• Food Science and Biotechnology
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• v.17 no.3
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• pp.637-641
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• 2008

This study investigated the heat stability of L-ascorbic acid (AA) in acetic acid solution. To analyze the degradation of AA using high performance liquid chromatography (HPLC), AA was measured at a wavelength of 244 nm in acetic acid and 265 nm in distilled water. During the storage of AA in acetic acid or distilled water at $37^{\circ}C$, degradation of AA was slower in acetic acid than in distilled water. On examining various ratios of AA to acetic acid, the stability of AA at $100^{\circ}C$ for 30 min was the highest when the concentration of acetic acid was 10 times higher than the concentration of AA. After acetic acid was added into AA degraded by heating, the AA is stabilized by reheating. Ultimately, these results indicate that degraded AA is reduced by hydrogen ions dissociated from acetic acid, and the rate of reduction of degraded AA in acetic acid solution is improved with heat processing.

• Korean journal of food and cookery science
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• v.18 no.5
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• pp.487-494
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• 2002

This study was conducted to investigate the thermal stability of water-soluble and fat-soluble vitamins dissolved in water and milk by various heat treatments. Vitamin samples were prepared by dissolving them in water and milk at various concentrations, and were heat treated for 30 min at 65$\^{C}$, 15 sec at 85$\^{C}$, 5 sec at 100$\^{C}$, 121$\^{C}$ at 15 min, the levels of residual vitamin were measured by using HPLC. Milk samples were fortified with vitamins before and after UHT treatment. As heating over 100$\^{C}$, riboflavin in water were destructed more than 92% but fortified in milk showed less than 20% destruction, suggesting that riboflavin was protected by milk components. Also retinol heated ever 100$\^{C}$ was more stable in milk than in water. L-Ascorbic acid and cholecalciferol(D$_3$) showed a similar destruction rate in water and in fortified milk. L-ascorbic acid was easily destructed by UHT treatment. Destruction of thiamin and tocopherol was increased in fortified milk. Among tour capsulated water-soluble vitamins, L-ascorbic acid was much more stable compared with powder form. Nicotinic acid and folic acid either in capsule or powder form showed a slight destruction by heat treatment. The results suggested that the fortification of unstable vitamins such as L-ascorbic acid, thiamin, tocopherol and cholecalciferol(D$_3$) should be made in milk after heat treatment.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.315-325
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• 2020

Boron compound had many advantages as wood preservative, but it was prone to leaching. Improving boron preservation was required to extend the service life of fast growing and low durability red jabon (Antochephalus macrophyllus) hardwood. This study aimed to evaluate the dimensional stability, color change and durability of modified red jabon wood by double impregnation with boron and methyl methacrylate (MMA) and heat treatment. Impregnation I used boric acid or borax, and impregnation II used MMA, while heat treatment used temperatures of 90 ℃ or 180 ℃ for 4 hours. The dimensional stability, leachability, water absorption, color change and decay resistance of modified red jabon wood were tested. The results showed that MMA impregnation increased the dimensional stability of red jabon wood, while the leaching and water absorption in the wood significantly reduced. Heating at 180 ℃ caused less water absorption and higher dimensional stability of the wood than that of heating at 90 ℃. Impregnation with boric acid and MMA followed by heating at 90 ℃ resulted in the highest wood ASE, 89.9%. The color change (∆E^*) of wood increased significantly after MMA impregnation and heating at 180 ℃. Boric acid impregnation caused more resistant wood than borax impregnation against decay fungi and termites. Impregnation with boric acid and MMA followed with heating at 180 ℃ increased significantly the wood resistance against decay fungi and termites.

• Journal of the Korean Home Economics Association
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• v.28 no.2
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• pp.37-45
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• 1990

The purpose of this study was to determine the foaming properties of two small red bean protein isolates at various conditions. Data concerning the effects of pH, temperature, MaCl concentration, sugar concentration and protein concentration on the properties such as solubility, foam expansion, foam stability were presented. The results were summarized as follows : 1. The crude protein contents of two small red beans were 26.14% and 22.71%. The percentage of nonpolar amino acid group was the highest and that of sulfur containing amino acid group was the lowest. 2. Protein solubility showed the minimum at pH 4.5 which is isoelectric point of small red bean protein isolate adn heat treatment lowered solubility(P<0.05). At pH 4.5, solubility increased sighificantly as 0.4M NaCl was added. However, the effect of sugar concentration in the solubility was not significant. 3. Foam expansion of two small red bean protein isolates was high at pH 4.5 and heat treatment at 10$0^{\circ}C$ lowered foam expansion(P<0.05). While addition of NaCl, sugar did not affect the foma expansion, gradual increment of the protein isolates concentration up to 9% decreased the foma expansion slightly. 4. Foam stability was significantly high at pH 4.5 and heat treatment at 10$0^{\circ}C$ lowered foam stability. Addition of sugar caused slight decrease in foam stability. From 1% to 9% suspension, foma stability increased significantly as protein concentration increased(P<0.05)

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.32-34
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• 1998

Phytase from Aspergillus species is a very heat unstable enzyme which inactivates to a great extent during the thermal processing of animal feed formulation. Various protein stabilization additives were tested to improve its heat stability. Among them, a basic amino acid, L-arginine remarkably increased the thermal stability of phytase in an aqueous solution state.

• Korean journal of food and cookery science
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• v.14 no.5
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• pp.492-497
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• 1998

The stabilizing effect of fructooligosanharide (FO) on hen＇s egg yolk immunoglobulin (yIgG) by heat and acid was investigated. The heat stability of yIgG at 70∼80$^{\circ}C$ was enhanced in a concentration-dependent manner by adding 0∼50% (w/v) FO to a yIgG solution. Acid-induced inactivation of yIgG was also suppressed in a concentration-dependent relationship by addition of FO. Addition of 50% FO almost completely stabilized yIgG at pH 3. The remarkable stablizing effect of FO on yIgG may enhance the use of yIgG as functional food ingredients.

• Journal of the Korean Wood Science and Technology
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• v.51 no.6
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• pp.431-446
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• 2023

Samama wood (Anthocephalus macrophyllus (Roxb) Havil) is a fast-growing and lesser-utilized wood species that has inferior properties; therefore, its quality needs to be improved. This research aimed to determine the effect of citric acid impregnation at high curing temperatures on the dimensional stability and mechanical properties of wood. Citric acid solution with 10% concentration (w/w) was impregnated into wood samples by vacuum-pressure method (-0.5 cmHg, 30 min; 0.7 MPa, 3 h), followed by curing process at 140℃, 160℃, and 180℃ of temperature for 1 h. In comparison, the other wood samples were heat treated at the same temperatures and time. The results showed that the increase in curing and heat temperatures for both treatments were directly proportional to the dimensional stability, but inversely proportional to the mechanical properties. Citric acid impregnated had higher density, dimensional stability, and mechanical properties, except for modulus of rupture, than that of heat treatment. The optimum temperature is suggested at 160℃ in both treatments.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.616-621
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• 2020

Sinapinic acid is a widely-distributed phenolic acid in various edible plants. In this study, changes in chemical stability and biological activities of sinapinic acid by heat treatment were evaluated at different pH values. The decomposition of sinapinic acid with heating at 95℃ was accelerated at higher pH; the residual levels after 10 min of heating were 80, 45 and 24% at pH 6, 7 and 8, respectively. Levels of reactive oxygen species derived from sinapinic acid also increased after heating at pH 7 and 8. ABTS radical scavenging activities and ferric reducing antioxidant power of sinapinic acid were reduced significantly after heating at pH 7 and 8. The cytotoxic activity of sinapinic acid against HCT116 cells was significantly enhanced after heating at pH 8 with decreased glutathione levels. The results suggest that heat treatment causes changes in the chemical stability and biological activities of sinapinic acid, and such changes are more prominent at higher pH.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.619-623
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• 1996

Some physical and physiological properties of di-D-fructofuranose dianhydrideIII (DFAIII), as a new sweetener, were investigated via in vitro experiments. The disaccharide was prepared by decomposing inulin with inulin fructotransferase (depolymerizing) from Arthrobacter sp. A-6. DFAIII had more excellent heat and acid stability than sucrose. This was one of the most desirable properties especially for the oligomer types of sweetener. DFAIII showed the least pH drop in the Streptococcus mutans culture, compared with the other saccharides examined. This indicates that the sugar will be fairly effective for preventing dental caries. The saccharide also had a selective Bifidus growth-promoting effect in PYF medium. Whereas, E. coli did not show growth promotion in the DFAIII-containing medium. In the co-culture of Bifidus longum and E. coli in the BL medium, Bifidus longum had a selective growth while the growth of E. coli appeared rather to be inhibited.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3808-3814
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• 2023

The thermal stability of nitric acid solutions after contact with non-irradiated and irradiated tributyl phosphate (TBP) and its solution in Isopar-M has been studied. It has been established that exothermic processes occur during heating due to the interaction of soluble radiolysis products and the decomposition of the extractant with nitric acid. Such processes can occur at temperatures below 100 ℃, but unlike a thermal explosion that occurs in seconds, they are longer in time and are accompanied by weak heat evolution. Their intensity depends on the composition of the extractant, the concentration of HNO₃, and the volume ratio of the organic and aqueous phases. The presence of extractant degradation products in raffinates does not pose a risk of a rapid evolution of gaseous products during evaporation, however, the presence of reducing agents can significantly increase the intensity of the exothermic decomposition of raffinates.