小米挤压膨化加工工艺参数研究

以小香米、冀优2号、冀谷十七3个不同品种小米为材料,采用DSE-25型双螺杆挤压膨化机加工挤压膨化食品,研究加工温度、物料含水量、小米品种对扭矩、压力等设备系统参数和径向膨化率(SEI)、产品水分(PM)、水溶性指数(WS)、吸水性指数(WAI)等产品质量指标的影响。研究结果表明,加工温度、物料含水量、小米品种及其交互效应对小米挤压膨化产品质量和系统参数的影响达到极显著水平。随着加工温度、物料含水量升高,扭矩、4区压力、5区压力、径向膨化率呈下降趋势;随着加工温度升高,物料含水量减少,产品水溶性指数呈上升趋势,而产品水分、吸水性指数则呈下降趋势。与小米品种K2相比。K1、K3对应的产品水分含量低、径向膨化率小、水溶性指数高。     

荞麦挤压膨化产品的理化特性研究

为明确操作参数对荞麦挤压膨化产品特性的影响,确定产品理化特性间的关系,从淀粉分子结构角度解释产品理化特性的变化,本文以荞麦粉为原料,利用德国布拉本德DSE-25型双螺杆挤压机,通过响应面试验设计,系统研究物料含水量、加工温度、螺杆转速及其交互作用对膨化产品截面膨化率、水溶性指数、吸水性指数、色泽等理化特性以及挤压膨化产品淀粉分子结构的影响。结果表明,加工温度、螺杆转速是影响截面膨化率、水溶性指数、吸水性指数的重要因素;水分含量、螺杆转速是影响黏度、淀粉平均分子半径、重均分子质量的重要因素。淀粉平均分子半径与水溶性指数、色差呈显著负相关,与吸水性指数、黏度呈显著正相关。截面膨化率与其它产品特性无显著相关性。剪切效应加剧,淀粉降解程度加大,平均分子半径减小。在水分含量较高、温度较低、螺杆转速较小条件下,单位机械能耗较小,荞麦挤压膨化物中淀粉平均分子半径较大,吸水性指数和黏度较大,水溶性指数和色差较小。通过挤压处理可改善荞麦淀粉的水溶性、吸水性、黏度等理化特性。     

玉米挤压工艺条件的优化及其理化特性的研究

以玉米籽粒为原料,以膨化度为指标,在单因素试验基础上,采用响应面分析法研究挤压工艺条件对玉米籽粒膨化特性的影响,并分析其主要理化特性.结果表明,回归方程能较好地预测玉米膨化度随挤压工艺参数变化的规律,玉米挤压膨化的最佳工艺条件为物料粒度60目,物料含水量24.5％,挤压温度164℃,转速400r/min,膨化度3.42％.玉米经挤压后还原糖、可溶性膳食纤维、吸水性指数、水溶性指数、糊化度分别提高361.54％、134.38％、80.20％、186.4％和794.12％,淀粉、不溶性膳食纤维分别降低26.03％和36.67％,蛋白质含量基本不变,玉米的理化特性得到有效改善.     

挤压工艺对青稞粉产品特性的影响

以纯青稞粉为原料,研究挤压工艺参数对青稞挤压熟化产品的膨化度、水溶性指数、吸水性指数和糊化度影响;并对比挤压前后青稞粉的微观结构、糊化特性和消化特性。结果表明:当挤压参数为机筒温度140℃、物料含水率为15%、螺杆转速为125 r/min时,获得质量相对比较好的挤压产品,在此条件下,青稞挤压粉的膨化度为3.258,水溶性指数和吸水性指数分别为15.30%和461.51%,糊化度为90.08%;挤压后青稞粉出现明显的孔隙结构,糊化性质得到改善,消化率提高11.15%。     

西农黑大穗小麦挤压膨化加工研究

以普冰9946小麦为对照,研究西农黑大穗挤压膨化过程中加工温度、物料含水量、喂料速度变化对挤压膨化的扭矩、4区压力、5区压力、单位机械能耗、产品比容、径向膨化率、脆度、硬度的影响。结果表明,在试验范围内,温度为T1时,西农黑大穗产品比容、径向膨化率高,单位机械能耗高;温度为T3时,产品脆度高、硬度低,膨化率低。含水量为20%时,产品物理特性相对较好;含水量为22.5%时,单位机械能耗较低。喂料速度为20 g/min时,产品物理特性较好,单位机械能耗较高。加工过程中,西农黑大穗的扭矩、压力均高于对照,单位机械能耗和产品物理特性与对照差异极显著(P0.01)。     

大米淀粉组成与挤压特性之间的相关性研究

分析11种大米的淀粉组成和挤压特性,探讨总淀粉、直链淀粉含量以及淀粉直/支比与膨化度、吸水性、水溶性、容重、硬度等挤压特性之间的相关性。结果表明:直链淀粉含量与吸水性呈显著正相关(r=0.879)、与水溶性呈显著负相关(r=-0.876),与膨化度之间也具有一定的相关性(r=0.530),与容重及硬度无显著相关性;淀粉直/支比与吸水性(r=0.848)呈显著正相关,与水溶性呈显著负显著(r=-0.827),与膨化度具有一定的相关性(r=0.512),但与容重及硬度无显著相关性。大米的直链淀粉含量以及淀粉直/支比与膨化度、吸水性等挤压特性具有相关性,直链淀粉含量和淀粉直/支比可作为大米挤压加工中原料选择和复配的依据。     

裸燕麦与玉米淀粉混合挤压膨化技术研究

以裸燕麦粉和玉米淀粉为原料,采用DSE-30双螺杆挤压膨化机,进行了生产挤压膨化食品的技术研究。螺杆转速设定为25 Hz,喂料速度40 g/min,选用直径为5.0 mm的模口进行测试,以膨化度、质构特性、吸水性指数、水溶性指数等为指标,采用感官评价和综合评价方法,通过正交试验发现:物料加水量4%、IV区膨化温度180℃、燕麦与玉米淀粉物料质量比4∶6具有较好的膨化和物性效果。     

人参粉挤压制品膨化特性的研究

探讨双螺杆挤压条件对人参挤压制品膨化品质的影响,以人参粉末为原料,利用双螺杆挤压机制备产品,分析不同物料含水量和机筒温度对制品的径向膨化率、水溶性指数、吸水性指数以及显微结构的影响.结果表明,人参挤压制品的径向膨化率在物料含水量30%、机筒温度100℃时最高(1.32),气孔细小而均匀.水溶性指数随物料含水量的增加而减少,随温度升高而增加,在20%、140℃时水溶性指数最高(44.77%).人参经双螺杆挤压不仅发生膨化,而且其制品质地疏松、均匀,有望开发膨化类人参保健休闲食品.     

葛根全粉挤压膨化棒工艺优化及其品质分析

目的 探究挤压膨化工艺和原料配方对葛根全粉膨化棒膨化特性和质构特性的影响,并对配方进行优化。方法 在单因素试验中研究玉米粉添加量、葛根全粉添加量、水添加量、螺杆转速、挤压温度对膨化棒膨化度、质构、吸水性指数和水溶性指数的影响,以膨化度为考察指标通过正交试验确定葛根全粉挤压膨化棒制备工艺;此外,比较了不同原料制备的膨化棒的微观结构和膨化特性。结果 葛根全粉膨化棒膨化度在葛粉全粉添加量12.5%、玉米粉添加量60%、水添加量2%、螺杆转速33Hz、挤压温度175℃时最高;对比不同原料制备膨化棒的形态和特性发现最优工艺制备的膨化棒截面具有更小孔洞和更多褶皱,裂断强度最低,为591.91g,硬度和脆度值介于玉米和大米膨化棒之间,分别为9660.30g和8401.88g;吸水性指数最高而水溶性指数最低,分别为597.76%和19.55%。结论 通过工艺优化确定了挤压膨化棒最优制备工艺,葛根全粉添加量为12.5%,超过85%的葛根黄酮得以保留,该研究为粉葛全质化利用提供主要重要理论依据。     

高蛋白营养膨化粉的工艺研究

以豆粕为主要原料,与玉米、绿豆混合,利用小型单螺杆挤压膨化机进行膨化实验,研究了不同物料水分含量、模头温度、螺杆转速对产品膨化效果的影响,并对挤压膨化过程中产品的水溶性和吸水性的变化进行了研究分析。确定最佳的挤压膨化工艺参数为:模头温度140℃,水分含量为19%,螺杆转速为180r/min,经过挤压膨化后,原料的水溶性和吸水性增大。     

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.