低温和低氧储藏对糙米发芽前后γ-氨基丁酸含量的影响

通过测定糙米在不同温度(-18、4、10℃、室温)和不同气体储藏环境(CO2、N2、空气、真空)下的发芽前后GABA含量、GAD和蛋白酶活力变化,以及储藏后糙米的发芽率、细胞膜透性、脂肪酸值、MDA值和淀粉粒微观形态,以确定生产高GABA发芽糙米的适宜储藏条件。结果表明,储藏早期(0~90 d),10℃储藏适于维持糙米中GABA含量,储藏60 d时糙米中GABA含量高出室温下64.46%;4℃和-18℃适于维持发芽糙米中GABA含量,储藏120 d时糙米发芽72 h后GABA含量分别高出室温下124.24%和43.59%。在N2和CO2环境中储藏可有效减缓糙米中GABA含量的下降,其中CO2较适于高GABA糙米的短期储藏,在30d时高出空气环境下储藏的98.80%;低氧储藏有利于糙米发芽后GABA的积累,在N2、CO2、真空条件下储藏60 d时发芽糙米中GABA含量分别高出空气储藏下70.58%、55.39%、71.53%。     

顶空固相微萃取-气质联用分析不同储藏条件下小麦粉挥发性成分变化

利用顶空固相微萃取和气相色谱-质谱(HS-SPME-GC/MS)对不同储藏条件下的小麦粉挥发性成分进行研究。对固相微萃取头、萃取温度、萃取时间和解析时间进行条件优化。实验结果表明:小麦粉挥发性成分的最佳分析条件为,萃取头DVB/CAR/PDMS;萃取温度80℃;萃取时间60 min;解析时间3 min。经鉴定分析小麦粉中挥发性成分主要有烃类、醛类、酮类、醇类、有机酸及杂环类等多种成分。原样和储后2个月样中最高的是烃类和醛类,其次为醇类、酮类。储藏2个月后,变化较明显的挥发性物质有己醛、苯甲醛、辛醛2、-壬醛、己醇、十二烷、十六烷和十八烷。     

油菜籽热风干燥后储藏品质的研究

油菜籽经过热风干燥后置于模拟度夏条件下储藏,测定其储藏期间的水分含量、发芽能力、油的酸值、油的过氧化值等品质变化;并用固相微萃取-气质联用法测定储藏期间菜籽的挥发性成分,探索菜籽挥发性成分与菜籽品质之间的关系.结果表明:种用菜籽的干燥温度控制在70℃以下为宜;菜籽油的酸值在储藏期间波动在0.21～0.28 mg/g范围内,属于国家二级油品质;油的过氧化值总体呈现缓慢波动上升的趋势,保持在0.22～ 2.65 mmol/kg范围,为国家一级油品质,经110℃高温干燥的菜籽的油过氧化值在储藏至第5个月后开始呈现劣变趋势;挥发性成分2-乙基-1-己醇随着储藏时间的延长,相对含量下降;酸类挥发性成分呈现波动上升的趋势,与菜籽的过氧化值具有很强的线性正相关性.     

发芽糙米在不同储存温度下品质变化的研究

采用模拟发芽糙米在打开包装的状态,通过比较发芽糙米水分、脂肪酸值、直链淀粉、γ-氨基丁酸、霉菌含量和细菌总数的变化,研究发芽糙米在5℃、常温(秋季)、35℃3种不同储存温度下品质的变化。结果表明:发芽糙米在存放过程中,温度对其水分、直链淀粉含量影响较小;但是对其γ-氨基丁酸、霉菌含量和细菌总数影响显著。发芽糙米在高温下储存,品质极易变坏,低温有利于发芽糙米的储存。     

储藏期对发芽糙米富集γ-氨基丁酸的影响

以早籼稻品种"早944"为对象,测定储藏0～27个月期间,其糙米发芽率、发芽72 h时谷氨酸脱羧酶活力及γ-氨基丁酸的变化,以研究原料储藏期对发芽糙米富集γ-氨基丁酸的影响。结果表明,随着储藏期的延长,发芽率、谷氨酸脱羧酶活力及γ-氨基丁酸含量下降显著(P<0.05),且下降速率加快。糙米发芽率月平均下降速率为2.03%,谷氨酸脱羧酶月平均失活速率为0.09 U/100 g,γ-氨基丁酸含量月平均下降速率为1.10 mg/100 g。经相关性分析,发芽糙米中谷氨酸脱羧酶活力与γ-氨基丁酸含量呈极显著正相关(r=0.969 5,P<0.01)。     

加热温度对南美白对虾挥发性成分的影响

采用电子鼻和固相微萃取-气相色谱-质谱（solid phase microextraction gas chromatography-massspectrometry,SPME-GC-MS）联用技术分析不同温度条件下南美白对虾虾肉的挥发性气味成分。电子鼻结果显示不同温度处理对虾肉的挥发性成分的影响较显著,35 ℃和45 ℃的挥发性成分类似但仍有差异;SPME-GC-MS分析得出,南美白对虾虾肉在35、45、60、80、95 ℃分别确定出21、24、36、43 种和49 种挥发性成分。35 ℃检测的挥发性成分可代表生虾肉,其中对风味影响较显著的有1-戊醇、1-辛烯-3-醇、壬醛等。随着温度的升高,挥发性成分中的烷烃类物质相对含量显著升高、醇类物质相对含量减少、碳原子大于10以上的饱和醛种类以及相对含量增加、芳香族化合物更加丰富。95 ℃检测出的挥发性成分可代表熟虾肉,其中对风味影响较大主要是十六醛、十八醛、二丁基羟基甲苯等。     

超声波处理对发芽糙米主要成分变化的影响

采用28kHz和40kHz的超声波对糙米进行0、2、4、8、16和32min处理后35℃下发芽24h,分析发芽糙米主要成分和相关酶活性的变化。结果表明,两种频率的超声波处理均可提高发芽糙米中可溶性蛋白和游离氨基酸、γ-氨基丁酸含量,且分别在8min和16min达到峰值。较长时间处理时,28kHz有助于糙米发芽过程中淀粉的降解和还原糖的生成;40kHz能显著提高发芽糙米的α-淀粉酶活力。     

糙米发芽的制备技术研究

以重庆主要种植的稻米为试材,研究了其糙米制备发芽糙米的工艺技术和主要成分变化。结果表明,制备发芽糙米的最适稻米品种为丰优香粘,其最适工艺技术条件为浸泡温度30℃、浸泡时间15 h、发芽温度35℃、发芽时间25 h;发芽糙米中淀粉含量低于精白米和糙米,还原糖、蛋白质、γ-氨基丁酸和游离氨基酸含量均高于精白米和糙米。     

超高压处理对发芽糙米酒中γ-氨基丁酸及挥发性成分的影响

以发芽糙米为原料酿造米酒,对发芽温度、发芽时间、超高压处理压力、超高压处理时间进行单因素实验,考察不同条件下酒中γ-氨基丁酸(γ-aminobutyric acid,GABA)含量,并对米酒成品采用顶空固相微萃取(HS-SPME)结合气相色谱质谱联用(GC/MS)技术检测发芽糙米酒中的挥发性成分。结果显示,发芽条件为温度28℃、时间20 h,获得的发芽糙米GABA含量较高,为346.7 μg/g。发酵后获得的发芽糙米酒GABA含量为24.7 mg/L。在超高压处理压力200 MPa、超高压处理时间30 min,获得的糙米酒成品GABA含量较高,达到27.4 mg/L。在200 MPa处理后的发芽糙米酒中共检测出醇类12种,酯类20种,酮类5种,酸类1种。相较于未经超高压处理的发芽糙米酒,超高压处理后的发芽糙米酒中酯类种类增加,醇类含量减少,酸类含量减少。通过感官评价,发现200和300 MPa处理的样品均优于未处理组,说明加压处理提高了发芽糙米酒的滋味,大大提高了米酒的风味品质。     

发芽糙米产品开发与应用前景

发芽糙米作为一种新型功能性食品,可提高稻米附加值,丰富米制品市场。该文评述发芽糙米活性成分、制备工艺和产品开发的研究现状,并提出以下研究和开发方向:(1)拓宽原料来源,深入研究糙米品种中GABA含量差异的内在机理,选育高含量品种作为发芽原料;优化发芽工艺、富集GABA,并研究其后续加工和储藏的变化规律;解析发芽率较低的储备早籼稻谷中GABA的变化规律,拓宽储备稻谷用途和降低原料成本。(2)研究植酸在发芽糙米内源酶作用下的转化规律和富集利用。(3)开发和优化发芽糙米生产效率和降低生产成本关键技术。(4)开发控制发芽过程的微生物含量新技术,保证产品安全。     

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.