贝莱斯芽孢杆菌处理对厚皮甜瓜保鲜效果及保护酶活性的影响

为探究生防菌处理对厚皮甜瓜保鲜效果和保护酶活性的影响,本研究选用西州蜜25号厚皮甜瓜作为研究对象,通过在25 ℃和4 ℃条件下在厚皮甜瓜表面接种贝莱斯芽孢杆菌BG-2,测定贮藏期间拮抗菌在厚皮甜瓜表面定殖特性、保鲜效果和厚皮甜瓜过氧化物酶（Peroxidase,POD）、多酚氧化酶（Polyphenol oxidase,PPO）和苯丙氨酸解氨酶（Phenylalnine ammonialyase,PAL）活性的变化。结果表明,在25 ℃和4 ℃条件下,拮抗菌在厚皮甜瓜表面定殖数量均呈现先上升后下降的趋势且能稳定定殖。接种拮抗菌的厚皮甜瓜腐烂效果、抑制pH和可溶性固形物含量的下降显著优于对照组（P<0.05）。POD和PAL活性呈现先上升后下降的趋势,PPO活性在室温下呈现先上升后下降趋势,在低温下呈现缓慢上升趋势。25 ℃下,拮抗菌处理组POD在第20 d时酶活最高,PAL和PPO在第10 d时酶活最高;4 ℃下,拮抗菌处理组POD和PAL在第20 d时酶活最高。PPO处理在第40 d时酶活最高。且拮抗菌处理过的厚皮甜瓜酶活始终高于病原菌处理组。在25 ℃和4 ℃贝莱斯芽孢杆菌BG-2均能在厚皮甜瓜表皮上稳定定殖,抑制贮藏期厚皮甜瓜腐烂,延缓pH、可溶性固形物、POD、PPO和PAL酶活性下降,且BG-2和低温相结合对上述效果更好。本研究为延长新疆厚皮甜瓜贮藏期提供理论依据,为生防菌作用在厚皮甜瓜采后保鲜提供技术支持。     

1- 甲基环丙烯复合焦亚硫酸钠处理对厚皮甜瓜的保鲜效果

以陕西省阎良区厚皮甜瓜为试材,采用1-甲基环丙烯(1-MCP)、焦亚硫酸钠(Na2S2O5)以及二者结合的处理方法,研究厚皮甜瓜采后生理变化及贮藏品质。结果表明：1-MCP结合Na2S2O5处理能明显延缓厚皮甜瓜硬度下降,抑制可溶性固形物含量快速上升,有效少果实腐烂,同时抑制苯丙氨酸解氨酶和过氧化物酶的活性,使过氧化氢酶和超氧化物岐化酶活性处于较高水平。在这种处理方式下,贮藏80d后,果实腐烂指数0.37、商品果率80%。1-MCP结合Na2S2O5复合处理对厚皮甜瓜具有很好的保鲜效果。     

不同处理方式对厚皮甜瓜的贮藏保鲜效果研究

以陕西省阎良区厚皮甜瓜为试材,采用1-甲基环丙烯(1-MCP)、焦亚硫酸钠(Na2S2O5)、噻苯咪唑(TBZ)结合气调等处理方法,研究了厚皮甜瓜的采后生理变化及贮藏品质,得出了厚皮甜瓜的贮藏方法。结果表明,采用1-MCP结合Na2S2O5处理,能抑制苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)的活性,使过氧化氢酶(CAT)和超氧化物岐化酶(SOD)活性处于较高水平,明显延缓厚皮甜瓜硬度的下降,抑制可溶性固形物含量快速上升,有效地减少果实腐烂,用该处理贮藏80d,果实腐烂指数0.37,商品果率80%。另外,厚皮甜瓜在TBZ结合气调的方式下贮藏也具有较好的贮藏保鲜效果。     

采后热处理对厚皮甜瓜贮藏品质的影响

为探讨采后热处理贮藏厚皮甜瓜的效果,以“玉金香”厚皮甜瓜为试材,研究采后53℃热水浸泡处理3min 对果实贮藏品质的影响。结果表明：热水处理可明显降低果实失重率,在贮藏第10 天时,处理组果实失重率较对照组低32.4%;热处理也可较好地保持果实硬度,在贮藏第10 天时,处理组果实硬度较对照组高30%;热处理还可延缓果实可溶性固形物和可滴定酸含量的下降,较好地保持果实的感官品质。热处理可作为一项采后保鲜措施应用于厚皮甜瓜贮藏。     

采前翠贝喷洒及采后壳聚糖涂膜对厚皮甜瓜低温贮藏期间冷害及品质的影响

厚皮甜瓜(Cucumis melo L.)对低温敏感,在低温条件下贮藏易发生冷害,导致果实品质下降,货架期缩短。本实验以"玛瑙"厚皮甜瓜为材料,研究了在果实发育期(幼果期、膨大期、网纹形成期及采前48 h)单独400 mg/L翠贝4次喷洒、采后单独1.5%壳聚糖涂膜及采前、采后结合处理对果实低温(5℃)贮藏期间冷害及品质的影响。结果表明,采前单独翠贝喷洒或结合采后壳聚糖涂膜均可有效减轻贮藏期间的厚皮甜瓜冷害,明显降低果实细胞膜渗透率和丙二醛(MDA)含量,其中以采前翠贝处理对冷害的控制效果最好,在贮藏第21 d时,处理果实的冷害指数仅相当于对照组的1/3。同样,以上3种处理还延缓了贮藏期间果实可溶性固形物(TSS)和可滴定酸(TA)的下降,保持了果实良好的品质。其中,采前翠贝处理对维持果实的硬度和亮度、色泽效果较好;而采后壳聚糖涂膜对延缓果实TSS下降,降低失重率的效果较为突出。     

臭氧处理对厚皮甜瓜采后生理及贮藏品质的影响

在6℃贮藏条件下,分别对86-1厚皮甜瓜采用浓度为2.5、1.5、0.6μL/L臭氧间隙处理(每48 h处理1次),结果表明,2.5μ/L臭氧间隙处理能显著抑制厚皮甜瓜86-1的呼吸与乙烯的生成,延缓果实的衰老,并显著地抑制可滴定酸和还原糖含量的下降,能明显地延长厚皮甜瓜86-1的贮藏期并维持甜瓜品质.而臭氧处理浓度越低,贮藏效果越差,贮藏期越短.     

不同处理方式对厚皮甜瓜贮藏品质的影响

以‘千玉1号’厚皮甜瓜为试材,采用噻苯咪唑(TBZ)熏蒸、焦亚硫酸钠(Na2S2O5)、1-甲基环丙烯(1-MCP)结合气调贮藏等处理方法,研究了不同处理方式下厚皮甜瓜贮藏期间果实品质的变化。结果表明,厚皮甜瓜经TBZ熏蒸后置于贮藏环境中,放入Na2S2O5和1-MCP,在气体成分5%O2+7%CO2+88%N2、温度(1.0±0.5)℃、相对湿度85%~90%条件下贮藏,能延缓果实可溶性固形物含量和可滴定酸含量下降,减少水分散失,抑制相对电导率上升,有效地保存总糖含量和原果胶含量,降低果实腐烂损失,使果实硬度保持在较高水平。经该处理后贮藏50 d,甜瓜商品果率91%,果实外观新鲜,感官品质良好,保鲜效果理想。     

不同贮藏低温对厚皮甜瓜果实品质的影响

以"金红宝"厚皮甜瓜为材料,研究采后不同低温贮藏(3、7、9℃)对果实贮藏期间品质的影响。结果表明:7℃可有效的维持果实品质,延缓失重率、硬度和TSS的下降,保持TA和VC含量;9℃虽可保持果实的采后品质但总体不如7℃;3℃下果实失重率、硬度、TSS和TA含量下降迅速,VC和果皮色度也显著低于7℃和9℃。由此表明,果实贮藏在3℃下发生了冷害,导致了品质的劣变,7℃可最大限度地保持"金红宝"甜瓜的品质。     

不同臭氧处理对甜瓜采后生理影响

以哈密瓜西州蜜17号为实验材料,在低温(6~8℃,RH80%~85%)环境下对甜瓜分别采取不同臭氧浓度(2.14、4.28、6.42 mg/cm~3)和不同间隔时间(12、24、48 h)处理,每次通入臭氧后进行密闭处理40 min,研究不同臭氧处理对甜瓜在整个贮藏保鲜42 d中的变化。结果表明:臭氧处理能够有效延缓相对电导率的上升,可滴定酸和抗坏血酸平均每天仅下降1.1%、1.2%,臭氧对其下降起到了明显的抑制作用,同时降低了23%的呼吸速率,推迟7 d出现呼吸高峰,腐烂指数仅为对照组的6.8%。臭氧浓度4.28 mg/cm~3、处理间隔时间24 h可以最好的保持甜瓜果实采后品质,延长了低温贮藏时间。本文为甜瓜采后贮运保鲜提供了可行的方法。     

用SPME方法分析不同贮藏方式厚皮甜瓜香气成分的研究

采用固相微萃取(SPME)与气相色谱一质谱联用(GC-MS)的方法,对在6±0.5℃冷藏条件下,采用O24%～6%,CO2 0.2%～0.5%的气体成分进行CA贮藏和每48h处理1次,每次处理时间为3min,处理后臭氧浓度为0.45μL/L的臭氧间隙处理贮藏的新疆厚皮甜瓜"金凤凰"的香气成分进行了比较研究.贮藏52d时,上述两种贮藏方式的厚皮甜瓜中分别测定出30余种挥发性物质,其中CA贮藏的厚皮甜瓜中检测出20种酯类,占峰面积的85.49%,臭氧间隙处理的厚皮甜瓜中检测出17种酯类,占峰面积的67.15%.研究表明,酯类是构成厚皮甜瓜香气的主要成分.两种贮藏方式的厚皮甜瓜在贮藏52d时,挥发性物质的组成和相对含量差异显著,与臭氧间隙处理相比,O24%～6%,CO20.2%～0.5%的CA贮藏更能有效地保持厚皮甜瓜中的香气成分.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status