, were analyzed. Both strains optimally grew at 30℃, pH 7.0, and 1.0% NaCl. Cells of both strains were heterofermentative and facultatively anaerobic rods, demonstrating negative reactions for catalase and oxidase. Major fatty acids (>10%) identified in both strains were C_18:1 ω9c, C_16:0, and summed feature 7 (comprising C_19:1 ω6c and/or C_19:1 ω7c). The genomic DNA G+C contents of both strains were 44.7 mol%. The 16S rRNA gene sequence similarity (99.9%), average nucleotide identity (ANI; 99.9%), and digital DNA-DNA hybridization (dDDH; 99.7%) value between strains BK2^T and LMG 11983 indicated that they are different strains of the same species. Strain BK2^T was most closely related to Weissella confusa JCM 1093^T and Weissella cibaria LMG 17699^T, with 100% and 99.4% 16S rRNA gene sequence similarities, respectively. However, based on the ANI and dDDH values (92.3% and 48.1% with W. confusa, and 78.4% and 23.5% with W. cibaria), it was evident that strain BK2^T represents a distinct species separate from W. confusa and W. cibaria. Based on phylogenetic, phenotypic, and chemotaxonomic features, strains BK2^T and LMG 11983 represent a novel species of the genus Weissella, for which the name Weissella fermenti sp. nov. is proposed. The type of strain is BK2^T (=KACC 22833^T=JCM 35750^T).

• Journal of The Korean Society of Grassland and Forage Science
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• v.44 no.1
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• pp.50-57
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• 2024

Silage inoculants, crucial in modern silage production, comprise beneficial microorganisms, primarily lactic acid bacteria (LAB), strategically applied to forage material during ensiling. This study aimed to compare the effectiveness of various inoculants produced by different companies. Five treatments were evaluated, including a control group: T1 (Lactobacillus plantarum), T2 (Lactobacillus plantarum + Pediococcus pentosaceus), T3 (Lactobacillus plantarum + Pediococcus pentosaceus + Lactobacillus buchneri), T4 (Lactobacillus plantarum + Lactobacillus acidophilus + Lactobacillus bulgaricus), and T5 (Lactobacillus plantarum + Pediococcus pentosaceus + Enterococcus faecium). Italian ryegrass was harvested at the heading stage and treated with these silage inoculants. Samples were collected over a 60-day ensiling period. Co-inoculation with L. plantarum and P. pentosaceus (T2) resulted in significantly higher CP compared to the control group co-inoculation exhibited with resulted in Lactobacillus plantarum and Pediococcus pentosaceus in the T2 treatment exhibited higher CP content of 106.35 g/kg dry matter (DM). The T3 treatment, which included heterofermentative bacterial strains such as Lactobacillus buchneri, exhibited an increase in acetic acid concentration (11.15 g/kg DM). In the T4 treatment group, which utilized a mixed culture of Lactobacillus acidophilus and Lactobacillus bulgaricus, the NH₃-N/TN content was observed to be the lowest (20.52 g/kg DM). The T5 containing Enterococcus faecium had the highest RFV (123) after 60 days. Expanding upon these findings, the study underscores not only the beneficial effects of particular inoculant treatments on silage quality but also underscores the potential of customized inoculation strategies in maximizing nutrient retention and overall silage preservation.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3104-3104
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• 2001

The research described here was undertaken with the aim of monitoring, optimizing and ultimately controlling the production of heterofermentative microbes used as starters in the salami industry. The use of starter cultures in the fermented meats industry is a well-established technique used to shorten and standardize the ripening process, and to improve and control the organoleptic quality of the final product. Starter cultures are obtained by the submerged cultivation of suitable microorganisms in stirred, and sometimes aerated, fermenters where monitoring of key physiological parameters such as the concentration of biomass, substrates and metabolites suffers from the general lack of real-time measurement techniques applicable to aseptic processes. In this respect, the results of the present work are relevant to all submerged fermentation processes. Previous work on the application of on-line NIR spectroscopy to the lactic acid fermentation (Dosi et al. - Monreal NIR1995) had successfully used a system based on a measuring cell included in a circulation loop external to the fermenter. The fluid handling and sterility problems inherent in an external circulation system prompted us to explore the use of an in-line system where the NIR probe is immersed in the culture and is thus exposed to the hydrodynamic conditions of the stirred and aerated fluid. Aeration was expected to be a potential source of problems in view of the possible interference of air bubbles with the measurement device. The experimental set-up was based on an in-situ sterilizable NIR probe connected to the instrument by means of an optical fiber bundle. Preliminary work was carried out to identify and control potential interferences with the measurement, in particular the varying hydrodynamic conditions prevailing at the probe tip. We were successful in defining the operating conditions of the fermenter and the geometrical parameters of the probe (flow path, positioning, etc.) were the NIR readings were reliable and reproducible. The system thus defined was then used to construct and validate calibration curves for tile concentration of biomass, carbon source and major metabolites of two different microorganisms used as salami starters. Real-time measurement of such parameters coupled with the direct interfacing of the NIR instrument with the PC-based measurement and control system of the fermenter enabled the development of automated strategies for the interactive optimization of the starter production process.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.472-479
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• 2002

The antimicrobial effects of metabolites from isolated strains from feces of Korean newborn baby and from Dongchimi against six food-borne microorganisms, and characteristics of the metabolites were investigated.. The metabolites from isolated strains adjusted pH to 3.5, 4.0, and 4.5 showed strong growth inhibition against S. Typhimurium, and S. Enteritidis. The metabolites has kept its inhibition activities to the pathogens after catalase, trypsin or pepsin treatment. In addition, antimicrobial activity of metabolites was not decreased by heat treatment at $121^{\circ}C$ for 15 min. D2 and F35-2 strains were confirmed homofermentative and F20-3 was heterofermentative bacteria identified by final organic acid and gas production. The amount of lactic acid produced by D2 and F35-2 strains after 24 h of incubation was 1.84 and 1.85% respectively, but F20-3 strain produced acetic acid (0.22%) and lactic acid (0.91%).

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.1
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• pp.7-14
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• 2016

The objective of this study was to determine the effect of bacterial inoculation (Lactobacillus plantarum or combo inoculant mixed with Lactobacillus plantarum and Lactobacillus buchneri) and addition of fibrolytic enzyme on chemical compositions and fermentation characteristics of whole crop barley (WCB) and triticale (TRT) silage, their ruminal in vitro fermentation, and digestibility. In TRT silage, enzyme addition significantly (p<0.01) decreased NDF content compared to no enzyme addition treatment. Organic acids such as lactate and acetate contents in WCB and TRT silages were significantly (p<0.01) higher compared to those in the control. Particularly, lactate content was the highest in L. plantarum treatment. Fibrolytic enzyme treatment on both silages had relatively higher lactic acid bacteria content, while mold content was lower in both treatments compared to that in the control. In vitro dry matter digestibility was generally improved in WCB silages. It was higher (p<0.01) in TRT with mixed treatment of L. plantarum, L. buchneri, and enzyme compared to others. In vitro ruminal acetate production was relatively higher in treatments with both enzyme and inoculant additions compared to that in the control. Therefore, the quality of silage and rumen fermentation could be improved by inoculants (L. plantarum and L. buchneri) regardless whether whole crop barley (WCB) or triticale (TRT) silage was used. Although it was found that fibrolytic enzyme addition to both silages had various quality and rumen fermentation values, further study is needed.