烤烟叶片成熟与衰老生理特性研究

通过对烟叶成熟与衰老密切相关的膜脂过氧化系统研究发现,在烟叶成熟与衰老过程中,叶绿素和类胡萝卜素含量持续降低,前者降解速率较快,打顶后SOD活性先降后升,下二棚叶适熟后,SOD活性持续上升,其它叶位则呈现下降,POD活性和Pr含量逐渐降低,MDA活性逐渐升高;在下二棚叶尚熟至适熟时是膜脂过氧化与抗氧化平衡转折的关键时期.     

NO处理对鲜切胡萝卜生理生化变化的影响

研究以鲜切胡萝卜为对象,采用0.1 mmol/L的一氧化氮(NO)供体硝普钠(sodium nitroprussiate,SNP)浸泡处理2 h,测定了其在4℃、贮藏期15 d的感官品质和生理生化相关指标的变化,分析了NO处理对鲜切胡萝卜保鲜效果的影响。结果表明,NO有效地降低了鲜切胡萝卜白化发生速率。NO处理能提高抗氧化相关酶活性,如抗坏血酸过氧化物酶(Ascorbate peroxidase,APX)、过氧化氢酶(Catalase,CAT)。同时,NO处理降低鲜切胡萝卜组织的电导率、抑制了脂氧合酶(Lipoxygenase,LOX)活性,减少了丙二醛(malondialdehyde,MDA)含量的积累,延迟了膜脂过氧化的发生,减轻了鲜切胡萝卜细胞膜受损程度。另外,NO处理还能够抑制与苯丙烷代谢相关的酶活性,如多酚氧化酶(Polyphenol oxidase,PPO)、过氧化物酶(Peroxidase,POD)、苯丙氨酸解氨酶(Phenylalanine ammonia lyase,PAL)以及总酚、类黄酮等次生代谢物质的积累进而延迟鲜切胡萝卜白化进程。NO通过提高鲜切胡萝卜抗氧化能力、降低与苯丙烷代谢途径相关的酶活性,进而改善了产品的感官质量,延长贮藏期。     

发酵香肠葡萄球菌、微球菌生理生化特性的研究

采用中国传统发酵香肠作为样品,从中分离纯化出葡萄球菌,且对其做生理生化特性鉴定,以对发酵香肠的菌株进一步的筛选,从中选出不产粘液、发酵葡萄糖不产气、不产色素、不产H2S、不具有氨基酸脱羧酶、不产氨、15℃能还原硝酸盐、pH值4.5务件下生长的菌株作为发酵香肠中的优良葡萄菌株.     

茉莉酸甲酯处理对软枣猕猴桃生理生化变化的影响

以软枣猕猴桃\     

Occurrence of Pectinatus and Megasphaera in the Major UK Breweries

The occurrence of beer spoilage bacteria belonging to the genera Pectinatus and Megasphaera in ten major UK breweries was investigated. The sampling points were selected from fermentation areas, beer conditioning areas and beer bottling and canning sites. Multiplex PCR methodology was used for detection of three Pectinatus and three Megasphaera species using species‐specific primers. The presence of six Lactobacillus species was also examined. Overall, 117 samples were analysed from ten breweries; six samples were positive for the presence of Pectinatus species and three samples were positive for the presence of Megasphaera species, while 34 samples were positive for the presence of Lactobacillus species. Lactobacillus species appeared to be the major potential spoilage microorganisms. Although none of the actual beer samples were found to be positive for Pectinatus and Megasphaera species, their occurrence in aerobic brewery environments indicates sanitation problems and revealed the presence of highly established biofilms in some breweries.     

硅窗简易气调冷藏的山楂生理生化变化的研究

选取北方常见的山楂品种—敞口山楂,对其在适宜贮藏环境下(温度0℃左右,RH为85%~90%,O2 15%~16%,CO2 2%~3%)的生理生化变化规律进行了研究。结果发现:敞口山楂属典型呼吸跃变型果实;其多聚半乳糖醛酸酶(简称PG)活性变化与呼吸强度的变化、乙烯释放量之间存在有一定相关性。在此研究的基础上,结合其它果品的研究成果,揭示了山楂果较耐贮藏的机理。     

茉莉酸甲酯处理对软枣猕猴桃生理生化变化的影响

以软枣猕猴桃“丰绿”为试材,探讨茉莉酸甲酯处理对采后软枣猕猴桃果实生理生化变化的影响,结果表明:不同浓度茉莉酸甲酯处理,能够有效的降低软枣猕猴桃的呼吸强度,抑制果实硬度的下降和可溶性固形物的增加,延缓VC含量的下降此外,处理还可诱导POD、CAT两种酶活性的上升,抑制PPO、LOX两种酶活性的增加,有效增强了软枣猕猴桃果实组织的抗性,在各种处理中,以0.15mmol/L MeJA处理效果最好.     

Characterization of Pectinatus and Megasphaera Strains by Automated Ribotyping

A total of 32 Pectinatus and Megasphaera strains, isolated from spoiled beer or brewery environments and identified by conventional methods, were analysed by the automated RiboPrinter® System. One strain from each ribotype was further subjected to partial 16S rDNA sequencing to confirm the ribotyping results. The restriction enzyme EcoRI was used in ribotyping of Pectinatus strains. Eight strains, identified by conventional tests as P. cerevisiiphilus, generated five different ribotypes. The strains of three types were considered to be members of P. cerevisiiphilus, but the strains of two types were most probably members of a new species within the genus Pectinatus. The 24 strains identified by conventional tests as P. frisingenis generated nine different ribotypes. The similarity between the ribotypes was rather low, but all these strains obviously belonged to the same species. Thirteen Megasphaera cerevisiae strains were analysed with three restriction enzymes EcoRI, Pstl and PvuII and four, six and three different ribotypes, respectively, were generated resulting in seven different combinations. The best discrimination among these strains was obtained with Pstl. According to these results 12 of 13 brewery strains were considered to be M. cerevisiae, but one strain most probably represented a new species within the genus Megasphaera. During the work, 14 RiboPrint® patterns of Pectinatus, five of Megasphaera, two of Selenomonas and two of Zymophilus were created with EcoRI. In addition seven patterns of Megasphaera were created with Pstl and four with Pvull. All these identification patterns (genetic fingerprints) were saved at the database of VTT for future use.     

鲜切莴苣生理生化变化及其保鲜技术的研究进展

该文基于近几年国内外有关鲜切莴苣的研究,分析莴苣加工后的品质变化,并总结了鲜切莴苣物理、化学和生物保鲜技术的研究现状,旨在为鲜切莴苣尤其是鲜切蔬菜保鲜技术的研究提供理论参考。     

干旱胁迫对不同大豆品种叶片光合及生理特性的影响

采用盆栽试验,研究了干旱胁迫对4个抗旱大豆品种和4个普通大豆品种叶片的光合特性、叶绿素荧光特性和一些生理特性的影响。结果表明,干旱胁迫下R2、R4、R6三个时期大豆叶片的净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）均呈下降趋势,普通品种相比抗旱品种下降更为显著;在R2期,胞间二氧化碳浓度（Ci）下降较大,普通品种的下降最为显著,表观叶肉导度（AMC）变化极小;在R4期和R6期,Ci下降幅度变小,AMC呈下降趋势,以普通品种的下降最为显著,推测光合能力下降可能与非气孔限制因素有关。干旱胁迫下光合电子传递量子效率（Фpsii）、光化学猝灭（qP）和表观光合量子传递效率（ETR）均降低,非光化学猝灭（NPQ）升高,原初光能转化效率（n／hz）变化不大。干旱胁迫下叶片丙二醛、脯氨酸和可溶性糖含量增加。     

Escherichia coli heat-stable enterotoxin: biochemical and physiological effects on the intestine

E. coli which elaborate suckling mouse active small MW heat-stable enterotoxin (STa), are important causes of diarrhea in animals and man. These STa's share the property of causing intestinal secretion and diarrhea by virtue of inhibiting the absorption of sodium and chloride and possibly stimulating the secretion of chloride. STa's seem to act in the colon as well as the small intestine and the alterations in intestinal ion and water transport are probably mediated by the guanylate cyclase-cyclic GMP system. Glucose transport is unaffected. STa also causes alterations in the myoelectrical activity of the small intestine which may result in the loss of normal peristaltic activity. STa binds in a reversible fashion to specific receptors on the surface of small intestinal and colonic epithelial cells. The mechanisms whereby occupation of the STa receptors lead to activation of the guanylate cyclase system and intestinal secretion are unknown but may involve influx of calcium through calcium channels, stimulation of prostaglandin synthesis and release of free radicals.     

乳酸钙处理对鲜切菠菜生理生化的影响

采用0.25%、0.5%、0.75%和1.00%的乳酸钙处理鲜切菠菜,研究其在4℃贮藏过程中的生理生化变化。结果表明,0.75%的乳酸钙处理能显著增高SOD活性,抑制POD和PPO活性、电导率和MDA含量上升(p<0.05),降低呼吸强度、失重率、维生素C损失和叶绿素的降解(p<0.05)。由此可见,乳酸钙处理具有延缓鲜切菠菜生理生化反应进程、延长其货架期的作用。      

果蔬冰点与其生理生化指标关系的研究

贮藏温度是影响果蔬贮藏寿命的关键因素。利用同步法测定了35种果蔬的冰点温度及其可溶性固形物含量、密度和含水量,并确定其相关性,为确定果蔬的贮藏保鲜温度条件提供理论依据。结果表明:果蔬含水量和可溶性固形物含量与冰点温度的相关性分别达到极显著水平;果蔬密度与冰点温度的相关性没有达到显著水平。果蔬冰点温度随着果蔬含水量增加呈递增趋势,而随着可溶性固形物含量的增加呈递减趋势,这将为新鲜果蔬的冷藏保鲜及加工提供可靠的理论和数据参考。     

硫对烤烟生长发育及生理生化指标的影响

采用液培试验研究了硫对烤烟生育期、主要农艺性状、关键酶活性、MDA含量和根系活力等生理生化指标的影响。结果表明,0 mmol/L和2 mmol/L处理的烤烟株高、茎围和干物质积累量显著高于其它处理;2 mmol/L和4 mmol/L处理的烤烟叶片的硝酸还原酶活性较高;从旺长到成熟期SOD酶活性随硫浓度的升高而升高,团棵期2 mmol/L处理的SOD活性最低;从团棵期到现蕾期,2 mmol/L处理的MDA含量最低,其它处理MDA含量随硫浓度的升高而升高,在成熟期各处理烤烟叶片MDA含量差异不显著;0 mmol/L和2 mmol/L处理烤烟的根系活力随硫浓度升高而升高,4、8、16、32 mmol/L处理的根系活力随硫浓度的升高而降低。     

鲜切南瓜贮藏过程中生理变化的研究

采用新鲜南瓜为实验材料,经切割处理后,将鲜切南瓜筘藏在5℃和10℃下.在贮藏过程中分析测定了鲜切南瓜乙烯释放量、颜色、失重率、PPO和POD酶活性、总酚和可溶性蛋白质含量等生理生化指标,并且分析了10%下鲜切南瓜伤害部位细胞以及远离伤害部位细胞的有关酶活性的变化.结果发现,南瓜切割后产生了颜色发白、乙烯生成量增加、PPO和POD活性提高等显著的生理生化变化,总酚和可溶性蛋白质含量也发生了不同程度的变化.研究还表明,由于伤害刺激信号转导作用,鲜切南瓜不但在伤害部位细胞具有较高PPO、POD酶活性,而且远离伤害部位细胞酶活性也有一定程度的增加.实验结果认为,鲜切南瓜对伤害的生理反应是整体响应.     

Heat and anaerobic treatments affected physiological and biochemical parameters in tomato fruits

The aim of the present work was to evaluate the effect of thermal and anaerobic treatments on physiological and biochemical parameters in a variety of tomatoes (Lycopersicon esculentum Mill. cv. Colt 45). Treatments applied to mature green tomatoes were: (A) heat treatments by water immersion at 42 °C for 30 min (HS30′) or for 60 min (HS60′); or by air at 38 °C for 72 h (HS72h); and (B) anaerobic treatments carried out at 20 °C under humidified nitrogen atmosphere for 3 days (ANA3d) or 6 days (ANA6d). After treatments, fruits were stored at 2 or 14 °C. Parameters evaluated were: colour, total acidity, major organic acids, firmness, and ethanol and acetaldehyde concentration. Anaerobic and long-term heat shock treatments inhibited colour development irrespective of storage temperature. Air heat treatment reduced tritratable acidity by increasing malic acid metabolism. Anaerobic treatments induced ethanol accumulation, which could be reversed during storage for the short treatment (3 days), but not for the longer treatment (6 days). Acetaldehyde concentration was increased by anaerobic treatments, but also by immersion in hot water for 60 min, which would produce a “low-aerobic” environment.     

香椿采后生理学变化及其保鲜技术研究进展

香椿作为一种木本蔬菜,因营养价值高受到了广泛的喜爱。然而随着人们生活水平的不断提高以及对食品安全问题的普遍关注,希望安全且能够较长时间食用香椿。因此对香椿保鲜也提出了新的要求。本文从采后生理学变化,物理保鲜,化学保鲜,生物保鲜角度总结国内外有关香椿的研究成果,分析了香椿采后生理生化及品质的变化,采后不同的保鲜技术对香椿品质的影响,并对未来香椿保鲜方式和研究方向进行展望。旨为在延长香椿贮藏期,提高其经济价值,为香椿加工及保鲜技术的研究提供理论参考,同时也为木本蔬菜保鲜提供参考。     

不同贮藏条件对莱阳茌梨生理生化变化的影响

试验分别探讨了自然室温(25～5)℃贮藏条件下用PVC膜包装和不用PVC膜包装以及低温(3±1)℃贮藏条件下用PVC膜包装和不用PVC膜包装对莱阳茌梨生理生化变化的影响。结果表明:低温贮藏条件下,用PVC膜包装和不用PVC膜包装其贮藏效果均优于自然室温条件下用PVC膜包装和不用PVC膜包装,其中以自然室温条件下不用PVC膜包装的贮藏效果最差,贮藏时间最短;而低温贮藏条件下用PVC膜包装的贮藏效果最佳,能最大程度上降低梨果实的呼吸强度,减缓相对电导率的上升速度,抑制可溶性固形物、可滴定酸和Vc含量的下降。     

水杨酸处理对采后桑葚生理生化特性的影响

研究不同浓度水杨酸(0、0.5、1、1.5、2mmol/L)处理对桑葚果实贮藏期间生理生化特性的影响。实验结果表明:水杨酸处理桑葚果对维持果实可溶性固形物、可滴定酸、硬度、色彩饱和度和维生素C含量有较好作用,显著提高了贮藏期间果实的总花色苷含量和DPPH自由基清除率,综合而言,1.5mmol/L水杨酸处理桑葚效果最优。      

基于BP神经网络的仓储小麦的生理生化指标预测

BP神经网络算法在粮食仓储领域拥有巨大的应用价值和潜力。本研究尝试将BP神经网络引入仓储小麦品质预警模型,以天津储粮抽检数据为对象,通过对室内温度的记录,样品水分、淀粉、蛋白质等11项生理生化指标的定期检测,利用BP神经网络算法进行仓储小麦的品质预测与影响分析。仿真结果表明,基于BP神经网络的数据预测方法具有较小的过程误差和较高的结果准确性,为仓储小麦的品质预测提供了一种有效的研究方法。