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.     

壳聚糖澄清荔枝果醋的研究

研究了壳聚糖对荔枝果醋的澄清效果,测定了荔枝果醋澄清前后主要成分的变化。经过单因素试验和正交试验,壳聚糖澄清荔枝果醋的最佳工艺条件确定为：壳聚糖用量5g/L、澄清处理pH3.5、澄清处理时间8h、澄清处理温度30℃。在此最佳工艺条件下,壳聚糖对荔枝果醋有良好的澄清效果,可以较好地降低荔枝果醋中蛋白质和单宁的含量,从而有效地改善其贮藏稳定性。     

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%.     

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%.     

苹果柚子复合果醋的稳定性研究

为了优化苹果柚子复合果醋的稳定性,试验采用单因素试验和响应曲面法对其工艺进行了研究,建立并分析了各主要影响因子与离心沉淀率关系的数学模型。单因素试验结果表明:壳聚糖用量对离心沉淀率影响极显著、澄清温度影响显著和澄清时间影响极显著。通过RSM响应曲面法的进一步分析显示,回归方程P值0.0001,R2Adj为0.9740和Adeq.Precision(信噪比)为22.738,说明所建模型与试验值的拟合度很好。苹果柚子复合果醋的稳定性工艺参数为壳聚糖用量0.55g/L、澄清温度55.9℃和澄清时间5.8h;经试验验证,在此条件下离心沉淀率为0.0235%,与理论计算值0.0238%基本一致。     

雪莲果梨果醋澄清工艺的优化研究

以果胶酶为澄清剂对雪莲果梨果醋进行澄清处理,研究了果胶酶用量、酶解pH、酶解温度和酶解时间对雪莲果梨果醋澄清效果的影响,在单因素试验的基础上,采用正交试验对酶用量、酶解pH、酶解温度和酶解时间等工艺参数进行优化,得到最佳工艺条件为:果胶酶用量0.03%、酶解pH 3.5、酶解温度40℃、酶解时间150min,该条件下澄清后果醋透光率为89.3%,澄清效果好。     

百香果果酒澄清技术研究

为解决百香果果酒存储期间出现浑浊现象的问题,本文为陈酿百香果酒为原料,以透光率和感官评分作为澄清效果的评价指标,对比了自然澄清法、离心法、活性白土澄清法、果胶酶澄清法、壳聚糖澄清法和膜过滤法等6种澄清方法对百香果果酒的澄清效果,并对澄清剂的最适添加量进行了探究。结果表明,6种澄清方法的澄清效果为：活性白土澄清法＞果胶酶澄清法＞膜过滤法＞壳聚糖澄清法＞离心法＞自然澄清法。膜过滤法、离心法、果胶酶澄清法和壳聚糖澄清法处理百香果果酒后,口感与色泽发生了明显变化。活性白土澄清法能较好地对百香果果酒进行澄清,且保持百香果果酒原有的品质,其最适添加量为9%。经过澄清处理后百香果果酒呈金黄色,澄清透明,口感良好,且在保质期内均未再出现浑浊现象。     

壳聚糖澄清姜汁工艺条件的研究

用壳聚糖为澄清剂对姜汁进行澄清试验,研究了壳聚糖用量、温度、澄清时间、pH等工艺条件与姜汁透光率的关系.通过正交试验筛选出壳聚糖澄清姜汁的最佳工艺条件为:壳聚糖用量0.4 g/L、温度50℃、pH为6.0、反应时间40 min.澄清后,果汁透光率达98%以上,壳聚糖是一种有效的姜汁澄清剂.     

活性炭负载壳聚糖对香蕉皮果醋澄清作用的研究

以活性炭负载壳聚糖制成固体澄清剂,用其处理香蕉皮果醋。最佳工艺条件是：澄清剂添加量3%、搅拌时间6min、作用温度25℃,过滤可得到透明、稳定性较高的香蕉皮果醋,放置6个月无沉淀。     

壳聚糖澄清草莓胡萝卜复合果蔬汁工艺研究

以壳聚糖为澄清剂,研究了壳聚糖添加量、果蔬汁溶液pH、澄清温度和时间对草莓胡萝卜复合果蔬汁的澄清效果。单因素试验显示:壳聚糖用量为0.25～0.4 g/L,复合果蔬汁pH为3.5～4.1,澄清温度为40℃～50℃,澄清时间为45 min～55 min时,复合果蔬汁的透光率和出汁率均达到峰值。通过正交试验获得的最佳工艺条件为:壳聚糖用量0.35 g/L,澄清时间为45 min,澄清温度为50℃,复合果蔬汁pH为4。验证试验显示此工艺条件处理的草莓胡萝卜复合果蔬汁透光率达到93.6%。     

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.     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the