沙田柚果醋澄清技术的研究

以皂土、果胶酶、明胶+单宁、壳聚糖、硅藻土、PVPP 6种澄清剂对沙田柚果醋进行澄清处理,优选出最佳的澄清剂,研究其添加量、澄清时间、澄清温度对沙田柚果醋澄清效果的影响.结果表明,壳聚糖为最佳澄清剂,壳聚糖添加量为0.10 g/L、澄清时间为5 h、澄清温度为40 ℃时,澄清效果最佳,沙田柚果醋的透光率达到95.2%.     

甲壳素负载麦饭石复合物对保健食醋和果醋的澄清作用

将天然高分子甲壳素作为澄清剂的主体,研制甲壳素-麦饭石复合澄清剂。将80目麦饭石与甲壳素的0.5%盐酸溶液按1:1.2(g/mL)混合制成固体复合澄清剂,用其来处理保健食醋和果醋。得出最佳澄清工艺条件:澄清剂添加量1.0g/100mL、室温搅拌6min。分别用甲壳素、麦饭石对保健食醋和果醋都有一定的澄清效果,而复合澄清剂中的甲壳素与麦饭石的良好的澄清作用相互促进,澄清效果更加显著。澄清后的保健食醋具有琥珀色透明液体。甲壳素-麦饭石复合澄清剂对果醋的澄清效果比保健食醋更加显著,对其他营养成分的影响较小,说明甲壳素-麦饭石复合澄清剂是一种优良的澄清剂。     

野木瓜果醋的澄清研究

该文以壳聚糖、硅藻土、果胶酶、琼脂、明胶-单宁作为澄清剂对野木瓜果醋进行澄清处理,并对不同澄清剂处理的野木瓜果醋澄清效果进行对比.实验结果表明,当加入3%(v/v)的明胶-单宁澄清后的野木瓜果醋透光率达89.10%,比未添加澄清剂的野木瓜果醋透光率增加了14.34%,起到了较好的澄清作用.     

金柑果醋澄清工艺的研究

通过探讨不同澄清剂对金柑果醋澄清效果的影响,优选出壳聚糖为最佳澄清剂,研究了壳聚糖添加量、澄清时间、澄清温度对金柑果醋澄清效果的影响,并通过L9(34)正交试验确定了金柑果醋澄清的最佳条件.结果表明,壳聚糖添加量为1.25g/L、澄清时间为3.Oh、澄清温度为50℃时,澄清效果最佳,金柑果醋的透光率达到99.8%.     

蓝莓果醋澄清剂的筛选

以自制蓝莓发酵果醋为原料,采用壳聚糖、硅藻土、果胶酶、明胶、单宁对蓝莓果醋进行一系列单一澄清剂和复合澄清剂的澄清实验,并对透光率、酸度、可溶性固形物含量进行测定。研究结果表明,单一澄清剂中,果胶酶、明胶、单宁澄清效果较为理想,最佳添加量为3%,透光率分别为64.7%、62.0%、61.0%;复合澄清剂中,果胶酶∶明胶∶单宁（8∶1∶1）,添加量5%澄清处理蓝莓果醋,透光率达64.5%。综合澄清稳定性考虑,选择复合澄清剂果胶酶∶明胶∶单宁（8∶1∶1）处理蓝莓果醋效果最佳。成品果香怡人、酒体澄清丰满。     

发酵型石榴果醋澄清剂的筛选及工艺条件优化

为得到适合发酵型石榴果醋澄清的澄清剂,以澄清度(T)为指标,先采用单因素试验从3种澄清剂(壳聚糖、明胶、皂土)中进行筛选,然后利用正交试验优化合适澄清剂的工艺条件。结果表明,3种澄清剂均可提高发酵型石榴果醋的澄清度(T),其中,壳聚糖处理的果醋澄清度(T)最佳、效果最好,其次是皂土和明胶;正交试验优化得到的最佳澄清工艺条件为:按照0.3 g/L用量加入壳聚糖后,在30℃、pH值为4的条件下处理1.5 h,发酵型石榴果醋的澄清效果最佳,澄清度(T)高达0.98,醋体清澈透明且均一稳定。     

壳聚糖对百香果醋澄清作用的影响研究

以壳聚糖为澄清剂对百香果醋进行澄清处理,研究了壳聚糖用量、澄清温度和澄清时间对澄清效果的影响。确定了适宜澄清条件为:壳聚糖用量0.1 g/L、澄清温度40℃、澄清时间90 min。利用壳聚糖澄清百香果醋能较好地避免二次混浊现象。     

一步发酵法酿造桑椹果醋工艺条件

以含有一定酒精的桑椹汁为原料,采用一步发酵法即直接向原料中接种活化的醋酸菌液进行醋酸发酵酿造桑椹果醋,通过单因素试验和正交试验确定其最佳酿造工艺条件。结果表明,最佳酿造工艺条件为：酒精体积分数6%、搅拌转速130r/min、醋酸菌接种量15%(体积分数)。通过比较3 种单一澄清剂对桑椹果醋的澄清效果,结果表明：1% 壳聚糖溶液对桑椹果醋的澄清效果最佳,其最佳添加量为1.6mL/100mL。采用此工艺可以得到澄清透明、呈浅玫瑰红色、具有醋和桑椹复合风味的桑椹果醋。     

模糊数学法在沙棘果醋感官评定中的应用

采用微生物发酵法酿制沙棘果醋,通过添加不同的澄清剂对果醋进行处理,利用模糊数学法对其进行了感官评定,结果表明:壳聚糖可有效澄清沙棘果醋,酿制的产品酸甜可口,具有沙棘果的清香,产品符合国家标准。     

果胶酶对百香果醋澄清作用的研究

以果胶酶作为澄清剂对百香果醋进行澄清处理,研究了酶用量、酶解温度和时间对澄清效果的影响.根据果胶酶对百香果醋澄清的单因素试验结果,采用正交试验对果胶酶用量、酶解温度和酶解时间等工艺参数进行优化,确定了适宜的反应条件为:果胶酶用量120mg/kg、温度45℃、反应时间150min.利用果胶酶澄清百香果醋能较好地避免二次混浊现象.     

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.     

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.     

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.     

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.