川渝火锅用牛油关键风味物质的鉴定Identification of key flavour substances of beef tallow used in Sichuan-Chongqing hotpot

旨在为不同风味需求火锅底料的研究提供参考依据，通过消费者偏好分析和挥发性风味成分的含量与种类从6种牛油（3种市售牛油、未精炼牛油、脱胶牛油、精炼牛油）中筛选出最受消费者喜爱的牛油，并采用顶空固相微萃取结合气相色谱-质谱联用技术、香味提取物稀释分析法、气味活度值法、风味重组和风味缺失实验对其风味物质进行鉴定。结果表明：精炼牛油的消费者偏好平均得分最高且挥发性物质组成最丰富，其含有23种风味物质，包括醛类10种、酸类5种、杂环类4种、醇类3种和酮类1种；根据牛油风味物质的气味活度值，确定牛油的7种关键风味物质为（E,E）-2,4-壬二烯醛、（E）-2-辛烯醛、乙酸、2-戊基吡啶、辛醛、1-辛烯-3-醇和2-戊基呋喃，通过风味重组和风味缺失实验得出（E,E）-2,4-壬二烯醛、（E）-2-辛烯醛、乙酸和辛醛对牛油风味的贡献最大，2-戊基吡啶、1-辛烯-3-醇和2-戊基呋喃对牛油风味的贡献次之。综上，确认了牛油中7种关键风味物质，可为牛油产品风味的合理开发提供参考。In order to establish a foundation for researching the diverse flavour requirements of substances in hotpot bases, six types of beef tallow(three types of commercially available beef tallow, unrefined beef tallow, degummed beef tallow, and refined beef tallow) were used as materials, the most popular beef tallow was selected based on customer preference analysis and the content and type of volatile flavour components, and the flavour substances of the most popular beef tallow were identified using headspace solid-phase microextraction-gas chromatography - mass spectrometry, dilution analysis of flavour extracts, odour activity values, flavour reconstitution and flavour deletion experiments. The results indicated that refined beef tallow received the highest average score in the consumer preference analysis and had the most substantial chemical composition with 23 volatile substances including 10 kinds aldehydes, 5 kinds acids, 4 kinds heterocyclic, 3 kinds alcohols and 1 kind ketone compounds. Based on the odour activity values of beef tallow flavour substances, 7 kinds key flavour substances of beef tallow were identified as (E,E)-2,4-nonadienal, (E)-2-octenal, acetic acid, 2-pentylpyridine, octanal, 1-octen-3-ol and 2-pentylfuran. Flavour reconstitution and deletion experiments showed that (E,E)-2,4-nonadienal, (E)-2-octenal, acetic acid and octanal contributed the most to beef tallow flavour, followed by 2-pentylpyridine, 1-octen-3-ol and 2-pentylfuran. In conclusion, the 7 kinds key flavour substances are determined in the beef tallow, which can provide a reference for the rational development of beef tallow product flavours

基于古地磁与~(230)Th定年的西沙西科1井乐东组生物礁沉积年代的初步研究

生物礁是重要的自然资源,在全球气候变化与碳循环中扮演了重要角色.磁性地层学是建立年代框架的有效手段,但是,由于生物礁沉积物中天然剩磁强度弱,南海地区生物礁的磁性地层学研究尚未很好展开.为此,本文利用西沙群岛西科1井乐东组生物礁沉积样品进行了详细的岩石磁学和磁性地层学研究.结果显示,西沙群岛乐东组记录了布容正极性时、奥杜维尔正极性时和松山负极性时.通过对比已有的钻孔资料,本文认为应基于岩石地层特征这一标准将西沙地区的乐东组埋深予以统一.在此基础上,综合磁性地层与~(230)Th定年结果,本文将乐东组的底界限定在~2.0 Ma.</p