• Microbiology and Biotechnology Letters
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• v.46 no.3
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• pp.210-224
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• 2018

Warqe (Ensete ventricosum) has been traditionally fermented in an earthen pit to yield a carbohydrate-rich food product named kocho, for generations. A fermentation enhancer (gammaa) was added to this fermenting mass to enhance the fermentation process. The objectives of this study were to assess the physicochemical properties and microbiota of the kocho fermentation enhancer culture to reduce losses. Cross-sectional study design was implemented to collect 131 gammaa samples on the first day of fermentation. The samples were further classified into four groups according to the duration of fermentation (14, 21, 30, and 60 days) practised in various households traditionally. The results showed that the fermentation time significantly affected the physicochemical properties and microbial load of gammaa (p < 0.01). As the fermentation progressed from day 1 to 60, the pH decreased and the titratable acidity increased. The total coliform, Enterobacteriaceae, aerobicmesophilic bacteria (AMB), yeast, and mould counts were significantly reduced at the end of fermentation. In contrast, the number of lactic acid bacteria (LAB) increased significantly until day 30 of fermentation, because of the ability of the LAB to grow at low pH. Lactobacillus species from LAB isolates and Enter obacteriaceae from AMB isolates were the most abundant microorganisms in gammaa fermentation. However, the Enterobacteriaceae and Lactobacilli species count showed decreasing and increasing trends, respectively, as the fermentation progressed. These isolates must be investigated further to identify the species and strain, so as to develop gammaa at the commercial scale.

• Journal of Microbiology and Biotechnology
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• v.24 no.12
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• pp.1664-1672
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• 2014

In this study, a fibrous bed bioreactor (FBB) was used for $\small{D}$-lactic acid ($\small{D}$-LA) production by Sporolactobacillus inulinus Y2-8. Corn flour hydrolyzed with ${\alpha}$-amylase and saccharifying enzyme was used as a cost-efficient and nutrient-rich substrate for $\small{D}$-LA production. A maximal starch conversion rate of 93.78% was obtained. The optimum pH for $\small{D}$-LA production was determined to be 6.5. Ammonia water was determined to be an ideal neutralizing agent, which improved the $\small{D}$-LA production and purification processes. Batch fermentation and fed-batch fermentation, with both free cells and immobilized cells, were compared to highlight the advantages of FBB fermentation. In batch mode, the $\small{D}$-LA production rate of FBB fermentation was 1.62 g/l/h, which was 37.29% higher than that of free-cell fermentation, and the $\small{D}$-LA optical purities of the two fermentation methods were above 99.00%. In fe$\small{D}$-batch mode, the maximum $\small{D}$-LA concentration attained by FBB fermentation was 218.8 g/l, which was 37.67% higher than that of free-cell fermentation. Repeate$\small{D}$-batch fermentation was performed to determine the long-term performance of the FBB system, and the data indicated that the average $\small{D}$-LA production rate was 1.62 g/l/h and the average yield was 0.98 g/g. Thus, hydrolyzed corn flour fermented by S. inulinus Y2-8 in a FBB may be used for improving $\small{D}$-LA fermentation by using ammonia water as the neutralizing agent.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.722-726
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• 2005

The use of isolated wine yeasts in winemaking processes is preferable to spontaneous fermentation. Selection criteria of wine yeast strains depend also on capacity and rate of fermentation and on alcohologenic capabilities. Our studies have described the dynamics of fermentation of wine musts by some isolated wine yeast strains of Saccharomyces genus: strains 6 and 8 of S. cerevisiae var. ellipsoideus (S. ellipsoideus) and strains 5 and 7 of S. bayanus var. oviformis (S. oviformis). All have high technological properties and all are adapted for the specific pedoclimatic conditions of some areas of Sibiu viticultural region. The selected strains were used as inocula to ferment Sauvignon, Muscat Ottonel, Rose Traminer, and Pino Gris musts in controlled laboratory conditions. It was found that higher initial oxygen concentration in must is necessary to accelerate the fermentation of all the wine yeast strains studied. In order to obtain quality wines, strains with considerable fermentative capacity, high alcohologenic capabilities, and a good conversion efficiency are recommended.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.37-42
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• 2002

Factors affecting the production of bacterial cellulose and organic acids in Kombucha fermentation were investigated. Kombucha was obtained by the fermentation (for 12 days at 3$0^{\circ}C$) of the green/black tea extract, supplemented with 10% white sugar, using an Oriental tea fungus as starter. Hitgher initial pH increased acid production with decreased cellulose production. With a cellulose pellicle or tea fungus broth as a starter, a 1~3 mm thick cellulose layer developed as a top layer every four days, and was removed subsequently while continuing fermentation. Addition of 30 mL tea fungus broth (13%, v/v) in Kombucha fermentation resulted in maximum production of a cellulose pellicle, indicating weak acid production. Yield of cellulose production at an early stage of fermentation was also higher when Kombucha was inoculated with a cellulose pellicle. In fact, addition of 1% (v/v) alcoholic beverage in the Kombucha fermentation activated the cellulose production, coupled with four times higher acid production.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.883-889
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• 1988

The salted small shrimps(Acetes japonicus) were fermented for 3 months at room temperature. During the period of fermentation, the changes of shrimp protein properties were determined. The extractability of soluble protein was slightly decreased in 1 month fermentation, but thereafter increased. The contents of 10% TCA soluble fraction were gradually increased during 3 month fermentation, and the rate of 10% TCA soluble fraction/total soluble protein was also greatly increased during the period of fermentation. Sephadex G-100 gel filtration pattern was changed after 1 month fermentation, showing the disappearance of low molecular weight protein peaks, the decomposition and the delay of elution time of main shrimp protein peaks. Polyacrylamide gel disc electrophoresis patterns showed the degradation of main protein bands into lots of smaller bands after 1 month fermentation. The contents of total free amino acids were slightly decreased in 1 month fermentation and then gradually increased during the Period of fermentation. The rate of free amino acids/soluble protein was steadily increased during the period of fermentation, but the rate of free amino acids/10% TCA soluble fraction was decreased continually during the period of fermentation. The contents of most free amino acids were increased during the period of fermentation, but those of histidine and arginine were greatly decreased in 1 month fermentation. Ammonia was increased after 1 month fermentation. The pH value of salted shrimp was slowly changed during 3 months of fermentation, showing increase from 7.8 to 8.2.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.10
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• pp.1580-1590
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• 2019

Objective: The aims of this study were to select one strain of Lactobacillus plantarum (L. plantarum) for a potential indigenous safe starter culture with low level antibiotic resistant and low biogenic amine production and evaluate its effect on biogenic amines reduction in Moo som. Methods: Three strains of indigenous L. plantarum starter culture (KL101, KL102, and KL103) were selected based on their safety including antibiotic resistance and decarboxylase activity, and fermentation property as compared with a commercial starter culture (L. plantarum TISIR543). Subsequently, the effect of the selected indigenous safe starter culture on biogenic amines formation during Moo som fermentation was studied. Results: KL102 and TISIR 543 were susceptible to penicillin G, tetracycline, chloramphenicol, erythromycin, gentamycin, streptomycin, vancomycin, ciprofloxacin and trimethoprim (MIC90 ranging from 0.25 to $4{\mu}g/mL$). All strains were negative amino acid-decarboxylase for lysis of biogenic amines in screening medium. For fermentation in Moo som broth, a relatively high maximum growth rate of KL102 and TISIR543 resulted in a generation time than in the other strains (p<0.05). These strain counts were constant during the end of fermentation. Similarly, KL102 or TISIR543 addition supported increases of lactic acid bacterial count and total acidity in Moo som fermentation. For biogenic amine reduction, tyramine, putrescine, histamine and spermine contents in Moo som decreased significantly by the addition KL102 during 1 d of fermentation (p<0.05). In final product, histamine, spermine and tryptamine contents in Moo som inoculated with KL102 were lower amount those with TISIR543 (p<0.05). Conclusion: KL102 was a suitable starter culture to reduce the biogenic amine formation in Moo som.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.642-647
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• 2003

In order to investigate utilization possibility of persimmon peel as a source of vinegar, we had been examined the alcohol and acetic acid fermentations of persimmon peel. In the first stage, alcohol fermentation, alcohol content was maximum value (8.22%) in 12.43 mL/g of added water, $12.41^{\circ}Brix$ of initial sugar content and 48.05 hr of fermentation time. Acidity was minimum value (0.30%) in 12.18 mL/g of added water, $13.72^{\circ}Brix$ of initial sugar content and 46.22 hr of fermentation time. In the second stage, acetic acid fermentation, acidity was maximum value (6.40%) in 2.02% of initial acidity, 67.98 rpm of agitation rate and 6.94 day of fermentation time. Browning color was minimum value in 1.50% of initial acidity, 150.0 rpm of agitation rate and 6.0 day of fermentation time. To manufacture persimmon vinegar using persimmon peel, in the first stage, optimal alcohol fermentation conditions was 12mL/g in added water, $12^{\circ}Brix$ in initial sugar concentration and 48 hr in fermentation time. In the second stage, optimal acetic acid fermentation conditions was 1.8% in initial acidity, 70 rpm in agitation rate and 6 day in fermentation time using Acetobacter sp. PA97.

• Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.192-197
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• 2011

The objective of this study was to select an effective microbial strain to improve the functional qualities of Eisenia bicyclis water extract by fermentation. For this purpose, several microorganisms isolated from traditional Korean fermented foods were inoculated and cultivated in E. bicyclis water extract. Ultimately, yeast strain YM-1 was selected for further study based on its total phenolic compound (TP) content and antioxidant activity, which were enhanced by microbial fermentation. The extract fermented by YM-1 exhibited a superior TP content and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity compared to extracts fermented by other microbes. The highest TP content and DPPH radical scavenging activity were observed after one day of YM-1 fermentation. Yeast strain YM-1 was identified as Candida utilis based on an analysis of its physiological characteristics. During fermentation of the extract by C. utilis YM-1, no significant difference was observed in the proximate composition, including moisture, crude lipid, crude protein, and crude ash. Fermentation by C. utilis YM-1 resulted in enhanced biological activity, including increases in the TP content and antioxidant activity. Thus, fermentation by C. utilis YM-1 is an attractive strategy for developing value-added food ingredients.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.340-344
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• 2000

Microbial oxidation of D-sorbitol to L-sorbose by Acetobacter suboxydans is of commercial importance since it is the only biochemical process in vitamin C synthesis. The main bottleneck in the batch oxidation of sorbitol to sorbose is that the process is severely inhibited by sorbitol. Suitable fed-batch fermentation designs can eliminate the inherent substrate inhibition and improve sorbose productivity. Fed-batch sorbose fermentations were conducted by using two nutrient feeding strategies. For fed-batch fermentation with pulse feeding, highly concentrated sorbitor (600g/L) along with other nutrients were fed intermittently in four pulses of 0.5 liter in response to the increased DO signal. The fed-batch fermentation was over in 24h with a sorbose productivity of 13.40g/L/h and a final sorbose concentration of 320.48g/L. On the other hand, in fed-batch fermentation with multiple feeds, two pulse feeds of 0.5 liter nutrient medium containing 600g/L sorbitol was followed by the addition of 1.5 liter nutrient medium containing 600g/L sorbitol at a constant feed rate of 0.36L/h till the full working capacity of the reactor. The fermentation was completed in 24h with an enhanced sorbose productivity of 15.09g/L/h and a sorbose concentration of 332.60g/L. The sorbose concentration and productivity obtained by multiple feeding of nutrients was found to be higher than that obtained by pulse feeding and was therefore a better strategy for fed-batch sorbose fermentation.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.704-708
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• 2015

For the analysis of multiple-reaction intermediates for long-chain dicarboxylic acid biotransformation, simple and reproducible methods of extraction and derivatization were developed on the basis of gas chromatography with flame ionization detector (GC-FID) instead of mass spectrometry. In the derivatization step, change of the ratio of pyridine to MSTFA from 1:3 to 9:1 resulted in higher peak intensity (p = 0.021) and reproducibility (0.6%CV) when analyzing 32 g/l ricinoleic acid (RA). Extraction of RA and ω-hydroxyundec-9-enoic acid with water containing 100 mM Tween 80 showed 90.4-99.9% relative extraction efficiency and 2-7%CV compared with those with hydrophobic ethyl acetate. In conclusion, reduction of the pyridine content and change of the extraction solvent to water with Tween 80 provided compatible derivatization and extraction methods to GC-FID-based analysis of longchain carboxylic acids.