纤维酶法制备可溶性麸皮膳食纤维工艺条件的优化

以小麦麸皮膳食纤维为原料,采用纤维素酶解法对小麦麸皮膳食纤维进行改性,制备可溶性麸皮膳食纤维。通过正交试验优化工艺条件,确定了纤维素酶解的最佳工艺条件:料液比1∶10、酶用量20 U/g、酶解p H 4.8、酶解温度60℃、酶解2 h,可溶性膳食纤维得率为12.67%。     

小麦麸皮不溶性膳食纤维提取工艺研究

以小麦麸皮为原料,研究了其不溶性膳食纤维提取方法。采用单因素和正交试验法优化了小麦麸皮不溶性膳食纤维的提取工艺,最佳提取工艺参数为α-淀粉酶用量0.5%,NaOH浓度3.0%,碱解时间40 min,酶解时间60min。最佳条件下小麦麸皮不溶性膳食纤维的提取得率87.29%,该提取方法极大地提高小麦麸皮中不溶性膳食纤维的得率,试验将为小麦麸皮在食品行业的综合利用提供理论参考。     

食用菌酶解改性型膳食纤维对人体机能影响研究

为了研究食用菌酶解改性型膳食纤维对人体机能的影响,文章对食用菌膳食纤维进行了酶解改性处理,并分析其酶解改性后膳食纤维的性质特征,同时设定相应的试验环节分析其对人体机能的影响。通过分析该酶解前后的膳食纤维功能性质发现,酶解后得到的膳食纤维表面结构发生变化,结构层次感加强,空隙由密实走向稀松。基于膳食纤维结构的变化,其对葡萄糖、胆固醇的吸附能力均得到显著的增强,同时抗胃酸消化能力得到提升。通过多组性质测定可以看出,酶解后膳食纤维调节肠道菌群作用得到提升,对人体肠道乳酸含量具有间接调节功能,有助于促进肠道蠕动。在后续的研究中,将主要对此类膳食纤维的应用途径进行研究。     

小麦麸皮膳食纤维挤压加工工艺研究

以小麦麸皮膳食纤维为原料,采用双螺杆挤压机对其进行挤压加工,以提高小麦麸皮膳食纤维中可溶性膳食纤维的含量。研究了挤压温度、物料含水量和螺杆转速对原料中可溶性膳食纤维含量的影响,研究结果表明:麸皮含水量20%,挤压温度170℃,主机转速185 r/min时,麸皮原料中可溶性膳食纤维含量由3.22%提高到10.14%。通过高效液相色谱、扫描电镜检测及持水力与膨胀力试验显示,加压处理可以有效地增加可溶性膳食纤维的含量,以及改变麸皮的表面结构。     

双酶法提取小麦麸皮膳食纤维的工艺研究

以小麦麸皮为原料,采取双酶提取法制备小麦麸皮膳食纤维,通过正交实验得出最佳提取条件为:α-淀粉酶添加量为0.6%,α-淀粉酶酶解pH为6,α-淀粉酶酶解温度为70℃,碱性蛋白酶添加量为0.3%,碱性蛋白酶酶解pH为9,碱性蛋白酶酶解温度为55℃,此时小麦麸皮膳食纤维提取率为71.94%。     

燕麦麸皮与挤压燕麦麸皮特性比较

对燕麦麸皮和挤压燕麦麸皮进行碱法和酶法水解,并研究最优条件。通过碱解和酶解发现,燕麦麸皮的碱解液和酶解液中的蛋白质含量和β-葡聚糖含量都要高于挤压燕麦麸皮。另外通过傅里叶红外光谱及扫描电子显微镜对燕麦麸皮和挤压燕麦麸皮的微观结构进行分析,发现两者微观结构差别很大,燕麦麸皮的微观结构简单分散,表面平滑平整,而挤压燕麦麸皮的微观结构层次复杂,挤压特征明显,表面粗糙。最后对两者进行美拉德反应,对反应后的提取液进行气相色谱分析,发现燕麦麸皮含有28 种不同芳香物质,挤压燕麦麸皮含有29 种,二者主要芳香物质含量差别较大。     

酶法提取小麦麸皮膳食纤维工艺研究

以小麦麸皮为原料,采用酶法制备膳食纤维,通过正交实验得出最佳提取条件:α-淀粉酶用量0.4%,α-淀粉酶酶解时间50min,蛋白酶用量0.2%,蛋白酶酶解时间50min,此时小麦麸皮膳食纤维得率为81.3%。     

改性处理对绿豆皮膳食纤维结构及功能特性的影响

以绿豆皮膳食纤维为试验对象,采用挤出改性、酶解改性、挤出-酶解复合改性3种处理方式对其进行改性处理。以持水力、持油力、膨胀力、阳离子交换能力、吸附葡萄糖能力和吸附胆固醇能力为评价指标,研究改性处理对绿豆皮膳食纤维功能特性的影响。以扫描电子显微镜、X射线衍射和傅里叶变换红外光谱法表征改性处理对绿豆皮膳食纤维结构的影响。结果表明:挤出-酶解复合改性处理的效果最明显,其功能特性得到显著改善,持水力、持油力、膨胀力、阳离子交换能力、吸附葡萄糖能力分别是未改性绿豆皮膳食纤维的1.46,1.15,1.87,6.98,1.66倍;在pH 2和pH 7条件下对胆固醇的吸附能力分别达(2.38±0.05)mg/(mL·g)和(3.45±0.12)mg/(mL·g)。扫描电子显微镜观察结果表明,挤出-酶解复合改性处理后的绿豆皮膳食纤维表面结构粗糙、疏松,出现多层褶皱或多孔性特征。X射线衍射、傅里叶变换红外光谱结果表明,挤出-酶解复合改性处理后的绿豆皮膳食纤维的相对结晶度最低,各纤维素组分重新分布,部分不溶性膳食纤维(IDF)向可溶性膳食纤维(SDF)转化。结论:挤出-酶解复合改性处理是一种改性膳食纤维的较好方法,可为提高绿豆皮膳食纤维的利用率和进一步开发利用其营养价值提供理论依据。     

白腐菌发酵对麸皮性质的影响

为了提高麸皮的附加值,探究了白腐菌发酵对麸皮性质的影响。以白腐菌发酵麸皮为研究对象,以漆酶酶解和未处理麸皮为对照,测定溶胀性、持水性、膳食纤维含量、植酸含量等多种理化指标。结果表明:经白腐菌发酵和漆酶酶解的麸皮可溶纤维含量明显提高,持水性和持油性升高,溶胀性和植酸含量降低。白腐菌发酵后麸皮表面结构变得疏松多孔。为麸皮资源的开发利用提供理论依据。     

小麦麸皮膳食纤维的微波-酶法改性研究

以小麦麸皮为原料,研究微波功率、微波时间、酶添加量、酶处理时间对膳食纤维化学特性和生物活性的影响,同时测定了改性后膳食纤维的抗氧化和还原能力特性。结果表明:微波-酶法对麦麸膳食纤维改性效果明显,改性后膳食纤维样品分子量明显下降,单糖组分不变但比例发生较大变化,傅里叶红外测定证明酚类活性物质的存在,膳食纤维组分没有发生变化,示差扫描量热法测定得出改性膳食纤维具有较高的热稳定性。通过该试验改性的膳食纤维具有较高的抗氧化特性,有很好的发展前景。     

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.