• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.86-91
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• 1989

To investigate the effect of NaCl concentration and nitrogen sources in the medium for the Streptococci on the intra- and extracellular proteinase(ICP and ECP) which have been known as one of the major causes for the bitter peptide formation, Streptococcus lactis $ML_8$ and Streptococcus cremoris $ML_4$ strains were incubated at 0-4% NaCl in the medium and Na-caseinate as a nitrogen source 0-100%, and the cell growth, ICP and ECP activities were analyzed. As the concentration of the NaCl in the medium increased, the growth and ECP activity decreased but the ICP $activity/10^{10}$ cells increased on the contrary. This implied that the NaCl in the medium affects only the ECP which is associated mainly to the cell wall and cell membrane but not the ICP activity. When the content of the caseinate instead of other low molecular nitrogen sources were increased in the medium, the cell growth was lowered while the ECP activities increased probably by induction of proteinase production.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.71-79
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• 1988

For the purpose of producing low salt fermented anchovy by accelerated method with a strong proteolytic bacteria, in this study, a strong proteolytic bacterium was isolated from low salt fermented anchovy and its bacteriological characteristics and properties of protease were experimented. The results obtained were as fellows : three proteolytic bacteria, Aeromonas anaerogenes Barillus subtilis and Staphylococcus saprophyticus were isolated from low salt fermented anchovy($4\%\;of\;salt,\;4\%\;of\;KCl,\;0.5\%\;of\;lactic\;acid,\;6\%$of sorbitol and $4\%$ of alcohol extract of red pepper) after 40 days fermentation. Among these strains, which grow best at $30^{\circ}C$, pH 7.0, B. subtilis was found the best proteolytic strain and benefit for industrial use as shown $0.95\;hr^{-1}$ of specific growth rate, $89{\mu}g-Tyr/hr.ml$ of maximum activity after 12 hrs culture in TPY broth. The protease produced by by B. subtilis showed maximum activity at $35^{\circ}C$, pH 7.0, and molecular weight was estimated to be 23,000 by Sephadex G-100 filtration, and it was supposed to be a kind of metal chelator sensitive neutral protease from the results of strong sensitivity against EDTA, o-phenanthroline and metal ions such as $Cu^{2+},\;Ni^{2+},\;Fe^{2+}.Km$ value of that by method of Lineweaver-Burk was determinded to be $0.73\%$ for casein as a substrate.

• Korean journal of food and cookery science
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• v.26 no.3
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• pp.323-329
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• 2010

Studies on the tenderizing effect of fruits has been limited even though fig, kiwifruit, pear, and pineapple cultivated in Korea are utilized commonly during cooking for their proteolytic properties. Therefore, the characteristics of these fruits were investigated by treating beef with their crude protease extracts. The protease effects of crude protease extract from the fruits on casein and myofibrilar protein were in the following order : pineapple > kiwifruit > fig > pear. Electrophoretic analysis results found that pineapple, kiwifruit, and fig cleaved myosin heavy chain into smaller fragments. The myofibrilar fragmentation ratio of crude protease extracts was the highest for pineapple whileas the lowest for pear. Ground fruits (5% and 10%) increased amounts of soluble nitrogen and decreased shear force of beef. Pineapple was the most effective while pear was the least effective. Decrease in springiness and gumminess was observed by texture profile analysis of beef treated with fruits, especially pineapple and kiwifruit. Among the 5% treatments, pineapple and kiwifruit produced the highest tenderness. Additionally, 10% treatment was less preferable than the 5% treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.5
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• pp.1004-1009
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• 2001

Acid hydrolysates of cocoon was gained by acid hydrolysis of 2 N HCl, 11$0^{\circ}C$, 48 hours, neutralization and desalting from the cocoon. The amino acid compositions of acid hydrolysates of cocoon were glycine 43.25%, alanine 34.39%, serine 10.05% and valine 2.44%. The contents of essential amino acid was 10.05%. Food efficiency ratio of acid hydrolysates of cocoon group was equal to the reference protein, casein. Liver weight, GOT, GPT activity, serum albumin and serum total protein level of rats were not significantly different among the experimental groups. Therefore, the protein acid hydrolysates of cocoon is not of high quality. When the rat fed with high cholesterol, high lipid, and high sucrose diet was administered with 5% acid hydrolysates of cocoon, its plasma lipids concentration of acid hydrolysates of cocoon was favorably affected: its triglyceride was decreased, and the level of phospholipid and HDL cholesterol were increased. There was also an unfavorable effect: the levels of LDL cholesterol and total cholesterol went up. Therefore, the acid hydrolysates of cocoon is not a good protein food source, but is can be used a cosmetic, medical, or packing material. Further research will reveal how it will affect or improve plasma lipid.

• Food Science of Animal Resources
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• v.30 no.1
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• pp.102-109
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• 2010

Imitated cheese was prepared from whole milk powder and fermented milk and the moisture content, general components, noncasein nitrogen, nonprotein nitrogen and free amino acids were analyzed to determine the optimal ripening conditions needed to produce imitated cheese that was similar to natural cheese. The moisture content of the imitated cheese was 40.27% one day after being produced. The cheese was ripened using two different methods; at $12^{\circ}C$ with vacuum sealing and at $12^{\circ}C$ and 95% RH with a spray of Penicillium camemberti. The lactose content decreased rapidly from 24.64 to 5.43% at the $4^{th}$ wk of ripening when it was ripened with Penicillium camemberti. The degradation of protein by mold ripening in the imitated cheese was more rapid than that of vacuum sealing. The flavor and body texture were optimal at the $4^{th}$ wk ripening. The noncasein nitrogen and nonprotein nitrogen content increased from 28.10 to 54.05, and from 6.58 to 23.06 mg/mL, respectively, when ripened with P. camemberti. When the cheese was ripened at $12^{\circ}C$, 95% R.H with P. camemberti after 4 wks, all free amino acids increased significantly except asparagines. The total free amino acid and bitter amino acid concentrations increased from 8.40 to 34.87, and from 1.53 to 10.02 nmol/mg, respectively. When the imitated cheese was prepared, the protein degradation and flavor of the cheese was better when ripened with P. camemberti.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.510-516
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• 1993

This study was conducted to investigate biochemical characteristics of enzyme-added cheese base slurries during accelerated ripening. Trichloroacetic acid (TCA) soluble nitrogen of cheese base slurries increased rapidly during the first day of ripening and the rate of increase slowed down thereafter. Cheese base slurries showed lower level in the production of the nitrogen than Cheddar cheese slurries. Producctions of phosphotungstic (PTA) soluble amino nitrogen also showed similar trends as TCA soluble nitrogen. Electrophoresis revealed that all caseins in both cheese base slurries and Cheddar cheese slurries were hydrolyzed, but whey proteins in cheese base slurries were little hydrolyzed. Cheese base slurries produced free amino acids little more than half of Cheddar cheese slurries. Both slurries showed similar increasing trend in production of short-chain free fatty acids. The specificity of the fatty acids in the slurries was similar to that of natural ripened cheese. The results of this study showed that addition of enzyme was effective to accelerate cheese base ripening.

• Journal of Aquaculture
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• v.10 no.3
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• pp.327-334
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• 1997

This study was conducted with Israeli strain of common carp to determine apparent protein, lipid and gross energy digestibility coefficients and apparent calcium and phosphorus availabilities of the following feedstuffs : steam-dried white fish meal (WFM-S), flame-dried white fish meal (WFM-F), brown fish meal (BFM), soybean meal (SBM), corn gluten meal (CGM), sesame meal (SSM), wheat flour (WFL), brewer's yeast (BY) and monocalcium phosphate (MCP). Test diets consisting of a 70:30 mixture of refoernce diet to test ingredient were utilized with chromic oxide as an external indicator. Fecal collection was made during 10 days before the end of feeding trial lasted for 27 days. The best weight gain and feed utilization were found in fish fed MCP containing test diet. Protein digestibility was high for most ingredients, ranging from 81.2% for BY to 91.9% for SBM, with the exception of SSM which was 77.6%. Lipid digestibility coefficients ranged 74% for CGM to 85.8% for two kinds of white fish meal. Digestible energy coefficients were generally high for fish meals, ranging from 77.4% for WFM-S to 81.3% for WFM-F, whereas those for plant feedstuffs were significantly (P<0.05) lower, from 64.5% for CGM to 70.6% for BY. Phosphorus availability from fish meals was variable with a low of 6.6% for WFM-F and a high of 13.6% for WFM-S. Phosphorus availability from SBM and BY was 7.3% and 57.2%, respectively. Calcium and phosphorus availabilities from MCP were 84.6% and 80.6%, respectively. These results provide more precise information concerning nutrients and energy utilization of Israeli strain of common carp and will allow ingredient substitutions in practical diet formulations based on levels of availabile protein and phosphorus.

• Journal of Nutrition and Health
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• v.17 no.3
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• pp.210-216
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• 1984

The growth response, lipid deposition, fat free body mass and energy expenditure of weanling rats fed the equal amount of isocaloric diets containing 8%, 13% and 18% casein were investigated. After a period of 30day feeding, the rats fed low level of protein diet were 43.01g lighter than 18% protein group (weight gains of ${85.57}{\pm}{7.50g}$ vs. ${128.58}{\pm}{11.64g}$, p<0.01). Despite of the smaller body size, there were no significant differences in lipid deposition in grams per carcass. Whereas, nitrogen accumulation was significantly greater in 13% and 18% protein fed groups compared to 8%. The estimated energy expenditure were 4,576.61 kJ, 5,440.80kJ and 5,607.67kJ for 8%, 13% and 18% protein groups respectively. The part of excess energy consumed by the low protein group may have been dissipated. The malic enzyme activity in the liver of rats was found to be unaltered by different dietary treatments. From these observations, it was conluded that the retarded growth response in lower protein level may have been originated from the shortage ge of protein supply rather than that of the energy. The protein restriction appeared to be resulted in the lower fat free compartment without affecting the ability of rats to synthesize body lipid in a similar rate to the higher protein group when energy intakes were equalized.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.165-172
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• 2014

Mixed fermentation of cow milk was performed by sequential co-cultures with Bacillus subtilis and Lactococcus lactis. After a first fermentation step with B. subtilis for 6 h, the number of viable cells increased to $2.5{\times}10^8$ CFU/mL. The second fermentation step with L. lactis resulted in increased viable cells $1.09{\times}10^{10}$ CFU/mL for 3 days and increased acidity. However, the number of viable B. subtilis cells was decreased greatly to $5{\times}10^1$ CFU/mL following fermentation with L. lactis. Milk proteins were markedly hydrolyzed by the first fermentation after 2 h, and the second fermentation induced curd formation in milk. However, after 4 h, the first fermentation resulted in higher whey separation and 80 mg% tyrosine content. Gamma-aminobutyric acid (GABA) production was dependent upon the degree of protein hydrolysis by first fermentation. Second fermentation resulted in 0.14% GABA. The milk fermented by B. subtilis indicated the rough surface of yogurt depended upon the degree of protein hydrolysis. In conclusion, set-type yogurt was efficiently produced by co-culturing of milk, and fortifying with peptides, GABA, and probiotics.

• Journal of Aquaculture
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• v.10 no.1
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• pp.87-95
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• 1997

This experiment was conducted for compare domestic experimental microparticulated diets with imported commercial microparticulated diets in olive flounder larvae, Paralichthys olivaceus (Temminck et Schlegel). Fish larve were fed four microparticulated diets from 8th day after hatching. Four diets were two commercial microparticulated diets D and H, and experimental microparticulated diets K1 and K2 formulated each with different protein sources (diet K1 ; squid meal, blood meal, yeast extract, chlorella powder, olive flounder muscle, Lys, and Met ; diet K2 ; whole egg protein, krill meal, short-necked clam meal, squid muscle, live yeast, yeast extract, and casein). There were no significant differences on body weight, body length and survival rates among four diet treatments up to the 40th day after hatching. At the 83th day after hatching, fish fed diet D had a significantly higher survival rate than that of fish fed diet K2, whereas there was no significant difference between to diet H and K1. Fish fed diet D had a significantly higher body weight than these of fish fed diaet K1 and K2, whereas there was no significant difference between fish fed diet D and H. There was no significant difference on EPA and DHA of body fatty acid composition among four diet treatments up to the 83th day after hatching. These results show that nutritionally well-ballanced domestic microparticulated diets for olive flouner lavae can be developed.