马铃薯片常压油炸工艺优化研究

对影响常压油炸马铃薯片品质的工艺参数进行了优化研究。结果表明,在柠檬酸溶液浓度为0.10%～0.25%、预干燥时间为10～40min和油炸温度为170～200℃的范围内,以薯片的丙烯酰胺含量、含油量和脆度为指标,常压油炸薯片的最佳工艺条件为:薯片切片采用柠檬酸溶液浓度为0.20%的柠檬酸水溶液浸泡后,于85℃预干燥30min,最后用180℃恒温油炸至熟。     

预干燥时间对微波低油薯片的影响

传统油炸马铃薯片的含油量高达30%以上,降低薯片的含油量很有必要。通过单因素试验探讨了预干燥时间对微波低油马铃薯片脆度、色泽和含油量的影响,结果表明:利用微波生产马铃薯片可以降低薯片含油量到20%以下;不同的预干燥时间能得到不同初始水分含量的半成品;预干燥温度85℃时,干燥时间对产品的脆度、色泽和油含量都有影响,干燥时间在35min时,马铃薯片的脆度最好;干燥时间长,产品的色泽相对较浅;产品的含油量大体上是随着干燥时间的增加而减少。     

不同预加工方式对马铃薯片中丙烯酰胺的影响

研究不同预加工方式对油炸马铃薯片中丙烯酰胺生成的影响,进而探讨一种可有效抑制马铃薯片中丙烯酰胺含量的方法。将马铃薯片在不同温度（120℃ ～200℃）及不同时间（0 ～30 min）下进行油炸处理,通过品质指标及丙烯酰胺含量的变化趋势确定最佳油炸时间及温度,利用高效液相色谱法测定经热烫和添加剂浸泡后马铃薯片中丙烯酰胺的含量,并计算丙烯酰胺抑制率。在未进行预处理条件下,随着油炸时间及油炸温度的增大,质量损失率、色差呈整体上升趋势,水分活度、水分含量及还原糖含量呈整体下降的趋势,丙烯酰胺含量呈先上升后下降的趋势;在油炸前进行不同预处理对马铃薯片中的丙烯酰胺具有显著抑制作用,90℃热烫处理协同5 g/L半胱氨酸溶液浸泡处理10 min对马铃薯片中丙烯酰胺的抑制率达到了100%。因此,热烫协同半胱氨酸溶液浸泡处理是一种可有效抑制马铃薯片中丙烯酰胺含量的方法。     

均匀设计法优化甘薯薯片油炸工艺

为了优化甘薯薯片油炸工艺,采用单因素与均匀设计法相结合,以甘薯薯片含油量、亮度L~*值、黄色b~*值为指标,并对数据进行逐步回归分析。优化最佳工艺组合为:切片厚度2 mm,热烫时间1 min,食盐浓度3%,食盐浸泡时间15 min,预干燥温度60℃,干燥时间90 min,油炸温度130℃,油炸时间2 min。优化工艺得到的甘薯薯片含油量低于市售薯片,亮度L~*值和黄色b~*值高。     

复合马铃薯片油炸工艺研究

以马铃薯淀粉和马铃薯全粉为主要原料,对复合马铃薯片的油炸工艺参数进行了研究。采用正交试验,确定了生产低含油量、低丙烯酰胺(AA)含量、高脆度复合薯片的最佳油炸工艺参数,即油炸前坯料的含水量控制在20%左右,含盐量2%左右,油温以160℃为佳,炸制时间为40 s,油炸薯片丙烯酰胺含量为0.28 mg/kg,在市售薯片基础上降低26.32%;含油量为23.36%,降低了1.47个百分点。     

低含量丙烯酰胺的油炸马铃薯片加工工艺研究

根据之前所做的单因素实验结果,确定以原料品种、浸泡液的柠檬酸浓度、预干燥时间以及油炸温度四个因素来做四因素四水平正交实验,并对实验结果进行数据分析。根据分析结果确定了生产低丙烯酰胺含量的油炸马铃薯片的最佳加工工艺条件为:以大西洋品种的马铃薯为原料,采用浓度为0.5%的柠檬酸水溶液浸泡,85℃鼓风干燥20min,最后在180℃的油温下恒温油炸至熟。     

基于均匀设计和主成分分析的甘薯薯片油炸工艺优化

为优化甘薯薯片油炸工艺,采用单因素和均匀设计相结合进行试验,对均匀设计试验数据进行多元回归分析。单因素试验表明:切片厚度、预干燥阶段和油炸阶段对含油量、L*值和b*值有较大影响;均匀设计逐步回归分析表明:油炸时间对含油量影响显著(P=0.011),食盐水质量分数对含水量影响显著(P=0.022),油炸温度和油炸时间对L*值影响极显著(P=0.001),预干燥时间和油炸时间对b*值影响显著,食盐水浸泡时间、食盐水质量分数、预干燥温度、预干燥时间和切片厚度对脆度的影响符合二次多项式回归模型(P=0.001);指标主成分分析表明:提取2个主成分能解释87.4%的指标信息,达到指标降维目的;岭回归分析建立了综合得分回归模型,相关系数R为0.997,能很好地拟合产品的综合得分;偏最小二乘法回归分析预测最佳综合评分工艺参数为切片厚度2 mm、热烫时间1 min、质量分数1%食盐水浸泡20 min、预干燥温度60℃、预干燥时间70 min、油炸温度150℃、油炸时间1 min,验证综合评分为0.89,综合评分高于均匀设计试验组最高值0.86。优化工艺所得产品具有含油量低、颜色和脆度俱佳等特点,相关模型具有良好的预测能力。     

油炸马铃薯片中丙烯酰胺形成的影响因素的研究

丙烯酰胺是富含碳水化合物和氨基酸的食品经高温加热发生美拉德反应而产生的,但有关影响丙烯酰胺形成因素的研究却较少。探讨了油炸温度、原料中还原糖和氨基酸含量、鲜薯切片浸泡液的柠檬酸浓度、油炸前薯片的水分含量及抗氧化剂和油的使用时间对丙烯酰胺形成的影响。结果表明:原料中还原糖和氨基酸含量越高,产品中生成的丙烯酰胺就越多;油炸温度越高,产品中丙烯酰胺含量也相应越高;浸泡液柠檬酸浓度越大,产品中丙烯酰胺含量越低;而随着半成品中含水量的降低,产品中的丙烯酰胺含量也逐渐减少;在油中添加不同浓度的BHT和TBHQ以及采用使用时间不同的油,对加工出来的薯片之间丙烯酰胺含量没有显著的影响。     

均匀设计法优化甘薯薯片常压油炸工艺

为了对甘薯薯片常压油炸工艺进行优化,采用均匀设计法进行试验,以含油量、含水量、黄色b*值、亮度L*值为考察指标,对数据进行逐步回归分析。结果表明:适当增加预干燥时间可以降低产品含油量,适当提高预干燥温度有利于减少产品含水量和增加产品亮度,适当延长油炸时间可以降低含水量、改善颜色,预干燥温度和预干燥时间的交互作用对含油量有负促进效应,预干燥温度和油炸温度的交互作用、预干燥温度和油炸时间的交互作用以及油炸温度和油炸时间的交互作用均对含水量有正促进效应,油炸温度和油炸时间的交互作用对颜色品质和含油量有负促进效应。优化工艺组合为:预干燥温度90℃,干燥时间60min,油炸温度120℃,油炸时间4min;得到的薯片品质优于市售同类产品,这将为生产甘薯薯片的中小企业提供一些技术参考。     

热烫预处理降低鲜切油炸薯片中丙烯酰胺的工艺优化研究

研究热烫预处理对鲜切油炸薯片中丙烯酰胺的影响和薯片油炸工艺优化。在相同条件下,分别对原料进行热烫和非热烫处理,在不同油炸温度和时间条件下进行油炸试验,采用DNS法测还原糖,液质联用法检测薯片中丙烯酰胺含量。结果表明,通过对切片的马铃薯进行热烫处理,即75℃热烫150s,能明显降低还原糖含量,160℃油炸120s,可降低丙烯酰胺含量至67.18μg/kg。     

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.     

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.