黄精为滇黄精、黄精或多花黄精的根茎,含有多糖、皂苷、黄酮、木脂素、氨基酸、醌类化合物、维生素、生物碱及多种微量元素等对人体有益的成分,具有抗氧化、抗肿瘤、降血糖、免疫调节、抗菌抗炎、抗病毒等功效,是具有较高药用价值和营养价值的药食同源植物.从古至今,黄精在药用领域的研究较为广泛,随着我国经济的发展和人们对健康保健重视的提高,黄精食品不断发展.本文主要阐述了黄精的营养成分及生物活性,深入分析了其在加工利用方面的研究现状,以期为黄精在食品领域的深入开发利用提供参考.

为确定炮制黄精多糖（PPP）的最佳提取工艺,本试验以黄精为原料,进行炮制,利用超高压技术提取PPP,分析了压力强度、保压时间、料液比对PPP提取率的影响,采用Box-Behnken响应面分析法（RSM）优化PPP提取条件,并对所得多糖进行动物体内试验,分析小鼠血清、肝脏和左腿腓肠肌中相关酶的活性变化,探究其提高机体运动耐力机制。结果表明,PPP最佳提取工艺条件为:液料比23 mL·g -1 、保压时间6.73 min,压力强度293 MPa,在此条件下PPP得率为13.46%;能显著提高小鼠力竭游泳时间（P＜0.05）,相比于游泳对照组,小鼠血清中尿素氮（SUN）、乳酸（Lac）和肝脏丙二醛（MDA）含量显著下降（P＜0.05）,同时乳酸脱氢酶（LDH）活性下降、Ca 2+ Mg 2+ -ATP酶及肌酸激酶（CK）活性上升,对提高小鼠运动耐力具有较好的效果。本研究结果为超高压提取PPP奠定了基础,并为PPP提高运动耐力的机制研究提供了数据支持。

冷冻面团作为一种半成品,通过冷冻贮藏可以维持面团性能,延长面团保存期,被广泛应用于食品连锁加工过程中.本文综述了影响冷冻面团品质的因素,探讨了当前国内冷冻面团研究存在的难点,旨在为我国冷冻面团的发展提供参考.

OBJECTIVEPurpose of this work was to explore the distribution of LuxS/AI-2 quorum sensing system in Edwardsiella, and analyze expression characteristics and biological function of the key gene luxS accompanying the growth of Edwardsiella.METHODSThe full-length of AI-2/LuxS of Edwardsiella tarda was cloned by PCR based on the sequence on NCBI, then characteristics and conservative structure of this protein-coding gene were analyzed using web database and bioinformatics tools. The anti-rabbits serum was prepared after this protein was purified through prokaryotic expression. The expression level of luxS gene was analyzed during different growth stages using Western blot and further the distribution of luxS gene in Edwardsiella tarda was studied by this technique. To explore whether the specific LuxS is AI-2 dependent we used the method of antibody neutralization to analyze the effect of the anti-rabbits serum on the growth of Edwardsiella tarda. RESULTS] The luxS gene was obtained by PCR, its length was 516 bp, and the sequence was highly conserved in Edwardsiella tarda. Results of Western blot analysis showed that LuxS expression level was the lowest in the lag phase and began increasing when entered index phase. It reached the peak in the late index phase and decreased in decline phase. Moreover, Antibody neutralization results showed that, it can elongate the growth plateau phase, but it has no significant effect on bacterial growth.CONCLUSIONThe key gene of luxS was highly conserved, and LuxS/AI-2 was widely distributed among Edwardsiella tarda. The expression level of luxS gene was different during every growth period, expression of LuxS protein reached the highest level in the late index phase.

日本沼虾,别名青虾或河虾,隶属于节肢动物门、甲壳纲、十足目、长臂虾科、沼虾属,是我国重要淡水食用虾,经济效益显著,但近年来随着养殖规模的发展,养殖密度的提高,人工饵料的投喂,水体有机质的积累,疾病危害越来越严重,制约日本沼虾养殖业发展.本文主要介绍几种常见疾病及其防治技术,供养殖工作者参考. 1 黑鳃病 该病是近年来日本沼虾的常见病,该病传染性强,发病率高,常引起大量死亡. 1.1 致病因素 (1)弧状杆菌感染;(2)虾塘有机物过多,导致病菌繁殖感染虾体;(3)聚缩虫寄生虫感染;(4)饲料中缺乏Vc. 1.2 临床症状 体色黑,复眼变白,多集中在岸边浅水处,行动迟缓,对外界刺激反应不灵敏,病虾鳃部成红色,上有黑色斑点,严重的鳃为全黑色,胃呈透明色,内充盈液体,无食物,肝胰腺红黄色,质脆易碎,肌肉韧性较差.

This paper aimed to study the effect of hot water treatment for killing foodborne pathogens on fresh- cut cucumber while maintaining its freshness. Based on the sensory quality of fresh-cut cucumber after hot water treatment,selected hot water treatment conditions,and further studies of hot water treatment in reducing foodborne pathogens in water and on surface of fresh-cut cucumber were carried out. The results showed that:the high initial concentration numbers of 5.42 and 5.16log CFU/g for Salmonella Typhimurium and Listeria monocytogenes respectively on fresh-cut cucumbers treated by 60℃ 5min heat treatment,were reduced to under detection line,although fresh-cut cucumber antioxidant value reduced and cell membrane permeability increased,but the measured hardness did not change,maintaining fresh sensory and good eating value.

The water culture method was adopted to study the effects of exogenous ABA on the growth of cucumber seedlings and activities of antioxidant enzymes under nitrate stress.The results showed that the nitrate stress inhibited the growth of cucumber seedlings significantly,especially the growth of aboveground.Compared to the check,spraying different concentrations of exogenous ABA could alter the activity of SOD and APX in varying degrees,and decrease the content of MDA in cucumber seedlings with two or three leaves.

This paper studied the effects of a substrate, a product (phosphate) and its analog (vanadate) on the phytase activity. When the concentration of phytate was less than 0.6 mmol/L, the reaction rate increased with the increasing concentration of phytate. And when it was between 0.6 mmol/L and 1.6 mmol/L, the reaction rate changed little, but when it was more than 1.6 mmol/L, the reaction rate decreased with the increasing concentration of phytate. The result showed that high concentrations of phytate inhibited the phytase activity. The K's value for phytate was estimated to be 2.0 mmol/L. The enzyme activity was inhibited by vanadate with phytate and pNPP as substrate, respectively. The inhibition type was uncompetitive, with the Ki values 62.89 μmol/L and 2.42 μmol/L, respectively. The enzyme activity was also inhibited by phosphate with pNPP as substrate and the inhibition type was competitive with the Ki 1.45 mmol/L.