• Korean Journal of Food Science and Technology
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• v.21 no.3
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• pp.379-386
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• 1989

The soy milk prepared from soy protein concentrate was treated with microbial protease or papain. Growth and acid production by Lactobacillus acidophilus in soy milk containing partially hydrolyzed proteins were investigated. Sensory evaluation of yogurt beverage prepared from protease treated soy milk was also performed. Protease treatment of soy milk enhanced acid production by lactic acid bacteria, particularly in case of microbial pretense and simultaneous treatment by two types of protease showed synergistic effect. pH and number of viable cells were not affected markedly by pretense treatment. Microbial pretense treatment up to 15 minutes or papain treatment up to 45 minutes enhanced acid production, but further treatment up to three hours did not affect the acidity markedly. rho sensory evaluation showed that overall acceptability and taste of soy yogurt beverage were slightly improved when soy milk was treated with microbial pretense of 0.2% or papain of 0.2%. The amount of non-protein nitrogen considerably increased by pretense treatment of 15 minutes and it increased gradually by further treatment up to three hours.

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.795-802
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• 2014

The aim of this study was to determine the effects of temperature and supplementation with skim milk powder (SMP) on the microbial and proteolytic properties during the storage of cottage cheese. Cottage cheese was manufactured using skim milk with 2% SMP and without SMP as the control, and then stored at $5^{\circ}C$ or $12^{\circ}C$ during 28 days. The chemical composition of the cottage cheese and the survival of the cheese microbiota containing starter lactic acid bacteria (SLAB) and non-starter culture lactic acid bacteria (NSLAB) were evaluated. In addition, changes in the concentration of lactose and lactic acid were analyzed, and proteolysis was evaluated through the measurement of acid soluble nitrogen (ASN) and non-protein nitrogen (NPN), as well as electrophoresis profile analysis. The counts of SLAB and NSLAB increased through the addition of SMP and with a higher storage temperature ($12^{\circ}C$), which coincided with the results of the lactose decrease and lactic acid production. Collaborating with these microbial changes, of the end of storage for 28 days, the level of ASN in samples at $12^{\circ}C$ was higher than those at $5^{\circ}C$. The NPN content was also progressively increased in all samples stored at $12^{\circ}C$. Taken together, the rate of SLAB and NSLAB proliferation during storage at $12^{\circ}C$ was higher than at $5^{\circ}C$, and consequently it led to increased proteolysis in the cottage cheese during storage. However, it was relatively less affected by SMP fortification. These findings indicated that the storage temperature is the important factor for the quality of commercial cottage cheese.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.234-241
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• 1996

Two hundreds and thirty lactic acid bacteria, mostly isolated from Kimchi, including type strains were used for analysis of cellular fatty acids. The 230 test strains were recoverd in 7 major and 1 single clusters defined at Euclidian distance of 17.5. These aggregate taxa were equivalent to the genus Leuconostoc (aggregate group A, B, C and D), the genus Lactobacillus (aggregate group F), the genera Lactobacillus and Pediococcus (aggregate group E) and the genera Leuconostoc and Lactobacillus (aggregate group G). It is concluded as evident that FAMEs (Fatty Acid Methyl Esters) profile of cell can be used as a criterion in classification of lactic acid bacteria from kimchi. Additional comparative taxonomic studies need to be carried out on well chosen representative strains to determine the most appropriate methods of value.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.40-47
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• 2005

Modeling and simulation for simultaneous saccharification and fermentation (SSF) process in bioconversion of paper mill sludge to lactic acid was carried out. The SSF process combined the enzymatic hydrolysis of paper mill sludge into glucose and the fermentation of glucose into lactic acid in one reactor. A mathematical modeling for cellulose hydrolysis was developed, based on the proposed mechanism of cellulase adsorption deactivation. Another model for simple lactic acid fermentation was also made. A whole mathematical model for SSF was developed by combining the above two models for cellulose hydrolysis and lactic acid fermentation. The characteristics of the SSF process were investigated using the mathematical model.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.3
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• pp.174-178
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• 2014

The present study was planned to analyze the nutritional quality, microbial counts and fermentative acids in Italian ryegrass (IRG) 80% and alfalfa 20% (IRG-HV) mediated silage inoculated with lactic acid bacteria (LAB) as a probiotic strain for 3 months. Crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF), total digestible nutrient (TDN) and In-vitro dry matter digestibility (IVDMD), lactic acid bacteria (LAB), yeast and fungi counts and fermentation metabolites such as lactic acid, acetic acid and butyric acids were analyzed. The result shows that the nutritional quality and metabolite profiles of silage were significantly improved with LAB. For microbial counts, LAB showed dominant followed by yeast as compared with control silage. The pH of the silage also reduced significantly when silage inoculated with LAB. The result confirmed that silage preparation using different crops with L. plantarum inoculation is most beneficial for the farmers.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.675-690
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• 2007

Bacteriocins in Gram-positive bacteria have attracted much attention because many have a strong antimicrobial activity also against bacteria outside the genera of the producers. Lantibiotics and the pediocin-like bactericins have attracted most attention since they kill a broad spectrum of Gram-positive bacteria including important pathogens. But many other promising Gram-positive bacteriocins have been thoroughly characterized. Recent studies have shown that bacteriocins may playa role in the intestinal flora to protect us against the food-borne pathogens. Bacterial genome sequencing has demonstrated that there may be an arsenal of such compounds and we are only seeing the top of the iceberg. The present review gives a short outlook of the field of bacteriocins with focus on lactic acid bacteria and includes recent findings.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1163-1169
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• 2004

An unstructured mathematical model is presented for lactic acid fermentation based on the energy balance. The proposed model reflects the energy metabolic state and then predicts the cell growth, lactic acid production, and glucose consumption rates by relating the above rates with the energy metabolic rate. Fermentation experiments were conducted under various initial lactic acid concentrations of 0, 30, 50, 70, and 90 g/l. Also, a genetic algorithm was used for further optimization of the model parameters and included the operations of coding, initialization, hybridization, mutation, decoding, fitness calculation, selection, and reproduction exerted on individuals (or chromosomes) in a population. The simulation results showed a good fit between the model prediction and the experimental data. The genetic algorithm proved to be useful for model parameter optimization, suggesting wider applications in the field of biological engineering.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.1
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• pp.96-99
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• 2003

The objective of this study was to evaluate the effects of various organic acids on microbial characteristics and Salmonella typhimurium in pork loins. Fresh pork loins were sprayed with various organic acids such as lactic acid, citric acid and acetic acid at various concentrations (0.5, 1, 1.5 and 2%). After spraying, the samples were packaged by HDPE film under air and stored at $4^{\circ}C$ for 14 days, and analyzed. Microbial deterioration of pork loins during the aerobic cold storage was delayed by organic acid spray. The bactericidal effect of acids increased with the increasing concentration. However, the inhibitory activity of organic acids during the storage varied with the kinds and concentrations of the acids. As for total plate counts, acetic acid was found to have the highest bactericidal activity, whereas citric acid was found to be the most inhibitory for coliform and S. typhimurium.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.664-671
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• 2006

Modeling the growth kinetics of lactic acid bacteria (LAB), one of the most valuable microbial groups in the food industry, has been actively pursued in order to understand, control, and optimize the relevant fermentation processes. Most modeling approaches have focused on the development of single population models. Primary single population models provide fundamental kinetic information on the proliferation of a primary LAB species, the effects of biological factors on cell inhibition, and the metabolic reactions associated with cell growth. Secondary single population models can evaluate the dependence of primary model parameters, such as the maximum specific growth rate of LAB, on the initial external environmental conditions. This review elucidates some of the most important single population models that are conveniently applicable to the LAB fermentation analyses. Also, a well-defined mixed population model is presented as a valuable tool for assessing potential microbial interactions during fermentation with multiple LAB species.

• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.404-413
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• 2022

The process of manufacturing craft beer involves a wide variety of spontaneous microorganisms, acting in different stages of the brewing process, that contribute to the distinctive characteristics of each style. The objective of this work was to compare the structure of microbial communities associated with two different craft beer styles (Doppelbock and Märzen lagers), at a late maturation stage, and to identify discriminative, or style-specific taxa. Bacterial and fungal microbial communities were analyzed by Illumina sequencing of 16S rRNA gene of prokaryotes and the ITS 2 spacer of fungi (eukaryotes). Fungal communities in maturating beer were dominated by the yeast Dekkera, and by lactic acid (Lactobacillus and Pediococcus) and acetic acid (Acetobacter) bacteria. The Doppelbock barrels presented more rich and diverse fungal communities. The Märzen barrels were more variable in terms of structure and composition of fungal and bacterial communities, with occurrence of exclusive taxa of fungi (Aspergillus sp.) and bacteria (L. kimchicus). Minority bacterial taxa, differently represented in the microbiome of each barrel, may underlie the variability between barrels and ultimately, the distinctive traits of each style. The composition of the microbial communities indicates that in addition to differences related to upstream stages of the brewing process, the contact with the wood barrels may contribute to the definition of style-specific microbiological traits.