蒸发光散射液相色谱测定无糖酸奶中糖醇

建立无糖酸奶中糖醇测定的蒸发光散射检测器方法。采用氨基柱Waters柱CarbohydrateHighPerformance(4.6×250mm,4μm),以乙腈-水(75∶25,体积分数)为流动相,流速1.0mL/min;蒸发光散射检测器载气压力172kPa,漂移管温度45℃,进样量10μL。木糖醇、山梨醇、麦芽糖醇的线性范围均为0.025 mg/g～1.000 mg/g,定量限均为0.10%,样品的平均加标回收率范围分别为85.5%～92.7%、92.2%～147.7%、101%～139.8%,相对标准偏差分别为1.65%、2.67%、2.53%。该方法操作简便、快速、准确,应用于无糖酸奶中糖醇的分析,取得了较好的结果。     

真空油炸苹果脆片防潮降油研究

本文报道了真空油炸苹果脆片防潮、降油的新方法。在35％的麦芽糊精溶液(以下略为B)、B和0.3％的胍尔豆胶。B和0.3％CMC-Na分别浸渍之后,油炸的苹果脆片在相对空气湿度100％条件下,能保持其脆性5小时以上,而其它糖浸渍的苹果脆片较快变软。B和0.3％胍尔豆胶、B和0.3％CMC-Na浸渍、油炸的苹果脆片,含油率降为10％左右。     

基于平衡迭代规约层次聚类的无线传感器网络流量异常检测方案

针对现有网络流量异常检测方法不适用于实时无线传感器网络(WSN)检测环境、缺乏合理异常判决机制的问题,该文提出一种基于平衡迭代规约层次聚类(BIRCH)的WSN流量异常检测方案.该方案在扩充流量特征维度的基础上,利用BIRCH算法对流量特征进行聚类,通过设计动态簇阈值和邻居簇序号优化BIRCH聚类过程,以提高算法的聚类...     

Sugar Transport,Metabolism and Signaling in Fruit Development of Litchi chinensis Sonn: A Review

Litchi chinensis Sonn. is an important evergreen fruit crop cultivated in the tropical and subtropical regions. The edible portion of litchi fruit is the aril, which contains a high concentration of sucrose, glucose, and fructose. In this study, we review various aspects of sugar transport, metabolism, and signaling during fruit development in litchi. We begin by detailing the sugar transport and accumulation during aril development, and the biosynthesis of quebrachitol as a transportable photosynthate is discussed. We then document sugar metabolism in litchi fruit. We focus on the links between sugar signaling and seed development as well as fruit abscission. Finally, we outline future directions for research on sugar metabolism and signaling to improve fruit yield and quality.     

马铃薯抗性淀粉对高脂血症大鼠的降血糖血脂作用

探究马铃薯抗性淀粉对高脂血症大鼠的降血糖血脂作用,48只大鼠,按体重随机分成空白对照组和模型对照组,高脂饲料饲喂2周后按总胆固醇(TC)水平随机分为5组:高脂模型组,阳性对照组,马铃薯抗性淀粉高、中、低剂量组.干预6周,测定各组大鼠的体质量、肝脏系数、血脂水平等指标,并观察大鼠肝脏组织病理切片.结果发现,与空白组比较,...     

Comparison of enzyme activities involved in flavour precursor formation in unfermented beans of different cocoa genotypes

The activities of endoprotease, aminopeptidase, carboxypeptidase and invertase (cotyledon and pulp) were studied in unfermented beans of 10 genotype samples with different flavour characteristics (high and low cocoa flavour). Analysis of variance showed that significant differences in enzyme activities exist between certain genotypes. Aminopeptidase and endoprotease activities in beans of the PA7 genotype were higher than in all others. Principal component analysis (PCA) showed that the PA7 genotype (high cocoa flavour) was very different from the UIT1 genotype (low cocoa flavour). Although significant differences exist, no simple and general relationship is established between the flavour potential of a genotype and the level of key enzyme activities in unfermented beans. Carboxypeptidase is of key importance for peptide and free amino acid formation, but differences in enzyme activity could not be correlated to flavour potential of the genotype. It is suggested that the level of enzyme activities present in unfermented beans is not a limiting factor for optimal formation of flavour precursors during the fermentation process. © 2000 Society of Chemical Industry     

The effect of pre‐harvest pruning of cassava upon root deterioration and quality characteristics

One of the major constraints of cassava as a crop is its perishability. Physiological deterioration, parenchymal blue–black vascular streaking, often starts within 24 h after harvest. This paper presents the results of a detailed study of the effects of pre‐harvest pruning upon post‐harvest physiological deterioration (PPD) and some other quality characteristics. Six cultivars, grown at CIAT (Centro International de Agricultura Tropical), with varying intrinsic susceptibility to PPD, were assessed at pruning–harvest intervals of 0, 2, 4, 6, 8, 10, 15, 20, 25, 28 and 39 days. After harvesting, the roots were analysed. For the unpruned plants a low susceptibility was found to coincide with a low dry matter content and a high sugar content. After pruning, the susceptibility for all cultivars was drastically reduced, reaching a minimum of around 25% of the original value for a pruning–harvest interval of up to 25 days. Beyond this interval the plants slowly develop new leaf canopy, normal assimilation sets in again and the starch content increases. Analysis of the cassava roots revealed a relationship between the combined sugar and starch contents and the interval duration, and that sugar and starch contents were inversely related to each other. The sugar content increased with the interval period, probably as a result of starch hydrolysis. Other properties such as the contents of dry matter, cyanogen, scopoletin, amylose and reducing sugars and the starch pasting properties were not affected by pruning to a comparable, interval‐dependent, extent. It is concluded that the sugar content, ie the sugar/starch ratio, of cassava roots is positively related to their resistance to post‐harvest physiological deterioration. © 2000 Society of Chemical Industry     

A study of peroxidase and amylase isoenzymes in different radish cultivars during winter storage

The changes in activities of soluble peroxidase (EC 1.11.1.7; POD) and amylase (EC 3.2.1.1) and in levels of soluble protein and reducing sugar are investigated in three cultivars of radishes (Raphanus Sativus L) in winter storage for 150 days. It has been shown that the activity of peroxidase increases at first and then decreases during the storage. The highest POD activity appears on the 90th day. The levels of reducing sugars change similarly. Peroxidase isoenzymes (types and activities) in these radish cultivars are obviously different during the storage. The highest activities of peroxidase isoenzymes are observed in Xinlimei (XLM) and the lowest in Dihuangying (DHY). The difference between the radish cultivars is also observed in the peroxidase isoenzyme types. Both cationic and anionic peroxidase isoenzymes appear in the radish during storage. The activities and PAGE bands of the amylase isoenzymes decrease with increasing storage time. The activities of amylase are the lowest in the XLM but highest in the DHY. A similar change is found for the levels of soluble protein during the storage: the levels are highest in XLM and lowest in DHY. These results suggest a possible correlation between the activity of peroxidase and the level of reducing sugar during storage. © 2000 Society of Chemical Industry     

Effect of sugar replacement by polyols and acesulfame‐K on properties of low‐fat cookies

The effect of sucrose replacement by polyols or fructose on dough rheology and properties of low‐fat cookies was studied. Polydextrose was used to replace 35% of fat in low‐fat cookie formulations. The rheological properties of dough were affected by sugar replacement. Maltitol and fructose resulted in dough with high values of hardness and consistency and low adhesiveness and cohesiveness, while lactitol, sorbitol and xylitol had the opposite effect. The properties of cookies prepared with maltitol and lactitol were similar to sucrose ones. Sorbitol cookies had acceptable properties too. In addition, lactitol and sorbitol improved the texture of low‐fat cookies, making them softer and less brittle. Xylitol also affected texture favourably, but not flavour. Mannitol was found not suitable for cookie formulation, as it restricts spread and imparts unpleasant flavour and appearance to the cookies. Fructose was judged unacceptable too, because it led to bitter aftertaste and dark colour. Cookies with polyols or fructose were less sweet than sucrose ones, but supplementation with acesulfame‐K increased sweetness and improved perceived flavour and general acceptance. © 2000 Society of Chemical Industry     

聚氮杂环季铵盐的絮凝杀菌性能研究

将天然聚合物Ｆ６９１粉、环氧氯丙烷分别与吡啶、喹啉、吖啶等氮杂环化合物反应，得到了３种聚氮杂环季铵盐ＦＰＣ、ＦＱＣ、ＦＡＣ。这３种制剂在模拟油田污水中具有絮凝作用和脱除、杀灭硫酸盐还原菌的作用。其絮凝效果在中性条件下近似于而在碱性条件下则优于阳离子聚丙烯酰胺ＰＡＭＣ。３种制剂中，ＦＡＣ的除菌、灭菌效果最好。