The effects of xanthan and guar gums on staling of gluten-free rice cakes baked in different ovens

The objective of this study was to determine the effects of different concentrations of xanthan and guar gums and their blends on staling of gluten-free rice cakes baked in microwave-infrared combination oven (MW–IR) and to compare the cakes with conventionally baked ones. Gums were added at concentrations of 0.3% and 1.0%. For preparation of gum blend, 0.5% xanthan gum was mixed with 0.5% guar gum. In order to understand the staling behaviour of cakes, cakes were stored at 22 ± 2 °C for 120 h. Xanthan-guar gum blend decreased hardness, weight loss, retrogradation enthalpy and the change in setback viscosity values of cakes during storage for both types of ovens as compared to control formulation. It was found that oven type was a significant factor in affecting staling parameters of gluten-free cakes.     

草莓复合涂膜保鲜效果的研究

以草莓为实验原料,采用魔芋精粉、丁香提取物和氯化钙复合涂膜方法对草莓进行涂膜保鲜实验。选择失重率和Vc含量为指标,以单因素实验和正交实验优化保鲜膜配方,结果表明,常温下,魔芋精粉浓度0.5%、丁香提取物浓度2.0%、氯化钙浓度1.2%的复合涂膜剂对草莓的保鲜效果最好,有效地延长了保质期。该最佳配比的复合涂膜剂在低温下对草莓的保鲜效果比在室温下更显著,相关指标明显优于室温下的涂膜组。     

魔芋葡甘聚糖颗粒阻溶剂的筛选与应用

报道三种魔芋葡甘聚糖颗粒阻溶剂的配方组成,并利用阻溶剂A进行了魔芋精粉湿法制备试验。阻溶剂A由硼酸盐──柠檬酸盐──亚硫酸盐组成,其主体成分为硼酸盐,在鲜魔芋块茎磨碎时加入磨浆机中,能有效地防止魔芋葡甘聚糖颗粒的溶胀粘连。     

家具用人造板的质量要求

阐述了人造板作为家具用材的几个主要质量指标,如游离甲醛释放量、握镙钉力、厚度偏差、含水率等,并叙述了人造板在家具业中的发展方向.     

苦荞-小麦混合粉流变学特性及烘焙特性研究

该文对苦荞小麦混合粉粉质特性、拉伸特性进行系统研究。随着苦荞粉比例增加,形成时间、稳定时间缩短,弱化度上升,评价值下降,拉伸参数均呈下降趋势;且苦荞粉比例越大,下降幅度越大。另外,面包烘焙实验表明,苦荞添加量为10％和20％时,苦荞面包尚有较好烘焙特性,添加量增至30％时,烘焙特性显著下降,添加量达40％或50％时,烘焙特性极差。     

木材原料中金属离子的测定及分布的研究

利用原子吸收光谱测定了有代表性的几种针叶木和阔叶木原料中金属元素分布及含量,并利用扫描电镜—能谱仪分析了原料的不同部位中金属离子的分布规律。结果发现在实验范围内,各种木材原料中都存在由多种金属离子构成的复杂体系;不同种原料中金属离子的含量和成分存在着很大差异;针叶木Ｆｅ、Ｍｎ 含量显著,高于阔叶木;同种原料中,边材金属离子含量一般高于心材;不同生长环境会导致木材金属离子分布出现差异。纸浆中的金属离子主要来源于原料本身,因此对金属离子含量不同的原料,纸浆漂前的除过渡金属离子预处理条件应该不同。     

全麦面条不同制作阶段挥发性风味物质比较分析

全麦熟面加工过程伴随着各种复杂的物理和化学反应,其挥发性风味物质在不同制作阶段香气特征尚不明确。本研究旨在揭示在熟面制作过程中气味物质的变化原因,为开发、改善、生产销售全麦鲜熟面提供指导。本研究采用气相色谱-离子迁移谱( GC-IMS) 联用技术,比较分析全麦粉、全麦生鲜面、全麦鲜熟面样品的挥发性组分。结果显示,共定性识别出55种挥发性风味物质,以醇类、醛类和酮类化合物为主。全麦粉制作成生面过程会加快全麦粉中脂质氧化或是氨基酸分解产生醛、醇、酯。煮制会使全麦面条中醛和醇的溶解和释放,并通过脂质氧化和热分解来调节酯和酮的浓度。以p＜0.05且VIP＞1为标准,共筛选出24种标志性差异化合物,这可能是造成全麦粉、全麦生面、全麦熟面风味差异的主要挥发性风味物质。     

损伤淀粉含量对小麦粉品质及淀粉和谷朊粉分离效果的影响

以市售金苑特制一等粉为原料,采用行星式球磨机,分别处理0、5、10、15 h ,制得不同损伤淀粉含量的小麦粉。用不同损伤淀粉含量的小麦粉为原料,分离、提取A淀粉和谷朊粉,随即测定淀粉和谷朊粉湿基的得率,冷冻干燥后测定各样品的得率与纯度、水溶物含量及样品白度等,探索损伤淀粉含量对淀粉和谷朊粉分离效果的影响。试验结果表明,经研磨处理后的小麦粉,研磨时间越长,小麦粉中损伤淀粉含量越高;随着研磨时间的增加,小粒径粉含量增大,水分降低,降落数值降低。在淀粉和谷朊粉分离过程中,损伤淀粉含量与淀粉得率呈极显著正相关（r＝0．990）,与谷朊粉得率无显著相关性（P＞0．05）。     

Specific detection and quantification of Aspergillus flavus and Aspergillus parasiticus in wheat flour by SYBR® Green quantitative PCR

Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. These mycotoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus, two closely related species with different array of aflatoxins. In this work, two specific quantitative PCR (qPCR) assays were developed to detect and quantify both species in wheat flour using primers based on the multicopy ITS2 rDNA target sequence. The species specificity of the assays was tested in a wide range of strains of these species and others colonizing the same commodities. The sensitivity of the assay was estimated in 2.5 pg/reaction in both species. Discrimination capacity for detection and relative quantification of A. flavus and A. parasiticus DNA were analyzed using samples with DNA mixtures containing also other fungal species at different ratios. Both qPCR assays could detect spore concentrations equal or higher than 10⁶ spores/g in flour samples without prior incubation. These assays are valuable tools to improve diagnosis at an early stage and in all critical control points of food chain integrated in HACCP strategies.     

挤压对低温脱脂花生粕氮溶指数的影响

以低温脱脂花生粕为原料,采用挤压技术,在单因素实验的基础上,利用Box-Benhnken的中心组合实验设计原理,氮溶指数(NSI)为考核指标,确定了花生粕挤压改性的最佳工艺条件,建立了数学模型。结果表明,低温脱脂花生粕挤压改性的最佳工艺条件为模孔直径12mm、物料含水量11.8%、挤压温度65℃、螺杆转速300r/min。在该工艺条件下花生粕的NSI为82.20%,和挤压前相比提高15.42%。