• Journal of Microbiology and Biotechnology
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• 제1권2호
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• pp.130-135
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• 1991

The effects of media composition on citric acid fermentation using surface immobilized Saccharomycopsis lipolytica were studied. The use of the standard medium for these organisms resulted in rapid decrease of citric acid production and a transformation of immobilized cell morphologies from a yeast-type to a mycelium-type. When the standard medium was enriched with vitamins, trace minerals, a growth factor and ammonium to form a Vigorous Stationary Phase (VSP) fermentation type medium, relatively stable citric acid production (10 mg/lㆍh) was obtained. Using the VSP type medium, the surface immobilized cells also retained their yeast-type form.

• 한국수산과학회지
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• 제56권2호
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• pp.253-258
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• 2023

This study was conducted to inhibit histamine formation in salt-fermented anchovy Engraulis japonicus fish sauce, by lowering the pH using 1% citric acid as food additive during the initial fermentation stage. The fish sauce samples were prepared with fresh anchovies used immediately after being caught (F), and left at ambient temperature for 4 h, and 24 h with 25% salt, 1% citric acid, and without citric acid for a 6-month fermentation period. The content of ammonia nitrogen, total nitrogen, and glutamic acid in fish sauce was unaffected by the addition of citric acid during the fermentation period. The histamine content of F and 4 h samples were 20.5-30.6 and 77.4-119.3 mg/kg, respectively. The histamine content of F and 4 h samples with 1% citric acid was 4.1-8.7 and 50.4-56.1 mg/kg, respectively. Furthermore, addition of citric acid did not inhibit histamine formation in 24 h sample that had lower freshness quality. Additionally, effective inhibition of histamine is observed during manufacturing of salt-fermented anchovy fish sauce on an industrial scale, suggesting that lowering the initial pH using 1% citric acid does not alter the taste and flavor of the fish sauce.

• Journal of Microbiology and Biotechnology
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• 제10권1호
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• pp.51-55
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• 2000

Surface culture fermentation using Aspergillus niger was studied for gluconic and citric acid production at different C/N ratios. A culture of A. niger was found to produce either gluconic acid alone, a mixture of gluconic and citric acid, or citric acid alone depending on the level of nitrogen in the medium (4 to 18mM). Glucose oxidase from the mycelial mat was also analyzed at different levels of nitrogen in the media. By choosing the level of nitrogen in the medium at the start of fermentation, it is possible to produce either of the two acids as the dominant product or the two together as a mixture.

• 한국자원식물학회지
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• 제33권3호
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• pp.194-199
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• 2020

This study was carried out to get the information of Plum tree (192 germplasm) collected in Korea, and to evaluate the organic acid contents and fermentation solution. The organic acid content of fruit was 50.9 ± 6.0 mg/g, and which was composed of 55.5% of citric acid, 43.4% of malic acid and 1.1% of oxalic acid, and showed large difference among germplasms. Oxalic acid and malic acid made no differences in organic acid content according to flesh color, whereas citric acid and total organic acid contents were highest in orange color and lowest in whitish green. Malic acid, citric acid and total organic acid contents did not show differences among fruit weight groups, but oxalic acid content was highest at fruit weight of 5.1 ~ 10.0 g and lowest at more than 20.1 g. The sugar content of fermentation solution of fruit was 55.7 ± 1.6 °Brix and the harvest rate was 116.7 ± 8.7%. The correlation coefficients among fruit weight, the sugar content (°Brix) and harvest rate of fermentation solution were very low, and there were correlations of r=-0.551^⁎⁎ between fruit weight and oxalic acid, r=-0.767^⁎⁎ between malic acid and citric acid, and r=0.834^⁎⁎ between citric acid and total organic acid content.

• Korean Chemical Engineering Research
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• 제52권3호
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• pp.402-406
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• 2014

본 실험에서는 농부산물인 밀짚을 고체배지로 사용하여 Aspergillus niger NRRL 567에서 구연산 생산 시, 발효조건과 첨가제가 구연산 생산에 미치는 영향을 단일변수(one-factor-at-a-time) 최적화를 이용하여 주요 인자의 순차적 최적화를 수행하였다. 발효 72시간에서 온도, 수분함량, 입자크기, pH와 첨가제 농도를 최적화했을 때, 각각 $30^{\circ}C$, 70%, 0.5~1.0 mm, pH 5.5와 4% 메탄올 첨가조건에서 최대 구연산 생산인 206.0 g/kg 건조중량 (DM)을 확인할 수 있었다. 이는 최적화 이전 구연산 최고 생산인 74.5 g/kg DM 대비 177% 증가한 결과이다. 최적화 실험에서 도출된 조건을 밀짚, 옥수수대와 피트모스(peat moss)에 적용하여 고체발효를 수행하였을 때, 발효 120시간에서 각각 231.8, 213.8, 240.2 g/kg DM 구연산 생산을 확보하였다. 본 실험 결과는 밀짚과 옥수수대 등의 목질계 농부산물을 이용한 구연산 생산 시, 고체발효법이 기존의 액체발효법의 대체가 가능함을 시사하였다.

• 한국식품영양과학회지
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• 제29권4호
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• pp.575-581
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• 2000

본 연구는 사과과즙 및 감을 부재료 로 첨가하여 고추장을 담금하고 이들 과실고추장의 숙성에 따른 성분 변화를 조사하였다. 수분활성도는 숙성기간이 경과함에 따라 감소하는 경향이었으며, 사과고추장이 감고추장보 다 수분활성도가 높았다. 환원당 함량응ㄴ 숙성 초기 사과고추장과 감고추장 각각 10.95, 10.30%에서 시간이 경과됨에 따라 증가하여 숙성 10주째에 각각 16.68, 19.14%로 최고치를 나태내었다. 유리당 성분으로 사과고추장은 숙성 12주째에 maltose 10.55%, glucose 8.47%, fructose 3.02%로 나타났으며, 감고추장은 숙성 6주째에 maltose 21.65%, glucose 8.71%, fructose 2.98%로 maltose 함량이 특이적으로 높았다. 유기산으로 citric acid, malic acid, lactic acid, oxalic acid가 검출되었으며, 2종의 과실고추장 모두 citric acid와 malic acid의 함량이 높았다. 과실고추장의 총 유리아미노산은 사과고추장에서 188.59~420.94mg%, 감고 추장에서 154.67~316.93 mg%로, 숙성 10~12주에서 최고치를 나타내었으며 aspartic acid, proline, glutamic acid 등의 함량이 비교적 높았다.

• Mycobiology
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• 제48권2호
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

• 한국미생물·생명공학회지
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• 제32권2호
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• pp.154-157
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• 2004

고정화된 Aspenillus niger 세포가 우유공장폐수에서 발효로 구연산을 생산하는데 이용되었다. 구연산 생산균주로서 A. niger ATCC 9142가 3일간 전배양되었으며, 약 2.5∼3.5 mm Ca-alginate beads 로 포획되었다. 최적의 pH와 온도는 각각 3.0과 $30^{\circ}C$였다. 발효에 대한 최적 희석률은 $0.025h^{－1}$ 인 것으로 계산되었다. 구연산의 최대 생산량은 최적화된 발효조건과 함께 4.5 g/$\ell$에서 얻어졌다. 고정화된 Aspergillus niger ATCC 9142에 의해 생산된 구연산의 수율은 70.3%였다. Shake-flask배양실험에 비해 연속식 배양실험 결과가 고정화 세포에 의해 20%증가되었다. 따라서 우유공장폐수는 구연산 발효기질로서의 이용가치가 있다고 볼 수가 있겠다.

• 한국식품조리과학회지
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• 제15권5호
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• pp.459-468
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• 1999

The purpose of this study was to evaluate the effect of bamboo(Idae) leaves on the taste and preservation of Dongchimi. Dongchimi was prepared by the method described in the literatures and fermented at 10$^{\circ}C$ for 75 days. The amounts of bamboo leaves used to cover the Donchimi was 1, 3, 5 and 7% of radish weight. Total vitamin C content increased gradually in the initial stage of the fermentation periods, and then it decreased gradually. Regardless of the amount of bamboo leves, the reducing sugar content increased gradually from the initial stage of fermentation increased rapidly after 8 days of fermentation. As the amount of bamboo leaves increased, the reducing sugar content was retained longer, which reflected the retardation of Dongchimi fermentation. The free amino acid contents in all of the Dongchimi samples were in order of arginine > glutaric acid > aspartic acid > alanine at the initial period of fermentation, but the order changed to arginine > alanine > glutamic acid > valine as fermentation proceeded over 23 days. Among the five non-volatile organic acids identified, the levels of malic acid and citric acid were decreased during fermentation, while those of lactic acid, fumaric acid, and succinic acid were increased. There was a significant increase in lactic acid, succinic acid, malic acid, and citric acid contents during fermentation. The content of water soluble pectin(WSP) was higher than other pectins at the initial stages, but the content of WSP decreased as fermentation proceeded.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.874-878
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• 2012

곰팡이균을 이용한 구연산 생산에 있어 액체배양의 초기 pH는 구연산 생산에 유의한 영향을 미친다고 알려져 있다. 본 연구에서는 고체배양에서 Aspergillus niger를 이용한 구연산 생산에 여러 pH의 완충용액이 구연산 생산에 미치는 영향을 밝혀 최적의 완충용액을 찾고자 연구하였다. 실험에 적용된 여러가지 완충용액은 구연산 생산에 영향을 미치며 높은 초기 pH 조건에서 구연산 생산성이 우수한 것으로 나타났다. 여러가지 완충용액 중, phosphate (pH 8.6) 완충용액과 carbonate 완충용액(pH 10.0)이 고체발효에서 구연산 생산에 가장 적합함을 알 수 있었다. Carbonate 완충용액(pH 10.0)을 사용하여 고체배지의 초기 pH를 6.8으로 하였을 경우, 최대 구연산 생산인 564.3 g/kg solid substrate 얻을 수 있었다. 또한, 염기 또는 산을 사용하여 고체 배지의 초기 pH를 4.42로 조정한 배지에 비해 phophate 완충용액을 사용한 pH 4.48의 고체배지에서 구연산 생산성이 1.5배 증가함을 알 수 있었다. 이는 완충용액의 사용이 구연산 생산에 의한 배지의 산성화를 방지해 세포성장과 생산성을 높였다고 결론지을 수 있다.