• Journal of Life Science
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• v.10 no.2
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• pp.131-139
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• 2000

Lecithin-free egg yolk protein (EYP), the by-product of lecithin extraction from egg yolk, which is denatured with an organic solvent, would normally be discarded. In this study, the denatured protein was renatured with alkali, and hydrolyzed with Alcalase in order to utilize by-product. The hydrolysate was separated through a series of ultrafiltration membranes with molecular weight cut-off (MWOO) of 10, 5 and 1 kDa, and the antioxidative activities of the hydrolysates was investigated. The 5K hydrolysate, permeate from 5 kDa membrane, showed stronger antioxidative activity than 10 K and 1 K hydrolysate which were permeated from 10 kDa and 1 kDa membrane, in a linoleic acid autoxidation system. In addition, the optimum concentration of antioxidative activity for 5 K hydrolysate was 1%, and the activity was about 37% higher as compared with α-tocopherol. The synergistic effect was also increased by using the hydrolysates with α-tocopherol.

• Journal of Life Science
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• v.10 no.5
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• pp.475-483
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• 2000

Normally, aerobic cells are protected from the damage of free radicals by antioxidative enzymes such as catalase, superoxide dismutase (SOD), glutathione (GSH) peroxidase and GSH-S-transferase. In this study, we have investigate the effect of egg yolk protein hydrolysates on antioxidative activity and the activity of antioxidative enzyme in cultured hepatocytes (Chang). Without the pretreatment with hydrolysate, about 50% of the hepatocytes were killed within 2h by 225$\mu$M tert-butyl hydroperoxide (t-BHP). By contrast, fewer than 20% of the 5 K hydrolysate (permeate from 5 kDa membrane and not passed through 1 kDa membrane)-pretreated hepatocytes were killed by the same concentrations of t-BHP. In addition, the activities of catalase, GSH peroxidase and GSH-transferase were significantly increasing with the treatment of 5 K hydrolysate. These results suggest that 5 K hydrolysate exerts antioxidative effect by increasing activity of antioxidative enzymes.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.35-39
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• 1998

An enzymatic process was developed to produce protein hydrolysater form defatted soya protein. Various unit operations were tried, and the effects of pre- and post-treatments on the product characteristics such as degree of hydroylsis (DH), free amino acid content (%FAA) and average molecular weight (MW) were investigated. The use of acid washes showed no difference in %DH. Increasing pH during pre-cooking gave lower %DH. Alkaline cooking made too much insoluble protein, thus the protein yield was too small. A better hydrolysis with more acceptable taste was obtained when the combination of Neutrase/Alcalase/Flavourzyme was used in place of Alcalase/Flavourzyme combination; Untoasted defatted soya was more effective on the proteolysis than toasted one. The MW of the evaporated and spray dried product was higher than that of undried product, due to precipitation of low-solubility components. When ultrafiltration and the product concentration carried out the product separation by reverse osmosis, the solubility and the taste of the product were improved. The difference between enzyme hydrolysate and acid hydrolysate was significant in free amino acid composition, especially in tyrosine, phenylalanine, glutamine and asparagine.

• Food Science of Animal Resources
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• v.40 no.6
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• pp.1033-1043
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• 2020

This study investigated the impacts of gelatin hydrolysate addition on the technological properties and lipid oxidation stability of cooked sausage. Gelatin hydrolysate was prepared from pork and duck skin gelatin, through stepwise hydrolysis using collagenase and pepsin. The cooked sausages were formulated without gelatin (control) or with 1% pork skin gelatin, 1% duck skin gelatin, 1% pork skin gelatin hydrolysate, and 1% duck skin gelatin hydrolysate. The pH, color characteristics, protein solubility, cooking loss, and textural properties of cooked sausages were evaluated, and the 2-thiobarbituric acid reactive substances (TBARS) value was measured weekly to determine lipid oxidation stability during 4 wk of refrigerated storage. Enzymatic hydrolysis of gelatin decreased protein content and CIE L* but increased redness and yellowness (p<0.05). When 1% gelatin or gelatin hydrolysate was incorporated in cooked sausage, however, little to no impacts on pH value, moisture content, protein content, color characteristics, protein solubility, and cooking loss were found (p>0.05). The addition of 1% duck skin gelatin hydrolysate increased the cohesiveness and chewiness of cooked sausages. The inclusion of 1% duck skin gelatin accelerated lipid oxidation of cooked sausages during refrigerated storage (p<0.05), whereas duck skin gelatin hydrolysate caused a lower TBARS value in cooked sausage compared to duck skin gelatin. The results show comparable effects of gelatin and gelatin hydrolysate addition on the technological properties of cooked sausages; however, the oxidative stability of raw materials for gelatin extraction should be evaluated clearly in further studies.

• Preventive Nutrition and Food Science
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• v.20 no.3
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• pp.183-189
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• 2015

In the present study, an optimum protease was selected to hydrolyze the egg white liquid protein for the antioxidant peptides. Alcalase treatment yielded the highest amount of ${\alpha}$-amino groups (15.27 mg/mL), while the control (no enzymatic hydrolysis) showed the lowest amount of ${\alpha}$-amino groups (1.53 mg/mL). Alcalase also gave the highest degree of hydrolysis (DH) value (43.2%) and was more efficient for egg white liquid hydrolysis than the other enzymes. The Alcalase hydrolysate had the highest radical-scavenging activity (82.5%) at a concentration of 5.0 mg/mL. The conditions for enzymatic hydrolysis of egg white liquid with Alcalase were selected as substrate : water ratio of 2:1. Five percent Alacalse treatment did not show significant (P>0.05) increases of DH and ${\alpha}$-amino nitrogen content after 24 hhydrolysis. Thirty two hour-hydrolysis with 5% Alcalase is sufficient to make antioxidative egg white liquid hydrolysate from egg white liquid. DPPH and ABTS radical-scavenging activities were significantly (P<0.05) higher after enzymatic digestion. These results suggest that active peptides released from egg-white protein are effective radical-scavengers. Thus, this approach may be useful for the preparation of potent antioxidant products.

• Journal of Applied Biological Chemistry
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• v.64 no.1
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• pp.97-102
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• 2021

In this study, enzymes were screened for hydrolysis of defatted perilla seed residue (DPSR) and optimal conditions for enzymatic treatment were determined to produce the hydrolysate of DPSR. Also its antioxidant activity and utilization as a culture medium were examined. The combined treatment of Alcalase and Ceremix is most effective for solubilization of protein and carbohydrate in DPSR. The optimal dosage, pH, and reaction time for enzymatic treatment were found to be 2.0% (w/w), 7.0, and 2 h, respectively. Treatment with optimal conditions of enzymes dramatically increased reducing sugar, soluble protein, and total phenolic content. The hydrolysate of DPSR possessed better scavenging activity against cation and free radicals than enzyme-untreated extract. When Leuconostoc mesenteroides 310-12 was cultured in the hydrolysate of DPSR, cell population rapidly increased compared to enzyme-untreated extract, and titratable acidity increased in proportion to the bacterial growth. In conclusion, these results imply that the hydrolysate of DPSR could be utilized as a bacteria culture medium as well as a physiologically active material with antioxidant activity.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.9-14
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• 2005

Batch enzymatic hydrolysis of egg yolk protein by protease was carried out at laboratory scale coupled to an ultrafiltration module. Effect of ethanol concentrations on the performance of enzymatic hydrolysis was studied to determine the optimum condition of recovery of hydrolysate. The enzymatic hydrolysis was conducted stepwise with following conditions, $50^{\circ}C$, pH 10.0 and pH 6.5. Ethanol concentration was changed from 10 to $40\%$ (w/w). As ethanol concentration was increased, the recovery yield of total solid and protein in enzymatic hydrolysate was also increased. The content of sialic acid and protein in hydrolysate was independent of ethanol concentration. We also investigated the effect of ethanol concentration on the performance of ultrafiltration. As the concentration of ethanol in yolk protein was increased, the recovery yield of product was increased. Ultra­filtration of egg yolk protein hydrolysate was conducted to increase the content of sialic acid. Four ultrafiltation modules were used in this study, and we evaluated the performance of the UF modules. When Amicon module was used, the recovery percentage of total solid in retentate was $6.0\%$, which is the highest among the modules used. In spite of the difference in the recovery yield of total solid, the purity of sialic acid in retentate was about $2.0\%$, which was 5 times higher than that in feed. It was concluded that the recovery yield and the purity of sialic acid did not correlate with the types of modules and the size of MWCO.

• Journal of Life Science
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• v.10 no.2
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• pp.140-149
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• 2000

In order to utilize marine processing waste which would normally be discarded, cod liver protein was hydrolysed by ${\alpha}$-chymotrysin, and the hydrolysate was investigated for the new angiotensin I converting enzyme (ACE) inhibitor. Thy hydrolysate was separated into three major types, with molecular weight cut-off (MWCO) values less than 10 kDa, 5 kDa and 1 kDa of ultrafiltration membranes, respectively. ACE inhibitory peptides were isolated from the fractions passed through MWCO 1 kDa membrane, and purified by using ion-exchange chromatography on a SP-Sephadex C-25 column, gel filtration on a Sephadex G-15 column, and HPLC on an ODS column. The purity was identified with capillary electrophoresis. The amino acid sequences of two peptides were Met-Ile-Pro-Pro-Tyr-Tyr (IC50=10.9 ${\mu}$M) and Gly-Leu-Arg-Asn-Gly-Ile (IC50=35.0 ${\mu}$M)

• Journal of Marine Bioscience and Biotechnology
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• v.10 no.1
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• pp.1-8
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• 2018

The objective of this study was to purify and characterize the ${\beta}-secretase$ inhibitor from enzymatic hydrolysates of blackfin flounder muscle, for development of a novel anti-dementia agent that may be used in the drug or functional food industries. ${\beta}-secretase$ inhibitory peptide was purified from various enzymatic hydrolysates of blackfin flounder muscle. Among six enzymatic hydrolysates, the Alcalase hydrolysate revealed highest ${\beta}-secretase$ inhibitory activity. Consecutive purification of the blackfin flounder muscle hydrolysate using Sephadex G-25 column chromatography and octadecylsilane C18 reversed phase HPLC techniques were used to isolate a potent ${\beta}-secretase$ inhibitory peptide composed of 5 amino acids, Leu-Thr-Gln-Asp-Trp (MW: 526.7 Da). The $IC_{50}$ value of purified ${\beta}-secretase$ inhibitory peptide was $126.93{\mu}M$. Results of this study suggest that peptides derived from blackfin flounder muscle may be beneficial as anti-dementia compounds in functional foods or as pharmaceuticals.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.26-32
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• 2015

Four types of straw, namely, soybean, wheat, corn, and rice, were investigated for use in lactic acid production. These straws were mainly composed of cellulose, hemicellulose, and lignin. After pretreatment with ammonia, the cellulose content increased, whereas the hemicellulose and lignin contents decreased. Analytical results also showed that the liquid enzymatic hydrolysates were primarily composed of glucose, xylose, and cellobiose. Preliminary experiments showed that a higher lactic acid concentration could be obtained from the wheat and soybean straw. However, soybean straw was chosen as the substrate for lactic acid production owing to its high protein content. The maximum lactic acid yield (0.8 g/g) and lactic acid productivity (0.61 g/(l/h)) were obtained with an initial reducing sugar concentration of 35 g/l at 30℃ when using Lactobacillus casei (10% inoculum) for a 42 h fermentation period. Thus, the experimental results demonstrated the feasibility of using a soybean straw enzymatic hydrolysate as a substrate for lactic acid production.