基于近红外光谱技术的柑橘罐头品质测定方法的研究

为了快速检测柑橘罐头主要营养指标的含量,实验对柑橘罐头进行光谱采集,通过偏最小二乘(PLS)线性拟合建立关于柑橘罐头总糖、总酸、黄酮和维生素C的近红外定量分析模型。通过分析比较不同的光谱预处理方法对近红外光谱模型的影响,其中经归一化预处理后建立的总糖和黄酮模型最优,相关系数分别为0.9156和0.9147,交互验证均方根误差(RMSECV)为0.6305%和2.7028 mg/100 g;平滑预处理后总酸的相关系数为0.8921,RMSECV为0.0539%;以原始光谱数据建立的维生素C模型的相关系数为0.9129,RMSECV为1.4323 mg/100 g;预测集总糖、总酸、黄酮和维生素C的相关系数分别为0.8519、0.8106、0.8334和0.8425,预测均方根误差(RMSEP)为0.8969%、0.0638%、3.6055 mg/100 g和1.9732 mg/100 g。实验结果表明:应用近红外光谱技术测定柑橘罐头中总糖、总酸、黄酮和维生素C的含量是可行的。      

RAG1 and RAG2: nuclear genes involved in the dependence/independence on mitochondrial respiratory function for growth on sugars

The analysis of five independent isolates of Kluyveromyces lactis shows that CBS 2359, CBS 683 and CBS 4574 could grow in the presence of mitochondrial inhibitors (antimycin A, oligomycin or erythromycin) and that CBS 2360 and CBS 141 were unable to grow in the presence of drugs. The resistant growth was observed only on glucose and not on other fermentable carbon sources (galactose, lactose). The phenotype 'growth on glucose in the presence of mitochondrial inhibitors' was called Rag+. This phenotype was found to be controlled by two unlinked nuclear genes: RAG1 and RAG2. Either of their recessive alleles, rag1 and rag2, led to the Rag- phenotype (i.e. the failure of growth on glucose in the presence of antimitochondrial drugs). Rag- strains represent the case in which fermentative growth becomes absolutely dependent on the functioning of the normal respiratory chain.     

2021年上半年我国食糖市场形势分析与后市展望

目的：探究食糖与L-阿拉伯糖复配后对C57BL/6N小鼠血糖的影响,为开发低血糖生成指数食物提供理论参考。方法：通过灌胃方式给予小鼠复配糖糖水,并以葡萄糖为参考食物,以二甲双胍为阳性对照品分别灌胃,在给糖（药）后的0、15、30、60、120 min时测量小鼠血糖值,通过曲线下面积增幅（Increamental area under the curve,IAUC）、血糖峰值、血糖生成指数（Glycemic index,GI）等指标评价复配糖对小鼠血糖的影响。结果：与葡萄糖组相比,白砂糖或红糖与L-阿拉伯糖复配后均可显著降低IAUC值（P<0.05）、血糖峰值（P<0.05）,在相同可利用碳水化合物的水平下,由于红糖中脂肪、蛋白质、水分、灰分、钾、镁、锌、铬、磷、碘以及总多酚、总黄酮等含量均显著高于白砂糖（P<0.05）,白砂糖复配糖在C57BL/6N小鼠中的GI值为52,红糖复配糖在C57BL/6N小鼠中的GI值为42。结论：L-阿拉伯糖与白砂糖或红糖复配后均可有效控制小鼠血糖升高、减缓血糖波动。小鼠血糖变化规律与人类非常接近,推测白砂糖复配糖和红糖复配糖具有成为低GI食品的潜力。红糖中富含的铬、锌、镁、磷、碘和多酚、黄酮类物质可能起到辅助降血糖的作用。     

干海参外源性总糖的测定方法

建立市场中掺糖干海参(糖干海参)的检测方法。对提取出的外源性总糖进行测定,从而判定干海参在加工过程中是否添加了糖类物质。比较提取溶剂、乙醇体积分数、提取温度、提取时间和料液比对提取条件的影响。最终确定最佳的干海参总糖提取条件为:称取1g样品,加入50mL 80%的乙醇溶液,40℃水浴振荡提取1h。利用苯酚-硫酸法进行测定。该外源性总糖的检测方法线性范围为0～80mg/L;测试液在1h以内稳定性良好;方法精密度满足实验需求,相对标准偏差在2%以内;以淡干和盐干海参为本底,样品加标回收率在82.97%～98.68%之间,相对标准偏差为1.38%～3.45%。本方法操作简单、快速、稳定性好且准确度高,可保留参体结构性多糖。应用于市售样品进行测定,可以有效甄别出掺糖干海参。     

废弃白酒糟酸水解工艺的优化

以废弃白酒糟为研究对象,利用正交实验考察了混和酸浓度、时间和温度对酒糟酸水解效果的影响,以木糖浓度和还原糖浓度为评价指标优化工艺条件,并探索最佳的超声波预处理条件。结果表明,在常温条件下,以500W功率、超声波预处理酒糟10min时酸水解效果更佳。最优的酸水解条件为混合酸浓度为2.5%、水解时间为2.5h,温度为120℃。该条件下,木糖浓度和还原糖浓度达到651.62μg/mL和11.85mg/mL。      

植物甾醇酯功能及开发前景展望

该文概述植物甾醇酯的性质、重要生理功能、安全性及其在食品、医药、化妆品等领域应用,并展望其开发前景。     

POLYCYCLIC AROMATIC HYDROCARBONS IN PRODUCTS OF A BEET SUGAR FACTORY IN VOJVODINA: LEVELS AND INTAKES

The levels of 16 EPA polycyclic aromatic hydrocarbons (PAHs) were investigated in samples of sugar beets and their products representative for a beet sugar factory located in the central part of Vojvodina, the main agricultural region in Serbia. The sum of the detected PAHs ranged from 51 pg g ^?1 ww for molasses to 391 pg g ^?1 ww for dried sugar beet pulp. The concentration of benzo(a)pyrene (BaP) for all sample types was about or less than 100 pg g ^?1 ww, which is far less than the existing Serbian and EU tolerances set for some foodstuffs. The Serbian intake of BaP via total sugar consumption that ranged from 70–85 g per capita day ^?1 , was assessed to be from 0.029 to 0.035 ng kg ^?1 b.w. day ^?1 . Furthermore, the toxic equivalency factor (TEF) approach was used to estimate the carcinogenicity of PAH mixture found in analyzed samples.     

新型蔗糖基聚羧酸高效减水剂的合成与性能

以自制甲基丙烯酸蔗糖酯（MASE）、丙烯酸（AA）、甲基丙烯酸（MAA）、烯丙基磺酸钠和烯丙基聚乙二醇（A PEG ）为原料,以过硫酸钾为引发剂,自由基共聚法合成蔗糖基聚羧酸高效减水剂。研究了反应时间、蔗糖酯含量及引发剂用量对蔗糖基聚羧酸高效减水剂性能的影响。并通过流动度测试、红外光谱表征及黏度对减水剂的结构与性能进行了分析与比较。各组分物质的量nAA ：nMAA ：nSAS ：nAPEG ：nMASE ＝3∶1∶2∶1∶0．2,MASE含量为4．9wt．％,引发剂为单体用量1．9wt．％,反应时间为5h时合成的减水剂性能最好。在水灰比为0．29,折固掺量为0．3w t ．％,水泥净浆流动度达到340mm。