稻米食味品质测定技术胶稠度测定的重要性及其测定的影响因素

稻米食味品质是稻米品质指标的重要组成部分,对稻米食味品质评价技术的研究可指导流通过程中稻米品质优劣的评价,且对优质稻米的育种和推广起到重要作用。稻米食味品质测定包括直接评价(感官评价)、间接评价(理化指标评价)及仪器评价(近红外装置等)技术,其中胶稠度测定技术是理化指标中较重要的一项检测技术。在进行胶稠度测定时对其测定结果的影响因素很多,样品的细度、含水量及加入碱液浓度的微小变化,对测定结果有较大的影响。     

优质稻谷中直链淀粉含量测定方法的探讨

直链淀粉是评价稻米食用、蒸煮品质的一项重要指标,也是优质稻谷定级指标之一.直链淀粉测定过程中样品粉粒大小是影响测定结果的一个重要因素,国标方法要求是φ180μm细度.通过对φ180μm细度、φ150μm细度的样品分别进行测定,结果表明采用φ150μm细度的样品进行检测的重现性是好的,结果是准确可靠的.而采用φ150μm细度可同时测定稻谷中胶稠度等指标,这样在稻谷品质测报工作中可大大提高工作效率.     

优质稻谷胶稠度测定要点及应注意的问题

胶稠度是评价稻米食用品质和储藏品质的一项重要指标 ,国家新发布实施的优质稻谷质量标准已将其正式列入。本文就胶稠度检测的步骤、操作要点以及与此相关的稻米精度、样品细度、米胶浓度、溶剂、温度等应注意的问题 ,作了系统介绍。     

优质稻谷胶调度测定要点及应注意的问题

胶稠度是评价稻米食用品质和储藏品质的一项重要指标,国家新发布实施的优质稻谷质量标准将其正式列入,本文就胶稠度检测的步聚,操作要点以及与此相关的稻米精度,样品细度,米胶浓度,溶剂,温度等应注意的问题,作了系统介绍。     

直链淀粉含量与稻米的糊化温度及胶凝度的关系

测定了169个稻米样品的直链淀粉含量、糊化温度及胶凝度。结果表明：影响稻米蒸煮及食用品质的直链淀粉含量、糊化温度及胶凝度在一定程度上是相关的。一般直链淀粉含量低则糊化温度高而胶凝度较软。除直链淀粉含量外,其它一些因素也影响稻米的糊化温度及胶凝度。     

不同因素对茶多糖凝胶特性的影响

采用质构仪测定不同质量浓度、加热温度、保温及放置时间、pH值、钙离子浓度等对茶多糖的凝胶强度、胶黏性、咀嚼性、弹性、内聚性等的影响。结果表明：能形成茶多糖凝胶的条件是茶多糖质量浓度不低于5mg/mL、保温温度不低于50℃;茶多糖凝胶强度与质量浓度、加热温度成正比,放置时间过长、酸性或碱性过强都会降低其凝胶强度,钙离子对茶多糖凝胶的形成没有促进作用。     

应用近红外透射光谱法测定稻米胶稠度研究

以195份稻米为样品,利用近红外透射光谱分析仪,对样品进行光谱扫描,并利用化学法测定胶稠度.利用近红外定标软件,采用多种计量数学处理方法和不同的回归统计方法进行定标曲线的开发和比较,得到了稻米胶稠度测定的近红外分析数学模型,数学模型的定标标准偏差(SEC)、交叉检验标准误差(SECV)和定标决定系数(RSQ)分别为:10.35、10.51和0.827 9.内部交叉验证和外部验证结果表明近红外定量分析胶稠度有很高的准确度.     

米饭质构特性测定方法的研究(Ⅲ)——米饭质构测试的最佳条件探讨

用天津小站米(粳米)和南充顺心大米(籼型杂交稻米),参照GB/T 15682-2008米饭样品制备方法制作米饭样品,并利用质构测试仪采用TPA模式对米饭样品的质构特性进行测定,主要通过单因素试验考察了压缩程度和压缩速度对米饭硬度测定值的影响,并通过正交试验探讨了米饭质构测定的最佳测试条件.结果表明:在压缩程度为50％条件下,不同压缩速度的米饭硬度测定值的变异系数为2.8％～7.7％;压缩程度、压缩速度、米饭样品制作与测试温度、放置时间对硬度测定值都有高度显著(P＜0.01)的影响,各因素对米饭硬度测定值的变异幅度大小无影响.以米饭硬度测定值变异幅度为指标的米饭质构测定的最佳条件为:米饭放置时间90 min、米饭样品制作与测试温度20℃、压缩程度50％、压缩速度50 mm/min.     

稻米加工精度对胶稠度测定的影响

通过选用不同直链淀粉含量的稻谷样品,加工成不同等级大米,测定其对胶稠度的影响,结果表明:不同加工精度的大米对胶稠度的影响程度与样品本身直链淀粉含量有关,直链淀粉含量越高,影响越大。对于直链淀粉含量大于19%的样品,加工精度相差四个等级,胶稠度测定结果可差50%～100%。     

淮稻13号稻米食用品质的研究

选择淮稻13号、武育粳3号、淮稻9号、扬辐粳8号、盐粳1号、镇稻88等6种常见粳稻米品种,分别测定其含水率、粗蛋白质含量、直链淀粉含量、脂肪酸值等主要理化指标,并进行加热吸水率、膨胀率、碱消值、胶稠度等蒸煮品质检测及蒸煮品质评分.测定结果显示,在6种粳稻米中,淮稻13号稻米综合评价指标最高.研究结果表明,淮稻13号粳稻米食用品质优良,是一种优良的食用稻米.     

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