This study aimed to compare the total phenolic content (TPC) and antioxidant activities of A. rigidula extracts. It also aimed to identify phenolic acids present in the extracts. The 2,2-azinobis-(3-ethylbenzothiazoli...This study aimed to compare the total phenolic content (TPC) and antioxidant activities of A. rigidula extracts. It also aimed to identify phenolic acids present in the extracts. The 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and ferric thiocyanate lipid peroxidation antioxidant assays were performed. High performance liquid chromatography was used to identify phenolic acids. There was no solvent effect on TPC nor on scavenging activities, and inhibition of lipid peroxidation (p > 0.05) among solvent extracts. On the other hand, 1:1:3 water: acetone: methanol extract (10.22 mg GAE/g sample) had significantly higher reducing potential than 50% ethanol extract (EE) (9.259 mg GAE/g sample) (p < 0.05);but EE was not significantly different from 80% methanol extract (9.781 mg GAE/g sample) (p > 0.05). Phenolic fraction designated as fraction 4 had the highest antioxidant activity (p < 0.05) with 69.49% ABTS scavenging activity and FRAP reducing potential, 22.26 mg of GAE/g sample. DPPH scavenging activities of fractions 4 (55.59%) and 5 (55.64%) were significantly higher than the other fractions (p A. rigidula extracts contain gallic, caffeic, vanillic, p-coumaric, salicylic acids and vanillin.展开更多
The effect of four additives (surfactants and dispersant) that were supplied by Hercules Chemicals Singapore Pte Ltd on kraft pulping and bleaching of Eucalyptus camaldulensis and Acacia mangium has been studied. The ...The effect of four additives (surfactants and dispersant) that were supplied by Hercules Chemicals Singapore Pte Ltd on kraft pulping and bleaching of Eucalyptus camaldulensis and Acacia mangium has been studied. The use of additives results in a more removal of extractives, and in a more uniform cook with lower screen rejects in eucalyptus, lower residual alkali, and in an improvement in brightness of eucalyptus pulps. At low additive charge level, a reduction of kappa number generated without clear loss of pulp yield in acacia cook.展开更多
采用正交实验法首次研究高氨环境中马占相思栲胶的浅色化改性方法,探讨了氨水用量、过氧化氢用量、马占相思用量及反应温度等因素对改性马占相思溶液颜色的影响,同时考察了改性马占相思对天然胶乳蛋白质的固定作用.结果表明:改性处理后...采用正交实验法首次研究高氨环境中马占相思栲胶的浅色化改性方法,探讨了氨水用量、过氧化氢用量、马占相思用量及反应温度等因素对改性马占相思溶液颜色的影响,同时考察了改性马占相思对天然胶乳蛋白质的固定作用.结果表明:改性处理后,马占相思溶液颜色变浅,静置48 h颜色无明显改变,优选的改性条件为氨水量0.3份、过氧化氢1.0份、质量分数20%的马占相思栲胶溶液用量8份、保温反应温度80℃;改性马占相思具有固定胶乳蛋白质的作用,对于优化条件下制备的改性马占相思,当其用量为天然胶乳重量(干重)的1%时,可使天然橡胶膜中可提取水溶性蛋白质(EP)含量降至(45.58±6.27)μg/dm2,远小于ASTM D 3577-2009和GB 24788-2009标准对EP的限量值.展开更多
文摘This study aimed to compare the total phenolic content (TPC) and antioxidant activities of A. rigidula extracts. It also aimed to identify phenolic acids present in the extracts. The 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and ferric thiocyanate lipid peroxidation antioxidant assays were performed. High performance liquid chromatography was used to identify phenolic acids. There was no solvent effect on TPC nor on scavenging activities, and inhibition of lipid peroxidation (p > 0.05) among solvent extracts. On the other hand, 1:1:3 water: acetone: methanol extract (10.22 mg GAE/g sample) had significantly higher reducing potential than 50% ethanol extract (EE) (9.259 mg GAE/g sample) (p < 0.05);but EE was not significantly different from 80% methanol extract (9.781 mg GAE/g sample) (p > 0.05). Phenolic fraction designated as fraction 4 had the highest antioxidant activity (p < 0.05) with 69.49% ABTS scavenging activity and FRAP reducing potential, 22.26 mg of GAE/g sample. DPPH scavenging activities of fractions 4 (55.59%) and 5 (55.64%) were significantly higher than the other fractions (p A. rigidula extracts contain gallic, caffeic, vanillic, p-coumaric, salicylic acids and vanillin.
文摘The effect of four additives (surfactants and dispersant) that were supplied by Hercules Chemicals Singapore Pte Ltd on kraft pulping and bleaching of Eucalyptus camaldulensis and Acacia mangium has been studied. The use of additives results in a more removal of extractives, and in a more uniform cook with lower screen rejects in eucalyptus, lower residual alkali, and in an improvement in brightness of eucalyptus pulps. At low additive charge level, a reduction of kappa number generated without clear loss of pulp yield in acacia cook.
文摘采用正交实验法首次研究高氨环境中马占相思栲胶的浅色化改性方法,探讨了氨水用量、过氧化氢用量、马占相思用量及反应温度等因素对改性马占相思溶液颜色的影响,同时考察了改性马占相思对天然胶乳蛋白质的固定作用.结果表明:改性处理后,马占相思溶液颜色变浅,静置48 h颜色无明显改变,优选的改性条件为氨水量0.3份、过氧化氢1.0份、质量分数20%的马占相思栲胶溶液用量8份、保温反应温度80℃;改性马占相思具有固定胶乳蛋白质的作用,对于优化条件下制备的改性马占相思,当其用量为天然胶乳重量(干重)的1%时,可使天然橡胶膜中可提取水溶性蛋白质(EP)含量降至(45.58±6.27)μg/dm2,远小于ASTM D 3577-2009和GB 24788-2009标准对EP的限量值.
