• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.301-310
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• 2018

Various catalysts such as formic acid, acetic acid, sodium hydroxide, sodium bicarbonate, carbon dioxide and nitrogen gas were used for hydrolyzates production from deoiled mackerel muscle by subcritical water hydrolysis. Above 99% hydrolysis yield was obtained using sodium bicarbonate catalyst at $260^{\circ}C/70bar$. Histamine and heavy metals concentration were reduced in hydrolyzates. Highest amount of amino acid (400.36 mg/g) and reducing sugar (24.75 mg/g) were found in hydrolyzate obtained at $260^{\circ}C/70bar$ and $220^{\circ}C/30bar$, respectively with sodium bicarbonate catalyst. Antioxidant and ACE-inhibitory activities were significantly higher in hydrolyzates obtained using sodium bicarbonate than that of others.

• Korean Chemical Engineering Research
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• 제53권2호
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• pp.199-204
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• 2015

지방산 생산을 위한 돈지의 아임계수 가수분해 공정을 최적화하기 위하여 17-run 중심합성법(central composite design)에 기초한 반응표면법(response surface methodology)이 사용되었다. 반응 온도, 오일 대비 물의 몰 비, 반응 시간과 같은 변수 및 이들의 상관관계가 지방산 함량에 미치는 영향을 조사하였으며, 지방산 함량을 예측하기 위하여 2차 다항 회귀방정식이 제안되었다. 최대 지방산 함량을 얻을 수 있는 반응 조건은 $288.5^{\circ}C$, 39.5몰 비, 29.5분이었으며, 이 조건에서의 예측 및 실제 지방산 함량은 각각 97.06% 및 96.99%였다.

• Preventive Nutrition and Food Science
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• 제22권2호
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• pp.131-137
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• 2017

Maximum production of isoquercetin and quercetin simultaneously from rutin by subcritical water hydrolysis (SWH) was optimized using the response surface methodology. Hydrolysis parameters such as temperature, time, and $CO_2$ pressure were selected as independent variables, and isoquercetin and quercetin yields were selected as dependent variables. The regression models of the yield of isoquercetin and quercetin were valid due to the high F-value and low P-value. Furthermore, the high regression coefficient indicated that the polynomial model equation provides a good approximation of experimental results. In maximum production of isoquercetin from rutin, the hydrolysis temperature was the major factor, and the temperature or time can be lower if the $CO_2$ pressure was increased high enough, thereby preventing the degradation of isoquercetin into quercetin. The yield of quercetin was considerably influenced by temperature instead of time and $CO_2$ pressure. The optimal condition for maximum production of isoquercetin and quercetin simultaneously was temperature of $171.4^{\circ}C$, time of 10.0 min, and $CO_2$ pressure of 11.0 MPa, where the predicted maximum yields of isoquercetin and quercetin were 13.7% and 53.3%, respectively. Hydrolysis temperature, time, and $CO_2$ pressure for maximum production of isoquercetin were lower than those of quercetin. Thermal degradation products such as protocatechuic acid and 2,5-dihydroxyacetophenone were observed due to pyrolysis at high temperature. It was concluded that rutin can be easily converted into isoquercetin and quercetin by SWH under $CO_2$ pressure, and this result can be applied for SWH of rutin-rich foodstuffs.

• Fisheries and Aquatic Sciences
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• 제16권2호
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• pp.71-78
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• 2013

Subcritical water hydrolysis was carried out in a batch reactor to produce valuable materials, such as low-molecular weight (MW) peptides and essential amino acids with antioxidant properties, from heat-dried squid viscera. Hydrolysis of squid viscera was performed at 160 to $280^{\circ}C$ for 3 min. The yield was increased by increasing the temperature and pressure, while the protein content of squid viscera hydrolysate decreased with increasing temperature. Low-MW peptides were detected in all hydrolysates by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The highest yields of free and structural amino acids in heat-dried squid viscera hydrolysate were at $160^{\circ}C$ and were $411.95{\pm}1.15$ and $346.62{\pm}1.25$ mg/100 g, respectively. All essential amino acids were detected in viscera hydrolysates; leucine was the most abundant. Antioxidant activities of hydrolysates were highest at $220^{\circ}C$. Greater than $98{\pm}0.26%$ of the ABTS antioxidant activity was retained in hydrolysates after long-term heat treatment.

• Preventive Nutrition and Food Science
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• 제21권2호
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• pp.132-137
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• 2016

Enhanced production of individual phenolic compounds by subcritical water hydrolysis (SWH) of pumpkin leaves was investigated at various temperatures ranging from 100 to $220^{\circ}C$ at 20 min and at various reaction times ranging from 10 to 50 min at $160^{\circ}C$. Caffeic acid, p-coumaric acid, ferulic acid, and gentisic acid were the major phenolic compounds in the hydrolysate of pumpkin leaves. All phenolic compounds except gentisic acid showed the highest yield at $160^{\circ}C$, but gentisic acid showed the highest yield at $180^{\circ}C$. The cumulative amount of individual phenolic compounds gradually increased by 48.1, 52.2, and $78.4{\mu}g/g$ dry matter at $100^{\circ}C$, $120^{\circ}C$, and $140^{\circ}C$, respectively, and then greatly increased by $1,477.1{\mu}g/g$ dry matter at $160^{\circ}C$. The yields of caffeic acid and ferulic acid showed peaks at 20 min, while those of cinnamic acid, p-coumaric acid, p-hydroxybenzoic acid, and procatechuic acid showed peaks at 30 min. Antioxidant activities such as 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power values gradually increased with hydrolysis temperature and ranged from 6.77 to 12.42 mg ascorbic acid equivalents/g dry matter and from 4.25 to 8.92 mmol $Fe^{2+}$/100 g dry matter, respectively. Color $L^*$ and $b^*$ values gradually decreased as hydrolysis temperature increased from $100^{\circ}C$ to $140^{\circ}C$. At high temperatures ($160^{\circ}C$ to $220^{\circ}C$), L* and b* values decreased suddenly. The $a^*$ value peaked at $160^{\circ}C$ and then decreased as temperature increased from $160^{\circ}C$ to $220^{\circ}C$. These results suggest that SWH of pumpkin leaves was strongly influenced by hydrolysis temperature and may enhanced the production of phenolic compounds and antioxidant activities.

• 한국축산식품학회지
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• 제34권2호
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• pp.151-157
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• 2014

This study investigated the effects of three proteases (trypsin, pepsin and chymotrypsin) on the hydrolysis efficiency of porcine placenta and the molecular weight (Mw) distributions of the placental hydrolysates. Because placenta was made up of insoluble collagen, the placenta was gelatinized by applying thermal treatment at $90^{\circ}C$ for 1 h and used as the sample. The placental hydrolyzing activities of the enzymes at varying concentrations and incubation times were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and gel permeation chromatography (GPC). Based on the SDS-PAGE, the best placental hydrolysis efficiency was observed in trypsin treatments where all peptide bands disappeared after 1 h of incubation as compared to 6 h of chymotrypsin. Pepsin hardly hydrolyzed the placenta as compared to the other two enzymes. The Mw distribution revealed that the trypsin produced placental peptides with Mw of 106 and 500 Da. Peptides produced by chymotrypsin exhibited broad ranges of Mw distribution (1-20 kDa), while the pepsin treatment showed Mw greater than 7 kDa. For comparisons of pre-treatments, the subcritical water processing (37.5 MPa and $200^{\circ}C$) of raw placenta improved the efficiency of tryptic digestions to a greater level than that of a preheating treatment ($90^{\circ}C$ for 1 h). Consequently, subcritical water processing followed by enzymatic digestions has the potential of an advanced collagen hydrolysis technique.

• 한국식품과학회지
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• 제47권6호
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• pp.772-778
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• 2015

최근 아임계수 가수분해는 전통적인 단백질 가수분해법의 대체방법으로서 관심을 받고 있으며, 고단백질원으로부터 아미노산을 회수하는데 효과적인 공정이 될 수 있을 것으로 기대되고 있다. 본 연구에서는 대표적인 식물성 단백질원인 분리대두단백질을 선택하여 대두단백질의 아임계수 가수분해에서 가장 중요한 인자인 대두단백질의 초기농도, 반응온도, 반응시간의 영향을 연구하여 대두단백질로부터 아미노산을 생산할 수 있는 조건을 최적화하고자 하였다. 대두단백질 수열분해액의 실온에서 pH는 $200^{\circ}C$에서 20분간 처리했을 때 pH는 7.3으로 중성이었으나 온도가 증가할수록 pH가 증가하여 $270^{\circ}C$에서 10.3으로 알카리성을 나타내었다. 반응온도 $220^{\circ}C$까지는 수열분해액은 분산상태를 이루었으나 $230^{\circ}C$ 이상에서는 분산상태가 파괴되고 단백질이 분리되어 하부에 침강층을 이루었으며 $240^{\circ}C$ 이상에서는 이 단백질층이 현저히 감소하였다. 반응온도는 $250^{\circ}C$, 반응시간 20분으로 고정한 조건에서 대두현탁액의 초기농도가 수열분해에 미치는 영향을 살펴본 결과 초기농도 10% (w/v)일 때 가수분해도 및 아미노산 수율이 각각 16.2% 및 22.3%로 가장 우수하였다. 또한 반응온도 $200-220^{\circ}C$ 범위에서는 가수분해도와 아미노산 수율은 서서히 증가하였으나 $230-250^{\circ}C$ 영역에서는 급격히 증가하였으며 $250^{\circ}C$ 이상에서는 다시 완만히 증가하는 경향을 보여 $250^{\circ}C$ 이상에서 아미노산 분해속도는 단백질 분해속도를 초과하였다. 표면반응분석법으로 예측한 결과 $268^{\circ}C$, 처리시간 35분에서 최적 아미노산 수율 43.5%를 얻을 수 있었다.

• Elastomers and Composites
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• 제58권3호
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• pp.121-127
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• 2023

The effect of diisocyanate type on the decomposition temperature of polyurethane (PU) hydrolysis was investigated in a subcritical water medium up to 250℃. PU samples were prepared using different types of diisocyanate: two aromatic diisocyanates (4,4'-methylene diphenyl diisocyanate (MDI) and methyl phenylene diisocyanate (TDI)), one unbranched aliphatic diisocyanate (hexamethylene diisocyanate (HDI)), and two cyclic aliphatic diisocyanates (4,4'-methylene dicyclohexyl diisocyanate (H₁₂MDI) and isophorone diisocyanate (IPDI)). The pressure had no effect on hydrolysis in the range of 70-250 bar. The decomposition temperature of the PU samples increased in the following order: TDI-PU (199℃) < H₁₂MDI ≈ IPDI ≈ HDI (218-220℃) < MDI-PU (237℃). This order of increase in temperature is related to the electron-donating ability of the group to connected to the nitrogen of the urethane unit. When the temperature of the (PU + water) mixture reached the specific decomposition temperature, the PU samples hydrolyzed completely within 5 min into primary amine and 1,4-butanediol. The hydrolysis products from MDI-PU and H₁₂MDI-PU were separated into a liquid phase rich in (BD + water) and a solid low phase rich in amine, whereas the products from TDI-, IPDI-, and HDI-PU existed in a single aqueous phase.

• Fisheries and Aquatic Sciences
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• 제25권7호
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• pp.357-379
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• 2022

Increased fisheries products have raised by-products that are discarded due to low economic value. In addition, marine by-products are still rich in protein and nutritional value that have biological activities and give benefits to human health. Meanwhile, there is raised pressure for sustainability practices in marine industries to reduce waste and minimize the detrimental effect on the environment. Thus, valorization by-products through bioactive peptide mining are crucial. This review focus on various ways to obtain bioactive peptides from marine by-products through protein hydrolysis, for instance chemical hydrolysis (acid and based), biochemical hydrolysis (autolysis and enzymatic hydrolysis), microbial fermentation, and subcritical water hydrolysis. Nevertheless, these processes have benefits and drawbacks which need to be considered. This review also addresses various biological activities that are favorable in pharmaceutical industries, including antioxidant, antihypertensive, anticancer, anti-obesity, and other beneficial bioactivities. In addition, some potential marine resources of Indonesia for the marine biopeptide from their by-product or undesired marine commodities would be addressed as well.

• Korean Chemical Engineering Research
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• 제48권6호
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• pp.747-751
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• 2010

본 연구에서는 아임계 수 가수분해 공정을 이용하여 동결건조 된 미역(Undaria pinnatifida)으로부터 아미노산 생산 조건 및 생성된 물질의 특성에 대하여 고찰하였다. 가수분해 장치는 회분식으로 설계 되었으며, 반응기는 내경 4.6 cm, $200cm^3$ 부피 용량의 Hastelloy 276 강으로 제작된 것을 사용하였다. 반응기 내부에는 교반기가 부착되어 100 rpm으로 연속적으로 교반되도록 하였다. 시료는 동결건조 된 미역 파우더와 회수율 향상을 위해 부가된 1% acetic acid를 촉매로 한 반응용액을 1:100(w/v) 비율로 혼합시켜 반응을 진행시켰다. 반응물질의 혼합을 위해 100 rpm으로 일정하게 교반하였으며, 반응온도와 압력 변화에 따른 아미노산 생성 회수율을 고찰하였다. 실험조건은 온도 $180{\sim}374^{\circ}C$, 반응시간 1시간이었다. 총 아미노산 함량은 고온의 조건에 비해 저온에서 높은 함량을 나타내었으며 분자량이 작은 아미노산(glycine, alanine, serine 등)이 분자량이 큰 아미노산들보다 높은 함량을 나타내었다. 아미노산의 최대 회수율($290.84{\mu}g/mL$)은 $220^{\circ}C$, 촉매 첨가조건에서 분석되었다.