• Journal of Life Science
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• v.21 no.1
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• pp.127-133
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• 2011

${\beta}$-Galactosidase was immobilized on chitosan bead by covalent bonding using glutaraldehyde. The characteristics of the immobilized enzyme were investigated. Maximum immobilization yield of 75% was obtained on chitosan bead. Optimum pH and temperature for the immobilized enzyme was 7.0 and $50^{\circ}C$, respectively. The immobilized enzyme showed a broader range of pH and temperature compared to a free one. A mathematical model for the operation of the immobilized enzyme in a packed-bed reactor was established and solved numerically. Under different inlet lactose concentrations and feed flow rate conditions, lactose conversion was measured in a packed-bed reactor. The experimental results of continuous operation in a packed-bed reactor were compared to theoretic results using Michaelis-Menten kinetics with competitive product inhibition and external mass transfer resistance. The model predicted the experimental data with errors less than 5%. Process optimization of continuous operation in a packed-bed reactor was also conducted. In a recirculation packed-bed operation, conversion of lactose was 97% in 3 hours. In a continuous packed-bed operation, the effect of flow rate and initial lactose concentration was investigated. Increasing flow rates and initial lactose concentration decreased the conversion of substrate.

• Journal of Microbiology
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• v.35 no.2
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• pp.134-140
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• 1997

Botrytis cinerea T91-1 has been shown to produce at least four different polygalacturonases into a liquid medium containing citrus pectin, a carbon sousrce. One of the enzymes, which had an apparent molecular weight of 66 kDa estimated by denatured polyacrylamide gel electrophoresis, was purified to electrophoretic homogeneity by a series of procedures including a cetone precipitation, ion exchange, heparin affinity, and reverse phase column chromatographies. The molecular weight of native enzyme was determined to be 64 kDa by gel permeation chromatography indicating the enzyme to be a single polypeptide chain. By viscometric analysis, the enzyme was revealed as exo-polygalacturonase. The enzyme activity was inhibited by divalent cations such as $Ca^{2+}$, $Mg^{2+}$, and Cu$^{2+}$. Km and Vmax for polygalacturonic acid hydrolysis were 0.33 mg/ml and 28.6 nM/min, respectively. The optimum temperature for enzymatic activity was 5$0^{\circ}C$. And the enzyme showed optimal pH values between 4.0 and 5.0. The enzyme was stable upto 12 hours in the range of pH 3 to 8 and at temperature below 3$0^{\circ}C$.

• Food Science and Preservation
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• v.10 no.1
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• pp.80-88
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• 2003

In order to establish the enzymatic hydrolysis system improving of taste and flavor in the preparation of soy protein hydrolysates using the enzymes with excellent hydrolytic ability and different hydrolysis pattern of soy protein, Degree of hydrolysis(DH) and surface hydrophobicity under the optimal conditions of enzyme reaction, hydrolysis patterns by the SDS electrophoresis and sensory evaluation of soy protein hydrolysates by enzyme reactions were investigated. Four enzyme reactions were highly activated at pH 7.0, 45$^{\circ}C$ under the optimal conditions. As result of changes on the pattern of soy-protein hydrolysates by SDS-electrophoresis, high molecular peptides of hydrolysates by No. 5(Mucor circinelloides M5) and No. 16(Bacillus megaterium B16) enzymes were slowly decrease and 66KD band of these were remained after 3hours reaction. Production of low molecular peptides of hydrolysates by No. 4(Aspergillus oryzae M4) and No. 95(Bacillus subtilis YG 95) enzymes were remarkably detected during the proceeding reactions. As results of HPLC analysis, low molecular peptides of 15∼70KD were mainly appeared during the proceeding enzyme reactions. And, the more DH was increased, the more SDS-surface hydrophobicity was decreased. Hydrolysates by No. 4 enzyme was not only the highest DH of all hydrolysates, but the strongest bitter taste in a sensory evaluation. Sweat taste among the hydrolysates showed little difference. But, when combinative enzymes were treated, combinative enzyme of No. 4(Aspergillus oryzae M4)and No. 16(Bacillus megaterium B16) showed the strongest sweat taste. In conclusion, we assumed that it will be possible to prepare the hydrolysates having functionality when soy-protein were hydrolyzed by these specific enzymes.

• KSBB Journal
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• v.19 no.4
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• pp.245-249
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• 2004

A combined method of autolysis and enzymatic hydrolysis of baker's yeast was developed for the production of yeast extract, which is widely used as a natural food ingredient. From statistical analysis, NaCl and ethanol addition were found to be significantly effective factors in autolysis of yeast. The optimum dosages of salt and ethanol were 3% and 1%, respectively. Heat treatment and the use of cell lytic enzyme were not significantly effecting on the autolysis. Yeast hydrolysate was prepared by autolysis, followed by enzymatic hydrolysis using proteases, nuclease and deaminase. Additionally, the hydrolysate was processed by downstream process including Maillard reaction and debittering. The total dry matter yield and total nitrogen yield for the process were 76% and 59%, respectively. Compared to a process using brewer's yeast, when baker's yeast was used as a raw material, a higher recovery yield was obtained.

• KSBB Journal
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• v.29 no.3
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• pp.193-198
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• 2014

Pretreatment of wastepaper using aqueous glycerol under high pressure was studied to enhance the enzymatic hydrolysis. The pretreatment was conducted over a wide range of conditions including temperatures of $150{\sim}170^{\circ}C$, sulfuric acid concentrations of 0.5~1.5%, and reaction times of 30~90 minutes. After the effect of glycerol concentration on the pretreatment performance was investigated, 70% glycerol was selected. As glycerol concentration was increased, higher digestibility was achieved due to higher lignin removal. The optimum condition was found to be around $160^{\circ}C$, 1%, and 60 minutes. At this condition, 60% and 35% of hemicellulose and lignin, respectively, were removed, while only 5% of cellulose was lost. The enzymatic digestibility was 76%, meaning that 73% of the glucan present in the initial substrate was recovered as glucose after enzymatic hydrolysis. Also, it was found that the temperature and acid concentration than the reaction time were more strongly related to the compositional removals and enzymatic digestibility.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.3
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• pp.211-214
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• 2006

Immobilized Candida antarctica lipase was used to catalyze the separation of ketoprofen into its components by means of esterification followed by the enzymatic hydrolysis of the ester product. In this study, ketoprofen underwent esterification to ethanol in the presence of isooctane. When the reaction was complete, 58.3% of the ketoprofen had been transformed into an ester. The ketoprofen remaining in solution after the reaction was complete consisted primarily of its S-enantiomer (83.0%), while the 59.4% of the ketoprofen component of the ester consisted of its R-enantiomer. We then subjected the ester product to enzymatic hydrolysis in the presence of the same enzyme and produced a ketoprofen product rich in the R-enantiomer; 77% of this product consisted of the R-enantiomer when 50% of the ester had been hydrolyzed, and 90% of it consisted of the R-enantiomer when 30% of the ester had been hydrolyzed. By contrast, the R-enantiomer levels only reached approximately 42 and 65%, respectively, when 50 and 30% of the racemic ester was hydrolyzed under the same conditions.

• Journal of Marine Bioscience and Biotechnology
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• v.10 no.1
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• pp.9-17
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• 2018

The aim of this study is to elucidate the biochemical properties of manno-oligosaccharides (MOS) hydrolyzed by extracellular enzyme of Bacillus N3. We strived to characterize the biochemical properties of MOS since N3 can effectively hydrolyzed natural polymannans such as galactomannan (GM) and konjac (glucomannan, KM), respectively. The hydrolysis of GM and KM was applied by the strain N3 in terms of reducing sugars and the highest production of reducing sugars was estimated to be about 750 mg/L and 370 mg/L respectively, which were quantified after 7 days of cultivation in the presence of both substrates. Hydrolysates derived from the hydrolysis of KM showed the significant antioxidant activity based on DPPH and ABTS radical scavenging activity with increasing of tyrosinase inhibitory activity. On the other hand, hydrolysates derived from the hydrolysis of GM showed only ABTS radical scavenging activity without showing significant changes on tyrosinase inhibitory activity. Our data suggest that those biological characteristics may be depend on the primary structure and the size of MOS, which may be useful as potent additives for diet foods.

• Korean Journal of Food Science and Technology
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• v.22 no.3
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• pp.234-240
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• 1990

Attempts have been made to optimize the hydrolysis conditions of the oyster and the mussel by the commercial proteolytic enzymes. Raw materials were digested with seven different commercial enzymes, and their quality parameters measured in terms of degree of hydrolysis and content of free amino nitrogen, nucleic acid-related substances. and free amino acids as well as sensory evaluation of optimization of their hydrolysis conditions. As a result, following enzymes have been disclosed as effective for enzymatic digestion: MKC-HT proteolytic, alcalase 0.6L and thermease for the oyster whereas MKC-acid fungal protease and thermoase for the mussel, respectively.

• KSBB Journal
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• v.23 no.6
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• pp.509-512
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• 2008

The hydrolysis reaction of soybean oil was conducted experimentally by various source enzymes. The analytical result of hydrolysate of soybean oil showed that the compositions were linoleic acid, olic acid, palmitic acid, and stearic acid in order. The enzymes CR-E and CC-E from Candida rufosa and Candida cylindracea had two hold or more hydrolysis conversions than those of Lipase 16, Novozyme 871, and Lipolase-100L under the same conditions. Therefore CR-E and CC-E were selected for further experiments. These two enzymes had similar ranges of optimun conditions as follows: pH 3-6, $35-45^{\circ}C$, and water to soybean oil ratio of 3.3 or above. They finally got conversions 95% above.

• Journal of Microbiology and Biotechnology
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• v.17 no.5
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• pp.800-805
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• 2007

Two endoglucanases with processive cellulase activities, produced from Fomitopsis palustris grown on 2% microcrystalline cellulose(Avicel), were purified to homogeneity by anion-exchange and gel filtration column chromatography systems. SDS-PAGE analysis indicated that the molecular masses of the purified enzymes were 47 kDa and 35 kDa, respectively. The amino acid sequence analysis of the 47-kDa protein(EG47) showed a sequence similarity with fungal glycoside hydrolase family 5 endoglucanase from the white-rot fungus Phanerochaete chrysosporium. N-terminal and internal amino acid sequences of the 35-kDa protein(EG35), however, had no homology with any other glycosylhydrolases, although the enzyme had high specific activity against carboxymethyl cellulose, which is a typical substrate for endoglucanases. The initial rate of Avicel hydrolysis by EG35 was relatively fast for 48 h, and the amount of soluble reducing sugar released after 96 h was $100{\mu}g/ml$. Although EG47 also hydrolyzed Avicel, the hydrolysis rate was lower than that of EG35. Thin layer chromatography analysis of the hydrolysis products released from Avicel indicated that the main product was cellobiose, suggesting that the brown-rot fungus possesses processive EGs capable of degrading crystalline cellulose.