复合植物水解酶提取花生油脂体工艺研究

为了提高花生油脂体的提取率,选用复合植物水解酶辅助提取花生油脂体。通过单因素实验考察了料液比、酶用量、酶解时间、酶解温度对复合植物水解酶提取花生油脂体提取率的影响。在单因素实验的基础上,采用正交试验对复合植物水解酶提取花生油脂体的工艺进行优化。实验结果表明,在所选取的参数范围内,各因素对花生油脂体提取率的影响由大到小为:料液比、酶解温度、酶解时间、酶用量。获得其较佳工艺条件为料液比1:4(g/mL)、酶用量1.25%、酶解时间80min、酶解温度50℃,在该条件下花生油脂体提取率为48.92%。     

生物酶法提取葡萄籽油的工艺研究

生物酶法提取植物油脂是一种新型的油脂加工方法，它既可提高油脂的提取率，又可获得品质较优的植物油脂。以葡萄籽为原料分别加入纤维素酶和中性蛋白酶进行酶解，通过试验分别得出两种酶提取葡萄籽油的最佳工艺参数：纤维素酶提取葡萄籽油的最佳工艺参数为：酶解温度为45℃、酶解时间为1．5h、酶解pH值为4．5、酶用量为3000U／g葡萄籽，油脂提取率为84．1％；中性蛋白酶提取葡萄籽油的最佳工艺参数为：酶解温度为55℃、酶解时间为2．0h、酶用量为2000U／g葡萄籽，油脂提取率为80．3％。对两种酶解提油工艺进行比较可知：中性蛋白酶提油工艺所需成本较低，提取率较高，适合于葡萄籽油的提取。     

超声波辅助水酶法提取巴塘核桃油工艺优化及其氧化稳定性

为确定超声波辅助水酶法(果胶酶、纤维素酶、中性蛋白酶)提取巴塘核桃油的最佳工艺及不同储藏条件对核桃油氧化稳定性的影响。通过单因素实验以及L₉(34)正交试验研究pH、酶解温度、酶解时间和加酶量对油脂提取率的影响,得到最佳提取工艺,并以过氧化值和酸价为指标研究该核桃油在不同温度、光照、容器材料以及抗氧化剂下的稳定性。结果表明:巴塘核桃油提取的最佳工艺为pH7、酶解温度45 ℃、酶解时间3.5 h、加酶量1.4%,在此条件下巴塘核桃油提取率为78.91%±0.03%;将此条件下提取的核桃油用铁罐灌装,置于冷藏、避光的条件下,并添加0.02% BHT+V_C(质量比1:1)作为抗氧化剂,其表现出的氧化稳定性较佳,具有较长的保质期。     

超声波辅助纤维素酶-碱液提取大枣皮红色素工艺的响应面优化研究

本实验研究了纤维素酶解提取大枣皮红色素的最佳工艺.运用响应面分析法筛选出了纤维素酶的最佳酶解条件;通过正交试验设计确定了最佳碱液提取条件.结果表明:当纤维素酶用量为底物的1.26%、酶解温度51.90℃、酶解体系pH值51.9、酶解时间60min、碱液浓度1.0%、提取温度80℃、提取时间35min时,大枣皮红色素的提取率最高,达到1.326μg/g.     

辣木叶酶法水解提取蛋白质工艺优化

为了优化纤维素酶与果胶酶水解提取辣木叶中蛋白质的提取工艺,以提取率为考察指标,运用单因素与正交试验研究了酶解温度、加酶量、pH、底物质量浓度与酶解时间5个因素对辣木叶蛋白质提取率的影响。结果表明:纤维素酶各因素对辣木叶蛋白质提取率影响的主次顺序为:酶解温度 > 底物质量浓度 > pH > 酶解时间 > 加酶量,最佳工艺条件为:酶解温度40℃、加酶量800 U/L、酶解pH5.0、底物质量浓度7.0 g/L、酶解时间70 min,在此条件下的提取率达到了43.85%。果胶酶各因素对辣木叶蛋白质提取率影响的主次顺序为:加酶量 > 底物质量浓度 > 酶解时间 > 酶解温度 > pH,最佳工艺条件为:酶解温度50℃、加酶量1400 U/L、pH4.0、底物质量浓度9.0 g/L、酶解时间50 min,提取率达到了32.26%。纤维素酶与果胶酶各因素对辣木叶蛋白质提取率的影响均达到了极显著水平（P<0.01）。在最佳工艺条件下,纤维素酶水解辣木叶提取蛋白质的效果优于果胶酶。     

坛紫菜水溶膳食纤维二次正交旋转组合法提取工艺的优化及其抗油脂氧化研究

以坛紫菜为原料,采用复合酶法提取水溶性膳食纤维,以猪油、菜油为材料考察其抗油脂氧化作用。在单因素实验基础上,采用二次正交旋转组合设计法对坛紫菜水溶性膳食纤维提取工艺进行优化,建立纤维素酶添加量(X1)、酶解pH(X2)、酶解温度(X3)和酶解时间(X4)等4个因素与水溶性膳食纤维提取率之间的回归模型。结果表明:纤维素酶法提取的最佳工艺参数为酶添加量1.1%、酶解pH5.8、酶解温度55℃和酶解时间1.5h,在此条件下坛紫菜水溶性膳食纤维提取率为9.80%±0.12%;膨胀力为1.97mL/g,持水力为276%,坛紫菜水溶性膳食纤维能明显减缓油脂POV值升高趋势,且具有一定的时间和浓度依赖性,显示坛紫菜可溶性膳食纤维具有一定的抗油脂氧化能力。     

超声波辅助水酶法提取木棉籽油的工艺优化及性质研究

以木棉籽为原料,采用超声波辅助水酶法提取木棉籽油。以木棉籽油的提取率为指标,利用正交试验优化提取工艺参数,并对所得油脂进行理化分析。优化后的最佳工艺参数:酶添加量0.8%(以木棉籽质量计)、初始pH 7.0、酶解温度45℃、复合酶质量比4∶1、酶解时间50min,在此条件下,木棉籽油提取率达到79.7%。所提取的木棉籽油颜色呈淡黄色,透明度好,酸价为3.22 mg·KOH/g,过氧化值为1.131 mmol/kg,皂化值为179.89 mg·KOH/g,碘值为165.79 g·I/100 g。     

水酶法提取青稞蛋白工艺研究

以纤维素酶作为水解酶,采用水酶法从青稞米籽粒中提取蛋白质。通过单因素实验和正交实验,得到提取青稞蛋白的最佳条件,即料/水比1:5、加酶量0·2%、酶解时间14h、酶解温度45℃、酶解pH6·5。在最佳条件下青稞蛋白的提取率为69·3%。     

纤维素酶法提取黑豆皮色素的工艺研究

研究了黑豆皮色素的酶法提取工艺.以黑豆皮色素的提取率为指标,采用单因素法和正交设计法对纤维素酶法提取工艺条件进行优选.实验结果表明,最佳提取工艺条件为:酶用量80U/mL,酶解温度50℃,pH4.5,酶解时间120min;该工艺条件下进行三次浸提,色素提取率达到96.8%,与未加纤维素酶的工艺相比,提取率提高了8.2%.     

大黄鱼肝油提取工艺优化及品质分析

以大黄鱼肝脏为原料,选用最佳的蛋白酶水解提取大黄鱼肝油,以提取率为评价指标,对酶解工艺条件进行优化,并分析其品质和脂肪酸组成。结果表明,大黄鱼肝油的最佳酶解工艺为中性蛋白酶添加量2.5%、料液比1∶2(g/mL)、pH 7.3、酶解时间4h、酶解温度50.3℃。该工艺条件下提取率为78.39%,其品质较淡碱法好,油脂澄清,酸价为(5.83±0.15)mg/g,碘价为(142.65±0.22)mg/100g,含有13种脂肪酸(较淡碱法多5种),且不饱和脂肪酸为8种,其中饱和脂肪酸含量为19.71g/100g,单不饱和脂肪酸含量为62.63g/100g,多不饱和脂肪酸含量为17.62g/100g。酶法提取大黄鱼肝油的提取率、品质及脂肪酸组成均优于淡碱法。     

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.     

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.     

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.     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.