• Title/Summary/Keyword: Autolysis

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Changes in the Chemical Composition and Flavor of Yeast Extracts during the Autolysis of Baker's Yeast (자기소화 시간에 따른 호모 Extract의 성분과 풍미의 변화에 관한 연구)

  • Lee, Cherl-Ho;Park, Chang-Real;Chung, Kyeoung-Sik
    • Korean Journal of Food Science and Technology
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    • v.13 no.3
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    • pp.181-187
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    • 1981
  • The changes in the chemical composition of yeast extracts during autolysis and their effect to the sensory quality were studied with baker's yeast, Saccharomyces cerevisiae. The amounts of extracted solids, proteins, amio-N. amino acids, especially glutamic acid, alanine and lysine, increased by the autolysis time up to 48 hrs. The results of sensory evaluation made by the multiple paired comparision test and Duncan's test indicated a significant difference is taste by the time of autolysis. In the profile test, the flavor character notes expressed by the panel were 17 different characters, 11 in aroma and 6 in taste. The character notes and the intensity of flavor changed with the time of autolysis. The sharp and beany flavor of the extracts which was autolyzed for 4 hours turned into meaty and worty flavor by 48 hours of autolysis. A proper arrangement of the flavor characters in the quantitative descriptive chart could provide a weighted value of the flavor grade. The aroma grade index and the taste grade index correlated to the amplitudes of the profile test.

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Analytical Properties for Insoluble Fraction of Yeast Extract by Autolysis (자기소화법에 의한 효모 Extract중 불용성 물질의 분석화학적 특성)

  • 김재웅;김동희
    • The Korean Journal of Food And Nutrition
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    • v.8 no.4
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    • pp.280-288
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    • 1995
  • Because yeast is rich in vitamins, nucleotides and essential amino acids, it has been used as a nutrient and dietary supplements. Particularly yeast extract functions as a seasoning, flavor enhancer in meats. In this study, naturally occurring insoluble components during yeast extract process by autolysis were microanalyses by using SEM, XRD, HPLC, GC, FT-lR and DSC. On the basis of useful datas, authors have characterized the analytical points for the purpose of improving products in the preparation of yeast extract.

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Inactivation of the Wall-Associated De-N-acetylase (PgdA) of Listeria monocytogenes Results in Greater Susceptibility of the Cells to Induced Autolysis

  • Popowska, Magdalena;Kusio, Monika;Szymanska, Paulina;Markiewicz, Zdzislaw
    • Journal of Microbiology and Biotechnology
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    • v.19 no.9
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    • pp.932-945
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    • 2009
  • Several species of Gram-positive bacteria have cell wall peptidoglycan (syn. murein) in which not all of the sugar moieties are N-acetylated. This has recently been shown to be a secondary effect, caused by the action of a peptidoglycan N-acetylglucosamine deacetylase. We have found that the opportunistic pathogen Listeria monocytogenes is unusual in having three enzymes with such activity, two of which remain in the cytoplasm. Here, we examine the enzyme (PgdA) that crosses the cytoplasmic membrane and is localized in the cell wall. We purified a hexa-His-tagged form of PgdA to study its activity and constructed a mutant devoid of functional Lmo0415 (PgdA) protein. L. monocytogenes PgdA protein exhibited peptidoglycan N-acetylglucosamine deacetylase activity with natural substrates (peptidoglycan) from both L. monocytogenes and Escherichia coli as well as the peptidoglycan sugar chain component N-acetylglucosamine, but not with N-acetylmuramic acid. As was reported recently [6], inactivation of the structural gene was not lethal for L. monocytogenes nor did it affect growth rate or morphology of the cells. However, the pgdA mutant was more prone to autolysis induced by such agents as Triton X-100 and EDTA, and is more susceptible to the cationic antimicrobial peptides (CAMP) lysozyme and mutanolysin, using either peptidoglycan muramidases or autolysis-inducing agents. The pgdA mutant was also slightly more susceptible than the wild-type strain to the action of certain beta-lactam antibiotics. Our results indicate that protein PgdA plays a protective physiological role for listerial cells.

Proximate Composition and Microbial Content Change of Broiler Waste Silage by Mixing with Wheat Bran and Oven-drying (닭폐기 부산물 Silage와 소맥피 혼합 및 오븐건조에 따른 일반성분과 미생물 총균수 변화)

  • Cha, Sang-Hyup;Cho, Jae-Huy;Chung, Kun-Sub;Chang, Pahn-Shick;Yi, Young-Hyoun
    • Korean Journal of Food Science and Technology
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    • v.27 no.1
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    • pp.63-67
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    • 1995
  • Broiler processing waste(offal) was homogenized and treated with the combination of acids. The offal was autolyzed(ensiled) at $25^{\circ}C$ for 72 hrs and analyzed for pH and fatty acid profile. The proximate composition and microbial content change of the autolyzed offal by mixing with wheat bran and ovendrying were evaluated. The initial pH value of the homogenized offal, 6.52 came down to 2.75 within 5 min after acidification and increased silightly to $3.06{\sim}2.92$ during autolysis. The proximate composition and fatty acid profile of the autolyzed offal were not substantially different from the unautoylzed offal. However, the log CFU(colony forming units)/g of total plate counts and fungal counts decreased from 7.45 and 7.11 to 3.39 and 2.03 after autolysis, respectively.

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Processing of Sardine Sauce from Sardine Scrap (정어리잔사를 이용한 정어리간장의 제조)

  • LEE Eung-Ho;CHO Soon-Yeong;HA Jae-Ho;OH Kwang-Soo;KIM Chang-Yang
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.17 no.2
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    • pp.117-124
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    • 1984
  • Sarine scrap usually comprises about $40\%$ of the raw fish in processing. The purpose of this study is to establish the desirable methods for proteinaceous materials from the sardine scrap through autolysis or enzymatic digestion and to convert them into useful by-products such as sardine sauce. Sardine scrap was chopped and mixed with equal weight of water, and be hydrolyzed them by autolysis and/or by addition of commercial proteolytic enzyme and various concentrations of sodium chloride. The optimal conditions for hydrolysis of sardine scrap were revealed in temperature at $55^{\circ}C$ and 4 hours digestion with bromelain($0.4\%$) and commercial complex enzyme ($6.0\%$), and those conditions were also applicated in autolysis. The maximum hydrolyzing rate of protein and released amino nitrogen were $82.5\%,\;5.2\%$ through autolysis, $84.3\%,\;5.8\%$ by bromelain digestion and $92.5\%,\;5.9\%$ by complex enzyme, respectively. In the products prepared from sardine scrap through autolysis or bromelain digestion, hypoxanthine was dominant, as $17.4 {\mu}mole/g$, dry matter for autolysis and $16.0 {\mu}mole/g$, dry matter, for bromelain digestion among the nucleotidcs and their related compounds, respectively. The abundant free amino acids were leucine, glutamic acid, lysnie, valine and alanine. The contents of those amino acids were $51.3\%,\;48.3\%$ of the total free amino acids, respectively. And the contents of 5'-IMP and TMAO were negligible but total creatinine was developed in value from $9.2\%\;to\;10\%$ of total extracted nitrogen. The flavor of sardine sauce prepared from sardine scrap by autolysis or enzyme digestion were not inferior to that of traditional Korean soy sauce by sensory evaluation.

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Studies on the Processing of Krill Sauce (크릴간장 제조(製造)에 관한 연구(硏究))

  • Lee, Eung-Ho;Cho, Soon-Yeong;Cha, Yong-Jun;Park, Hyang-Suk;Kwon, Chil-Sung
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.13 no.1
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    • pp.97-106
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    • 1984
  • The Antarctic krill, Euphausia superba, is drawing attention over the world as the largest source of unutilized proteins in the ocean. For the use of krill as a human food, processing conditions of krill sauce by autolysis and/or commercial proteolytic enzyme digestion were examined. The krill was chopped and mixed with equal weight of water, and hydrolyzed by autolysis and/or commercial proteolytic enzyme digestion. The optimal conditions for hydrolysis of krill were $52.5^{\circ}C$, pH 7.0-7.5, 3 hours by autolysis, $52.5^{\circ}C$, pH 6.3, 3hours by bromelain (0.5 %) digestion, and $52.5^{\circ}C$, pH 7.0-7.5, 3 hours by commercial complex enzyme (5 %) digestion, respectively The maximum hydrolyzing rate of protein were 83.2 % by autolysis, 89.7 % by bromelain digestion, 92.7 % by commercial complex enzyme digestion. After krill meat hydrolyzed by autolysis at optimum condition, inactivated at $100^{\circ}C$ for 20 minutes and filtered with Buchner funnel. Two kinds of products were prepared with krill hydrolysate and preservatives: one contained 10 % of sodium chloride and 0.06 % of benzoic acid and the other 10 % of sodium chloride and 3 % of ethyl alcohol. These products were filled in the sterilized glass bottle and sealed. The pH, volatile basic nitrogen, amino nitrogen, color value (L, a and b values) and viable counts of bacteria were determined during storage at $37^{\circ}C$. The results showed that the products could be preserved in good condition during one month at $37^{\circ}C$. As a method to reduce the sodium level in krill sauce, it is convinced that sodium chloride could be replaced half in partially by potassium chloride. In the products prepared from krill by autolysis, bromelain or commercial complex enzyme digestion, hypoxanthine and 5'-IMP were abundant among the nucleotides and their related compounds as 15.3-20.4 ${\mu}mole/g$, dry solid, 2.2-2.5 ${\mu}mole/g$, dry solid, respectively. The abundant free amino acids were lysine, leucine, proline, alanine and valine. The contents of these amino acids were 67.4 %, 69.4 %, 69.8 % of the total free amino acids of each products. And TMAO, betaine and total creatinine were low in contents. The flavor of krill sauce prepared from krill by autolysis or enzyme digestion was not inferior to that of traditional Kerean soy sauce by sensory evaluation.

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Simultaneous Production of Invertase and Yeast Extract from Baker's Yeast (Baker's yeast로부터 invertase 및 yeast extract 동시 생산공정)

  • 최순자;정봉현
    • KSBB Journal
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    • v.13 no.3
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    • pp.308-311
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    • 1998
  • A novel process was developed to simultaneously produce invertase and yeast extract from baker's yeast using ultrafiltration (UF) and microfiltration (MF) membrane processing. After the extraction of invertase under the optimal condition obtained in this study, invertase was separated from yeast cells using a hollow fiber membrane with a pore size of 0.1 $\mu\textrm{m}$. The resulting permeate containing invertase was concentrated using a hollow fiber membrane with a nominal molecular weight cut-off of 30 kDa. The yeast cell and permeate solutions, which were obtained after MF and UF membrane processing, respectively, were mixed together, and the autolysis was performed at 50$^{\circ}C$ in the presence of 5% (w/v) ethanol and 1% (w/v) NaCl. As a result, the yeast extract and invertase could be simultaneously produced from baker's yeast by this novel process.

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리보핵산 관련물질을 함유한 Yeast Extracts 제조에 Streptomyces faecalis MSF 배양액의 이용

  • 임억규
    • Microbiology and Biotechnology Letters
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    • v.25 no.5
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    • pp.512-519
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    • 1997
  • RNA accumulating strain of Torulopsis versatilis MT-1 was cultured in molasses medium for higher contents of RNA in cell. Yeast cells were harvested at logarithmic phase on synchronous culture. Yield of cells on dry base to input sugar was 59.5%. Crude protein content was 55.1% in cell. RNA content was 13.9%. Some problems found in the process for the preparation of yeast extracts were improved by the addition of culture broth of Streptomyces faecalis MSF which secrete RNase (5' nuclease and 5' adenylic acid deaminase). When the culture broth of S. faecalis MSF was added in autolysis process 46% of RNA in cell was converted to I and G(5' inosinic acid and 5' guanylic acid) in extract. By addition of 3-7% culture broth of S.faecalis MSF in autolysis or enzymolysis process at the start or early stage, RNA in extract was converted easily to I and G and protein in cells was easily extracted and hydrolyzed to amino acid. Taste of those yeast extracts was delicious. The yeasty smell in yeast extracts was removed. And cell debris was easily removed from extract.

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Microscopical Observation on Postmortem Autolysis in Liver of Korean Native Cattle (한우간장(韓牛肝臟)의 사후(死後) 자가융해(自家融解)에 관(關)한 광학현미경적관찰(光學顯微鏡的觀察))

  • Kwak, Soo Dong;Lee, Cha Soo
    • Korean Journal of Veterinary Research
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    • v.20 no.2
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    • pp.93-97
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    • 1980
  • To observe sequential postmortem autolysis in liver of Korean native cattle, liver placed in controlled environment chamber at $23-27.5^{\circ}C$ was treated after various intervals and observed with light microscope. The nuclear fading accompanied by margination of the chromatin in the hepatocytes appeared by 3 to 6 hours, and reduction of the cytoplasmic stainability and haryolisis began at 15 hours after death. Pyknosis of Kupffer's cells was noted by 3 to 20 hours, thereafter followed the decrease in staining of nuclei, but the nuclei were visible until 50 hours after death. Sinusoids and space of Disse were markedly distended at 10 hours, thereafter spaces of Disse were more dilatable than sinusoids. A large number of the erythrocytes in blood vessels were lysed, and the cytoplasmic stainability was largely reduced at 25 hours and nearly disappeared at 40 hours after death.

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