真空管太阳能集热器热风干燥试验研究

随着对食品干燥的需求变多,干燥过程往往要消耗大量能源,课题组提出把真空管太阳能集热器和干燥箱结合起来,对物料进行热风干燥。设计一个带有回风系统的干燥箱,采用控制变量法对胡萝卜热风干燥进行试验研究,分析空气流量、热风温度等因素对干燥箱干燥性能的影响。试验表明:空气流量越大,物料的干燥速率越小;当干燥箱进口的热风温度升高时,物料的热质交换更充分,因此干燥进程得以加快。提出的真空管太阳能集热器热风干燥系统可以达到节能目的并有效快速地对物料进行干燥。     

微波干燥温度和物料厚度对铁棍山药片品质的影响

以新鲜铁棍山药为材料,采用光纤插入物料中心在线控制微波干燥的物料温度、厚度的方式进行干燥,通过单因素试验法进行干燥加工处理,采用索氏提取法提取样品中的多糖,同时采用苯酚硫酸比色法测定经不同干燥参数制备的样品的多糖得率,以自制作微波干燥系统进行重量记录以及物料的温度控制,色差计测样品色泽进而评价干燥的效果。结果发现:在控制不同的物料温度且厚度为5 mm时,最高的多糖得率的物料温度为50℃且此时白度值最大,但所需干燥时间最长;物料温度为60℃时改变物料的厚度,得到最高的多糖得率的物料厚度为5mm。综合比较可知,实际微波干燥生产时以温度60℃且物料厚5mm干燥的效果更好。     

基于模糊控制的南美白对虾冰—低温热泵干燥控制系统设计与试验

目的：满足南美白对虾冰—低温热泵干燥过程中对温度的精细化要求。方法：设计了基于西门子S7-300 PLC的热泵干燥控制系统。该系统采用模糊控制策略,利用Matlab模糊逻辑工具箱设计了“二维输入一维输出”的模糊控制器。根据对虾干燥工艺设计了数据采集程序和执行程序控制干燥箱温度,并通过人机界面对干燥过程进行监控与管理,实现温度的自动控制。结果：模糊控制下冰、低温干燥箱稳态后最大温差分别为0.8,1.1 ℃。与常规PID控制相比,温度波动范围分别减小了46.7%,57.7%;冰—低温联合干燥能够有效去除对虾内的水分,并较好地保留其色泽,且在收缩率与复水率上有一定优势。结论：该控制系统运行稳定,能够快速调节干燥箱温度,且控制精度高,具有良好的控制效果。     

中间水分大豆振动-真空微波联合干燥过程的研究

为了进一步研究中等含水率物料的干燥特性,解决传统干燥方法中物料干燥不均匀、品质下降严重等问题,将振动和真空单元与微波干燥相结合,比较了干燥过程中微波功率、装载量和振动频率对含水率的影响.综合考察了同等条件下热风干燥、传统微波干燥、微波振动干燥和微波真空振动干燥的干燥特性结果表明:在真空度-0.065MPa以下,微波输出功率0.5～ 1.0W/g,传动电机转速350～550r/min的范围内,提高微波功率质量比、增加转速、优化装载量均有助于缩短干燥时间、提高干燥效率;振动-真空微波联合干燥与传统热风干燥相比能耗降低70％,与微波振动干燥相比爆腰率降低60％.在降低能耗量的同时保证了物料的干燥品质.     

利用低场核磁共振技术研究调味山药片真空微波干燥过程中水分的变化规律

为研究调味山药片真空微波干燥过程中内部水分含量、分布及状态变化情况,采用低场核磁共振技术,测定不同微波功率下微波真空干燥过程中的横向弛豫时间T2反演谱,进而分析调味山药片内部的水分状态及其变化规律。结果表明：微波功率越高,自由水和不易流动水被除去所需的时间越短,其中对自由水作用尤为明显,但过高的微波功率会导致物料出现焦化现象;调味山药片干基含水率与核磁共振总峰面积之间呈线性关系,可以预测调味山药片真空微波干燥达到干燥终点所需的时间。核磁共振图像显示调味山药片干燥过程中水分含量的增加和减少均是由外而内,干燥结束时,剩余水主要存在于调味山药内层。水分含量的变化对调味山药片干燥后的品质有显著影响,低场核磁共振及成像技术为调味山药片干燥过程中水分的变化提供了直观的参考依据,本研究可以为调味山药片的真空微波脆化工艺设计、优化干燥参数、控制干燥过程及提高产品质量提供参考。     

金银花环形微波干燥装置的设计与研究

通过对新鲜金银花的微波干燥工艺进行了试验研究。根据工艺试验结果设计了微波干燥设备。该微波灭菌设备由微波发生器、微波干燥箱、排湿系统、控制系统、传动系统、微波漏能抑制机构和机架等组成。对该设备灭菌装置进行了干燥试验,试验结果表明,该装置达到预期设计目标。     

微波干燥稻谷的试验研究

微波是一种具有热效应和较强穿透特性的电磁波,物料吸收大量微波能并将其转化为热能,物料内表同时升温、蒸发带走水分,达到干燥物料的目的。本次试验研究了微波干燥稻谷的应用,介绍了微波干燥稻谷的机理、实验设备以及影响微波干燥稻谷的工艺参数。     

微波干制菠菜工艺参数的试验研究

以提高蔬菜干制品质为目的,采用自制的微波干燥试验装置,研究了不同干燥功率、物料铺放厚度及排湿风速对菠菜微波干燥特性的影响。采用正交试验的极差分析和方差分析方法,分析了不同干燥参数对干制菠菜品质和能耗的影响。结果表明:不同微波干燥参数对菠菜微波干燥特性和干制品质有显著的影响,物料脱水过程主要处于恒速阶段,微波干燥功率为1.125W/g,铺放厚度为1.5cm,风速为75m/min时,可确保菠菜干燥后的食用价值且便于储存,而且能耗较低。     

基于控温的莲子微波干燥特性及干燥品质研究

为了探索基于控温下的莲子微波干燥特性及干燥品质,研究不同微波功率、物料表面温度区间对莲子微波干燥特性的影响,对莲子进行了微波控温干燥试验,并将基于控温下的微波干燥莲子与热风干燥莲子在品质上进行了分析。研究结果表明:物料表面温度对莲子干燥影响较大,物料表面温度区间越大,莲子干燥速率越快,干燥时间越短;微波干燥功率对莲子干燥影响较小。采用7种常见的薄层干燥模型对控温微波干燥过程进行拟合,结果表明Midilli模型是最适合描述在莲子微波控温干燥过程中水分变化规律的薄层干燥模型。根据Fick第二定律得出莲子控温微波干燥的有效扩散系数为8.9891×10-10~2.22431×10-9 m2/s;由Arrhenius方程得出莲子微波控温干燥的活化能为79.85 kJ/mol。两种干燥方式干燥的莲子复水率差异不显著(p>0.05);莲子控温微波最短干燥时间低于热风干燥。研究结果可为莲子控温微波联合干燥工艺提供参考。     

微波干燥粮食初探

微波加热干燥物料与热空气加热的机理不同,微波加热对高水分粮食和具有坚硬外壳物料的干燥效果比热空气干燥效果好。国外有许多有关报导,并研制出大型粮食微波干燥机。国内有关资料很少,玉米、稻谷属于不易干燥的粮食品种,用微波炉对其进行干燥,实验结果表明,经微波加热后影响稻米品质的脱支酶其活力明显下降,而稻米的食用品质和糊化特性变化不大;稻谷、玉米微波干燥应采用低功率、长流程的干燥工艺,稻谷受热温度不超过５０     

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.