加工工艺因素对黑蒜营养素与功效成分的影响

综述了黑蒜中的水分、蛋白质、氨基酸、糖类、5-羟甲基糠醛、酚类、黄酮类、生物碱、阿霍烯等营养成分和功效,介绍了时间、预处理、温度等工艺因素对上述成分的影响,为黑蒜的生产工艺优化与品质研究提供了参考。     

超临界下有机酸对稻秆水解糖化的影响

采用间歇式反应器在超临界条件下,以有机酸（甲酸、乙酸和丙酸）为催化剂对稻秆进行水解糖化研究,重点考察反应温度、反应时间、固液比对还原糖产率的影响。实验表明：有机酸的加入有利于稻秆的水解糖化,稻秆水解速率和还原糖产量都有所提高,这种趋势在加入甲酸时最为明显;随着反应时间的延长,还原糖产量会逐渐减少;适当提高固液比有助于增加还原糖产量。稻秆超临界水解糖化的最佳条件：甲酸体积分数3％、固液比4：60（g／mL）、反应温度410℃、反应时间5min,在此条件下,还原糖产量最高,达6．65g／L。     

UV-B对不同发育时期离体蓝莓主要果实品质及相关酶活性的影响

该研究以幼果期、白果期、转色期的离体‘北陆’蓝莓果实为试材,设置0(CK)、5、10、15min紫外光辐照处理,24h后取样分析蓝莓果实中可溶性糖、总酚、类黄酮和花青苷含量,以及苯丙氨酸裂解酶(PAL)和查尔酮异构酶(CHI)活性的变化,探究UV-B紫外照射处理对不同发育时期蓝莓主要果实品质及相关酶活的影响。结果显示:(1)对于幼果期蓝莓,5min UV-B处理可显著增加果实内可溶性糖含量;10min UV-B处理果实PAL活性增加效果最为显著;15min UV-B处理对果实总酚和花青苷积累的促进作用最大,但显著降低了类黄酮含量和CHI活性。(2)对于白果期蓝莓,5min UV-B处理显著增加了果实类黄酮含量和CHI活性,10min处理使果实可溶性糖和总酚含量较对照分别增加25%和18%;15min处理对果实花青苷含量和PAL活性影响作用最大。(3)对于转色期蓝莓,各处理除果实可溶性糖及类黄酮含量降低外,其余物质含量均显著增加。(4)UV-B处理并未改变果实发育过程中可溶性糖、总酚、类黄酮和花青苷含量及PAL、CHI酶活性的积累规律。(5)蓝莓果内PAL活性与其可溶性糖、总酚和类黄酮的积累呈极显著正相关关系,而CHI活性仅与其可溶性糖呈极显著正相关。研究表明,UV-B辐照处理促进了幼果期和白果期可溶性糖的积累,也能促进不同发育时期蓝莓果实总酚和花青苷及白果期类黄酮的积累,对蓝莓果实主要品质能够产生积极的影响。     

变温处理对西红花花芽分化及其生理生化的影响

以西红花球茎为材料,设置20℃-25℃-20℃(T1)、20℃-30℃-25℃(T2)、25℃-35℃-25℃(T3)及25℃-30℃25℃(经验变温对照,CK1)和25℃25℃25℃(恒温对照,CK2)共5组三阶段(Ⅰ-Ⅱ-Ⅲ)变温处理,在各阶段采集球茎样品,用石蜡制片方法观察西红花花芽的分化情况,并测定各处理组球茎...     

过热蒸汽处理对猪肉品质及氧化稳定性的影响

为改善猪肉食用品质,研究过热蒸汽处理对猪肉品质与氧化稳定性的影响,以确定适宜的过热蒸汽处理条件,为过热蒸汽处理肉制品提供理论基础和参考依据。以猪肉为原料,分析过热蒸汽在不同的处理温度及处理时间下对猪肉的理化性质、感官品质及氧化稳定性的影响。猪肉经过热蒸汽处理后,随着加热温度的升高和时间的延长,蒸煮损失增大,水分含量降低,pH上升,硫代巴比妥酸(TBA)值增大,过氧化值呈先升高后降低的趋势。扫描电子显微镜(SEM)扫描结果显示：在同一加热时间下,随着加热温度的升高,猪肉肌纤维结构显著收缩。通过对猪肉的质构分析和感官评价可知：在同一加热时间下,随着加热温度的升高,猪肉的硬度与咀嚼性增加,弹性与回复性先增加后减小。综合感官评价与以上研究结果,猪肉在150℃过热蒸汽下处理25 min时,感官评分最高,食用效果最佳。     

变温对两种昆虫发育速率的影响

报道了松毛虫赤眼蜂和瓜螟在多组恒温、交替变温下的发育历期。对结果的分析表明,温度交替对这两种昆虫在任一温度下的瞬时发育率无明显影响,恒温下和变温下完成发育所需的热量无显著差异或基本相似。     

昼夜变温幅度对小菜蛾不同发育阶段生活史性状的影响

【目的】昼夜变温幅度对昆虫的发育、存活、寿命、繁殖等核心生命活动有非常重要的影响。以往研究主要以恒温为主,温度设置不符合自然界中昼夜温度波动变化,无法明确温度波动幅度与恒温之间的生物效应差别。【方法】本研究采用了二步变温,模拟了不同的昼夜温度波动幅度(25±2℃,25±4℃,25±6℃,25±8℃,25±10℃和25±12℃)与相应恒温25℃,研究了不同变温幅度对十字花科世界性害虫小菜蛾Plutella xylostella不同生活史阶段中发育、存活、寿命与繁殖的影响。【结果】结果表明,变温幅度对小菜蛾不同阶段的发育、存活、寿命与繁殖影响存在显著差异。25±2℃,25±4℃和25±6℃对小菜蛾生活史性状的影响与恒温(25℃)相似,但25±10℃和25±12℃却产生了显著的负面影响。【结论】我们发现,较大的昼夜变温幅度显著影响小菜蛾不同阶段的发育、存活、寿命与繁殖,而适宜夜低温在一定程度上修复了日高温胁迫对小菜蛾的不利影响;并且认为昼夜变温幅度作为影响昆虫核心生命活动一种重要决定因素,必需纳入到昆虫种群数量预测模型中,才能真实地反映自然界中复杂变温模式对昆虫生态学效应的影响,才能提高昆虫田间发生预测预报的准确性。     

不同温度对独蒜兰开花和生长的影响

该研究采用人工温室于3种培养温度(20℃/15℃、15℃/10℃、10℃/5℃)条件下,分析独蒜兰生长开花进程以及假鳞茎中有机物质含量的动态变化。结果表明:(1)于20℃/15℃(模拟原生地开花期自然温度)处理下,独蒜兰进入初花期的时间比15℃/10℃、10℃/5℃处理下分别提前24d和53d,花期分别延长了4d和6d。(2)独蒜兰的花色以10℃/5℃处理较深,但该处理中有哑蕾出现。(3)老假鳞茎生长开花过程中,20℃/15℃处理的淀粉含量呈升高趋势,15℃/10℃和10℃/5℃处理先升高后降低;3种温度处理下,可溶性糖均在花期含量最高,且10℃/5℃处理下可溶性糖含量、可溶性蛋白含量均保持较高水平。研究认为,20℃/15℃和15℃/10℃培养温度均有利于独蒜兰的生长和开花;独蒜兰休眠的假鳞茎不需要经过低温诱导解除休眠,随着温度上升,相应的生长发育进程就会启动。     

昼夜变温对小麦幼苗生长的影响：简报

昼夜变温条件下生长的小麦幼苗,其长度、干重、α-淀粉酶的活性都大于昼夜恒温条件下生长的小麦幼苗。较低的夜温有利于根的生长,使根冠比增大,但并不促进胚根切段的伸长。     

HPLC法测定不同产地黑丹皮中丹皮酚的含量

为建立黑丹皮药材中丹皮酚含量测定方法。采用菲罗门LunaC18(4.6 mm×250 mm,5μm)色谱柱,以甲醇-水(45∶55)为流动相,流速1.0 mL/min,检测波长274 nm。经测定丹皮酚含量在0.0432～0.324 ug范围内呈良好的线性关系(r=0.9999);平均回收率为104.07%,RSD=2.22%。该方法简便、准确、重现性好,适用于黑丹皮的质量控制。     

黑色地膜覆盖的土壤水热效应及其对马铃薯产量的影响

以马铃薯为研究材料,采用随机区组设计,设全膜覆盖垄沟种植(PM)和裸地平作(CK)两个处理,研究西北半干旱区黑色地膜覆盖的土壤水热效应及其对马铃薯产量的影响。结果表明:PM能增加马铃薯全生育期0—25 cm土壤温度1.5℃左右,增温效应呈"抛物线型";盛花期PM增温效果主要在8:00,14:00和20:00具有降温和稳定地温作用;同时,在平水年和欠水年,PM能促进马铃薯盛花期和薯块膨大期耗水,盛花期PM耗水量增加21.2%—50.5%,块茎膨大期增加5.4%—57.9%,但全生育期耗水量PM与CK差异不显著;PM在调节地温、促进关键生育期耗水作用下,产量较CK提高13.6%—64.5%,WUE提高24.1%—69.5%,差异均达显著水平。在年均降水391.4 mm条件下,连续4a地膜覆盖高产种植的0—200 cm土层土壤贮水量增加了123.4 mm,优化了土壤水分状况。     

Effect of growth temperature on the composition of phenols in pea roots

It was shown that, in pea (Pisum sativum L.) roots, flavans are a dominating component of the soluble phenol fraction. In plants grown at low temperature (8°C), flavan content during the early growth phase was lower than in plants grown at 22°C, but later it increased and was by 40% higher than in plants grown at 22°C. Total phenol content in the two treatments differed insignificantly. Low growth temperature decreased the content of some phenolic compounds in pea seedling roots.     

Effect of garlic oil on the levels of various enzymes in the serum and tissue of streptozotocin diabetic rats

Levels of red cell, serum acid, and alkaline phosphatases, serum amylase, alanine and aspartate transferase and bilirubin were examined in streptozotocin-induced diabetic rats treated with garlic oil and compared with the corresponding levels in diabetic control rats, normal rats and normal rats on garlic oil. Values of tissue amylase and total protein were also assessed from the pancreas, liver, and kidney. Treatment of diabetic rats with garlic oil significantly decreased the red cell phosphatase (p<0.01), serum acid and alkaline phosphatase (p<0.001) when compared to diabetic control rats. Serum alanine and asparate transferases were significantly (p<0.001) decreased as well as serum amylase (p<0.002) in garlic oil treated diabetic rats as compared with diabetic control rats. When treated with garlic oil, however, diabetic and normal rats showed significant increase (p<0.05) in the amylase levels of the pancrease, liver, and kidney.     

Effect of sequestering and reducing agents on stabilization of plant dehydrogenase activity in crude extracts

Initial and long-term loss of dehydrogenase activity in crude extracts of herbaceous, and, especially, of woody tissue occur partially because of the inhibitory influence of phenolics. In addition, oxidation of phenols by phenolase results in subsequent enzyme oxidation. Preparation of crude extracts with insoluble PVP, in comparison with anion exchange resins or celluloses, best decreases phenolic concentrations and least decreases dehydrogenase activity in crude extracts. However, removal of phenolics during tissue homogenation does not maximize dehydrogenase activity. Therefore, other methods must be used to stabilize dehydrogenase activity. Sodium ethylenediaminetetracetic acid or sodium azide promoted activity of both purified mushroom and crude plant phenolases. Quinone reduction with diethyldithiocarbamate (DIECA) or mercaptoethanol eliminated apparent phenolase activity, but DIECA inhibited dehydrogenase activity. Elevated concentrations of EtSH diminished initial decay of dehydrogenase activity. Combined use of EtSH and insoluble PVP further stabilized 6-phosphogluconate, glucose 6-phosphate, and malate dehydrogenase, but not glyceraldehyde 3-phosphate dehydrogenase.     

Predators modify the evolutionary response of prey to temperature change

As climate regimes shift in many ecosystems worldwide, evolution may be a critical process allowing persistence in rapidly changing environments. Organisms regularly interact with other species, yet whether climate-mediated evolution can occur in the context of species interactions is not well understood. We tested whether a species interaction could modify evolutionary responses to temperature. We demonstrate that predation pressure by Dipteran larvae (Chaoborus americanus) modified the evolutionary response of a freshwater crustacean (Daphnia pulex) to its thermal environment over approximately seven generations in laboratory conditions. Daphnia kept at 21°C evolved higher population growth rates than those kept at 18°C, but only in those populations that were also reared with predators. Furthermore, predator-mediated selection resulted in the evolution of elevated Daphnia thermal plasticity. This laboratory natural selection experiment demonstrates that biotic interactions can modify evolutionary adaptation to temperature. Understanding the interplay between multiple selective forces can improve predictions of ecological and evolutionary responses of organisms to rapid environmental change.     

Removal of the stem terminal and application of auxin change carbohydrates in Pinus banksiana cuttings during propagation

This study determined how surgical removal of the stem terminal, with indole-3-butyric acid (IBA) treatment, influenced concentrations and partitioning of carbohydrates in Pinus banksiana Lamb, cuttings during propagation. Seedlings and cuttings that originated from 90-day-old stock plants were untreated or treated by removing the stem terminal, followed by application of IBA to the severed apical or basal (cuttings only) stem. Fresh and dry weights of the basal 1-cm stems of cuttings were determined daily for the first 10 days of propagation (i.e., before roots were visible). In addition, basal 1-cm stems, upper (ca 9-cm) stems and needles of seedlings and cuttings were analyzed for sucrose, soluble reducing sugar and total non-structural carbohydrate. Net concentrations of each carbohydrate in cuttings were obtained by subtracting corresponding concentrations for similarly treated seedlings, yielding data directly related to only the physiology of rooting. Data for cuttings indicated that presence of the stem terminal combined with applied IBA positively influenced rooting through processes that increased basal stem fresh and dry weights before root emergence. Removal of the stem terminal influenced accumulation of net total carbohydrate in cuttings, but the major effect was on carbohydrate partitioning. Either type of IBA treatment after removal of the stem terminal usually resulted in different net carbohydrate concentrations in each tissue source of cuttings, compared with only removal of the terminal. Neither basal nor apical IBA treatment of cuttings without stem terminals yielded results for carbohydrate accumulation and partitioning like those obtained with intact cuttings. Removal of the stem terminal, even if followed by IBA treatment, may have lessened rooting potential of cuttings because it resulted in greater reducing sugarstarch concentration ratios in basal stems compared with those in intact cuttings.     

Altered expression of the Na+/H+ exchanger isoform-3 in experimental colitis: Effect of garlic

The sodium-hydrogen exchanger isoform, NHE-3 is essential for the absorption of sodium and water from intestine. Whether this protein plays any role in inflammatory bowel disease is less understood. To address this issue, NHE-3 mRNA and protein levels were estimated in the terminal ileum and colon of the rats having colitis induced with trinitrobenzenesulphonic acid (TNBS). The effect of garlic (Allium sativum) was also evaluated on the expression of NHE-3. The animals were treated with garlic extract intraperitoneally starting 2 h before the TNBS administration until day 4 post-TNBS administration and were sacrificed on day 5. In control animals, the levels of NHE-3 in colon was higher than the ileum. As a result of colitis, the levels of NHE-3 protein and mRNA increased both in the colon and terminal ileum. Garlic treatment of the colitic animals resulted in a selective suppression of NHE-3 in the terminal ileum. Colitis caused an induction of the myeloperoxidase activity, the marker of inflammation in the colon but not in the ileum. These findings suggest that induction of NHE-3 is not primarily due to inflammation. Selective suppression of this protein in ileum by garlic may cause loss of sodium chloride and water during colitis.     

棒状乳杆菌FZU63发酵对红茶汤风味品质改善的作用

乳酸菌发酵可赋予茶饮料独特的香气与滋味,且可改变其物质组成,产生益生因子等。目前,针对乳酸菌在不同发酵阶段对茶汤中风味物质形成影响的研究较少。本研究以从中国传统泡菜中筛选获得的棒状乳杆菌FZU63为发酵菌株,对不同发酵阶段红茶汤中的挥发性香气成分、还原糖、游离氨基酸、有机酸等含量的变化过程进行分析,并对发酵红茶汤的感官品质进行评价。结果表明,棒状乳杆菌FZU63以红茶汤中的葡萄糖、果糖、甘露糖和木糖作为发酵过程中的主要碳源物质。红茶汤经棒状乳杆菌FZU63发酵作用后,香气成分丰度显著增加,且主要香气组分结构发生改变,发酵红茶汤在花香、坚果香的基础上增添了水果香;此外,部分苦味氨基酸含量下降,甜味和鲜味氨基酸含量增加;并且,乳酸、苹果酸、柠檬酸等有机酸含量在发酵过程中呈现积累。同时,感官评定结果表明棒状乳杆菌FZU63发酵可改善红茶汤的感官品质,且在发酵48h后达到较优。本文系统分析了经棒状乳杆菌发酵不同阶段对红茶汤风味的影响,可为乳酸菌发酵茶饮料的品质控制与产业化应用提供理论参考。     

Fungi associated with black tea and tea quality in the Sultanate of Oman

Forty-eight samples of four popular commercial brands of black tea ( Camellia sinensis L.) were purchased from the local markets in Muscat area, Sultanate of Oman. Tea leaves were surveyed for mycoflora. Five fungal species were isolated with A. niger as the most dominant in all the brands having percentage contamination ranging between 0.66% and 30.34%. Other fungi isolated were Aspergillus flavus, Penicillium spp. and Pacelomyces spp. but having average percentages of 0.6%, 0.84% and 0.21% respectively. Significant differences were found among the batches contaminated by A. niger. None of the 25 A. flavus strains screened for aflatoxins were found aflatoxigenic. The total ash, water-soluble ash, and mineral concentration of the samples were within the British standards and were not affected by fungal contamination. The results showed that black tea is contaminated by fungi that might constitute health hazards for humans. The post harvest contamination of tea could be eliminated or reduced if processing is conducted under more hygienic conditions. This revised version was published online in June 2006 with corrections to the Cover Date.