不同处理对椰肉贮藏期间酶活性的影响

为明确椰肉中酶活性的影响因素,有针对性地控制酶的活动,研究低温、巴氏、80℃烘干、超高温及微波处理对椰肉贮藏期内中脂肪酶(LPS)、过氧化物酶(POD)和多酚氧化酶(PPO)活性的影响。结果表明：-25℃、低温、巴氏、80℃烘干、超高温和微波处理均对椰肉中的LPS、PPO和POD活性有一定抑制作用。对椰肉进行6 d以内的短期贮藏时,80℃烘干处理对脂肪酶、过氧化物酶和多酚氧化酶抑制作用明显;而对椰肉进行6～12 d长期贮藏时,超高温处理效果显著。通过对新鲜椰肉进行不同的处理,可以达到抑制椰肉内酶活性,提高椰肉品质的目的。     

冷冻对椰肉质构特性以及榨汁后流变学和脂肪球粒度分布特性的影响

冷冻贮藏保鲜是目前普遍公认的最为安全的食品保鲜方法之一,已被工业化广泛应用。本研究采用冷冻贮藏食品中常用的4种温度（-80、-40、-18、-10 ℃）对椰肉进行冷冻处理,经过自然解冻后对椰肉质构、榨汁后椰浆流变学和脂肪球粒度特性进行研究与分析。结果表明,冷冻后椰肉硬度明显减小,且随着冷冻温度的升高而减小;椰浆表现出假塑性流体的特征,冷冻使椰肉榨汁后的椰浆黏度、剪切应力和脂肪球粒度都增加,且随着冷冻温度的升高而增加,脂肪球颗粒均匀度下降。     

浅谈科学贮藏茶叶七种方法

科学贮藏茶叶必须分析茶叶质变的外界因素，讲究贮藏和保管方法。一、影响茶叶品质变化的因素由于茶叶具有吸湿、吸附的特性，加上贮藏过程中茶叶内在因素与外界环境因素的影响，茶叶极易发生变质。这些内外因素主要有以下5点：①茶叶自身含水量是影响茶叶品质劣变的最主要因素，如果茶叶含水量超过7％，则茶叶在贮藏中就易回潮而影响品质。②温度也是引起茶叶品质劣变的主要因素之一，贮藏温度越高，品质劣变越快、越显著，特别是对色泽、汤色、滋味的影响最大。③氧气在茶叶贮藏过程中也是使茶叶产生自动氧化引起质变的主要因素之一。④光…     

干燥剂和除氧剂对茶叶保鲜性能试验

茶叶在贮藏过程中,由于受到外界水分、氧气、光照、湿度等影响,其品质常出现陈化以及变质,这将大大影响茶叶的饮用价值和经济价值。如能控制这些条件,茶叶的变质问题即可防止,笔者在总结前人各种试验的基础上,用变色硅胶、还原性铁粉、硫代硫酸钠进行茶叶贮藏试验。     

红茶色素对香肠保鲜效果研究

香肠在贮藏过程中存在易腐败变质等问题.本文探讨了红茶色素在香肠保鲜中的作用.通过对酸价、过氧化值、TBARs值、色差△E值等理化指标和感官评价的分析,发现红茶色素在香肠贮藏过程中具有良好的保鲜作用,效果优于阳性对照TBHQ和亚硝酸盐.通过模糊评价,筛选出香肠保鲜最佳红茶色素浓度为0.08％.高温加速氧化破坏实验和Arrhenius经验公式预测表明,该浓度下红茶色素能把香肠在20℃、50％相对湿度(RH)条件下的延长货架期20天,延长保质期26％.     

贮藏时间对黑茶品质和功能特性的影响研究进展

茶叶在贮藏过程中因受到外界环境条件的影响使得茶叶中的内含物质和化学成分发生改变,从而影响茶叶感官品质及其功能特性。黑茶属于后发酵茶,因其耐贮藏的特性具有“越陈越香”的特点。本文主要从年份茶的鉴别技术、贮藏时间对黑茶品质及功能特性的影响等方面进行综述,为黑茶产业发展、茶叶收藏爱好者和消费者等提供参考。     

贮藏温度对马铃薯东农303的田间表现及块茎产量影响

<正>1 前 言 块茎贮藏是马铃薯生产管理的重要环节之一。特别是在黑龙江省无霜期较短的气候条件下,种薯块茎的贮藏时间平均在180 d以上。长时间的贮藏显然对种薯块茎的生理产生影响,从而影响以后的生长发育过程。影响块茎的贮藏因素很多,如温度、湿度、氧气浓度和二氧化碳浓度等,但在比较简易的贮藏条件下,只能对温度和湿度进行适当的调节来获得比较好的贮藏条件。然而,品种特性对贮藏条件的反映也有     

不同包装规格与绿茶品质的关系研究

用不同的包装规格，不同的贮藏条件，研究茶叶在贮藏过程中外形、香气、汤色、滋味随时间的变化规律，结果表明，冰箱(0～5℃)贮藏比室内自然贮藏效果要好；外形的变化主要受密封、光线影响；香气主要受密封条件影响；滋味、汤色受光线、温度、水分影响较大；光线对干茶色泽、汤色有较大影响。     

变质豆浆中腐败微生物的分离及其灭杀条件研究

对5种变质豆浆中的腐败微生物进行了分离，并对所分离的腐败微生物进行了感官实验，发现变质豆浆中的主要腐败微生物是三株细菌，而酵母、霉菌未检出。以二次灭菌的豆浆为培养基，通过正交实验确定了三株细菌中的最难杀灭细菌的有效灭菌方法：121℃下灭菌30min，同时添加300mg／kgNisin，该灭菌条件可使豆浆在37℃下贮存30天时细菌菌落未检出，但继续贮存至45天时，细菌菌落数超过100cfu／mL。     

介绍几种茶叶贮藏保鲜方法

茶叶具有很强的吸湿、吸收异气味以及陈化的特性,在贮藏过程中若受到空气、高温、高湿、光照以及不良异气味的影响,极易导致变质变味,甚至失去饮用价值,因此,茶叶的妥善保管甚为重要,下面介绍六种常见的茶叶贮藏保管方法。 1.常规贮藏:一般使用双盖茶听、长颈锡罐、小口陶瓷罐等容器贮茶,茶叶要装满,容器口要密封,置于阴凉、干燥、无不良异气味处妥善保管,这种贮茶方法,家庭常用。也可采用热水瓶的简易贮藏法,将茶叶     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).