担子菌中牛磺酸的检测

利用基于离子交换色谱原理氨基酸自动分析仪检测了一些常见食用菌中牛磺酸的含量。牛磺酸在磷酸丝氨酸及磷酸乙醇胺洗脱液中经色谱分析可得到清晰的对称峰。灵芝的牛磺酸含量为每100g干重含3.7～83umol。火菇在所检蘑菇中牛磺酸含量高,每100g湿重含（83.2±6.6)umol,与陆生植物相近。双孢蘑菇与香菇的牛磺酸含量相对较高,每100g湿重含量约49～55umol,牡蛎蘑菇及糙皮侧耳的鲜重含量分别为（8.9±0.712)umol、（3.7±0.3)umol,木耳及甘露地衣的干重含量分别为（19.5±2.1)umol、（9.3±1.5)umol。高牛磺酸、无胆固醇的蘑菇有望作为低胆甾醇类食物的替代品。     

便携式XRF仪现场快速测定土壤中Pb的可行性研究

便携式XRF分析仪具有轻便、快速和可测对象较多与测量元素较广等特点而广泛应用于矿石、土壤等方面快速检测,但土壤的现场快速测定结果的准确性有待进一步研究与探讨。以安宁河谷平原土壤中Pb为研究对象,通过对便携式XRF仪现场快速检测结果与实验室分析结果的对比和影响因素的分析,建立基于安宁河谷平原表层土壤快速测定结果的线性函数为y=1.170 9x-17.326 0(R~2=0.992 9,x为现场检测结果),探讨其影响因素,为该区域表层土壤中Pb快速检测结果提供依据。     

蜜饯果脯类食品中二氧化硫测定方法研究分析

[目的]建立一种适合实验室简便快速地测定蜜饯中二氧化硫的方法。[方法]利用全自动蛋白测定仪中蒸馏装置与全玻璃蒸馏的原理相同,分别用2种蒸馏方法对50批蜜饯样品的二氧化硫进行测定,测定结果采用t检验分析。[结果]分析表明,全自动蛋白测定仪蒸馏法与GB/T 5009.34第二法全玻璃蒸馏法测定蜜饯果脯类食品中二氧化硫的结果无显著差异。[结论]利用全自动蛋白测定仪蒸馏法测定二氧化硫,方法简便省时,结果准确可靠,适合蜜饯果脯类食品中二氧化硫的测定。     

脂肪自动测定仪法与国标法测定油菜籽含油量的比较研究

目的：比较脂肪自动测定仪法与国标的传统索氏抽提法检测油菜籽含油量的准确性与稳定性有无差异,以达到简化操作、节省时间的目的。方法：首先研究脂肪自动测定仪法测定油菜籽含油量的合适检测条件;选取10份样品分别用脂肪自动测定仪与国标法进行检测。结论：脂肪自动测定仪法检测油菜籽含油量结果和国标传统索氏抽提法无差异,与国标法相比,大大缩短工作时间,提高工作效率,值得进一步推广。     

Combined mutations in five wheat STARCH BRANCHING ENZYME II genes improve resistant starch but affect grain yield and bread-making quality

Increases in the proportion of amylose in the starch of wheat grains result in higher levels of resistant starch, a fermentable dietary fiber associated with human health benefits. The objective of this study was to assess the effect of combined mutations in five STARCH BRANCHING ENZYME II (SBEII) genes on starch composition, grain yield and bread-making quality in two hexaploid wheat varieties. Significantly higher amylose (∼60%) and resistant starch content (10-fold) was detected in the SBEII mutants than in the wild-type controls. Mutant lines showed a significant decrease in total starch (6%), kernel weight (3%) and total grain yield (6%). Effects of the mutations in bread-making quality included increases in grain hardness, starch damage, water absorption and flour protein content; and reductions in flour extraction, farinograph development and stability times, starch viscosity, and loaf volume. Several traits showed significant interactions between genotypes, varieties, and environments, suggesting that some of the negative impacts of the combined SBEII mutations can be ameliorated by adequate selection of genetic background and growing location. The deployment of wheat varieties with increased resistant starch will likely require economic incentives to compensate growers and millers for the significant reductions detected in grain and flour yields.     

正交设计法研究花生粗脂肪含量测定方法

以石油醚为浸提剂,选择浸提温度、浸提时间和淋洗时间3个因素,根据L9(34)正交设计表,用FOSS2050型脂肪测定仪对索氏提取法测定花生粗脂肪含量进行了研究。结果表明,淋洗时间对花生粗脂肪含量测定结果影响最大,其次是浸提时间;花生粗脂肪含量测定的最佳提取方案为浸提温度120℃、浸提时间80 min、淋洗时间30 min。     

Turbiscan Lab分散稳定性分析仪研究异丙甲草胺水乳剂物理稳定性

为获得不同因素对异丙甲草胺水乳剂物理稳定性的影响规律,同时验证Turbiscan Lab分散稳定性分析仪预测和评价水乳剂物理稳定性的可行性,利用Turbiscan Lab分散稳定性分析仪,结合加速试验[(54±2)℃,14d]结果,研究了乳化剂用量、体系pH和电解质离子等对磷酸酯盐稳定的异丙甲草胺水乳剂物理稳定性的影响。结果表明:乳化剂三苯乙烯基苯酚聚氧乙烯醚磷酸酯三乙醇胺盐(SCP)用量为6.0%(质量分数)时,水乳剂稳定性最好;过酸或过碱均会破坏水乳剂的稳定性,pH=9时水乳剂可获得较好的稳定性;Mg2+压缩油水界面双电层,导致水乳剂稳定性下降,且Mg2+添加浓度越大,水乳剂越不稳定。Turbiscan Lab分散稳定性分析仪以多重光散射为技术核心,在不破坏样品的前提下,能够准确测定乳状液中浮油、沉淀和液滴粒径大小的变化情况,与加速试验结果吻合度高,不仅能够缩短试验周期,而且可以分析不稳定现象发生的机理。     

Metabolite profiling of the response to high-nitrogen fertilizer during grain development of bread wheat (Triticum aestivum L.)

Wheat yield and quality are dependent largely on nitrogen (N) availability. In this study, we performed the first metabolomic analysis of the response to high-N fertilizer during wheat grain development using non-targeted gas chromatography-mass spectrometry (GC–MS). Quality parameter analyses demonstrated that high-N fertilizer application led to a significant increase in grain protein content and improvement in starch and bread-making quality. Comparative metabolomic profiling of six grain developmental stages resulted in identification of 74 metabolites, including amino acids, carbohydrates, organic acids and lipids/alcohol, which are primarily involved in carbon and N metabolism. Under high-N fertilizer treatment, numerous metabolites accumulated significantly during grain development. Principal component analysis revealed two principal components as being responsible for the variances resulting from N-fertilizer treatments. Metabolite–metabolite correlation analysis demonstrated that the high-N treatment group had a greater number of positive correlations among metabolites, suggesting that high-N fertilizer treatment induced a concerted metabolic change that resulted in improved grain development. Particularly, the high-N treatment-mediated significant accumulation of metabolites involved in the TCA cycle, starch and storage protein synthesis could be responsible for the improvement of grain yield and quality. Our results provide new insight into the molecular mechanisms of wheat grain development and yield and quality.     

玉米粉水解过程中还原糖的测定

为了测定玉米粉水解过程中还原糖的含量,将玉米粉在水浴中进行酸水解,加入的玉米粉、蒸馏水和稀硫酸的比例是1∶100∶15,温度保持在100℃。在水解的过程中,采用还原糖测定仪法和DNS法(3,5-二硝基水杨酸法)测定水解过程中的还原糖量,每1 h测定1次,从而准确地了解玉米粉的水解程度。结果表明:2种方法都比较适宜测定还原糖含量,但还原糖测定仪法更具优势,其稳定性好,重现性好,测定速度快,准确度高。