腊牛肝加工过程中挥发性风味物质变化分析

腊牛肝在加工过程中风味经历了复杂的变化,为探究腊牛肝加工过程中挥发性风味物质的变化,采用顶空固相微萃取与气相色谱-质谱联用仪,对加工0、1、2、3、4 d腊牛肝的风味物质进行定性半定量分析,并对筛选出的风味物质进行因子分析。结果显示,在腊牛肝加工过程中共检出71种挥发性风味物质,醇类、醛类和酯类为腊牛肝的特征性风味物质。在腊牛肝加工过程中,酸类物质的相对含量呈显著减少(P 0. 05)趋势,说明腊牛肝的腥味和不愉快气味减少;酯类和醛类物质的相对含量呈显著增加(P 0. 05)趋势,说明腊牛肝的清香、油香和脂香味增加。因子分析将筛选出的风味物质分为三类,分别为脂肪氧化产物,前体物质降解产物,美拉德反应产物。     

凤凰单丛茶加工过程中挥发性香气成分和生化成分的变化

目的：优化凤凰单丛茶加工工艺。方法：采用顶空固相微萃取法（HS-SPME）、气相色谱—质谱法（GC-MS）和分光光度计法等对凤凰单丛茶加工过程中不同阶段的茶叶挥发性香气和非挥发性生化成分进行提取、测定及分析。结果：加工过程中,凤凰单丛茶的醇类、醛类、酮类和酯类物质含量呈下降趋势,烷烃类和芳香环类物质含量呈上升趋势;非挥发性生化成分中茶多酚、氨基酸、咖啡碱和儿茶素含量逐渐减少;可溶性糖含量和水浸出物含量则逐渐增加。茶叶香气中,吲哚、α-法尼烯、橙花叔醇等含量大幅增加,是凤凰单丛茶茶叶重要的挥发性香气成分。结论：加工过程中,凤凰单丛茶的苦涩味和青草气逐渐减少,花果香味气体逐渐增加,形成了凤凰单丛茶特有的花果香味和香醇口感。     

The volatile constituents of tea

This paper reviews the chemistry of the volatile constituents of black tea with special reference to their origin and the influence of climate, differences between cultivars and processing on their composition. This information is discussed with the object of assessing the way in which some of the volatile compounds affect the flavour of tea. Attention is drawn to gaps in present knowledge.     

Changes in volatile aroma compounds of organic fragrant rice during storage under different conditions

BACKGROUND: Aroma of fragrant rice greatly affects palatability as well as consumer acceptability. Loss of desirable volatile compounds such as 2‐acetyl‐1‐pyrroline (2‐AP) and increase in volatile lipid oxidation products in aged rice have been reported. The aim of this study was to monitor the changes in key volatile compounds of organic red fragrant rice cv. Hom Daeng during storage. Effects of packaging material, storage temperature and time were evaluated using solid phase microextraction/gas chromatography/mass spectrometry. RESULTS: Thirteen key volatile compounds including ten lipid oxidation products were monitored. For samples vacuum packed in Nylon/LLDPE pouches at ambient temperature, significant increases in hexanal, 2‐pentylfuran, 1‐octanol and 4‐vinyl guaiacol and significant decreases in 2‐AP and geranyl acetone were found after the second month (P?0.05). Vacuum packing in OPP/Al/LLDPE pouches or storage at 15 °C better retarded the formation of volatile lipid oxidation products and greater retained desirable odorants, including 2‐AP. However, accumulation of lipid oxidation products and 4‐vinyl guaiacol was apparent after the sixth month under these storage conditions. CONCLUSION: A greater extent and higher rate of undesirable changes in volatile compounds were found in samples stored under Nylon/LLDPE/ambient temperature condition. Nevertheless, this condition is acceptable for the retail trade of organic rice in Thailand. Storage conditions using reduced temperature or better packaging materials may be more appropriate for exported rice or superior‐grade fragrant rice to better maintain the desirable rice aroma. Copyright © 2010 Society of Chemical Industry     

不同种黑米储藏期中花色苷的测定及微观结构分析

以黑米为原料,研究常规储藏条件下不同花色苷含量的黑米,对其花色苷的鉴定及相对含量的变化测定,并对黑米储藏期间微观结构、蛋白质二级结构进行观察和分析.通过HPLC-MS/MS技术分析4种黑米花色苷单体成分组成,结果表明4种黑米花色苷均由芍药素-3-O-葡萄糖苷、矢车菊素-3-O-葡萄糖苷和锦葵色素-3-O-葡萄糖苷单体构...     

Changes in volatile compounds upon aging and drying in oolong tea production

BACKGROUND: Long‐term storage (aging) with periodic drying of fresh oolong tea gives rise to so‐called old oolong tea. Alteration of aroma compounds is expected when a fresh oolong tea is converted into an old one, as the two teas smell drastically different. The aim of this study was to compare the volatile compounds in fresh and old oolong teas. RESULTS: Significant differences were observed between the volatile compounds in fresh and old oolong teas. This observation suggested that long straight chains of alcohols and acids were putatively decomposed while shorter‐chain acids, their amide derivatives and many nitrogen‐containing compounds were generated during the tea conversion processes. The overall patterns of volatile compounds observed in five different preparations of old oolong tea were fundamentally identical. This consensus pattern was different from that observed in oolong tea either stored for more than 10 years without drying or prepared at relatively low temperatures and short baking time. CONCLUSION: Characteristic aroma nitrogen‐containing compounds, including N‐ethylsuccinimide, 2‐acetylpyrrole, 2‐formylpyrrole and 3‐pyridinol, were consistently found in the examined old oolong teas. These compounds might be regarded as typical constituents at least for a certain kind of old oolong tea. Copyright © 2010 Society of Chemical Industry     

海南特色米中营养成分及挥发性风味物质的分布特征

以海南五种特色大米为原料,将其由外到内依次碾磨成三层,测定其营养成分,同时采用气相色谱-质谱联用技术(gas chromatography-mass spectrometry,GC-MS),探究大米中风味物质分布规律。结果表明：大米中非淀粉营养组成成分主要集中在外层;挥发性成分的种类及含量随着层数的递进逐渐降低,其中2-乙酰-1-吡咯啉仅在黑色稻谷和山兰香中检出;基于气味活性值(odor activity value,OAV)发现1-辛烯-3-醇、2-戊基呋喃和2-乙酰-1-吡咯啉对米饭风味具有重要贡献;通过对其主体风味物质进行主成分分析发现,大米各层分离良好,6-甲基-5-庚酮-2-酮、2-戊基呋喃、1-辛烯-3-醇和庚醛可作为区分不同粒层风味的重要挥发性成分。     

四种黑米花色苷抗氧化活性的构效关系

锦葵素、天竺葵-3,5-二葡萄糖苷、矢车菊素-3-葡萄糖苷和矢车菊素-3,5-二葡萄糖苷具有很高的抗氧化活性,是黑米抗氧化作用的主要成分.4种分子中B-4'-OH是强活性基,B-3'-OH、A-5、7-OH是增效基,因具有增效基数目和位置不同抗氧化活性表现出了一定的差异.     

青砖茶加工过程品质成分变化研究

目的研究青砖茶加工过程中各化学品质成分含量的变化,为青砖茶风味品质形成提供理论依据。方法以青砖茶发酵前、发酵后及成品为材料,比较分析样品水分、水浸出物、游离氨基酸、咖啡碱、茶多酚、儿茶素组分、茶黄素组分、粗纤维、黄酮、可溶性糖、可溶性果胶等含量变化。结果青砖茶加工过程中,水分含量基本不变,控制在9%左右;纤维素含量呈现上升趋势,成品达到(21.29±0.78)%;水浸出物、可溶性总糖、儿茶素、茶黄素-3'-没食子酸酯、茶黄素总量呈现下降趋势;黄酮含量总体较为稳定,为1.40%~1.83%;茶黄素-3,3'-双没食子酸酯基本稳定在1 mg/g左右;咖啡碱含量发酵后显著低于发酵前;氨基酸、茶多酚、表儿茶素、表儿茶素没食子酸酯、表没食子儿茶素、表没食子儿茶素没食子酸酯、儿茶素总量、茶黄素、茶黄素-3'-没食子酸酯、水溶性果胶均呈现下降后上升,但成品含量低于发酵前原料含量的趋势。结论青砖茶加工过程中不同生化成分变化趋势存在差异,成品与原料存在较大差异,具有粗涩味作用的成分含量降低,各成分间含量更加协调,为青砖茶醇和风味品质形成奠定基础。     

Changes in volatile compounds of Parma ham during maturation

Changes in the aromatic profile of Parma ham caused by the normal course of aging up to 12 months were examined in order to identify distinctive signals for different maturing periods (6, 9, 12 months).

The 28 samples analysed, divided among the three periods mentioned above, provided an aromatic profile in which methyl esters were the most relevant signals, followed by carbonyl compounds and alcohols.

The greatest discriminating power is to be ascribed to components such as 3-methylbutanal and ethyl esters, and alcohols like 1-propanol, 1-butoxy-2-propanol and 2-butanol.

These compounds were present in higher percentages at 12 months of aging.     

泡菜发酵过程挥发性风味成分的变化

采用SPME–GC–MS对泡菜在发酵过程中不同时期的挥发性风味进行分析。结果表明:泡菜的最佳食用期为48 h,不同时期的泡菜的挥发性成分差异明显;共鉴定出化合物111种,包括醇类、烃类、含硫化合物、酯类、醛类、酮类、酸类等。泡菜在发酵期间,酸类、醇类、含硫化合物的含量不断增长;在发酵后期,烃类、醛类、酮类化合物的含量不断下降。含硫化合物和醇类对泡萝卜的风味形成有较大贡献。     

Recent studies of the volatile compounds in tea

Tea aroma is one of the most important factors affecting the character and quality of tea. Recent advances in methods and instruments for separating and identifying volatile compounds have led to intensive investigations of volatile compounds in tea. These studies have resulted in a number of insightful and useful discoveries. Here we summarize the recent investigations into tea volatile compounds: the volatile compounds in tea products; the metabolic pathways of volatile formation in tea plants and the glycosidically-bound volatile compounds in tea; and the techniques used for studying such compounds. Finally, we discuss practical applications for the improvement of aroma and flavor quality in teas.     

Study of the dynamic changes in the non-volatile chemical constituents of black tea during fermentation processing by a non-targeted metabolomics approach

Fermentation is a critical manufacturing process to produce black tea, in which the chemical compositions are greatly changed. However, the dynamic changes of this sophisticated process are far from clear, and were often characterized by determining a small number of compounds. In this study, we applied a non-targeted metabolomics approach based on ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry to comprehensively profile the variations of metabolites in tea samples with various fermentation durations of 0, 1, 2, 4, 6, 8, 10, 12 and 14 h. Principal component analysis indicated obvious stepwise alterations of tea metabolome during the fermentation. Relative quantitation of 61 identified metabolites including catechins, dimeric catechins, flavonol glycosides, amino acids, phenolic acids, alkaloids, and nucleosides revealed distinct changes of phenol pathway. Dynamic changes of a part of these compounds were mapped for the first time. To the best of our knowledge, this study offered the most comprehensive profiles of metabolite changes during the tea fermentation process.     

Effect of the withering process on volatile compound formation during black tea manufacture

The amount and composition of volatile compounds in the volatile oils were compared between non-withered tea and withered tea. Important differences in the aroma constituents were found in the amounts of E-2-hexenal, Z-3-hexanol ester, linalool and its oxides, and methylsalcylate. In withered teas, the amounts of Z-3-hexenol ester, linalool and its oxides, and methylsalcylate were much greater than in non-withered tea, but the E-2-hexenal content was higher in non-withered tea. From the results it was thought that the withering process has an important role in the formation of volatile compounds in tea shoots during black tea fermentation.     

罐罐肉加工与贮藏过程中挥发性物质变化的研究

为了探明雅安罐罐肉挥发性物质的变化规律,本研究以不同加工与贮藏阶段的罐罐肉为对象,用同时蒸馏萃取结合气相色谱/质谱法对挥发性化合物进行分析。结果显示,罐罐肉在加工与贮藏过程中共检测出120种挥发性物质,醇、醛、酮、烃、酰胺、酯是主要成分,其中以己醛和2,4-癸二烯醛为主的醛类物质相对含量最高（最高达64.42%）。在加工过程中醛、酮、酯显著增加,并检测出酰胺类物质。在贮藏过程中醇、醛、酮的相对含量整体呈现下降趋势,烃类、酰胺类、酯类和其他化合物的相对含量整体呈上升趋势,并新产生了（2E）-2-十一碳烯醛、甲酸己酯、（Z）-9-十八烯酸酰胺和2-戊基呋喃等物质。      

Changes in taste compounds of duck during processing

Nanjing cooked duck is one of the few low temperature cooked meat products in traditional Chinese featured meat products. It is famous for its delicate processing, savoury, and tender flavour. Taste compounds of Nanjing cooked duck during processing, namely free amino acids, peptides and nucleotides, were analyzed. During boiling, both free amino acids and flavour nucleotides decreased significantly. Most peptides decreased during processing and the changes of total peptides were consistent with the nucleotides. Results showed that the special processes before boiling, especially brining, produced an increased of effect on the taste compounds, which could be the reason for the savoury taste of Nanjing cooked duck.