高氧处理对草莓果实抗氧化活性的影响

研究了60%和100%O2处理对草莓在5℃15d冷藏及后续20℃空气中1d货架存放期间果实Vc、总酚和花青素含量及抗氧化活性的影响。结果表明,采用60%和100%O2处理能有效抑制草莓果实Vc含量的下降,促进总酚和花青素含量及DPPH自由基清除能力的上升,从而提高了草莓果实的抗氧化活性。统计分析表明,总酚和花青素与DPPH自由基清除能力间具有显著的线性正相关关系,相关系数分别为0.8454和0.8997。因此,高氧处理提高草莓果实的抗氧化活性与果实总酚和花青素含量的增加有关。     

适宜后熟对猕猴桃果实冷藏后货架品质的影响

该文以‘贵长’猕猴桃为试材,研究适宜后熟对其冷藏后货架品质的影响。结果表明,猕猴桃果实采收后于阴凉处散去田间热,然后转入(4±0.5)℃贮藏,冷藏后货架成熟时果实呼吸速率、乙烯释放速率显著增加,抗氧化物质含量低,超氧阴离子(O-2)和H 2O 2快速积累,活性氧代谢失衡,从而导致其在冷藏40 d后货架时全部腐烂。猕猴桃果实后熟至可溶性固形物9.5%时再转入(4±0.5)℃贮藏,可有效抑制其冷藏后货架时呼吸速率和乙烯释放速率,减少果实营养物质损耗,维持果实抗氧化物含量和活性氧代谢平衡,进而降低果实的腐烂率,延长冷藏期。然而,猕猴桃果实后熟至可溶性固形物含量14.5%再冷藏则加速猕猴桃果实腐烂。因此,适宜后熟通过抑制乙烯释放速率、提高抗氧化物酶活性、维持活性氧代谢平衡来维持其冷藏后货架品质,为猕猴桃贮藏保鲜技术开发奠定了理论基础。     

草莓果实热空气和茉莉酸甲酯复合处理保鲜条件优化

探索热空气和茉莉酸甲酯(MeJA)复合处理对草莓果实保鲜的效果及其最优条件。采用响应曲面法研究不同复合处理条件对草莓果实在(5±1)℃、12d冷藏加20℃模拟货架1d后果实腐烂和主要品质指标的影响。结果表明草莓果实热空气和MeJA复合处理的最优条件为处理温度45.18℃、时间2.86h、MeJA浓度10.74μmol/L,验证实验说明该复合处理能有效抑制草莓果实腐烂,保持果实品质,且效果要显著优于两者单独处理。     

1-MCP对不同成熟度红阳猕猴桃保鲜效果及后熟品质的影响

旨在探究1-MCP对不同成熟度红阳猕猴桃保鲜效果及后熟品质的影响。研究在红阳猕猴桃不同成熟度期间[采收期Ⅰ(果实生长发育期110 d)、采收期Ⅱ(果实生长发育期120 d)、采收期Ⅲ(果实生长发育期130 d)、采收期Ⅳ(果实生长发育期140 d)]对其进行采收,通过浓度为0.5μL/L的1-MCP对果实进行熏蒸处理24 h[(25±1)℃],在冷藏(0±0.3)℃及货架[(25±1)℃]条件下研究其对果实的保鲜效果和后熟品质的变化。研究表明:适宜的采收期能够抑制果实的生理代谢,延长果实的贮藏期和维持更好的后熟品质。过早采收的果实(生长发育期110 d)干物质积累少,淀粉含量高,风味较差,果心硬度大,并且出现冷害症状;采收期过晚(生长发育期140 d)的果实成熟度最高,呼吸强度旺盛,不耐贮藏,商品价值最低;而采收期Ⅱ(生长发育期120 d)的果实贮藏期间代谢强度较低,保持了果实更好的硬度,在货架12 d时的果实腐烂率仅为14.86%,抑制了可溶性固形物含量、可滴定酸含量、Vc含量及原果胶含量的损失,延缓了水溶性果胶的上升,并且维持了SOD活性和POD活性,保证了果实的贮藏品质和后熟口感,其商品价值最高;采收期Ⅲ(生长发育期130 d)的果实腐烂率在货架12 d时为19.12%,并且1-MCP也能够较好地抑制果实的成熟衰老,维持了果实较好的口感,其商品价值次之。因此,红阳猕猴桃1-MCP处理的适宜采收期为生长发育期(120~130)d,适合长期贮藏。     

不同剂量60Co γ辐照对蓝莓果实贮藏品质的影响

目的探索~(60)Coγ辐照处理对蓝莓果实保鲜效果的影响。方法采用不同的辐照剂量处理"蓝丰"蓝莓,以辐照的蓝莓为研究对象,研究其果实表面微生物的种类和数量、果实腐烂率和硬度、以及相关感官品质在冷藏期间的变化规律。结果辐照处理对蓝莓果实表面微生物有很好的杀灭和抑制作用,辐照剂量越高,效果越好,且微生物对辐照剂量的敏感程度依次为:细菌霉菌酵母菌。0.5 kGy的辐照处理对冷藏期间蓝莓果实保鲜效果不明显(P0.05),3.0 kGy的辐照处理能够加速冷藏后期蓝莓的腐烂变质,适当的辐照剂量(1.0~2.5 kGy)能够很好地降低腐烂率,保持果实硬度和保护果实感官品质,其中2.5 kGy辐照剂量对蓝莓果实的保鲜效果最佳,贮藏35 d后,果实腐烂率最低(3.35%),果实硬度最高(1.08 kg/cm~2)。结论辐照保鲜蓝莓的最低有效剂量为1.0 kGy,最高耐受剂量为2.5 kGy,本研究为蓝莓的辐照保鲜提供了应用基础和科学依据。     

采后热处理对草莓果实货架品质的影响

在预实验基础上,采用热空气46℃-1h、48℃-30min,热水浸润44℃-20min、46℃-15min对采后新鲜草莓(品种:永丰)进行热处理。处理后的草莓置(1±0.5)℃条件下冷藏1d,(20±1)℃条件下3d,对果实的呼吸作用和品质进行检测,发现处理后果实的呼吸作用明显减弱,热处理能够有效地起到防腐抑菌的作用,热水浸润处理对于根霉生长繁殖的抑制作用明显。48℃热空气处理30min和44℃热水浸润20min的果实具有较好的货架品质。     

短期N2处理对冷藏猕猴桃衰老及货架期软化的影响

目的:研究短期N2处理时冷藏猕猴桃果实衰老及其货架期间软化的影响.方法:采用纯氮处理猕猴桃果实6 h,然后用聚乙烯薄膜袋(0.025 mm)包装,每袋1 kg,置于0～1℃下贮藏.每隔7 d取样,28 d后将果实置于常温(20℃)下观察.结果:短期N2处理抑制了猕猴桃果实冷藏期间总酸含量的下降,降低了可溶性固形物含量的增加幅度,并保持较高的VC含量;显著抑制了果实硬度的下降,尤其是前7 d硬度的快速下降;降低了冷藏果实(贮藏28 d)呼吸速率和乙烯释放速率的增加,提高了果实的抗氧化能力,较好地保持了细胞膜的完整性.此外,短期N2处理降低了称猴桃果实冷藏28 d后常温货架期间前3 d乙烯释放速率的增加,抑制了果肉硬度的下降,延缓了果实的后熟软化.结论:短期N2处理明显抑制了冷藏猕猴桃果实的衰老,改善了贮藏品质,延缓了常温货架期间果实的软化,保持了果实较好的商品性.     

采后热空气处理对嘎拉苹果品质及后熟特性的影响

研究采后热空气处理(38℃/4d)对嘎拉苹果品质及后熟特性的影响。嘎拉苹果采后立即经38℃、4d的热空气处理,后0℃冷藏6w。冷藏结束后取出,20℃下存放1w模拟货架。贮藏中或货架后测定各品质及后熟指标。研究发现,热空气处理降低了贮藏过程中果实的呼吸强度和乙烯释放量,加速了固酸比的上升和果皮的黄化,延缓了贮藏过程中果实的软化,降低冷藏末期和货架期后的细胞膜透性。货架期后,热处理组嘎拉苹果保持了更好的质地品质,感官评定发现热处理提高了贮藏后嘎拉苹果的硬度和脆度,提高了可接受度。可见,该热处理能较好保持嘎拉苹果贮藏品质,同时延缓其后熟。     

热水喷淋处理对草莓果实采后腐烂和品质的影响

本实验验采用55、60和65℃,20s热水喷淋(hot water rinsing and brushing,HWRB)处理"丰香"草莓,研究此热处理对常温贮藏(20℃ 3d)和冷藏(0℃12d)后的果实腐烂和品质的影响.研究发现,热水喷淋处理能显著降低处理后果实表面的微生物数量,有效抑制果实失重率和呼吸强度的上升,保持了较高的VC含量;经65℃热水处理的果实发病率最低,但部分果实在处理后其表面出现漂白干缩的现象,影响了它们的商品价值.60℃热水喷淋处理使果实的发病率显著低于对照组,在冷藏下对病害的防治效果更好,同时对果实的颜色、硬度、可溶性固形物和可滴定酸含量未产生不良影响,所以比较适合草莓的采后防腐保鲜处理.     

1-MCP对不同采收期“五九香”梨冷藏品质的影响

针对"五九香"梨果实长期冷藏和货架期间容易软化和产生黑皮的现象,本研究对3个采收期采收的"五九香"梨进行1.0μL/L 1-甲基环丙烯(1-MCP)处理,继而进行0℃冷藏和20℃货架贮藏。结果表明,冷藏期间,"五九香"梨果实的硬度下降,可溶性固形物含量(SSC)升高,黑皮和黑心增多,货架期间更为明显。1-MCP处理对冷藏期间"五九香"梨果实硬度和SSC的影响较小,但明显延缓冷藏后货架期果实软化和SSC升高,并且果实采收越晚,1-MCP的作用效果越显著;1-MCP还降低冷藏和货架期间黑皮指数和果心褐变指数,并以货架期间的效果明显,显著抑制果皮α-法尼烯及共轭三烯的生成。综合分析认为,1-MCP处理明显减少"五九香"梨货架期软化和黑皮现象,并对早期采收的"五九香"梨果实冷藏和货架期间的品质维持较好。1-MCP减少"五九香"梨黑皮发生的原因与抑制果皮共轭三烯的生成有密切的关系。     

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.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.