超声波的空化作用及其对多酚稳定性的影响

超声波因其能耗低、温升小,作为一种绿色、高效的加工手段,在食品工业中被广泛应用,但是在一定条件下超声波空化作用引起的消极声化学效应也不容忽视。本文以超声波在多酚提取中引起多酚失活的现象为例,详细介绍了超声波的空化作用及其影响空化作用的主要因素、超声波空化作用在水相产生羟自由基的机理,及其影响多酚稳定性的原因。      

两种纳米材料抑菌效果及对虾的保鲜效果研究

目的研究比较纳米银和纳米锌2种材料的抑菌效果和对虾的保鲜效果。方法以G~+和G~-为受试菌种,采用纸片扩散法研究纳米银和纳米锌的高、中、低浓度对细菌的抑菌效果。在此基础上,以总挥发性盐基氮(total volatile base nitrogen,TVBN)、菌落总数、感官、色度等为指标,研究其应用于南美白对虾4℃贮藏保鲜效果。结果纳米银对受试菌种的抑菌效果明显优于纳米锌;纳米银对G~+的抑菌效果优于对G~-的抑菌效果;以TVBN限值为指标,纳米银处理组较对照组在4℃下保存时间可延长48 h。结论纳米银可作为虾类保鲜材料开发的抑菌增效剂。     

大蒜的抗癌作用

文章重点总结近十年来国内外对大蒜抗癌作用研究的最新进展.主要从流行病学和动物模型两方面来阐述,并对大蒜抗癌的机理做了重点论述.     

不同添加物对莴笋液除臭效果的影响

目的 探究莴笋液清除恶臭源的机理,并分析不同添加物及配比对莴笋液清除NH3的影响。方法 以莴笋尾菜为原料,以NH3为指标,测定除臭前后莴笋尾菜液中整体有效成分的变化,探究其作用机理;然后分析表面活性剂、酸碱调节剂等添加物对莴笋液除臭效果的影响,并通过单因素实验、Plackett-Burman实验及响应面法优化制备莴笋尾菜基除臭液。结果 莴笋尾菜液除臭机理与酚类、黄酮类、挥发性芳香类等多个物质相关,但酚类及黄酮类化合物起主要作用;不同添加物对莴笋液除臭效果均有所影响,经添加物初选后的莴笋尾菜除臭液基础配方为：CATB、CAB-35、T-80、β-环糊精和柠檬酸钠;单因素及Plackett-Burman实验结果表明,CATB、CAB-35和柠檬酸钠是影响NH3清除率的显著因素,且CATB>柠檬酸钠>CAB-35;响应面优化所得的莴笋尾菜除臭液的最佳制备工艺参数为：莴笋尾菜液质量浓度0.05 g/mL、CATB 0.9%、T-80 0.5%、CAB-35 0.5%、柠檬酸钠0.3%、β-环糊精0.9%、水5%,此条件下莴笋尾菜除臭液对NH3的清除率最高,可达92.02%[NH3质量浓度为(397±1.5) mg/mL]。结论 本研究证明莴笋尾菜除臭液能够有效地清除以NH3为主要成分的臭味物质。     

Psychophysiological effect of odor

Techniques to measure the activity of the taste and odor molecules at the olfactory epithelium, taste bud, and brain response levels are now being used to determine and measure the actual transduction of the chemical information to the brain waves. We studied a number of methods of measuring brain wave responses to odorants and we settled on an electroencephalographic method of measuring the slow brain waves {>13 Hz} at the frontal location on the scalp. This technique known as contingent negative variation (CNV) measures the early component {at 400 to 1000 ms} of the beta wave variation, which can be negative, positive, or neutral depending on the odorant being presented to the subject. This component is almost independent of the subject's psychological state, degree of arousal, or level of consciousness and is known as the external component. The experimental paradigm creates a reproducible result in which odorants may be classified as stimulating, sedating, or neutral. These psychophysiological effects of odors on man appear to offer a means to determine precognitive responses directly related to the effect of the chemical messenger. There does not appear to be any bias as to sex, national origin, or race. At this point in our research efforts, we do not see evidence that there is a bias related to age. It is proposed that some of the problems of classical sensory evaluation can be helped by the use of psychophysiological recording techniques, such as CNV, as a measurement of brain activity and response to flavor and aroma.     

Glycemic effect of potatoes

Potatoes are the world’s third largest food crop and the most extensively consumed root vegetable. They have high starch content and are a major source of dietary carbohydrate in human nutrition. This review article considers potatoes as a food crop, the properties of potato starch, and methods of preparing potatoes domestically for consumption, before considering the effects of potatoes on postprandial glycemia. Potatoes have been classified as a food that causes high postprandial glycemia, which over the long term may increase the risk of obesity and chronic diseases such as type-2 diabetes and cardiovascular disease. Methods for measuring the glycemic effects of potatoes are considered. In vivo methods, such as the glycemic index are discussed and compared with in vitro tests that measure the breakdown of available carbohydrates in potatoes. The potential for developing potato varieties that have more slowly-digestible starch, and hence a lower glycemic effect, is considered.     

对偶效应代数

效应代数作为一种代数结构在量子结构和量子测量的基础研究中起到重要作用,也广泛被大家关注.引入了效应代数的对偶效应代数这一新概念,讨论了对偶效应代数的一些性质.给出了一些典型效应代数的对偶效应代数的具体形式,并建立了效应代数与其对偶的密切关系.     

冰温贮藏及出库方式对欧李保鲜效果的影响

以农大七号欧李为试材,通过对不同贮藏条件（冰温-0.5 ℃、冷藏4 ℃）下果实品质和生理生化指标的变化规律进行分析,探讨冰温贮藏对欧李果实的贮藏保鲜效果。分别测定了贮藏过程中欧李的生化指标、老化程度和抗氧化能力;同时对冰温贮藏后的欧李采用4种出库方式,探究其对冰温贮藏欧李营养成分的影响。试验结果表明：与4 ℃冷藏相比,冰温贮藏可以显著抑制欧李果实的呼吸速率和果实细胞膜透性的增加,延缓呼吸高峰和丙二醛的积累;有效减少果实失重率和果柄褐变率,维持果实硬度、提高好果率;显著抑制多酚氧化酶和过氧化物酶的活性,保持较高的超氧化物歧化酶活性。在对不同出库方式的比较中,间接出库至10 ℃能保持较稳定的可滴定酸含量和较高水平的维生素C、黄酮和总酚等营养物质。研究结果表明冰温贮藏更有利于果实品质的保持,最适宜的出库条件为间接出库至10 ℃。     

大豆低聚肽降胆固醇作用研究

目的:研究大豆低聚肽在降胆固醇方面的作用。方法:取5周龄SD雄性大鼠90只,随机分为6组(每组15只),即Ⅰ(对照组)、Ⅱ(蛋白组)、Ⅲ(多肽组)、Ⅳ(低聚肽组1)、Ⅴ(低聚肽组2)、Ⅵ(低聚肽组3),在实验环境下,构建高胆固醇模型,在对各组继续饲喂高胆固醇饲料的同时,对第Ⅱ组口腔灌喂大豆蛋白,对第Ⅲ组口腔灌喂大豆多肽,对第Ⅳ、Ⅴ、Ⅵ组分别灌喂不同剂量的大豆低聚肽,第Ⅰ组口腔灌喂同体积的饮用水。饲喂6周,分别收集粪便、血清和肝脏,测定血清和肝脏中的胆固醇和甘油三酯含量、粪便重量及其中的类固醇含量。结果:第Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ组血清和肝脏中的胆固醇和甘油三酯含量均有不同程度的降低,大鼠粪便的排泄量及粪便中类固醇的含量增加。大豆低聚肽组有剂量依赖性,高剂量大豆低聚肽组效果极显著。结论:大豆低聚肽具有比大豆蛋白和大豆多肽更强的降低胆固醇的作用,且这种作用具有剂量依赖性。      

褐变黑枸杞抗氧化作用的研究

为探究褐变黑枸杞对果蝇抗氧化作用,以果蝇为动物模型,在果蝇培养基中分别加入3mg/mL、12mg/mL褐变黑枸杞和红枸杞,检测其对果蝇寿命,超氧化物歧化酶(Superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)、丙二醛(malondialdehyde,MDA)等抗氧化酶活力及抗氧化相关基因表达的影响。结果表明:与正常组相比,褐变黑枸杞高剂量组果蝇的寿命明显延长(P<0.01),SOD和GSH-Px酶活力显著提高(P<0.05),MDA的含量显著降低(P<0.05),且和红枸杞组相比存在显著性差异(P<0.05);实时定量PCR结果显示:褐变黑枸杞能显著上调Cu-Zn SOD(SOD1)、Mn-SOD(SOD2)和CAT mRNA表达水平(P<0.05),MTH mRNA表达水平显著下调(P<0.05)。综上所述,褐变黑枸杞在体内具有很强的抗氧化活性,其作用机制可能是通过上调内源性抗氧化酶的表达,从而增强果蝇抗氧化能力,延缓果蝇衰老。     

水溶性含硫抗氧化剂的抗氧化效果的研究

本文研究了茶多酚 (TPP)、硫代二丙酸 (TDPA)、蛋氨酸 (Met)、胱氨酸 (Cys)等水溶性抗氧化剂的抗氧化效果 ,以及它们在使用时存在的问题。试验表明硫代二丙酸是一种高效、价廉的水溶性抗氧化剂     

Anti-allergic effect of strawberry extract

We examined the anti-allergic effect of strawberry extract on human peripheral blood mononuclear cells (PBMCs) and atopic dermatitis model mice NC/NgaTndCrlj. The addition of strawberry extract suppressed total IgE production in the cedar pollen antigen Cry j 1-stimulated PBMCs. Flow cytometric analysis showed that strawberry extract decreased the rate of CD3⁺CD4⁺ helper T cells by 17.3% and increased the rate of CD3⁺CD8⁺ cytotoxic T cells by 19.7% in PBMCs. Moreover, the extract inhibited the expression level of GATA3 that is the master regulator of type 2 helper T cells (Th2) in human primary pan T cells isolated from PBMCs. Oral administration of strawberry extract lowered dermatitis scores and serum IgE levels in mice. In addition, it also decreased the GATA3 expression level in mouse blood cells. These results revealed that strawberry extract suppressed the severity of atopic dermatitis through the down-regulation of serum IgE by inhibition of Th2 differentiation.     

Temporal dynamics of effect concentrations

In effect assessment the comparability and applicability of LCx and ECx values, which are calculated at single points in time during exposure, relies on the ability to perform a valid extrapolation to other time points of interest. The behavior of LCx in time has been extensively studied, and the behavior of ECx in time is expected to follow similar dynamics, as it is considered that the LCx is just a specific case of ECxs. However, most models have focused on validating the dynamics of LCx, and hardly anything is known about the time dependence of ECx for other endpoints or whether it is comparable to that of LCxs. We have created four scenarios where we study the dynamics of the ECx for different endpoints and how it is affected by the characteristics of two different compounds (carbendazim and pentachlorobenzene) and of two different life history strategies (hermaphroditic and sexually reproducing strains of Caenorhabditis elegans). The observed patterns of behavior in time of the ECx for body size and for reproduction showed unexpected dynamics that deviate considerably from that of the LCx. It was demonstrated that the temporal dynamics of ECx were very different for each particular endpoint. The shape of the ECx-time curves depends on the intrinsic characteristics of the endpoint of study, as well as on the characteristics of the compound and life history strategy of the organism. This makes extrapolation in time or between endpoints difficult and hampers the comparability of results based on this summary statistic. The interpretation of the results from toxicity tests can be improved through process-based modeling, as demonstrated on the current data set.     

Antimicrobial effect of rosemary extracts

A rosemary extract commercially exploited (Oxy'less) as an antioxidant of lipids in foods was dissolved in ethanol (100 mg/ml), and the solution was tested against foodborne microorganisms. For gram-positive bacteria, the MIC of the ethanolic solution was 1% for Leuconostoc mesenteroides, 0.5% for Listeria monocytogenes, 0.5% for Staphylococcus aureus, 0.13% for Streptococcus mutans, and 0.06% for Bacillus cereus. It slowed the growth of Penicillium roquefortii and Botrytis cinerea. Up to 1% of the ethanolic solution had no activity on the gram-negative bacteria Escherichia coli, Salmonella Enteritidis, and Erwinia carotovora and on the yeasts Rhodotorula glutinis and Cryptococcus laurentii. Antibacterial activity of the rosemary extract was strongly influenced by the composition of the media. The MIC was reduced by low pH, high NaCl contents, and low temperatures. Low pH and high NaCl concentration had a synergistic effect on the MIC of the rosemary extract for S. aureus. Lipids, surface-active agents, and some proteins decreased its antibacterial activity, whereas pectin had no effect. The inhibitory effect was little modified by heat treatment (100 degrees C). The natural microflora of pasteurized zucchini broth was inhibited by 0.5% of the rosemary extract. The antibacterial activity was linked to the compounds extracted with hexane, which are presumably phenolic diterpenoids.     

浅新企业文化的"阳伞效应"--有感于企业文化力

阳伞亦即雨伞,用来遮阳避日谓之阳伞,用来御风挡雨谓之雨伞,而把对外能遮阳避日、御风挡雨,对内能整合环境、营造宜人空间,起到类似阳伞反射和吸收太阳辐射作用的现象,笔者称其为"阳伞效应".它能使人不断趋利避害,为人创造"绿色"生存空间.自然界如此,具有强烈人文特色的企业文化同样存在"阳伞效应".