高筋小麦储藏品质变化的研究

研究选用郑麦366和西农979两种高筋小麦为研究对象,对小麦进行微波灭活,调节其生活力分别为0%、40%和90%,将其在35℃条件下恒温储藏,通过研究其在储藏过程中的发芽率、电导率、过氧化氢酶、湿面筋和糊化特性的变化,探讨小麦品质变化与其生活力之间的关系。为研究高筋小麦的储藏特性打下了一定的基础。结果表明:储藏过程中生活力越高的小麦其发芽率、湿面筋含量和过氧化氢酶活动度降低幅度越大;生活力越小的小麦电导率升高幅度越小;生活力为40%的小麦的峰值粘度、最终粘度和回生值变化的最多,衰减值变化最少。     

高温储藏玉米品质变化研究

以郑单958玉米为原料,进行鼓风干燥和调质处理,将水分含量分别调为为14.5%、11.7%、9.9%和7.8%,在35℃下密闭储藏,研究在储藏过程中玉米生活力、电导率、过氧化氢酶活动度、脂肪酸值和品尝评分值的变化,探讨高温储藏玉米的水分含量与其储藏品质变化的规律。结果表明:在35℃条件下,水分含量为14.5%的玉米的生活力、过氧化氢酶活动度和品尝评分值降幅大,分别为100%、90.4 mg H2O2/g和42.1分;水分含量为7.8%的玉米的电导率、脂肪酸值增幅最小,分别为10.84μS·cm-1·g-1和12.8 mg KOH/100 g。     

环境温度对油菜籽储藏品质的影响

采用不同温度(15、25、35℃)对不同水分含量(6.2％、7.9％、10.6％、12.3％)的国内普通双低油菜籽进行模拟储藏,系统研究了不同温度和水分含量对油菜籽储藏期间色泽及主要品质指标的影响.结果表明:油菜籽红度值a*和游离脂肪酸(FFA)含量均随着储藏时间延长而增加,储藏温度和水分含量愈高,增加速率越大;油菜籽过氧化氢酶活动度、氮可溶性指数均随着储藏时间延长而下降,其中在35℃条件下,高水分含量的油菜籽过氧化氢酶活动度、氮可溶性指数下降迅速.油菜籽红度值a*与FFA含量、过氧化氢酶活动度、氮可溶性指数等品质指标具有显著相关性,测定其色泽可有效表征油菜籽储藏过程中的品质变化.     

蛀食害虫侵害小麦后不同蛀蚀程度损伤粒储藏品质变化

探讨玉米象、米象和谷蠹3种重要的蛀食性储粮害虫蛀蚀小麦后不同蛀蚀程度的损伤粒的品质变化规律,指导科学评价小麦受害虫侵害后其储藏品质的优劣,为小麦科学储藏量化指标提供依据。选用河南产储藏3 a的商用小麦为材料,按不同虫种分组,检测不同蛀蚀程度损伤粒的小麦的品质指标中的水分、粗蛋白、SDS沉降值、湿面筋含量、干面筋含量、面筋吸水率和面筋指数。结果表明：随着损伤粒蛀蚀程度的增强,水分呈动态上升趋势;粗蛋白含量呈线性下降趋势;干湿面筋和面筋吸水率之间存在显著正相关性,都呈下降趋势;面筋指数由于害虫侵害筋力变差数值减少;而降落数值由于大量麸皮和害虫分泌的酸性物质的作用导致数值增加。     

氮气气调储藏启封前后小麦品质变化研究

研究了在温度为（30±2）℃、相对湿度在75%的条件下氮气气调启封前后小麦的加工品质变化，分析了小麦水分、蛋白质、湿面筋、降落数值、面筋吸水量、面团流变学特性等重要加工指标的变化规律。结果表明，氮气气调储藏60 d和启封后60 d的小麦粉蛋白质的数量和质量、面团流变学特性无显著变化。小麦初始阶段、气调储藏阶段和启封后的蛋白质、湿面筋（全麦粉）、面筋指数、面筋吸水量、湿面筋（小麦粉）、吸水率差异不显著。启封前小麦粉面团形成时间、面团稳定时间随时间逐渐增加，气调储藏阶段增速高于启封阶段的变化。小麦粉面团的拉伸能量值、拉伸阻力、拉伸比例随着启封时间延长逐渐增加，小麦从缺氧到富氧过程面团的筋力有所增强，面团从开始拉伸到拉断为止所需能量逐渐增大，但其延伸性变化不大。     

小麦储存品质判定指标的研究

研究了小麦在3年常规储藏过程中,湿面筋含量、面筋吸水量和降落数值的变化规律及特点,研究结果表明：湿面筋含量和面筋吸水量与小麦储藏时间的相关性不佳,而降落数值的变化与小麦储存年限相关性最好,可以反映小麦储藏品质劣变和储藏年限,建议将降落数值作为小麦储存品质的参考判定指标。     

不同储藏条件对小麦流变学特性的影响

为了解小麦籽粒在不同储藏条件下的品质变化,探索实验室小量样品的最适储藏条件, 本研究以强筋、中筋和弱筋小麦的籽粒和面粉为研究材料,对其在不同梯度温度（?20、4、35 ℃）和不同储藏时间（20、40、60 d）条件下的品质指标进行分析。结果表明:不同储藏条件对不同类型小麦的湿面筋含量、吸水量和弱化度的影响较小,均在允差内。以籽粒方式储藏时,强筋小麦在不同温度条件下各品质参数基本上都在允差范围内,但随着储藏时间的延长（60 d）,形成时间和拉伸面积超差。中筋小麦在不同温度条件下,湿面筋含量和粉质参数基本上都在允差内,但是对拉伸参数（拉伸面积、拉伸阻力和最大拉伸阻力）影响较大;尤其是当储藏条件为?20和35 ℃的情况下,除延伸性外,拉伸面积、拉伸阻力和最大拉伸阻力均有不同程度的超差。弱筋小麦在不同温度条件下湿面筋含量和拉伸各参数均在允差内,但对粉质参数（稳定时间和弱化度）影响较大,尤其是稳定时间。值得注意的是,弱筋小麦随着储藏时间的延长,粉质各参数测定值越接近对照,在允差范围内。另外,不同类型的小麦在4 ℃条件下以面粉方式储藏时,强筋和中筋小麦的湿面筋含量、流变学粉质参数和拉伸参数均在允差值内。因此,本研究认为4 ℃,≤60 d比较适宜小麦籽粒和面粉的储藏。     

高水分小麦发芽率和霉菌活动规律的相关性研究

粮食储藏过程中品质变化主要受到微生物活动的影响,本课题模拟自然储粮条件,将水分为14.5%、15.5%、16.5%、17.5%的小麦贮藏在4、12、22、32℃的生化培养箱,研究其霉菌的活动规律和小麦发芽率的变化。结果表明：温度和水分对贮藏过程中小麦内外霉菌总数变化有显著影响,随温度升高,水分含量增大,贮藏过程中霉菌数量增多,小麦发芽率降低,安全贮藏期缩短。水分含量为14.5%的小麦在低温条件下贮藏安全,32℃时,储藏期不超过25d;水分含量为17.5%的小麦在低温条件下储藏不超过一月,在32℃时不超过一周。水分含量介于14.5%～17.5%之间的小麦安全贮藏期介于这两种水分的小麦的安全期之间。     

温度与水分对薏仁米贮藏过程中脂肪氧化的影响

以兴仁薏仁米为试验材料,探讨不同温度(15, 25和35℃)和水分(10.5%, 12.0%和13.5%)对薏仁米储藏过程中脂肪氧化的影响。结果表明,薏仁米的储藏温度和水分越高,其油脂氧化速率越快。180 d时,不同温度下薏仁米的脂肪酸值、过氧化值、电导率增加范围分别为182.84%～233.46%, 167.09%～314.01%和33.13%～74.02%,肪酶活动度下降范围为22.49%～47.69%,不同水分下其增加范围分别为87.60%～259.31%, 109.76%～254.66%和0.97%～15.15%。脂肪酸值和过氧化值受温度与水分的影响最显著;温度对电导率的影响大;温度与水分对丙二醛含量影响差异显著,与样品调节水分的前处理密切相关;与温度的影响相比,含水量高低对脂肪酶活性影响更大。低温与低水分能有效延缓薏仁米贮藏过程中的脂肪氧化。     

小麦麸皮微波处理对全麦粉面筋品质和流变学特性的影响

目的探讨小麦麸皮微波处理灭酶对全麦粉面筋品质特性和流变学特性的影响。方法以中高筋小麦为原料,对麸皮微波处理后再回添到小麦粉中制得全麦粉,设置麸皮水分含量、微波处理时间和麸皮厚度3个变量因素,固定其中2个变量因素,探讨另1个变量因素对全麦粉中面筋特性和流变学特性的影响。结果麸皮水分含量对湿面筋含量、面筋吸水率、面团形成时间、吸水量、稳定时间和弱化度具有显著性影响,微波处理时间对湿面筋含量、吸水量、稳定时间和弱化度具有显著性影响,麸皮厚度对干面筋含量、面团形成时间、稳定时间、弱化度和粉质质量指数具有显著性影响。结论对全麦粉面筋品质和流变学特性的影响大小依次为麸皮水分含量、麸皮厚度、微波处理时间。     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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.