The concentrates with different maceral contents were obtained from Kailuan coking coals with different coal ranks(Ro;ranvarying from 0.88%to 1.73%)by float–sink separation in lab.Then these concentrates were charact...The concentrates with different maceral contents were obtained from Kailuan coking coals with different coal ranks(Ro;ranvarying from 0.88%to 1.73%)by float–sink separation in lab.Then these concentrates were characterized by proximate analysis,ultimate analysis,petrography analysis and coking index determination.The results show that the vitrinite is characterized as nature of lower carbon content,higher hydrogen content,higher volatile matter and stronger caking property compared to inertinite.The relationships between variation rate of volatile matter and maximum volatile matter and coal ranks are identified,and a linear model is developed for fast determination of the maceral contents.Compared to inertinite-rich concentrate,the blending ratio of vitrinite-rich concentrate is increased by 13%,which is considered to be a potential technique based on maceral separation for expanding the coking coal resources.展开更多
Aroma is an important component for characteristic of wine. β-glucosidase is an enzyme for enhancing wine aroma during fermentation and aging. The aim of this study was to evaluate β-glucosidase activities from 17 y...Aroma is an important component for characteristic of wine. β-glucosidase is an enzyme for enhancing wine aroma during fermentation and aging. The aim of this study was to evaluate β-glucosidase activities from 17 yeast strains. It was found that strain 71 B-1122 exhibited highest activity of β-glucosidase. The purified enzyme of this strain was characterized. The purified enzyme was added in Muscat must before wine making process. The must and wine were determined for volatile compounds by headspace-SPME/GC-MS and found that the hexyl acetate, linalool, phenethyl, nerol and geraniol compounds were significantly increased after treated with the enzyme. Sensory evaluation of the combined alcoholic fermentation and flavour enrichment of Muscat juice by adding of purified β-glucosidase enzyme showed well oenological properties especially aroma. Therefore, in producing wine, yeast strain selection and addition of β-glucosidase enzyme should be considered because they were important factors affecting wine aroma.展开更多
Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile co...Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile contaminants such as furan and its derivatives, and present a volatile profile of the most common furan derivatives in the described products. To measure concentration of chemical compounds such as furan and furan derivatives, fast and effective solid-phase micro-extraction/gas chromatography/mass spectrometry （SPME/GC/MS） methods were adapted. This study showed the differences in furan occurrence between Pytlowy and Staropolski, however, the greater differences were observed between different times and temperatures of baking rather than between the bread types. Clearly, the higher concentrations were found in products prepared during the longest baking time period of 50 min, and temperatures of 230 ℃ and 240 ℃. The highest furan level was detected in Staropolski 28.89 ± 1.16/μg/kg, baked for 50 min at 230 ℃ in bread crust. The volatile fraction of bread crust was composed of 5-9 furan derivatives while crumb layer contained only furan-2-pentyl. It was concluded that furan is present in almost each type of bread and percentage of furan derivatives in all volatile fractions ranged from 0.5 % to 60.6% in crust of examined bars.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities of China (No.2010YH11)
文摘The concentrates with different maceral contents were obtained from Kailuan coking coals with different coal ranks(Ro;ranvarying from 0.88%to 1.73%)by float–sink separation in lab.Then these concentrates were characterized by proximate analysis,ultimate analysis,petrography analysis and coking index determination.The results show that the vitrinite is characterized as nature of lower carbon content,higher hydrogen content,higher volatile matter and stronger caking property compared to inertinite.The relationships between variation rate of volatile matter and maximum volatile matter and coal ranks are identified,and a linear model is developed for fast determination of the maceral contents.Compared to inertinite-rich concentrate,the blending ratio of vitrinite-rich concentrate is increased by 13%,which is considered to be a potential technique based on maceral separation for expanding the coking coal resources.
文摘Aroma is an important component for characteristic of wine. β-glucosidase is an enzyme for enhancing wine aroma during fermentation and aging. The aim of this study was to evaluate β-glucosidase activities from 17 yeast strains. It was found that strain 71 B-1122 exhibited highest activity of β-glucosidase. The purified enzyme of this strain was characterized. The purified enzyme was added in Muscat must before wine making process. The must and wine were determined for volatile compounds by headspace-SPME/GC-MS and found that the hexyl acetate, linalool, phenethyl, nerol and geraniol compounds were significantly increased after treated with the enzyme. Sensory evaluation of the combined alcoholic fermentation and flavour enrichment of Muscat juice by adding of purified β-glucosidase enzyme showed well oenological properties especially aroma. Therefore, in producing wine, yeast strain selection and addition of β-glucosidase enzyme should be considered because they were important factors affecting wine aroma.
文摘Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile contaminants such as furan and its derivatives, and present a volatile profile of the most common furan derivatives in the described products. To measure concentration of chemical compounds such as furan and furan derivatives, fast and effective solid-phase micro-extraction/gas chromatography/mass spectrometry （SPME/GC/MS） methods were adapted. This study showed the differences in furan occurrence between Pytlowy and Staropolski, however, the greater differences were observed between different times and temperatures of baking rather than between the bread types. Clearly, the higher concentrations were found in products prepared during the longest baking time period of 50 min, and temperatures of 230 ℃ and 240 ℃. The highest furan level was detected in Staropolski 28.89 ± 1.16/μg/kg, baked for 50 min at 230 ℃ in bread crust. The volatile fraction of bread crust was composed of 5-9 furan derivatives while crumb layer contained only furan-2-pentyl. It was concluded that furan is present in almost each type of bread and percentage of furan derivatives in all volatile fractions ranged from 0.5 % to 60.6% in crust of examined bars.
