转Bt基因水稻的食用安全性评价研究进展

水稻（Oryza sativa）是我国重要的经济作物,其优化育种一直是研究的重点。苏云金芽孢杆菌（Bacillusthuringiensis,Bt）抗虫基因的出现,开辟了利用外源基因培育转基因抗虫作物的新领域。目前,转基因抗虫水稻的培育技术已日趋成熟,而其对人体的潜在安全性问题却备受争议。转Bt基因水稻能否实现商业化是人们关注的焦点。本文就转Bt基因水稻的食用安全性评价的研究进展进行综述,以期为我国转Bt基因水稻的风险评估和推广提供一些参考。     

抗凝冻酸奶的研制

为了改变酸奶货架期短,不易长期保藏,而影响酸奶的销售和发展的现状,采用不同工艺和添加食品抗凝冻剂,降低酸奶的冰点,加工出可以在0℃以下保藏的抗凝冻酸奶,而且不会影响风味、酸度和质地。试验结果表明,抗凝冻酸奶的最佳条件为:加糖量6%,接种量3.0%,发酵时间4.5h,复合抗冻剂加入量0.6%。     

木霉菌株利用作物秸秆产油脂研究进展

木霉能分泌产生纤维素酶、木聚糖酶和木质素酶,并能产生和积累微生物油脂,因此利用木霉能够分解木质纤维素类的作物秸秆,并利用分解木质纤维素产生的单糖、合成和积累油脂.该文介绍了微生物分解秸秆产油的意义,综述了木霉菌作为发酵秸秆产生微生物油脂的研究对象优势和利用木霉生产微生物油脂的研究现状及进展.     

利用LC-MS对保健酒中七种成分的定性分析研究

分别对神酒、健身酒、海马酒这3种保健酒中是否含有红景天苷、鲁斯可皂苷元、人参皂苷Rb1、腺苷、紫丁香苷、羟基红花黄色素和山奈素这7种成分进行定性研究。用LCMS-8050分别对3种保健酒和7种成分标准品进行分析,并对所得结果进行了比较总结。结果表明,3种保健酒中均检测出红景天苷、人参皂苷Rb1、腺苷和紫丁香苷;3种保健酒中均未检测出鲁斯可皂苷元和山奈素;健身酒和神酒中检测出羟基红花黄色素。     

采用催化自溶和生物破壁技术提取啤酒酵母细胞壁多糖

以废弃啤酒酵母为原料采用催化自溶与生物破壁技术生产细胞壁多糖。经过单因素试验后确定了酵母自溶的适宜条件:50～60℃,pH 5.0～6.0,食盐浓度0.8%,VB2浓度200 mg/L,料液比(g∶mL)1∶8～10,剪切微化处理约9 h以上。此外,确定了采用60℃下,1∶10的料液比,0.02%～0.03%的蛋白酶添加量和2%的NaOH浓度为细胞壁多糖的适宜提取条件。此方法得到的细胞壁多糖中甘露聚糖的含量>22%,葡聚糖的含量>35%。同时发现使用酪蛋白钠和改性淀粉作为酵母提取物的微胶囊化材料时,产品喷雾效果好,且不吸潮。     

干酪乳杆菌添加量对发酵牛肉串品质特性的影响

研究干酪乳杆菌的添加量对发酵牛肉串理化性质和感官特性的影响。将不同添加量的干酪乳杆菌分别与木糖葡萄球菌复配添加到牛肉中生产发酵牛肉串,测定发酵牛肉串在成熟过程中的pH值、水分活度(aw)、颜色、质构及感官指标的变化。添加干酪乳杆菌显著改善发酵牛肉串的品质,并且延长了货架期。菌种添加量107CFU/g和108CFU/g时牛肉串在发酵过程中气味、滋味、颜色、嫩度、黏聚性和咀嚼性差异不显著,而菌种添加量108CFU/g时发酵牛肉串总体可接受性较差,酸味较重。因此,确定发酵牛肉串中干酪乳杆菌的添加量为107CFU/g,发酵终点时牛肉串获得了较好的质量。     

Effect of concentration,pH and ionic strength on the kinetic self-assembly of acid-soluble collagen from walleye pollock (Theragra chalcogramma) skin

The effects of concentration, pH value and ionic strength on the kinetic self-assembly of acid-soluble collagen from walleye pollock (Theragra chalcogramma) skin were investigated. A two-phase kinetic process was provided which included the formation of nucleus center and nucleus growth, the first phase being the controlled step for collagen self-assembly. Collagen showed marked assembly behavior when concentration reaching and above 0.6 mg/mL, and higher concentration could accelerate collagen self-assembly. Rate constants of the first and second assembly phase both increased with pH to a maximum around pH 7.2 and then decreased, indicating that pH 7.2 was the optimum pH value for collagen self-assembly. The kinetics of collagen self-assembly could be modulated by NaCl concentration. The concentration of NaCl from 30 to 60 mM was more suitable to self-assemble for pollock skin collagen.     

Determination of the Nicotine Content in Solanaceae Vegetables by Solid-Phase Extraction Coupled with Ultra High-Performance Liquid Chromatography–Tandem Mass Spectrometry

A validated method based on solid-phase extraction and ultra high-performance liquid chromatography–triple quadrupole tandem mass spectrometry, with electrospray ionization operated in the positive ion mode and multiple reaction monitoring, was developed for the determination of nicotine in Solanaceae vegetables. Sample preparation involved liquid–solid extraction, centrifugation, filtration, and solid-phase extraction. Two kinds of solid-phase extraction adsorbents, based on different retention mechanisms, were investigated. Relatively higher recoveries were obtained with a hydrophilic–lipophilic-balanced cartridge. A deuterated internal standard was used for quantification. The limit of quantification (LOQ) of nicotine in different vegetables was found to be between 0.07 and 0.5 μg/kg. The nicotine levels in the vegetable samples were above the LOQs. The method described here is thus suitable for the analysis of large sample batches, because it provides accurate quantification, high sensitivity and rapid chromatographic separation with facile preparation. The solid-phase extraction cartridges and organic solvents used in this work are easy to obtain, enabling the application of this method in most analytical laboratories.     

榛蘑与菌丝体中蜜环菌素的超声波辅助提取条件优化及其提取物中化合物分析

目的:为分析榛蘑与菌丝体中化合物差异,本研究以东北野生榛蘑子实体和液态菌丝体为研究对象,探究蜜环菌素的最佳提取工艺条件,并对提取物中化合物进行分析。方法:以提取物得率和蜜环菌素含量为指标,采用超声波细胞破碎辅助石油醚进行萃取,通过单因素实验和正交试验对提取工艺参数进行优化;采用超高效液相色谱-串联质谱（UHPLC-MS/MS）技术,对液态菌丝体和榛蘑子实体中化合物进行分析和鉴定。结果:确定最佳提取工艺条件为料液比1:20 g/mL,超声波功率300 W,超声时间20 min,溶剂回流时间50 min,在该条件下液态菌丝体提取物得率为26.8%,蜜环菌素含量为0.74 mg/g;液态菌丝体和榛蘑子实体中化合物分别为305和592个。解析出16种蜜环菌素类和5种疑似蜜环菌素碎片物质,其中菌丝体中含有15种蜜环菌素和3种碎片,总含量分别为2.551和0.588 μg/mL;子实体中含有7种蜜环菌素和4种碎片,总含量分别为2.413和2.124 μg/mL。两者同有组分有6种蜜环菌素和2种碎片;液态菌丝体独有9种蜜环菌素和1种碎片为:10-dehydroxymelleoloede、蜜环菌辛素、Arnamiol、蜜环菌壬素、A52a、4-dehydroxyarmillarin、蜜环菌丙素、（4R,5S,7R,9S,13R）-2’,5-epoxy-4-dehydroxyarmillarin、4’-demethoxyarmillaribin以及碎片C;榛蘑子实体独有1种蜜环菌素和2种碎片为:Melledonal以及碎片D和E。结论:液态菌丝体蜜环菌素类化合物多于子实体中,为开发辅助功能食品及药物提供参考。