Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract.The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions,if any,did occur...Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract.The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions,if any,did occur between the collagen protein through its amino acids and the polyphenolic condensed tannin.The reaction products obtained were analyzed by matrix assisted laser desorption ionization time-of-flight(MALDI ToF)mass spectrometry.Reactions between the two materials did appear to occur,with the formation of a relatively small proportion of covalent and ionic linkages at ambient temperature but a considerable proportion of covalent linkages tannin-protein amino acids and the disappearance of ionic bonds.The linkages between the two materials appeared to be by amination of the phenolic–OHs of the tannin by the amino groups of the non-skeletal side chains of arginine,and by esterification by the–COOH groups of glutamic and aspartic acid of the aliphatic alcohol-OH on the C3 site of the flavonoid units heterocycle of the tannin.The proportion of covalent linkages increases markedly and predominate with increasing temperatures.This tightening of the tannin-protein covalent network formed may be an additional contributing factor both to leather wear resistance and performance as well to leather shrinking when this is subjected to excessive temperatures.展开更多
Restrictions on heavy metals,especially chromium,have encouraged alternative tanning systems that can reduce environmental and human health risks from conventional chrome-based tanning.In this work,metal-free combinat...Restrictions on heavy metals,especially chromium,have encouraged alternative tanning systems that can reduce environmental and human health risks from conventional chrome-based tanning.In this work,metal-free combination tanning was developed by using vegetable tannins and a triazine-based syntan containing active chlorine groups(SACC).Specifically,the relationship between leather performance(e.g.,hydrothermal stability and organoleptic properties)and technical protocols(e.g.,types and dose of tannins)was systematically established.The optimized protocol involving a unique procedure(i.e.,10%SACC pre-tanning,shaving,and 25%wattle tanning)endowed the leather with high shrinkage temperature(~92℃)and met the Chinese standards for shoe upper leather(QB/T 1873-2010).Our method not only produces zero chrome-containing solid wastes,but also uses~75%less tannin for leather manufacture.The excellent leather performance was ascribed to the synergistic effects,where SACC and wattle diffused into collagen fibrils and may bind to collagen via covalent,hydrogen and ionic bonding,locking the hierarchical structure of collagen from microfibrils to fiber bundles.Moreover,we summarized these findings and proposed a diffusion-binding-locking mechanism,providing new insights for current tanning theory.Together with the biodegradable spent tanning liquor,this approach will underpin the development of sustainable leather manufacture.展开更多
The objective was to create an Egyptian database on the contributors of fruit and vegetables in the diets of preschool children and to estimate the usual daily intakes of fruits, vegetables and vitamin C. A total of 5...The objective was to create an Egyptian database on the contributors of fruit and vegetables in the diets of preschool children and to estimate the usual daily intakes of fruits, vegetables and vitamin C. A total of 59 healthy boys and girls aged 2.5 - 6 years attending day care centers in urban Giza governorate completed the study by interviewing their mothers on 6x non-consecutive days using the 24 h dietary recall. Participants were classified according to age, gender and socioeconomic class. Prevalence of daily consumptions of fruits and vegetables amounted to 22% and 54%, respectively of the total children. The daily intakes of fruits and vegetables averaged 117.5 and 56.4 g, respectively. The consumption of different types of fruits and vegetables was unevenly distributed by different personal and social variables. Estimated daily vitamin C supply from the diet was 38 mg per child, which satisfied the respective recommended nutrient intake (RNI) of 30 mg for the first six years of life. However, the diet of 15% of the children covered less than 75% of RNI. Top fruits contributing to vitamin C were oranges, guava, watermelon, pears and grapes. Extra foods such as chipsy was consumed by 81% of the children, contributed 18% to daily vitamin C supply and also 58.6 mg sodium. A multilevel intervention strategy is warranted for promoting daily fruit and vegetable intake and healthy eating in early childhood.展开更多
文摘Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract.The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions,if any,did occur between the collagen protein through its amino acids and the polyphenolic condensed tannin.The reaction products obtained were analyzed by matrix assisted laser desorption ionization time-of-flight(MALDI ToF)mass spectrometry.Reactions between the two materials did appear to occur,with the formation of a relatively small proportion of covalent and ionic linkages at ambient temperature but a considerable proportion of covalent linkages tannin-protein amino acids and the disappearance of ionic bonds.The linkages between the two materials appeared to be by amination of the phenolic–OHs of the tannin by the amino groups of the non-skeletal side chains of arginine,and by esterification by the–COOH groups of glutamic and aspartic acid of the aliphatic alcohol-OH on the C3 site of the flavonoid units heterocycle of the tannin.The proportion of covalent linkages increases markedly and predominate with increasing temperatures.This tightening of the tannin-protein covalent network formed may be an additional contributing factor both to leather wear resistance and performance as well to leather shrinking when this is subjected to excessive temperatures.
基金National Natural Science Foundation of China(21978177,22178230)is gratefully acknowledged.
文摘Restrictions on heavy metals,especially chromium,have encouraged alternative tanning systems that can reduce environmental and human health risks from conventional chrome-based tanning.In this work,metal-free combination tanning was developed by using vegetable tannins and a triazine-based syntan containing active chlorine groups(SACC).Specifically,the relationship between leather performance(e.g.,hydrothermal stability and organoleptic properties)and technical protocols(e.g.,types and dose of tannins)was systematically established.The optimized protocol involving a unique procedure(i.e.,10%SACC pre-tanning,shaving,and 25%wattle tanning)endowed the leather with high shrinkage temperature(~92℃)and met the Chinese standards for shoe upper leather(QB/T 1873-2010).Our method not only produces zero chrome-containing solid wastes,but also uses~75%less tannin for leather manufacture.The excellent leather performance was ascribed to the synergistic effects,where SACC and wattle diffused into collagen fibrils and may bind to collagen via covalent,hydrogen and ionic bonding,locking the hierarchical structure of collagen from microfibrils to fiber bundles.Moreover,we summarized these findings and proposed a diffusion-binding-locking mechanism,providing new insights for current tanning theory.Together with the biodegradable spent tanning liquor,this approach will underpin the development of sustainable leather manufacture.
文摘The objective was to create an Egyptian database on the contributors of fruit and vegetables in the diets of preschool children and to estimate the usual daily intakes of fruits, vegetables and vitamin C. A total of 59 healthy boys and girls aged 2.5 - 6 years attending day care centers in urban Giza governorate completed the study by interviewing their mothers on 6x non-consecutive days using the 24 h dietary recall. Participants were classified according to age, gender and socioeconomic class. Prevalence of daily consumptions of fruits and vegetables amounted to 22% and 54%, respectively of the total children. The daily intakes of fruits and vegetables averaged 117.5 and 56.4 g, respectively. The consumption of different types of fruits and vegetables was unevenly distributed by different personal and social variables. Estimated daily vitamin C supply from the diet was 38 mg per child, which satisfied the respective recommended nutrient intake (RNI) of 30 mg for the first six years of life. However, the diet of 15% of the children covered less than 75% of RNI. Top fruits contributing to vitamin C were oranges, guava, watermelon, pears and grapes. Extra foods such as chipsy was consumed by 81% of the children, contributed 18% to daily vitamin C supply and also 58.6 mg sodium. A multilevel intervention strategy is warranted for promoting daily fruit and vegetable intake and healthy eating in early childhood.
