• Journal of Microbiology and Biotechnology
• /
• 제28권10호
• /
• pp.1581-1588
• /
• 2018

The growth of lactic acid bacteria (LAB) generates a high number of metabolites related to aromas and flavors in fermented dairy foods. These microbial proteases are involved in protein hydrolysis that produces necessary peptides for their growth and releases different molecules of interest, like bioactive peptides, during their activity. Each genus in particular has its own proteolytic system to hydrolyze the necessary proteins to meet its requirements. This review aims to highlight the differences between the proteolytic systems of Streptococcus thermophilus and other lactic acid bacteria (Lactococcus and Lactobacillus) since they are microorganisms that are frequently used in combination with other LAB in the elaboration of fermented dairy products. Based on genetic studies and in vitro and in vivo tests, the proteolytic system of Streptococcus thermophilus has been divided into three parts: 1) a serine proteinase linked to the cellular wall that is activated in the absence of glutamine and methionine; 2) the transport of peptides and oligopeptides, which are integrated in both the Dpp system and the Ami system, respectively; according to this, it is worth mentioning that the Ami system is able to transport peptides with up to 23 amino acids while the Opp system of Lactococcus or Lactobacillus transports chains with less than 13 amino acids; and finally, 3) peptide hydrolysis by intracellular peptidases, including a group of three exclusive of S. thermophilus capable of releasing either aromatic amino acids or peptides with aromatic amino acids.

• Journal of Dairy Science and Biotechnology
• /
• 제29권1호
• /
• pp.55-58
• /
• 2011

Certain lactic acid bacteria have anti-tumor activity, especially colon cancer. The fermented milk products containing that kind of lactic acid bacteria have to be recommended for human health as excellent health functional foods. This paper have been classified by 5 regions on the functions of lactic acid bacteria related to prevention of colon cancer. 1) Enhancing of host's immune response; Production of cytokines. 2) Binding and degradation of potential carcinogens; Binding and degradation of mutagenicity. 3) The changes of intestinal microflora and production of antitumorigenic or antimutagenic compounds; Production of azoxymethane. 4) Alteration of the metabolic activity of intestinal microflora; Decrease of harmful enzymes in intestinal tract. 5) Alteration of physicochemical conditions in the colon; Decrease of pH and bile acids contents.

• 한국식품과학회지
• /
• 제35권2호
• /
• pp.235-241
• /
• 2003

배양인삼 추출물을 첨가한 요구르트를 제조한 다음 그 품질 특성을 살펴본 결과, 배양인삼의 첨가로 요구르트의 젖산균 증식과 산 생성이 대조군보다 촉진되었고, 발효 24시간 후 생균수는 모든 군에서 $6.0{\sim}8.0×10^8\;CFU/mL$으로 발효시간이 경과할수록 점점 증가하였다. 점도는 대조군에 비하여 증가하였고, 특히 12시간에서 18시간 사이에 점도가 가장 높은 증가를 나타내었다. 총 아미노산 함량의 경우 대조군과 배양인삼 첨가군 모두 17여종의 아미노산이 존재하였으며, 0.5% 첨가군은 1.0% 첨가군에 비해 배양시간이 관계없이 4종의 아미노산을 제외한 대부분의 아미노산 함량이 많이 존재하였다. 유기산 함량은 대조군에 비해 0.5% 첨가군의 경우 24시간 발효시 젖산, 구연산, 개미산, 프로피온산의 생성이 증가되다가, 30시간 이후에는 이들 함량이 다소 감소되었다. 1.0% 첨가군의 경우는 배양시간이 증가할수록 개미산, 젖산, 초산의 함량이 증가되었다. 관능검사에서 배양인삼 0.5%와 1.0%의 첨가 요구르트가 전체적인 기호도에서 우수하였고 다른 항목들에서도 비교적 양호한 값을 보였다. 이와 같은 결과로 보아 $0.5{\sim}1.0%$의 배양인삼을 첨가하여 24시간 발효가 배양인삼 요구르트 제조에 가장 적합한 것으로 생각된다.

• 한국토양비료학회지
• /
• 제38권4호
• /
• pp.173-179
• /
• 2005

Biosolid 처리는 옥수수의 생장을 촉진시켰으며 중금속 흡수 또한 현저히 증가시켰다. 특히 다른 biosolid와 비교하여 Nu-earth 처리에서 옥수수 지상부의 Cd과 Zn의 흡수가 많은 것으로 나타났다. 옥수수의 중금속 흡수는 biosolid 자체의 중금속 함량과 밀접하게 관련되었는데, 크롬과 납의 흡수는 그 중 상관관계가 가장 낮았다. 근권의 유기산은 주로 lactic acid, acetic acid, propionic acid, butyric acid 및 oxalic acid 인 것으로 나타났다. 그 외 glutaric acid와 succinic acid, pyruvic acid 및 tartaric acid도 일부 발견되었다. Biosolid를 처리한 경우에는 butyric acid가 가장 많았으며 처리하지 않은 경우에는 acetic acid가 가장 많았다.

• 한국식품영양과학회지
• /
• 제27권3호
• /
• pp.425-432
• /
• 1998

The strain producing L-lactic acid from starch was isolated from kimchi. The isolated strain was identified as a homofermentative Streptococcus sp. through its morphological, cultural, biochemical characteristics, and named Streptococcus sp. JEJ-6. Lactic acids are of two types, one L-specific and the other D-specific form in a stereospecific form. Streptococcus sp. JEJ-6 produced selectively L-lactic acid from all of the tested carbon sources. The optimum conditions for the L-lactic acid production from the isolated microorganism were determined. For the maximum yield of L-lactic acid from Streptococcus sp. JEJ-6, the cell should be harvested at the early stationary phase, and the growth temperature, pH, and NaCl concentration should be 37$^{\circ}C$, pH 7.0 and 0.1%, respectively. 4% Soluble starch as substrate and organic nitrogen sources such as peptone and yeast extract should be used for the best yield. The optimum pH of the nicotinamide adenine dinucleotide(NAD)-dependent and NAD-independent lactate dehydrogenase(LDH) activities was pH 8.5 and pH 7.0, respectively.

• 한국식품저장유통학회지
• /
• 제12권5호
• /
• pp.501-506
• /
• 2005

본 연구에서는 유기산을 이용하여 칼슘 용해에 미치는 영향과 칼슘종류에 따른 용해특성을 조사하였다. 유기산종류에 따른 영향을 조사한 결과 해조칼슘은 초산과 젖산에서 잘 용해되었으나 구연산에서는 초기산도 4%이상에서 용해되었으며 주석산에는 칼슘이 용해되지 않았다. 초산과 젖산을 이용하여 칼슘종류에 따른 용해특성을 조사한 결과 초기산도가 높을수록 pH와 잔사량은 낮게, 적정산도는 높게 나타났다. 칼슘함량은 탄산칼슘과 해조칼슘에서 높았으며 젖산보다 초산이 칼슘가용화에 더 효과적인 것으로 나타났다.

• 한국식품조리과학회지
• /
• 제11권3호
• /
• pp.287-294
• /
• 1995

This study was carried out to determine optimal conditions in storing Andong sikhe. We made Andong sikhe according to the traditional recipe, and fermentation it has been stored either with (group B) or without (group A) "Saengkiwon Songi" for 40 days at 7${\pm}$2$^{\circ}C$. The changes of pHs, sweetness, the number of total bacteria and lactic acid producing bacteria, the quantities of organic acids and free sugars produced had been measured regularly since the 3rd day after fermentation. The results are as follows: The pH of both groups were 5.63 immediately after fermentation, and then gradually decreased to 4.02∼4.05. The sweetness was higher in group A (4.0) until the 15th day of storage, and then the same (17.5) in both groups. The sample from the 6th day in group A, and the samples from the 3rd and the 9th day in group B obtained the highest scores in their sensory evaluation. The numbers of total bacteria and lactic acid producing bacteria showed maxium on the 3rd day in both groups. 8 kinds of organic acids were detected, lactic acid being the most of all. 3 kinds of free sugars - fructose, glucose and maltose - were detected ; glucose and maltose have gradually increased throughout the storage period but fructose was not been detected after the 6th day in both groups.

• 한국미생물·생명공학회지
• /
• 제13권3호
• /
• pp.285-287
• /
• 1985

To investigate effective constituents of the many taste components in ordinary Korean soy sauce, we analyzed free amino acids, organic acids, free sugars and saline as taste components in ordinary Korean soy sauce, and determined sensory score of the ordinary Korean soy sauce taste with 45 persons of the trained pannels. The relationships between original data transformed with variables and sensory score of the ordinary Korean soy sauce were analyzed by stepwise multiple regression analysis. Eighty five percents of the ordinary Korean soy sauce taste is affected by twenty one kinds (Isoleucine, Leucine, Valine, NaCl, Lactic acid, Alanine, Phenylalanine, Tartaric acid, Sugar(\ulcorner), Proline, Malic acid, Glycine, Tryptophan, Arginine, Glutaric acid, Maltose, Histidine, Glucose, Fructose and Serine) of the taste components by stepwise multiple regression analysis of original data. Eighty one percents of the ordinary Korean soy sance taste is affected by sixteen kinds (Lactic acid, NaCl, Fumaric.Succinic acid, Tyrosine, Tartaric acid, Glycine, Malonic acid, Malic acid, Tryptophan, Glutaric acid, Methionine, Histidine, Cysteine, Maltose, Fructose and (Glutamic acid) of the taste components by stepwise multiple frgression analysis of original data transformed with square root. Eighty five percents of the ordinary Korean soy sauce taste is affected by nineteen kinds (Fumaric.Succinic acid, Lactic acid, Phenylalanine, NaCl, Tyrosine, Sugar(\ulcorner), Tartaric acid, Leucine, Glutaric acid, Methionine, Glycine, Tryptophan, Histidine, Proline, Cysteine, Glutamic acid, Maltose, Threonine and Oxalic acid) of the taste components by stepwise multiple regression analysis of original data transformed with logarithm.

• 한국식품조리과학회지
• /
• 제31권1호
• /
• pp.1-8
• /
• 2015

Organic acids are known as natural sanitizers. We examined the sanitizing effects of five organic acids (acetic acid, propionic acid, citric acid, malic acid, and lactic acid) and their persistence on three pectinolytic yeast strains isolated from decayed citrus, and the persistence of their sanitizing effects was determined during storage at $4^{\circ}C$ and $16^{\circ}C$. The 7~8 log CFU/mL of the mixed three yeast mixture was exposed to various concentrations of each organic acid for 1 min. The yeast mixtures decreased under detection limit(1 log CFU/mL) in 1% of acetic acid, followed by in 3% of propionic acid with the reduction of 5 log CFU/mL. The citric acid, malic acid, and lactic acid decreased the number of yeasts under detection limit at 7.5%. When treated with deionized water and 1~5% of organic acids were treated on the surfaces of citrus contaminated by yeasts, total numbers of the yeasts decreased under detection limit(3 log CFU) at 5% of acetic acid and 4 log CFU/piece at 5% propionic acid compared with deionized water. When treated with acetic acid and propionic acid on the stem ends of the contaminated citrus, total numbers of the yeasts significantly decreased 0.5 log CFU/piece at 3% of both organic acids. During storage at $4^{\circ}C$ and $16^{\circ}C$ for 20 days, total number of yeasts significantly decreased at 2% acetic acid compared with deionized water. This study suggested that organic acids could be used to sanitize microbial contaminants from citrus for storage and transportation.

• 유기물자원화
• /
• 제26권1호
• /
• pp.47-53
• /
• 2018

유기성 폐기물 소화공정의 발효액에서 젖산(lactic acid)을 회수하기 위해 화학침전법을 평가하였다. 젖산(lactic acid)의 회수율을 높이기 위하여 화학침전제 종류와 교반속도 및 침전시간 등 반응조건이 회수율 향상에 미치는 영향을 살펴보았다. 화학침전제의 종류에 관계없이 주입양이 증가할수록 젖산(lactic acid) 회수율이 증가하는 경향을 보였으며, CaO가 $Ca(OH)_2$와 $CaCO_3$에 비하여 높은 회수율을 나타냈다. CaO를 사용한 반응조건 최적화 실험결과, 교반속도 180 rpm, 침전시간 24 h, ethanol 주입량 25%(v/v)에서 회수율이 48%로 가장 높게 나타났다. 본 연구에서는 발효액 내 젖산(lactic acid)의 농도만 고려하여 주입할 침전제의 양을 계산하였기 때문에 실제 적용을 위해서는 발효액의 유기산 종류 및 농도를 고려하여 침전제의 투입량을 결정해야할 것이다. 유기물의 정성적 분석(FEEM, SEC) 결과로 볼 때 침전공정은 유기산의 특성에 큰 영향을 미치지 않았다.