• Journal of Dairy Science and Biotechnology
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• v.39 no.1
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• pp.36-50
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• 2021

This study aimed to evaluate the biological potential of functional food, i.e., specific peptides obtained from the hydrolysis of milk protein, by assessing their antioxidant and antibacterial properties. For the preparation of casein hydrolysates, commercial enzymes were added to 10% casein solution in a 1:200 (w/v) ratio, and samples were collected each hour. Based on the assessment of the degree of hydrolysis (DH) of casein hydrolysates, it was observed that the concentration of all enzymatic hydrolysates increased rapidly from 30 to 40 minutes. However, no change was observed in their concentrations after 150 minutes. Protamex® and Neutrase® exhibited the highest DH when compared to other enzymes. Furthermore, SDS-PAGE was performed for analyzing the proteolytic pattern of each enzyme, except for Flavourzyme®, and peptides in the size range of 20-25 kDa were identified. Subsequently, peptides produced by two enzymes were isolated using a preparative liquid chromatography system. Overall, NF3, NF4, PF5, and PF6 showed higher antioxidant potential than other peptide fractions. Moreover, NF7 and PF3 exhibited the highest antibacterial activity. In this study, we evaluated the biological potential of novel casein-derived peptides that may find application in the food and healthcare industry.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.667-673
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• 1992

The alumina-zirconia composite powders of core particle ZrO2 coated with Al2O3 were prepared by the hydrolysis-deposition of the mixed aluminum salt solution of Al2(SO4)3-Al(NO3)3-Urea. The effects of hydrolysis reaction and coating parameters on characteristics of coated powders and composites were also investigated. The degree of coating could be estimated from the ratio of tetra-/mono-ZrO2 present at the room temperature after heat-treating coated powders at 120$0^{\circ}C$ and the result of TEM observations. When the content of ZrO2 in the dispersed coating system, the coating time, and the volume ratio of water/solution were 50 mg/g, 180 min, and 5, respectively the coating efficiency was maximum (the ratio of tetra-/mono-ZrO2 was 87/13). The relative densities of coated Al2O3-ZrO2 composites sintered at 1$650^{\circ}C$ for 4 hrs were about 91~98% and the maximum ratio of tetra-/mono-ZrO2 in Al2O3-20wt% ZrO2 composites was 62/38.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.211-217
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• 1984

To study affinity of proteolytic enzymes to soy proteins, the physicochemical and functional properties of enzymatically modified protein products, kinetic parameters and degree of hydrolysis were measured using trypsin, alcalase (serine type protease) and pronase. Bacterial alcalase and pronase showed much greater affinity to soy protein than animal intestinal trypsin. This effect was very significant when unheated soy isolate was used as a substrate. Specific activities of these enzymes decreased with the increment of substrate concentration (over 2.0%, w/v) when heat denatured soy protein was used as a substrate. However, the decrease in specific activity was negligible at substrate concentrations lower than 2.0%. Polyacrylamide gel electrophoretic results showed that the pattern of 2S protein band changed distinctly in alcalase hydrolysis as compared with those of trypsin and pronase. Protein solubilities of alcalase and pronase hydrolyzates increased by 25-30%, at their pI (pH 5.0) over the control. Virtually no change was observed in solubility by trypsin hydrolysis. Heat coagulability and calcium-tolerance of the protein increased by enzymatic hydrolysis. No clear tendency, however, was observed for emulsion properties, foam expansion and the amount of free -SH groups. The enzyme treatment considerably decreased foam stability.

• Preventive Nutrition and Food Science
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• v.14 no.4
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• pp.323-328
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• 2009

Cryotin F could be used for hydrolyzing shrimp byproducts into bioactive ingredients, which could be used as value-added products. The objective of this study was to investigate the optimum condition for antioxidative activities of the enzymatic hydrolysate produced with Cryotin F using response surface methodology with central composite rotatable design. Shrimp byproducts (shells and heads) were hydrolyzed with Cryotin F. The experimental ranges of the independent variables for 20 experimental runs were 28.2-61.8${^{\circ}C}$ reaction temperature, pH 6-10 and 0.5-5.5% enzyme concentration. The degree of hydrolysis for the reaction products was measured. Their antioxidative activities were measured using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activity and Fe-chelating activity. The experimental method with central composite rotatable design was well designed to investigate the optimum condition for biofunctional ingredients with antioxidative activities using Cryotin F because of their high R2 values of 0.97 and 0.95 for DPPH-scavenging activity and Fe-chelating activity, respectively. Change in enzyme concentration did not significantly affect their antioxidative activities (p<0.05). Both DPPH scavenging activity and chelating activity against Fe for the enzyme hydrolysates were more affected by the pH of enzyme hydrolysis than by their action temperature. DPPH-scavenging activity was higher at acidic pH than alkali pH, while chelating activity against Few was inversely affected. Hydrolysate of shrimp byproducts showed high antioxidative activities depending on the treatment condition, so the optimum treatment of enzymatic hydrolysate with Cryotin F and other proteases can be applied to shrimp byproducts (shells) and other protein sources for biofunctional ingredients.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1144-1154
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• 2018

Both the calcium and collagen in bone powder are hard to be absorbed by the body. Although enzymatic hydrolysis by protease increased the bio-availability of bone powder, it was a meaningful try to further increase $Ca^{2+}$ release, oligopeptide formation and antioxidant activity of the sheep bone hydrolysate (SBH) by lactic acid bacteria (LAB) fermentation. Lactobacillus helveticus was selected as the starter for its highest protease-producing ability among 5 tested LAB strains. The content of liberated $Ca^{2+}$ was measured as the responsive value in the response surface methodology (RSM) for optimizing the fermenting parameters. When SBH (adjusted to pH 6.1) supplemented with 1.0% glucose was inoculated 3.0% L. helveticus and incubated for 29.4 h at $36^{\circ}C$, $Ca^{2+}$ content in the fermented SBH significantly increased (p<0.01), and so did the degree of hydrolysis and the obtaining rate of oligopeptide. The viable counts of L. helveticus reached to $1.1{\times}10^{10}CFU/mL$. Results of Pearson correlation analysis demonstrated that LAB viable counts, $Ca^{2+}$ levels, obtaining rates of oligopeptide and the yield of polypeptide were positively correlated with each other (p<0.01). The abilities of SBH to scavenge the free radicals of DPPH, OH and ABTS were also markedly enhanced after fermentation. In conclusion, L. helveticus fermentation can further boost the release of free $Ca^{2+}$ and oligopeptide, enhance the antioxidant ability of SBH. The L. helveticus fermented SBH can be developed as a novel functional dietary supplement product.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.724-732
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• 2021

This study used response surface methodology to investigate the optimal conditions to reduce the bitterness of alcalase-treated anchovy hydrolysate (AAH) by the aminopeptidase active fraction (AAF) derived from the common squid Todarodes pacificus hepatopancreas. The central composite design selected AAF/AAH ratio (X₁, %) and hydrolysis time (X₂, h) as independent variables, and the degree of hydrolysis (Y₁) and bitterness (Y₂) as dependent variables. The uncoded values of the multiple response optimization for independent variables were 3.4% for the AAF/AAH ratio and 9.2 h for the hydrolysis time. The predicted values of the yield and bitterness score of alcalase-AAF continuously treated anchovy hydrolysate (AAAH) under the optimized conditions were 68.9% and 4.6 points, respectively. Their measured values of 69.5% for yield and 4.6±0.5 points for bitterness were similar to the predicted values. The food components of AAAH were 91.4% (moisture), 7.5% (protein), 0.1% (lipid) and 0.6% (ash). The findings indicate the potential value for use as an anchovy seasoning base. The results also confirm that the bitterness of AAH was remarkably improved by AAF and implicates AAF derived from squid hepatopancreas as a good enzyme to catalyze reduced bitterness.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.202-208
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• 2010

This study examined the dependency of crystalline orientation and electric properties of sol-gel PZT film on hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The PZT thin films were prepared by using 2-Methoxyethanol-based sol-gel method and spin-coating on Pt/Ti/$SiO_2$/Si substrates. The 1-${\mu}m$-thick PZT films were coated and then fired in a furnace by direct insert method. The highly (111) oriented PZT film of pure perovskite structure could be obtained. We could control the degree of orientation by various parameters such as hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The highest measured remanent polarization, dielectric constant and piezoelectric coefficient are $24.16\;{\mu}C/cm^2$, 2808, and 159 pC/N, respectively.

• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.772-778
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• 2015

Hydrolysis of isolate soybean protein (ISP) using subcritical water (SCW) was conducted to study the feasibility for producing protein hydrolyzate. SCW hydrolysis of SPI suspension (5-15%) was conducted in an electrically heated batch reactor (2 L). The effects of temperature (230 to $270^{\circ}C$) and holding time (10 to 50 min) on the degree of hydrolysis (DH) and the production of amino acids were studied by surface response method. The DH was determined by derivatizing the hydrolyzates with ortho-phthalaldehyde (OPA) solution. It was confirmed that reaction temperature and holding time affected the hydrothermolysis of soybean protein. However, the holding time was less effective on amino acid yield when the temperature was higher than $230^{\circ}C$. In order to achieve optimal yields of amino acids exceeding 43%, the temperature should be within the range between 256 and $268^{\circ}C$ with holding time from 29 to 41 min, respectively. A maximum estimated amino acid yield of 43.5% was obtained at $268^{\circ}C$ for 35 min.

• Journal of the Korean Society of Food Culture
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• v.12 no.4
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• pp.375-382
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• 1997

The establishment of optimal producing condition for rice-based infant foods using modified rice powder was attempted. The modification of rice powder was prepared by microwave heating as well as partial enzymatic hydrolysis. Not only thermal treatment but also enzymatic hydrolysis on rice powder increased D.E. value from 1.25 to 3.81. The water binding capacity, swelling power, solubility, digestibility by ${\alpha}-amylase$, light transparency, and paste clarity of the modified rice powder compared to unmodified rice powder were increased from 107% to 249%, from 7.80 to 42.52, from 0.04% to 0.89ft, from 9.19% to 23.01, from 33% to 42%, and from 2.2% to 3.9%, respectively. On the other hand, gelatinization temperature, apparent viscosity, and degree of retrogradation of modified rice powder showed negative correlation with D.E. value. The 「results suggested that the thermal and enzymatic treatment on rice powder improved the physicochemical properties of rice based infant food by enhancing carbohydrate absorptionability and lowering the viscosity and opacity.

• KSBB Journal
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• v.4 no.3
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• pp.221-228
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• 1989

Celluose is an insoluble substrate, therefore, a proper mixing of the cellulose suspension is essential for an effective enzymatic hydrolysis. To study the effect of mixing motion of various enzyme reactors on enzymatic hydrolysis of cellulose, three distinct types of biroreator: vertical impeller type bioreator(VITB), horizontal paddle type bioreactor(HPTB), and tumbling drum type bioreactor(TDTB), were assembled and their performance was compared. The optimal agitation speed was 100rpm for VITB and HPTB, 200rpm for TDTB. The saccharification efficiency of each reactor was compared under the optimal agitation intensity. The highest degree of saccharification was achieved in the case of VITB, especially, at high cellulose concentration. The VITB seems to be the most suitable type of bioreactor that can maintain proper mixing pattern for effective enzyme reaction. In the view of energy consumption, the TDTB showed the lowest value: however, the energy consumption was rapidly increased at high concentration of celluose. To dertermine the most suitable type of bioreactor, the entire process, including substrate cost, substrate concentration, and feasibility of scale-up, needs to be evaluated.