Monomeric anthocyanins exhibit color variations at different pH, but they are highly unstable at physiological pH. To improve the stability, the effects of polyvinylalcohol on the anthocyanins of young red wine prepar...Monomeric anthocyanins exhibit color variations at different pH, but they are highly unstable at physiological pH. To improve the stability, the effects of polyvinylalcohol on the anthocyanins of young red wine prepared from Cambell Early grapes were examined in aqueous solution and in the solid phase on a cotton swab? and inert materials. Cyanidin-3-glucoside and mal-vidin-3-glucoside represented approximately 43.6% of total anthocyanins in the red wine. The anthocyanins decreased to 11.3% of the initial amount in aqueous solution at physiological pH after storage for 60 days at room temperature. On the other hand, from 66.9% to 87.2% remained in the solid phase on a cotton swab? and polypropylene membrane in the presence of polyvinylalcohol. The stability of the anthocyanins increased with the concentration of polyvinyl-alcohol in the solid phase but not in the aqueous solution. The anthocyanins were found to be condensed and immobilized in the complexes of anthocyanins and polyvinylalcohol on the poly-propylene membrane by phase-contrast microscopy analysis. The anthocyanins in the cotton swab? displayed color variations when dipped into different pH buffer solutions. These results suggest that anthocyanins from red wine stabilized in the solid phase by polyvinylalcohol can be used as a visual indicator of pH.展开更多
An analytical method using gas chromatography isotope ratio mass spectrometry(GC-IRMS)combined with solid phase micro-extraction(SPME)was developed to measure the 613C values of six typical volatiles commonly occurrin...An analytical method using gas chromatography isotope ratio mass spectrometry(GC-IRMS)combined with solid phase micro-extraction(SPME)was developed to measure the 613C values of six typical volatiles commonly occurring in wine(isoamyl acetate,2-octanone,limonene,2-phenylethanol,ethyl octanoate and ethyl decanoate)for the first time.SPME selected with a divinylbenzene/carboxen/polydimethylsiloxane fiber was combined with the GC-IRMS for pretreatment optimization.The optimized SPME parameters of extraction time,extraction temperature and salt concentration were 40 min,40℃ and 10%,respectively.The 613C values measured by SPME-GC-IRMS were in good agreement with those measured via elemental analyzer(EA)-IRMS and GC-IRMS.The differences range from 0.02‰to 0.44‰ with EA-IRMS and from 0 to 0.28‰ with GC-IRMS,indicating the high accuracy of the method.This newly established method measured the precision within 0.30‰ and was successfully validated to discriminate imported real wine samples with identical label but amazing price differences from different importers.展开更多
目的建立三重四极杆气质联用仪测定葡萄酒中氨基甲酸乙酯(EC)含量的方法。了解本市家庭自酿葡萄酒中氨基甲酸乙酯含量及影响因素。方法实验采用二氯甲烷对葡萄酒进行萃取,萃取液离心后,气相色谱-串联质谱法检测氨基甲酸乙酯含量,利用串...目的建立三重四极杆气质联用仪测定葡萄酒中氨基甲酸乙酯(EC)含量的方法。了解本市家庭自酿葡萄酒中氨基甲酸乙酯含量及影响因素。方法实验采用二氯甲烷对葡萄酒进行萃取,萃取液离心后,气相色谱-串联质谱法检测氨基甲酸乙酯含量,利用串联质谱的M R M方式有效降低基质干扰。结果该检测方法线性相关系数达到0.9991,峰面积的相对标准偏差为4.00%,加标回收率>85%,该方法检出限在0.6 μg/L以下。酒精度不同的各组样品氨基甲酸乙酯含量差异无统计学意义(P>0.05),保存时间(从酿造好到送检时间)不同的各组样品氨基甲酸乙酯含量差异有统计学意义(P<0.05)。结论该检测方法完全满足对红葡萄酒中氨基甲酸乙酯的日常监测。实验分析数据表明自酿葡萄酒保存时间越久其氨基甲酸酯含量越高,建议少饮用或者不饮用保存年份久的自酿葡萄酒。展开更多
从传统米酒曲中筛选到1株具有潜在应用价值的产香真菌ZT018,经形态学和18S r RNA鉴定为印度毛霉(Mucor indicus)。协同米根霉发酵米酒(记为MIX)时,ZT018能够迅速成为MIX中的优势菌,其形态也随发酵进行逐渐由菌丝态转向更利于各种香气成...从传统米酒曲中筛选到1株具有潜在应用价值的产香真菌ZT018,经形态学和18S r RNA鉴定为印度毛霉(Mucor indicus)。协同米根霉发酵米酒(记为MIX)时,ZT018能够迅速成为MIX中的优势菌,其形态也随发酵进行逐渐由菌丝态转向更利于各种香气成分生成的酵母态。顶空固相微萃取和气相色谱-质谱联用法对MIX的检测揭示:在整个发酵过程中,米酒主体香气中的乙酸苯乙酯、棕榈酸乙酯、异戊醇和2-苯乙醇在MIX中的含量均比纯种米根霉发酵米酒(记为SIM)有显著提高;另外,MIX中还发现了异丁醇、丙酸和柠檬烯等能够改善酒体香气融合和协调的其他香气成分。感官分析表明:印度毛霉ZT018协同米根霉发酵5~7 d的米酒品质最佳。此时,MIX中乙酸苯乙酯、棕榈酸乙酯、异戊醇和2-苯乙醇的含量分别为5.270~5.750、2.270~4.877、4.375~8.419、39.983~63.046 mg/L,较SIM分别提高了30.03%~38.06%、46.83%~15.68%、28.45%~23.81%和55.60%~22.91%。综合比较理化指标和感官分析结果,印度毛霉ZT018协同米根霉发酵的米酒品质更优,对提高米酒的香气质量有重要意义。展开更多
文摘Monomeric anthocyanins exhibit color variations at different pH, but they are highly unstable at physiological pH. To improve the stability, the effects of polyvinylalcohol on the anthocyanins of young red wine prepared from Cambell Early grapes were examined in aqueous solution and in the solid phase on a cotton swab? and inert materials. Cyanidin-3-glucoside and mal-vidin-3-glucoside represented approximately 43.6% of total anthocyanins in the red wine. The anthocyanins decreased to 11.3% of the initial amount in aqueous solution at physiological pH after storage for 60 days at room temperature. On the other hand, from 66.9% to 87.2% remained in the solid phase on a cotton swab? and polypropylene membrane in the presence of polyvinylalcohol. The stability of the anthocyanins increased with the concentration of polyvinyl-alcohol in the solid phase but not in the aqueous solution. The anthocyanins were found to be condensed and immobilized in the complexes of anthocyanins and polyvinylalcohol on the poly-propylene membrane by phase-contrast microscopy analysis. The anthocyanins in the cotton swab? displayed color variations when dipped into different pH buffer solutions. These results suggest that anthocyanins from red wine stabilized in the solid phase by polyvinylalcohol can be used as a visual indicator of pH.
基金supported by the fund of the Beijing Laboratory for Food Quality and Safety,Beijing Technology and Business University,China(No.FQS-201810)Science and Technology Commission of Shanghai Municipality,China(No.19DZ2284200).
文摘An analytical method using gas chromatography isotope ratio mass spectrometry(GC-IRMS)combined with solid phase micro-extraction(SPME)was developed to measure the 613C values of six typical volatiles commonly occurring in wine(isoamyl acetate,2-octanone,limonene,2-phenylethanol,ethyl octanoate and ethyl decanoate)for the first time.SPME selected with a divinylbenzene/carboxen/polydimethylsiloxane fiber was combined with the GC-IRMS for pretreatment optimization.The optimized SPME parameters of extraction time,extraction temperature and salt concentration were 40 min,40℃ and 10%,respectively.The 613C values measured by SPME-GC-IRMS were in good agreement with those measured via elemental analyzer(EA)-IRMS and GC-IRMS.The differences range from 0.02‰to 0.44‰ with EA-IRMS and from 0 to 0.28‰ with GC-IRMS,indicating the high accuracy of the method.This newly established method measured the precision within 0.30‰ and was successfully validated to discriminate imported real wine samples with identical label but amazing price differences from different importers.
文摘目的建立三重四极杆气质联用仪测定葡萄酒中氨基甲酸乙酯(EC)含量的方法。了解本市家庭自酿葡萄酒中氨基甲酸乙酯含量及影响因素。方法实验采用二氯甲烷对葡萄酒进行萃取,萃取液离心后,气相色谱-串联质谱法检测氨基甲酸乙酯含量,利用串联质谱的M R M方式有效降低基质干扰。结果该检测方法线性相关系数达到0.9991,峰面积的相对标准偏差为4.00%,加标回收率>85%,该方法检出限在0.6 μg/L以下。酒精度不同的各组样品氨基甲酸乙酯含量差异无统计学意义(P>0.05),保存时间(从酿造好到送检时间)不同的各组样品氨基甲酸乙酯含量差异有统计学意义(P<0.05)。结论该检测方法完全满足对红葡萄酒中氨基甲酸乙酯的日常监测。实验分析数据表明自酿葡萄酒保存时间越久其氨基甲酸酯含量越高,建议少饮用或者不饮用保存年份久的自酿葡萄酒。
