双波长分光光度法测定高粱中的直链淀粉和支链淀粉

直链淀粉和支链淀粉含量及其比例是高粱品质的重要指标。高粱是酿酒的主要原料之一,高粱品质的检测具有十分重要的意义。为此需要寻找一种快速、简便、准确测量高粱中直链淀粉、支链淀粉、淀粉含量的方法。文中以GB7648-87为基础,研究出一种运用双波长测定高粱中直链淀粉和支链淀粉含量的新方法。结果表明,新方法准确性高、重复性好、效率高,工作量小,适于批量分析。     

双波长分光光度法测定高梁中的直链淀粉和支链淀粉

直链淀粉和支链淀粉含量及其比例是高粱品质的重要指标。高粱是酿酒的主要原料之一，高粱品质的检测具有十分重要的意义。为此需要寻找一种快速、简便、准确测量高粱中直链淀粉、支链淀粉、淀粉含量的方法。文中以GB7648-87为基础，研究出一种运用双波长测定高粱中直链淀粉和支链淀粉含量的新方法。结果表明，新方法准确性高、重复性好、效率高，工作量小，适于批量分析。     

双波长分光光度法测定高粱中的直链淀粉和支链淀粉

直链淀粉和支链淀粉含量及其比例是高粱品质的重要指标.高粱是酿酒的主要原料之一,高粱品质的检测具有十分重要的意义.为此需要寻找一种快速、简便、准确测量高粱中直链淀粉、支链淀粉、淀粉含量的方法.文中以GB7648-87为基础,研究出一种运用双波长测定高粱中直链淀粉和支链淀粉含量的新方法.结果表明,新方法准确性高、重复性好、效率高,工作量小,适于批量分析.     

基于NIR的白酒酿酒高粱中关键指标的定量分析

文章基于近红外光谱分析技术(NIR)对酿酒高粱中支链淀粉和直链淀粉含量进行定量分析。采用无信息变量消除法(UVE)、无信息变量消除法结合遗传算法(UVE-GA)、无信息变量消除法结合连续投影算法(UVE-SPA)筛选建模特征波长,并结合偏最小二乘法(PLS)建立酿酒高粱中支链淀粉和直链淀粉定量分析模型。所建立的模型结果表明,上述3种波长筛选方法对模型均有一定程度的优化效果,其中无信息变量消除法结合遗传算法(UVE-GA)光谱波长筛选的方法得到的效果最佳,所建立的支链淀粉和直链淀粉模型的决定系数(R~2)分别为0.9523和0.9417,预测均方根误差(RMSEP)分别为1.2845和0.0901,相对分析误差(RPD)分别为12.1和34.18,模型的精确度和鲁棒性均有所提高,为现代白酒企业快速、简便、准确地测定酿酒原料高粱中直链淀粉和支链淀粉含量提供了科学的参考。     

直链淀粉与支链淀粉相容性研究进展

直链淀粉和支链淀粉之间的相容性直接关系到淀粉类食品的加工性能、形态结构、储存性能以及食用性能等.然而在大多数情况下,直链淀粉和支链淀粉混合物都表现出不相容性,容易造成淀粉类食品的外观无光泽、口感差、淀粉易发生老化等不良现象.综述了近几十年来国内外有关对直链淀粉与支链淀粉相容性的研究现状,并简述了判断直链淀粉与支链淀粉相容性所采用的一些主要分析技术和方法,以便使各种分析技术和方法能更广泛而深入地应用于直链淀粉与支链淀粉相容性研究,为生产具有良好外观、流变学味觉和化学味觉以及良好稳定性的淀粉类食品提供理论指导.     

直链淀粉含量及检测方法与抗性淀粉增抗效应研究

直链淀粉含量及其品质对抗性淀粉的形成有着重要的影响,采用碱液分散法和碘吸光度法测量早米淀粉、葛根淀粉、青稞淀粉、绿豆淀粉、高粱淀粉、藕淀粉6种淀粉类原料的直链淀粉含量,采用循环老化工艺增抗并测定抗性淀粉含量,结果表明,抗性淀粉的得率与原料中的直链淀粉含量有密切的关系,同时,也与各淀粉中直链淀粉和支链淀粉的分子结构、平均聚合度有一定关系,与碘吸光度法相比,碱液分散法测得的直链淀粉含量能更好地预测原料淀粉增抗后的抗性淀粉得率.     

粉葛直链淀粉与支链淀粉分离工艺研究

以粉葛为原料,对粉葛中直链淀粉和支链淀粉的分离工艺进行了研究。根据直链和支链淀粉的理化特性及结构的不同,采用正丁醇-异戊醇配合物沉淀法对粉葛直链和支链淀粉进行粗分离,再经正丁醇重结晶得到较纯的直链与支链淀粉,讨论了分离前对淀粉进行预处理、纯化次数、分离过程中离心时间对分离效果的影响。通过对淀粉-碘复合物光吸收特性分析和蓝值比较,表征分离得到的直链与支链淀粉的纯度。结果表明:直链淀粉纯化5次、支链淀粉纯化6次、分离前经过预处理、支链淀粉纯化时离心时间和速度为30min,5 000r/min的条件下,光谱分析测得的最大吸收波长和蓝值都落在直链淀粉与支链淀粉文献报道结果的相应数值范围内,表明此时分离效果最佳,正丁醇结晶法分离的直链和支链淀粉纯度较高。     

酿酒行业中支链淀粉快速检测方法的研究和应用

为了缩短检测白酒酿造的主原料高粱中支链淀粉含量的时间,减小操作过程中的人为误差。研究建立了快速检测淀粉和直连淀粉含量,通过计算得到支链淀粉含量的方法,对方法的检测效果进行了评价,并与国标方法进行比对,结果表明两者没有显著性差异。     

锥栗中直链和支链淀粉含量同时检测方法研究

用碘作显色剂,以双波长法检测锥栗果仁中支链、直链淀粉含量。对显色反应和光度测定的最佳条件进行考察。按照碘-直链淀粉复合物、碘-支链淀粉复合物各自的吸收光谱,直链淀粉的检测波长定为597nm与460nm,支链淀粉的检测波长定为534nm与706nm。代入回归方程可算出支链、直链淀粉含量。该方法得到的支链、直链淀粉的回收率在97%与102%的范围内窄幅波动,准确度较高。     

双波长比色法测定马铃薯直链/支链淀粉含量

将新鲜马铃薯中的淀粉提出后,采用双波长比色法测定了直链/支链淀粉含量。淀粉经I2-KI溶液染色,直链淀粉呈蓝色,支链淀粉呈紫色。535和570 nm用于直链淀粉含量测定,555和760 nm用于支链淀粉含量测定。结果表明,样品溶解是检测的关键,淀粉与碘试剂的反应时间会对测定结果造成一定影响。同时通过本方法的检测,新大坪品种马铃薯的直链淀粉含量为21.20%,支链淀粉含量为78.80%。     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status