• Biotechnology and Bioprocess Engineering:BBE
• /
• 제6권1호
• /
• pp.18-24
• /
• 2001

The advantage of using Streptomyces griseus HUT 6037 in the production of chitinase or chitosanase is that the organism is capable of hydrolyzing amorphous or crystalline chitin and chitosan according to the type of the substrate used. We investigated the effects of the enzyme induction time and chitin sources, CM-chitosan and deacetylated chitosan (degree of deacetylation 75-99%), on production of chitosanase. We found that this strain accumulated chitosanase when cells were grown in the culture medium containing chitosanaceous substrates instead of chitinaceous substrates. The highest chitosanase activity was obtained at 4 dyas of cultivation with 99% deacetylated chitosan. The specific activities of chitinase and chitosanase were 0.91 and 1.33 U/mg protein at 3 and 5 days, respectively. From the study of the enzymatic digestibility of various degrees of deacetylated chitosan, it was found that (GlcN)$_3$, (GlcN)$_4$and (GlcN)(sub)5 were produced during the enzymatic hydrolysis reaction. The results of this study suggested that the sugar composition of (GlcN)$_3$was homogeneous and those of (GlcN)$_4$and (GlcN)(sub)5 were heterogeneous.

• 한국식품조리과학회지
• /
• 제7권4호
• /
• pp.93-101
• /
• 1991

The object of this study was to investigate characteristics of kiwifruit protesae and effect of this enzyme on the functionality of casein. The specific activity of crudely prepared kiwifruit pretense on casein was 196.95 units/mg protein, it showed optimum activity at pH 3.0, $60^{\circ}C$. The degree of hydrolysis of casein with pretense treatment steeply increased to 73.5% and 78.9% for 10 and 20 minutes and then reached 84.1% and 89.3% for 1 and 4 hours, respectively. Solubility of non heated control group was 0.2% at pH 4, while the sample groups treated with enzyme for 0, 10 and 20 minutes were 14.5%, 19.2% and 24.0%, respectively. Casein treated with pretense showed marked increase in foam expansion near isoelectric point. However, enzymatically treated groups had lower foam expansion than the control groups. Foam stabilities of enzymatically modified group were lower than those of the control groups at all pH. Emulsifying activity of the non-heated control group was 0% at pH 4, while the groups modified enzymatically for 0, 10, and 60 minutes showed 51.0%, 55.5% and 54.5%, respectively.

• 한국식품과학회지
• /
• 제27권5호
• /
• pp.729-735
• /
• 1995

국내에서 생산되고 있는 4종류의 물엿에 대하여 $20^{\circ}C$와 $60^{\circ}C$의 온도에 저장중 품질 변화를 조사하였다. 저장 기간중 물엿의 색택은 흡광도, HMF 및 Hunter L 및 ${\Delta}E$ 값으로 측정하였을 때 모두 증가하였는데 전반적으로 저장 온도가 높고 가수분해 정도가 큰 물엿일수록 변색이 심하게 나타났다. 물엿은 모두 비뉴우턴 유체의 특성을 나타내었으며 저장중 악간의 증가만을 나타내었다. 그리고 저장기간중 물엿의 당조성은 단당류의 비율이 상대적으로 감소하고 이당류나 소당류의 비율이 약간 더 증가함을 알수 있었다.

• 한국식품과학회지
• /
• 제27권5호
• /
• pp.794-798
• /
• 1995

식품단백질의 효율적인 이용을 위하여 neutrase에 의한 glutamine과 asparagine 잔기의 탈아미드화에 관한 연구를 행하였다. Neutrase에 의한 BSA의 최적반응 조건은 $20^{\circ}C$, pH 10에서 3시간 반응시켰을 때로, 이때 BSA는 24%가 탈아미드화되었고. 동시에 2.9%가 가수분해되었다. 또한 pronase, bromelain, ficin 보다는 neutrase에 의한 BSA의 탈아미드화율이 높은 것으로 나타났다. 최적 탈아미드화 조건에서 neutrase에 의한 egg albumin, 분리콩단백 및 casein의 경우 탈아미드화에 수반하여 펩티드결합의 분해가 비교적 높게 관찰되었다.

• 한국세라믹학회지
• /
• 제45권11호
• /
• pp.744-749
• /
• 2008

The properties of the polymer-modified mortars are influenced by the polymer film, cement hydrates and the combined structure between the organic and inorganic phases. Also, this quality of polymer modified cement strongly depend on weather condition and polymer cement ratio. To overcome this problem, polymer-modified cement were prepared by varying polymer/cement mass ratio (P/C) with $0{\sim}20%$ and constant water/cement mass ratio of 0.5. The effect of polymer on the hydration of this polymer cement is studied on different polymer cement ratio. The results showed that the polymer cement paste have increased the viscosity in addition the amount of polymer dosage and the polymers is completed resulting in a reduced degree of hydration caused by different ion elution amount. Also we know that the reactants is calcium acetate as a results of chemical reaction between acetate group in EVA which is hydrolysis in water and $Ca^{2+}$ ion during hydration of cement.

• 한국세라믹학회지
• /
• 제32권9호
• /
• pp.1047-1055
• /
• 1995

Mn-Zn ferrite granules were formed by a spray-drying method of the slurry containing different kinds and concentrations of binders at various temperatures. The slurry was made by conventional ceramic processing method, that is, by mixing Fe2O3, MnO, ZnO powders (52 : 24 : 24 mol%), calcining and milling. Typical shape of the spray dried granules was spherical. The compaction behavior of these granules was dependent on the spray-drying temperature and the kind and concentration of binders. At lower pressure the granules were displaced and at higher pressure the granules were deformed and fractured to fill pores among the granules. The optimum concentration of the binder was 0.5wt%. The granules containing 0.5wt% PVA 205 were deformed and fractured well and the green density was higher than others. At higher concentrations of the binder the granules were deformed rather than fractured, therefore the green density was lowered because of the remaining unfilled pores. The decomposition temperature and the heat released were increased with increasing the concentration of the binders. The compaction response of the granules containing PVA 205 was more efficient than those containing PVA 217 and PVA 117. Green density was not dependent on the degree of hydrolysis of the binders. The compaction response of the granules spray-dried at 15$0^{\circ}C$ was most efficient.

• Applied Biological Chemistry
• /
• 제35권5호
• /
• pp.389-394
• /
• 1992

건열$(130{\sim}220^{\circ}C)$ 처리가 옥수수 전분의 성질에 미치는 영향을 조사하였다. 표면 색도의 경우 L값과 a값은 큰 차이가 없었으나 b값은 열처리에 따라 약간 감소하였다. Blue value는 $190^{\circ}C$ 이상에서 약간 증가하였고 물결합능력은 열처리 온도의 상승에 따라 증가하였다. 팽윤력은 시료간에 큰 차이가 없으나 $90^{\circ}C$에서의 팽윤력은 $190^{\circ}C$ 이상의 시료에서 약간 감소하였고 용해도는 $190^{\circ}C$ 이상에서 증가하였다. $190^{\circ}C$ 이상에서 고유점도의 상당한 감소, 전분결정도의 감소, 산 또는 효소에 의한 가수분해율의 뚜렷한 증가경향을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.234-235
• /
• 2007

Transparent nanosized $TiO_2$ sol has been made by sol-gel method, using Titanium(IV) isopropoxide precursor. To promote hydrolysis for titania is needed excess water, Oil bath and temperature about $80^{\circ}C$. $TiO_2$ sol is peptized ranging from pH 1 to 1.5 using hydrochloric acid for the stability of sol during a condensation reaction. The average particle size of $TiO_2$ sol was approximately 20nm. $TiO_2$-sillane sol was synthesized by surface treatment using MTMS to the $TiO_2$ sol. TEM analysis has been used to check the degree of dispersion and FT-IR analysis has been used to see if the sillane has been chemically bonded on the surface of $TiO_2$.

• 한국식품영양과학회지
• /
• 제26권6호
• /
• pp.1147-1151
• /
• 1997

To develop an onion sauce, reaction conditions of celluclast 1.5L and pectinex on onion were investigated and organoleptic evaluations were carried out. Degree of hydrolysis(D.H) of hydrolysate by a mixture of celluclast 1.5L and pectinex was a higher than that by each enzyme. Hydrolysate by a mixture of celluclast 1.5L and pectinex(1:3v/v) showed 86% of D.H. and total sugar content of the hydrolysate was 54mg/ml. Hydrolysates showed 83~86% of D.H. at reaction temperature of $25^{\circ}C$ to 45$^{\circ}C$. Total sugar content of the hydrolysate was increased with increasing temperature. D.H. and total sugar content of hydrolysate was 76~86% and 51~63mg/ml, respectively, under acidic conditions. D.H. and total sugar content of hydrolysate were also increased with increasing time. Bitterness, sweetness and ordor of roasted pork prepared by adding onion and onion hydrolysate were significantly different(p<0.05), but color and preference between two groups were not significantly different(p<0.05) between two groups. There was no significant difference(p<0.05) in sweetness and bitterness of the roasted pork prepared by adding different amounts of onion hydrolysate, although ordor and preference of the roasted pork were significantly different(p<0.05).

• 한국염색가공학회지
• /
• 제34권3호
• /
• pp.197-206
• /
• 2022

The purpose of this study was to confirm the optimal spinning conditions for PLA (Polylactic acid) as a fiber forming polymer. According to the melt spinning test results of PLA, the optimal spinning temperature was 258℃. However, it needs to note that relatively high pack pressure was required for spinning at 258℃. At an elevated temperature, 262℃, mono filament was broken easily due to hydrolysis of PLA at a higher temperature. In case of fiber strength, it was confirmed that the draw ratios of 2.7 to 3.3 were optimal for maximum strength of melt spun PLA. Above the draw ratio, 3.3, the strength of the PLA fibers was lowered. It was presumed that cleavage of the PLA polymer chain over maximum elongation. The heat setting temperature of GR (Godet roller) showed that the maximum strength of the PLA fibers was revealed around 100℃. The degree of crystallinity and the strength of the PLA fibers were decreased above 100℃. The optimal take-up speed (Spinning speed) was around 4,000m/min. Thermal analysis of PLA showed 170℃ and 57℃ as Tm (melting temperature) and Tg (glass transition temperature), respectively.