• Journal of Sericultural and Entomological Science
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• v.41 no.1
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• pp.54-60
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• 1999

Antheraea pernyi silk powder was prepared by treatment with HCl and NaOH. The degree of hydrolysis of Antheraea pernyi silk fiber was examined. The morphology and structural characteristics of Antheraea pernyi silk powder were investigated by using SEM, FTIR and X-ray diffractometer. As the concentration of HCl and NaOH and tratment temperature increased, in general, the degree of hydrolysis of Antheraea pernyi silk fiber increased. On the other hand, the degree of hydrolysis of Antheraea pernyi treated with 3 N NaOH at 120$^{\circ}C$ for 24 hr was 70 wt%, which was lower than that of 90$^{\circ}C$(83 wt%). The morphology of acid/alkali resistance fraction of Antheraea pernyi silk fibroin was transformed from fiber form to powered one with an increase of hydrolysis. The conformation of Antheraea pernyi silk powder characterized by FT-IR spectrometer and X-ray diffractometer ${\beta}$-sheet and ${\alpha}$-helix structure.

• Applied Biological Chemistry
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• v.44 no.4
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• pp.219-223
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• 2001

Effects of hemoglobin (Hgb) concentration and degree of hydrolysis (DH) of Hgb on the separation of heme-iron were examined to produce highly enriched heme-iron from Hgb hydrolysate. Separation efficiency of Hgb hydrolysate with different DH was studied at wide pH range (pH $1.0{\sim}11.0$). Separation efficiency expressed as heme-iron/peptide ratio increased with decreasing Hgb concentration. When 5% Hgb (pH 10.0) was hydrolyzed using commercially available Esperase for 5 h at $50^{\circ}C$, DH was 25%. The precipitation of heme-iron-enriched peptides were remarkably high at pH range $3{\sim}6$. Optimal pH range for heme-iron with high heme-iron/peptide ratio shifted to acidic pH with increasing DHs of Hgb. The enriched heme-iron fraction in the precipitates showed a single band through urea-SDS-PAGE, with a molecular mass of 1 kDa. In the dry heme-iron product produced in a pilot bioreactor, content of heme-iron and heme-iron/peptide ratio were 27.1 and 38.7%, respectively, and production yield was 9.3%.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.958-963
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• 1995

The hydrolysis of pen shell by-product by the APL $440^{TM}$, selected as the suitable alkaline protease on the basis of cost per unit enzyme activity, was optimized using response surface methodology(RSM). A model equation obtained from the results of RSM could be used for the prediction of degree of hydrolysis(DH) as follows: $%DH=51.126+2.419\;pH+2.415T-2.426S-2.846pH^2-4.211T^2-3.014t^2+2.419S^2$. From the ridge analysis, the conditions favoring the highest degree of hydrolysis were pH 10.2, $61.4^{\circ}C$, 2.58 hrs reaction time, 30.9% substrate concentration, and 0.32% enzyme/substrate ratio. The effect of autolysis affecting degree of hydrolysis in pen shell by-product was negligible. Hydrolysate produced under the optimal condition increased 3.5 times and 7.7 times in amino nitrogen and salinity, respectively, comparing with raw pen shell by-product.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.10
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• pp.1287-1293
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• 2008

This study investigated quality changes and functions of low-molecular soymilk according to hydrolysis time (30, 60, and 90 minutes). According to the results, pH of hydrolyzed groups were lower than that of the control group but it did not show a large difference according to hydrolysis time while sugar content was reduced with longer hydrolysis time. Although degree of hydrolysis and calcium tolerance increased with longer hydrolysis time, there was not a significant difference according to the time. Among free sugars, contents of glucose and fructose grew while those of sucrose and maltose tended to decline with time. Total free sugar content was the largest with 60 minutes of hydrolysis time recording 827.65 mg%. Total amino acid content was also the highest with hydrolyzed for 60 minutes recording 85.80 mg% and those of all hydrolyzed groups were higher than that of the control group. In addition, the content of essential amino acid increased significantly with time. In SDS-PAGE, checked for the tendency of becoming low molecules, molecular weights were found to be 33 kDa or less kDa in all hydrolyzed groups. When functional characteristics of soymilk such as electron donating, superoxide radical scavenging and ACE inhibitory activities were compared, longer hydrolysis time led to higher activities. From these results, overall quality of low molecular soymilk was superior when hydrolyzed for 60 minutes and the findings should be viable in the development of various types of functionally strengthened low-molecular soymilk in the future.

• The Korean Journal of Food & Health Convergence
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• v.6 no.6
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• pp.1-7
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• 2020

We compared the fermentation of 0 to 4 weeks by manufacturing a rapid low salt-fermented seahorse with a commercial Protamex added to the functional food, Hippocampus abdominalis. We studied amino acid composition, content and major amino acids related to flavor during the fermentation process of salt-fermented seahorse. In the enzyme-free group, it showed little change in the content of non-protein nitrogenous compounds, the content of amino acids and degree of hydrolysis. The Protamex enzyme treatment group was rapidly hydrolyzed in one week of ripening, resulting in increased non-protein nitrogenous compounds content, amino acid content and degree of hydrolysis, and minimal changes in the four weeks. The total amino acid contents ratio showed the highest content of glutamic acid in the enzyme additive group, glycine, alanine, which indicates sweet taste, and serine, the content of glycine, alanine, serine, and lysine, indicating sweet taste, has increased significantly over the enzyme-free group. Twenty species of free amino acid in the four-week of salt-fermented seahorse were detected. It detected 43.0% (6 species) in the enzyme-free group and 63.96% (7 species) in the enzyme additive group.

• Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.13-20
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• 2015

Calculated chemical scores (computed in relation to the FAO/WHO reference protein) for salmon liver protein hydrolysates indicated that all amino acids (other than methionine and threonine) were present in adequate or excess quantities; thus, the raw liver material is a good source of essential amino acids. The hydrophobic amino acids contents in hydrolysates prepared from Oncorhynchus keta and O. gorbuscha were 38.4 and 39.1%, respectively. The proportion of released peptides exceeding 500 kDa was reduced when hydrolysates were treated with the commercial enzyme Alcalase, although proportions in the following MW ranges were elevated: 100-500 kDa and <50 kDa. The optimal conditions for enzymatic hydrolysis were as follows: pH 7.0, $50^{\circ}C$, and a reaction time of 1 h. Of the different proteases tested, Alcalase was the most efficient for production of salmon liver hydrolysate with the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity. The hydrolysates prepared from salmon liver had a balanced amino acid composition. The liver protein hydrolysates contained low molecular weight peptides, some of which may be bio-active; this bio-active potential should be investigated. Inhibition of the DPPH radical increased with increased degree of hydrolysis (DH), regardless of protease type. DPPH radical scavenging abilities, antithrombotic effects and ${\alpha}$-glucosidase enzyme inhibition effects of O. keta liver hydrolysate increased in a dose-dependent manner. Thus, salmon liver hydrolysate may be useful in functional food applications and as a source of novel products.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.294-299
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• 1992

This study was to examine the effect of functional properties of soy protein isolate(SPI) and qualities of soybean curd upon proteolytic hydrolysis. SPI was hydrolyzed using proteolytic enzyme, bromelain. The protein content of SPI by microkjeldahl method was 84% and the degree of hydrolysis in modified soy protein isolate(MSPI) was 2.7%. The solubility of MSPI was higher than that of control at various pH tested and proteolytic hydrolysis was increased emulsion formation and foam expansion while decreased emulsion stability, foam stability and calcium precipitation. Modified soybean curdI, standard soybean milk: Modified soybean milk=3:1, was soft and springy soybean curd when the texture properties of soybean curd were tested by texture profile analysis using Instron and sensory evaluation. The rheological model of soybean curds was investigated by stress relaxation test. The analysis of relaxation curve revealed that the rheological behavior of soybean curds could be expressed by 7-element generalized Maxwell model. The equilibrium modulus and modulus of elasticity decreased as the ratio of modified soybean milk was increased.

• Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.174-178
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• 2011

This study aimed to determine the degree of hydrolysis and angiotensin-I-converting enzyme (ACE)-inhibitory activity of Giant Jellyfish Nemopilema nomurai (jellyfish) hydrolysates. The degree of hydrolysis using six proteolytic enzymes (Alcalase, Flavozyme, Neutrase, papain, Protamex, and trypsin) ranged from 13.1-36.8% and the inhibitory activities from 20.46-79.58%. Using papain hydrolysate, we newly isolated and characterized ACE-inhibitory peptides with a molecular weight of 3,000-5,000 Da that originated from jellyfish collagen. The purified peptide (FII-b) was predicted to be produced from an alpha-2 fragment of the type IV collagen of jellyfish. The N-terminal sequence of FII-b was Asp-Pro-Gly-Leu-Glu-Gly-Ala-His-Gly- and showed 87% identity to the collagen type IV alpha-2 fragment of Rattus norvegicus and a predicted protein from Nematostella vectensis, indicating that the ACE-inhibitory peptide originated from the collagen hydrolysate and had an $IC_{50}$ value of 3.8 ${\mu}g$/mL. The primary structure of the fragment is now being studied; this peptide represents an interesting new type of ACE inhibitor and will provide knowledge of the potential applications of jellyfish components as therapies for hypertension.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.23-28
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• 1984

Anchovy homogenates with or without salt were autolyzed at various pH and temperature conditions. In the initial hydrolysis during 20 hours, the highest autolysis of anchovy homogenate was achieved at pH 4 and $50^{\circ}C$. However, the addition of 20% salt changed the optimum condition to pH 6 and $50^{\circ}C$. When the digestion time was prolonged to 8 days, the most favorable temperature for the autolysis of salted anchovy was lowered to $40^{\circ}C$ compared with $50^{\circ}C$ of initial hydrolysis while the optimum pH was unchanged. Under the best conditions described above, 60.5% of anchovy nitrogen was converted to TCA-soluble nitrogen in 20 hr-incubation without salting, but it was reduced to 49.8% with salting. In the 8 days hydrolysis of salted anchovy, as much as 83.1% of total nitrogen was transformed into TCA-soluble nitrogen. Slight increase in the degree of hydrolysis up to 89.6% was occurred during subsequent ripening period of 52 days at ambient temperature.

• KSBB Journal
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• v.17 no.2
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• pp.137-141
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• 2002

Levan oligosaccoharides and low molecular weight levin were produced from levin by acid hydrolysis and following column chromatography. Levan hydrolysis was progressed proportionally as increased incubation time. In terms of levan hydrolysis reaction, no differences were found from the sources of levan. Optimum hydrolysis conditions for the formation of levan oligosaccharides were, 0.38 M H$_2$S0$_4$; and incubation at 95$\^{C}$ for 4 min. The purified products were determined as the mixture of oligosaccharides (degree of polymerization (DP) of 3-6), Two of lactic acid-producing bacteria, Lactobacillus plantarum KCTC 3104 and Pediococcus pentosaceus KCTC 3507, were studied in vitro for their ability to metabolize levin oligosaccharides. Apparently, the growth of both cells were increased by levin oligosaccharide diet, compared with those of levan diets, suggesting that levan oligosaccharides may be beneficial in selectively growth of lactic acid-producing bacteria.