• Korean Journal of Microbiology
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• v.6 no.3
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• pp.81-86
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• 1968

1. Amylolytic enzyme activities of Asp. oryzae and Asp. oryzae var. fulvus using the glucose as the carbon sources increased remarkably according to the decrease of the residual sugars. 2. The amylase productions of Asp. oryzae and Asp. oryzae var. fulvus were increased and enhanced when the organisms lave belen cultured in modified Koji media containing maltose as adaptive substrate. However, being devoid of maltose the level of amylase activities were lower and the begining of the production was prolonged. 3. The effects of C-sources on the amylase production of them were observed. The level of amylase activity varied with C-sources and their concentrations Marked increase of amylase production was afforded by starch and maltose. The effects of citric acid and tartaric acid were little or nothing. 4. Using the sucrose and lactose as the adaptive substrates both strains show the maximum amylolytic enzyme activities at the 3% concentrations of those sugars.

• The Korean Journal of Mycology
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• v.17 no.3
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• pp.149-153
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• 1989

One strain of Aspergillus niger K-25 producing an acid-stable ${\alpha}-amylase$ was isolated from the soil. The optimum culture conditions were investigated. The production of the acid-stable ${\alpha}-amylase$ was enhanced when the strain was incubated in a medium containing soluble starch 3.5%, peptone 2%, $KH_2PO_4$ 0.5%, $MaSO_4{\cdot}7H_2O$ 0.25% and $FeCI_3$ 1.0% at pH 3 for 7 days. However, higher activity of acid-stable ${\alpha}-amylase$ was demonstrated on wheat bran culture. Amylase production was doubled when A. niger K-25 was incubated on the wheat bran supplemented with fumaric acid buffer (pH 3).

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.700-709
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• 2016

The mitogen-activated protein kinase HOG1 (high-osmolarity glycerol response pathway) plays a crucial role in the response of yeast to hyperosmotic shock. Trichosporonoides oedocephalis produces large amounts of polyols (e.g., erythritol and glycerol) in a culture medium. However, the effects of HOG1 gene knockout and environmental stress on the production of these polyols have not yet been studied. In this study, a To-HOG1 null mutation was constructed in T. oedocephalis using the loxP-Kan-loxP/Cre system as replacement of the targeted genes, and the resultant mutants showed much smaller colonies than the wild-type controls. Interestingly, compared with the wild-type strains, the results of shake-flask culture showed that To-HOG1 null mutation increased erythritol production by 1.44-fold while decreasing glycerol production by 71.23%. In addition, this study investigated the effects of citric acid stress on the T. oedocephalis HOG1 null mutants and the wild-type strain. When the supplementation of citric acid in the fermentation medium was controlled at 0.3% (w/v), the concentration of erythritol produced from the wild-type and To-HOG1 knockout mutant strains improved by 18.21% and 21.65%, respectively.

• Food Science and Biotechnology
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• v.18 no.3
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• pp.732-738
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• 2009

An acidic polygalacturonase (PG) from Aspergillus kawachii was produced by solid state fermentation employing a polyurethane foam support. The conditions used for the production of acidic PG were particle size of support (0.6 or 500 $mm^3$) and fermentation time. From the factors studied, the particle size had important influence on enzyme production. The best conditions for acidic PG production were $0.6\;mm^3$ particle size, 18 hr at $30^{\circ}C$ and initial pH of 5.0. In addition, pectin was extracted from citrus pomaces (grapefruit, lime, and tangerine) by acidic PG at $50^{\circ}C$ for 24 hr with citric acid solution. Infrared spectroscopy showed that lime pomace had more high-methoxylated (65%) endogenous pectin than was obtained than from grapefruit or tangerine pomaces. The enzymatically extracted pectin yield in dry basis (d.b.) for grapefruit and lime pectins were 6.95 and 4.25%, respectively. The citric acid solution alone also contributed to pectin extraction from citrus pomaces (7-9%, d.b.). Limited pectin extraction by acidic PG from tangerine pomace was most likely due to the presence of low-methoxylated endogenous pectin. The enzymatic method for pectin extraction using acidic PG from A. kawachii is a promising technique for releasing highly polymerized pectic substances from high-methoxylated lime or grapefruit pomaces.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.1
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• pp.37-41
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• 2000

Physiocheical properties and chemical compositions of two plums(Oishiwase, Formosa ) produced in Kimcheon area were investigated . Chemical compositions of two plum cultivars were similar except nitrogen free extract(NFE) . NFE value of Formosa was higher than Oishiwase . Alcohol insoluble substance content, total soluble pectin, total sugar content and total organic acid content of Oishiwase were 2.08%, 14.16%, 5.07% and 949.16mg%, respectively. In case of Formosa cultivar, those were 50%, 15.42%, 5.91% and 985.91mg%, respectively. Fructose content among free sugars of two plum cultivars range from 3.97-3.45% and the other were glucose, sucrose and inositol, 1.83-1.53%, 0.08-0.05% and 0.04-0.03%, respectively. Malic acid content was 35-373mg% and others were levulinic acid, lactic acid, citric acid, succinic acid and fumaric acid in the decreasing order.

• Preventive Nutrition and Food Science
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• v.12 no.3
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• pp.167-172
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• 2007

This study was conducted to determine the effect of hygienic processing (HP) on the reduction of microorganisms during manufacturing of saengshik with two vegetables (carrots and cabbage) and two grains (barely and glutinous rice) compared to general processing (GP). For GP, distilled water was used for washing raw materials and equipment. For HP, aqueous ozone (3 ppm) in combination with 1% citric acid and 70% alcohol were used for washing raw materials and the equipment, respectively. In carrots, after cutting, total aerobic bacteria (TAB), yeast and mold (YM) and coliforms were significantly increased to 5.19, 8.04 and 2.08 ($log_{10}$ CFU/g), respectively (p<0.05). Washing effectively reduced the increased microorganisms from cross contamination during cutting, but cross contamination increased with subsequent GP drying and milling procedures to 8.56, 8.27 and 3.71 ($log_{10}$ CFU/g) for TAB, YM and coliforms, respectively (p<0.05). On the other hand, HP washing of carrots with 3 ppm ozone in combination with 1% citric acid showed higher antimicrobial effect than GP washing, significantly decreasing the number of microorganisms (p<0.05). Further cross contamination did not occur through drying and milling due to cleaning the equipments with 70% alcohol prior to processing. After milling, the number of TAB, YM and coliforms were significantly decreased to 3.89, 4.47 and not detectable level ($log_{10}$ CFU/g), respectively (p<0.05). Similar results were observed in cabbage and grains. During storage for two months at different temperatures (22 or $4^{\circ}C$), there were no changes in numbers of spoilage microorganisms in the packaged saengsik after either processing. This suggests the importance of HP for the reduction of microorganisms during saengsik production, and demonstrates the effectiveness of disinfection at each processing stage in minimizing contamination levels to enhance microbial safety of saengshik products.

• Food Science of Animal Resources
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• v.30 no.4
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• pp.575-581
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• 2010

This investigation was aimed at developing a ready-to-reconstitute beverage by utilizing probiotics and whey protein hydrolysates carrying bioactive peptides. Cheddar cheese whey was ultrafiltered. The 18% protein retentate was subjected to protein hydrolysis using Neutrase. The hydrolyzed retentate was further condensed to 35% total solids and spray-dried at $75^{\circ}C$ outlet air temperature. Different levels of sugar, citric acid and stabilizer were blended for spray-dried hydrolysates. Spray-dried hydrolysate was further inoculated with different levels of probiotics grown in a whey medium and dried in fluidized-bed drier at $40^{\circ}C$ to obtain a ready-to-reconstitute beverage. Hydrolysis was greatest at an enzyme:substrate ratio of 1:25 for 3 h. Spray-dried hydrolysate reconstituted to 1% protein and blended with 15% sugar, 0.2% citric acid and 0.15% xantham gum resulted in a superior product with no sedimentation. Accordingly, sugar, citric acid and xanthum gum were dry-blended with spray-dried hydrolysates. Bifidobacterium bifidum and Lactobacillus acidophilus that was grown separately in a whey medium, blended to produce 2% spray-dried hydrolysate and dried as described above resulted in a readyto-reconstitute beverage mix. The fluidized dried product typically exhibited a probiotic count of $10^8$colony forming units (CFU)/g. However, blending of probiotic to the retentate and direct spray-drying precipitously reduced the probiotic count to $10^4$ CFU/g of powder.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.365-374
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• 2010

The ash reduction effects and fuel property changes of spent mushroom substrates by acid solution extraction, and the production possibilities of wood pellet fuel using them were studied. The ash weight of spent Pleurotus eryngii substrates was reduced from 8.81%(w/w) to 3.33%(w/w), and calorific value was increased from 3,958.3 kcal/kg to 4219.2 kcal/kg when extracted with a mixture of Acetic acid 2%(w/w) and Anhydrous citric acid 1%(w/w) in condition of liquid ratio 1:8, extraction temperature $55^{\circ}C$ and extraction time 180 min. The ash weight of spent Flammulina velutipes substrates was reduced from 14.91%(w/w) to 4.07%(w/w), and calorific value was increased from 4,190.3 kcal/kg to 4,219.2 kcal/kg when extracted with a mixture of Acetic acid 3%(w/w) and Anhydrous citric acid 1%(w/w) in condition of liquid ratio 1:8, extraction temperature $65^{\circ}C$ and extraction time 180 min. The ash weight of spent Pleurotus osteratus substrates was reduced from 3.31%(w/w) to 0.59%(w/w), and the smallest reduction was in calorific value from 4,558.6 kcal/kg to 4,216.2 kcal/kg when extracted with a mixture of Acetic acid 1%(w/w) and Anhydrous citric acid 1%(w/w) in condition of liquid ratio 1:8, extraction temperature $65^{\circ}C$ and extraction time 180 min.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.700-706
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• 1990

The curd yogurt was prepared from milk or milk added with skim milk powder or soy proteins. Acid production by lactic acid bacteria in milk containing additive of 2% was investigated and quality of curd yogurt(sensory property and keeping quality) was examined. Some organic acids in curd yogurt were analyzed by HPLC. The soy proteins, particularly defatted soy flour or soy flour, stimulated acid production by lactic acid bacteria more than skim milk powder. Among the four organisms tested, Leuconostoc mesenteroides and Lactobacillus bulgaricus produced more acid than L. casei and L. delbrueckii. HPLC analysis of organic acids in curd yogurt showed that the amount of lactic acid and acetic acid markedly increased during the fermentation by L. bulgaricus for 24 hours while the amount of citric acid markedly decreased. The major organic acid produced during the fermentation was lactic acid. Addition of soy proteins to milk reduced sensory property of curd yogurt. Among the soy proteins tested, soy protein concentrate or soy protein isolate added sample showed better sensory acceptability than other samples. When curd yogurt was kept at $5^{\circ}C$ for two weeks, titratable acidity, pH and number of viable cells of curd yogurt were not changed.

• Journal of the Korean Wood Science and Technology
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• v.21 no.1
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• pp.7-14
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• 1993

To increase the production of mushrooms and the economic efficiency of mushroom cultivation, the pinchips(PC) and sawdusts(SD) of three Korean oak species were tested as cultivating media for Lentinus edodes with varing the composition of the media. The results are as follows. 1. Organic acids(tannic acid and citric acid), which were added in the PC medium to enrich the quality of mushrooms, did not increase the growths of the mycelia and the quality. 2. The mushrooms were able to be harvrested from six months after beginning the cultivation. No significant differences were found among the qualities of the mushrooms produced by various treatments. 3. The production rate of mushroom was relatively high with, 28.4~29.3% (700~730gr./2,500gr pack). The net profit estimated was about 1,450 won per pack.