发酵香肠的pH值、水分含量与水分活度(Aw)的关系及其对制品贮藏性的影响

对发酵香肠的 pH值、水分含量与水分活度 (Aw)的关系及其对制品贮藏性的影响作了初步的研究。结果表明 :水分活度的下降与 pH值及水分含量均是呈直线关系 ,随制品 pH和水分含量的降低 ,水分活度逐渐下降 ,但 pH值对水分活度的影响较小 ,水分含量影响较大。香肠的 pH值、水分含量和水分活度值越底其贮藏稳定性越高。     

面包加工工艺中水分的变化研究

采用红外水分测定仪测定面包在发酵、烘烤和冷却过程中各层水分的变化,研究面包在发酵、烘烤和冷却过程中各层水分的变化规律。面包面团在发酵过程中,皮部、瓤部和整个面包的水分含量上升,面包面团皮部水分上升12.7%,瓤部水分上升0.4%,整个面团上升0.8%。面包在烘焙过程中,热量随着水分汽化冷凝由面包皮层向瓤部转移而传递的,面包瓤部水分也因之升高,面包皮层水分蒸发降低。面包皮层水分从43%降到4.1%,面包瓤部水分先增加后减少,最高达到45.3%,烘烤结束后水分为44.6%,水分增加1.6%,面包整体水分下降7.5%。面包在冷却过程中,水分从面包瓤向皮部转移,面包皮层水分上升,瓤部水分下降。面包冷却结束时,水分从内到外依次下降。450 g面包在15℃下冷却30 min,水分下降到36%,达到面包包装要求的温度和水分指标。     

三明治贮藏过程中的水分迁移特性研究

三明治面包属于多组分食品,在其贮藏过程中水分从水分含量较高的馅中迁移到水分含量相对较低的面包中,导致了各部分感官质地的变化。水分迁移的发生主要是由于不同部位之间水分活度梯度的存在而引起的。影响水分迁移的因素有:水分活度梯度大小、贮藏温度、油脂含量等。水分活度梯度越大,水分迁移量及其速率越大;低温贮存4℃可以延缓水分的迁移速率;而面包部分中油脂的含量对水分迁移几乎没有影响,但在馅中添加油脂可以在一定程度上减少水分的迁移。     

浅析如何减少快速水分测定仪测定误差

用快速水分测定仪测定水分的过程中,样品中的杂质、样品水分过高或者过低、粮食颗粒水分不均匀、粮食颗粒过大均有可能影响测定的准确性。通过样品除杂与不除杂检测结果与标准法测定结果的对比、选取不同水分梯度的样品用快速水分测定仪测定水分、选取正常水分和高水分的样品按不同比例混合并与标准法测定水分的对比、选取已测定容重的样品用快速水分测定仪测定水分并与标准法测定水分的对比,确定以上因素对快速水分测定仪测定水分准确性的影响,分析误差产生的原因,并采取相应的措施以减少误差。     

水分含量对软烤扇贝质构和色泽的影响

通过分析不同水分含量软烤扇贝的质构特性和色度指标,探讨软烤扇贝水分含量与质构特性和色差指标的相关性.结果表明,软烤扇贝的水分含量与硬度、内聚性、回复性随着水分含量的下降而增大,硬度变化最为明显,弹性、胶黏性、咀嚼性随着水分含量的下降而减小,并且相关性显著.软烤扇贝的色泽随水分含量而变化,水分含量下降时,其L*值下降,a*、b*值上升.水分含量与水分活度之间具有良好的线性关系.     

3种不同检测方法测定大豆水分含量的差异分析

目的对比国标法、整粒烘ASAE法和快速水分法3种不同水分检测方法测定大豆水分含量的结果差异。方法取自3种不同产地的大豆,包括巴西大豆、美国大豆和国产大豆,进行大豆整籽粒和粉碎后的水分测定实验来比较大豆水分含量差异。同时对2种谷物粉碎仪差异进行了比较。结果以进口巴西大豆为例,用国标法测定水分平均值为7.76%,其中谷物磨测量值为7.75%,万用粉碎仪测量值为7.78%;ASAE法测得水分值为10.39%,快速水分仪测定值为10.7%。国标法水分测量值低于用ASAE法和快速水分仪法,且不同的粉碎磨粉碎后的水分测量值无明显差异(P 0.05)。通过对比,ASAE法和快速水分法测定的大豆整籽粒水分含量比较接近真实值,而粉碎后测得的水分含量比真实值低。结果表明,国标法中将大豆粉碎后水分测量值低于用ASAE法和快速水分仪法整籽粒法水分测量值(P0.05),且不同的粉碎磨粉碎后的水分测量值无明显差异。结论结合实际现场测量的实验环境、实验周期和成本等因素考虑,推荐谷物快速水分法为最佳检测方法。     

发酵香菇香肠理化特性变化研究

通过对香菇香肠发酵及干燥过程中的pH值、水分含量与水分活度（Aw）的测定与分析,发现香菇中水分活度与pH值及水分含量都呈线性关系,影响水分活度的主要因素是水分含量的变化。并对香菇香肠贮藏条件作了初步研究。     

微冻保鲜真鲷的水分迁移规律

对微冻保鲜条件下真鲷背部、腹部、尾部肌肉的水分含量、水分活度以及水分状态随贮藏时间的变化情况进行研究,并分析了各项指标的相关性。结果表明:随着微冻贮藏时间的延长,真鲷各部位的水分含量和水分活度变化趋势大体一致,呈现先降低后升高再降低的趋势。其中真鲷背部的水分含量最高,腹部含水量最低,二者差异显著(P0.05)。从水分活度来看,真鲷腹部的水分活度随贮藏时间变化较大,与背部和尾部的水分活度变化趋势一致。水分含量与水分活度的相关性不显著。从水分状态上看,真鲷肌肉中不易流动水含量最高,占88%~92%,不易流动水p T22与自由水p T23含量呈显著负相关性。贮藏后期,不易流动水的比例降低,自由水比例升高。     

烟片输送网自动补偿温湿度装置的应用与研究

在打叶复烤生产中,常对运输过程关键点中的物料水分、温度等进行测量分析。物料运输过程中,料层高度不同的物料水分和温度不同。表层物料长时间与空气接触,水分、温度散失严重。若不符合工艺标准水分的物料返入叶柜,会导致叶烤机入口来料水分不均匀,增加复烤操作难度。若小水分物料二次加工,会造成成品水分不均,预压装箱成品造碎率增加,烟叶水分和烟碱变异系数增大,影响产品质量。     

食品贮藏中水分的转移

<正>食品的水分转移不同于水分蒸发,水分蒸发是指食品中的水气化挥发,食品的含水量减小,重量减轻;而水分转移是水分在食品之间的传递,可分为两种情况:一种是在     

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