不同温度胁迫条件下太平洋牡蛎挥发性化合物的变化

为探究温度胁迫后太平洋牡蛎挥发性成分的变化,该研究采用感官评定、气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Spectroscopy,GC-IMS）、气相色谱-质谱联用（Gas Chromatography-Mass Spectrometer,GC-MS）结合多元统计分析的方法,对不同温度胁迫条件（12、22、32℃）的太平洋牡蛎挥发性成分进行了检测,同时测定了其存活率以及脂肪酸含量的变化。结果显示,胁迫6 d后,低温12℃组的存活率达到97.90%,n-3型多不饱和脂肪酸（Polyunsaturated Fatty Acid,PUFA）含量升高。感官评定、GC-IMS以及GC-MS结果显示辛醛等鱼腥味醛类成分含量下降,而呈紫罗兰气味的(E,Z)-2,6-壬二烯醛升至12.15%,提供了愉悦的气味。高温32℃胁迫后存活率降至26.00%,n-3 PUFA含量下降从46.07%下降至39.59%,同时饱和醛等腥味醛类含量显著上升,加重了太平洋牡蛎的腥味,导致牡蛎的品质严重下降。最后通过统计分析筛选6种关键成分：己醛、辛醛、(E,Z)-2,6-壬二...     

北部湾海区几种常见牡蛎基础营养及脂肪酸成分比较分析

目的 比较分析北部湾海区常见的熊本牡蛎、香港牡蛎和近江牡蛎鲜品的基础营养成分及脂肪酸组成.方法 以北部湾海区熊本牡蛎、香港牡蛎和近江牡蛎为实验样品,测定其水分、粗蛋白、粗脂肪和灰分的含量,并用气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)测定脂肪酸组成及含量...     

高沙岭潮间带大型底栖动物调查分析

分析了2004年4月天津塘沽高沙岭潮间带大型底栖动物的情况.共采集到现存大型底栖动物16种,生物量(湿重)为119.24 g/m2,生物密度为190.00个/m2.定量样品中的生物可以分为4大类,软体动物占主要地位,占总生物量的68.89%.相关分析表明,此潮间带的生物量较低,次级生产力的估算值为14.80 g/m2(去灰干重);主要营养级间的生产力比值明显小于林德曼效率,因而生态结构存在不稳定的环节.     

超声提取牡蛎中氨基酸的工艺条件研究

应用超声技术并通过单因素及正交试验来研究牡蛎中的氨基酸提取过程中的工艺条件及优化。单因素实验结果表明,料剂比对氨基酸收率影响较显著,正交试验获得超声提取牡蛎中氨基酸的最佳工艺条件为物料比为2∶15、水浴温度70℃、70W的超声功率处理10min。     

反式脂肪酸危害与控制

通过对食品中反式脂肪酸含量强制标示,向广大消费者指出反式脂肪酸对人体健康危害;同时对油脂加工业而言,这也意味着一场旨在减少食品中反式脂肪酸变革开始。     

蚝粉在蚝油生产上的应用

本文就蚝油中添加蚝粉和蚝油香精进行了实验和比较。结果表明，添加蚝粉的蚝油香气明显优于添加蚝油香的蚝油香气。     

花生四烯酸分离纯化方法研究进展

花生四烯酸是人体必需不饱和脂肪酸,具有极高保健价值。该文介绍并比较花生四烯酸分离纯化方法,主要包括低温溶剂结晶法,脲包法,银离子络合法,超临界萃取法,高效液相色谱法等方法。     

天津潮间带大型底栖动物特征

2006年10月4日-10月7日对天津蛏头沽、驴驹河以及高沙岭潮间带进行了大型底栖动物调查。调查结果表明,该区共有5大类底栖动物30种,其中软体动物最多,平均栖息密度为264 ind./m2,平均生物量为114.84 g/m2,蛏头沽潮间带的栖息密度和生物量是三个区域中最低的。北塘河口至蛏头沽潮间带香农-威纳多样性指数平均值为0.28,属于重污染区;临港工业区至独流碱河潮间带香农-威纳多样性指数平均值为1.67,属于中度污染区,并且历史上存在的毛蚶、缢蛏等经济贝类已很少见到。此次调查发现大量泥螺。     

Milk fatty acids as possible biomarkers to early diagnose elevated concentrations of blood plasma nonesterified fatty acids in dairy cows

Most cows encounter a state of negative energy balance during the periparturient period, which may lead to metabolic disorders and impaired fertility. The aim of this study was to assess the potential of milk fatty acids as diagnostic tools of detrimental levels of blood plasma nonesterified fatty acids (NEFA), defined as NEFA concentrations beyond 0.6 mmol/L, in a data set of 92 early lactating cows fed a glucogenic or lipogenic diet and subjected to 0-, 30-, or 60-d dry period before parturition. Milk was collected in wk 2, 3, 4, and 8 (n = 368) and blood was sampled weekly from wk 2 to 8 after parturition. Milk was analyzed for milk fatty acids and blood plasma for NEFA. Data were classified as “at risk of detrimental blood plasma NEFA” (NEFA ≥0.6 mmol/L) and “not at risk of detrimental blood plasma NEFA” (NEFA <0.6 mmol/L). Concentrations of 45 milk fatty acids and milk fat C18:1 cis-9-to-C15:0 ratio were subjected to a discriminant analysis. Milk fat C18:1 cis-9 revealed the most discriminating variable to identify detrimental blood plasma NEFA. A false positive rate of 10% allowed us to diagnose 46% of the detrimental blood plasma NEFA cases based on a milk fat C18:1 cis-9 concentration of at least 230 g/kg of milk fatty acids. Additionally, it was assessed whether the milk fat C18:1 cis-9 concentrations of wk 2 could be used as an early warning for detrimental blood plasma NEFA risk during the first 8 wk in lactation. Cows with at least 240 g/kg of C18:1 cis-9 in milk fat had about 50% chance to encounter blood plasma NEFA values of 0.6 mmol/L or more during the first 8 wk of lactation, with a false positive rate of 11.4%. Profit simulations were based on costs for cows suffering from detrimental blood plasma NEFA, and costs for preventive treatment based on daily dosing of propylene glycol for 3 wk. Given the relatively low incidence rate (8% of all observations), continuous monitoring of milk fatty acids during the first 8 wk of lactation to diagnose detrimental blood plasma NEFA does not seem cost effective. On the contrary, milk fat C18:1 cis-9 of the second lactation week could be an early warning of cows at risk of detrimental blood NEFA. In this case, selective treatment may be cost effective.     

膳食中的脂肪酸平衡

本文综述了膳食中三类脂肪酸（饱和脂肪酸、单不饱和脂肪酸及多不饱和脂肪酸）的营养学功能,并就有关膳食脂肪酸的平衡及n-6与n-3的合适比例作了总结。