不同包装方式对鲜切秦冠苹果贮藏品质的影响

以市售秦冠苹果为试材,结合柠檬酸保鲜剂处理,研究4 ℃贮藏条件下,普通包装、真空包装、高氧包装及充氮包装对鲜切秦冠苹贮藏品质变化规律的影响,确定最佳包装方式。结果表明:在综合鲜切苹果贮藏期各项指标的前提下,真空包装对鲜切苹果保鲜效果最佳,使鲜切苹果外观品质得以保持,延缓鲜切苹果的褐变进程和可溶性固形物含量降低速率,同时抑制了鲜切苹果贮藏期间多酚氧化酶(polyphenol oxidase,PPO)和过氧化物酶(peroxidase,POD)活性,减缓丙二醛(malondiadehyde,MDA)含量的升高。     

贮藏温度对鲜切菠萝生化品质的影响

为了保持和改善鲜切菠萝的贮藏品质,研究不同贮藏温度(0、4、6、8和12℃)对鲜切菠萝的品质及理化特性的影响.结果表明:0～4℃贮藏能够显著抑制鲜切菠萝的硬度下降现象以及含糖量(TSS)、含酸量(TA)和VC含量的降解损失,维持鲜切果实较低的多酚氧化酶(PPO)活性和过氧化物酶(POD)活性,延缓果实细胞膜透性的上升和丙二醛(MDA)含量的积累,使鲜切果实的感官和综合品质好,贮藏寿命长于6、8和12℃的果实.在0、4、6、8和12℃条件下,温度越高,鲜切菠萝的品质劣变越快.建议04℃为九成熟菠萝鲜切产品保鲜的适宜温度.     

热处理条件筛选及其提高鲜切芋头贮藏品质的生理机制

为延长鲜切芋头贮藏期,本文研究热处理温度和时长对鲜切芋头贮藏品质的影响,并探究热处理控制鲜切芋头褐变的生理机理。结果表明,38、60和100 ℃的热处理均能降低鲜切芋头失重率、延缓硬度下降、抑制褐变,表明热处理能提高鲜切芋头的贮藏品质。60 ℃热处理效果最好,且60 ℃热处理1 min的保鲜效果要好于同温度下30 s和3 min的热处理效果。热处理降低了鲜切芋头总酚含量,抑制了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性,延缓了鲜切芋头的酶促褐变。     

抗褐变剂和充气包装对鲜切芋头保鲜效果的研究

研究了抗褐变剂和充气包装(MAP)对4℃贮藏下鲜切芋头品质的影响,定期测定了鲜切芋头的色差、褐变度、相对电导率和多酚氧化酶(PPO)的活性,结果表明:抗褐变的最佳抑制剂组合为0.05% N-乙酰-L-半胱氨酸(NAC)+0.05% L-半胱氨酸;MAP处理以5% CO2+2% O2+93% N2的保鲜效果较好,6 d时鲜切芋头的感官品质仍在可接受的范围内。     

薄膜包装对鲜切芹菜抗氧化活性的影响

为研究不同薄膜包装对鲜切芹菜抗氧化能力的影响,文中以南京地产香芹为试验材料,采用2种薄膜(P1-12.75μm聚乙烯袋,P2-32.70μm聚乙烯袋)对芹菜进行包装处理,以12.75μm带孔聚乙烯袋包装作为对照(CK),在温度(7±1)°C,相对湿度80%~90%环境下贮藏。结果表明:鲜切芹菜在贮藏过程中,超氧化物歧化酶(SOD)活性下降,过氧化氢酶(CAT)活性先上升后下降,过氧化物酶(POD)活性在贮藏前期缓慢上升,后期出现峰值和波动,表明芹菜衰老加速。与对照相比,薄膜包装提高了DPPH、超氧阴离子自由基(O-2·)、羟基自由基(·OH)的清除能力和CAT、POD活性,P2薄膜包装还延缓了丙二醛(MDA)的积累、SOD活性下降和POD活性峰值的出现,表明薄膜包装能有效延缓鲜切芹菜的衰老进程,其中P2薄膜包装效果更佳。     

热处理联合不同包装对鲜切马铃薯贮藏品质的影响

为解决鲜切马铃薯贮藏品质劣变快、货架期短的问题,本研究探讨45℃热处理3 min联合真空包装和30%CO2+70%N2气调包装对鲜切马铃薯贮藏品质的影响。结果表明：热处理联合气调包装可延缓鲜切马铃薯呼吸速率的上升,显著抑制丙二醛（malondialdehyde,MDA）含量上升及苯丙氨酸解氨酶（phenylalanine ammonia-lyase,PAL）、过氧化物酶（peroxidase,POD）、多酚氧化酶（polyphenol oxidase,PPO）活力（P<0.05）,有效维持总酚、抗坏血酸（ascorbic acid,AsA）、可溶性固形物含量（soluble solids content,SSC）和淀粉含量,抑制细菌菌落总数的增长,保持马铃薯原有挥发性风味和感官品质。综上,热处理联合气调包装可以使鲜切马铃薯保持较好的感官和营养品质,抑制微生物生长以及褐变酶活性,从而延长鲜切马铃薯货架期。     

百里香精油抗菌涂层包装对鲜切生菜货架期内理化品质及微生物的影响

精油抗菌涂层包装是一种环保的包装技术。文中利用百里香精油抗菌涂层包装膜包装鲜切生菜,通过检测鲜切生菜货架期内的呼吸强度、抗坏血酸含量、多酚氧化酶活性、菌落总数等指标,并结合生菜感官品质,对比普通PE食品保鲜膜与抗菌包装膜在不同贮藏温度下(1、4、10℃)的保鲜效果差异,最后通过荧光假单胞菌的回接实验探究薄膜对鲜切生菜的优势腐败菌的抑制效果。结果表明:精油抗菌包装膜能较好地抑制鲜切生菜的呼吸强度、微生物生长及多酚氧化酶的活性,减少贮藏期内VC的损失,维持生菜良好的感官品质。当与4℃的低温贮藏结合时,可将鲜切生菜的货架期延长至5 d。     

气调包装对鲜切莲藕保鲜效果研究

为保持鲜切莲藕贮藏品质、延长货架期,研究气调包装对鲜切莲藕的保鲜效果.采用8种不同浓度配比的O2、N2和CO2气体对鲜切莲藕进行包装,置于4℃下贮藏,定期测定鲜切莲藕VC的含量、多酚氧化酶活性、褐变度以及pH值变化.结果表明:鲜切莲藕多酚氧化酶的活性与其褐变度有着密切关系,100%O2组处理的鲜切莲藕,其外观最好,多酚氧化酶活性受到抑制,VC含量比对照组的损失最小,pH值下降幅度比对照组低.     

外源乙烯对鲜切甘薯伤害生理效应的影响

采用新鲜甘薯为实验材料,经切割处理后,在4℃条件下,将鲜切甘薯在浓度为100、1000、10000μL/L的乙烯环境中密闭处理4℃,24h后进行贮藏。贮藏期间分析测定了鲜切甘薯颜色、失重率、呼吸强度、MDA(丙二醛)含量、LOX(脂氧合酶)和PPO(多酚氧化酶)活性等生理生化指标。结果发现:与对照相比,不同浓度的乙烯处理均可保持鲜切甘薯的色泽和失重率。低浓度的外源乙烯可抑制MDA含量的增加,外源乙烯对LOX的作用与其对MDA的作用一致。高浓度的外源乙烯可提高贮藏前期鲜切甘薯PPO活性,低浓度外源乙烯则提高了贮藏后期鲜切甘薯PPO活性,高浓度的外源乙烯处理可能通过增加了内源乙烯的合成,进而加速了呼吸代谢和衰老的速率。综合考虑,100μL/L的外源乙烯处理提高了鲜切甘薯的品质和抗性。     

柠檬酸处理抑制鲜切香蕉褐变的研究

研究在4℃贮藏条件下不同浓度柠檬酸处理鲜切香蕉防褐变效果的影响.结果表明,适宜浓度的柠檬酸处理能显著延缓鲜切香蕉失重率的下降,同时还抑制了鲜切香蕉多酚氧化酶(PPO)及过氧化物酶(POD)活性,降低了丙二醛(MDA)含量,有利于保持鲜切香蕉良好的外观品质和营养价值.综合各项理化指标来看,2.0％柠檬酸处理的贮藏效果最佳,1.0％柠檬酸处理次之.     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

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

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the