盐渍黄瓜护绿方法的探讨

以叶绿素含量为评价指标,分别采用单因素和正交试验研究了盐渍黄瓜加工过程的漂烫、护色、盐渍等工艺条件对其护绿效果的影响.结果显示,黄瓜漂烫的适宜条件为90℃漂烫2 min;黄瓜盐渍的最佳条件为食盐浓度15%,盐渍液pH 6.0,盐渍时间3天;护色剂的适宜配方为Cu2+400 mg/L+Zn2+400 mg/L,按拟定的加工流程和此优化条件下制作的黄瓜样品具有较好的护绿效果.     

烫漂处理对荷兰豆嫩荚干制的影响

荷兰豆是近年来深受国际市场欢迎的畅销蔬菜。对于荷兰豆嫩荚的干制过程,烫漂是一种行之有效的预处理方法。本研究结果表明:荷兰豆烫漂液中分别添加1%的食盐、200mg/L的柠檬酸或400mg/L的D-异抗坏血酸钠,可明显改善荷兰豆干制品质与干燥效率;烫漂工艺的最佳烫漂温度为95℃,烫漂时间为2min。     

山芹调味粉护色工艺及配方研究

利用正交设计试验对山芹菜调味粉加工前处理工艺及配方进行研究。分析了时间、温度、ZnCl_2对护色效果的影响,优化了山芹菜调味粉配方。结果表明,护色工艺参数最佳组合为ZnCl_2质量浓度350μg/m L,烫漂时间1.5 min,温度85℃;配方最佳组合为食盐添加量2%,蔗糖的添加量1%,味精的添加量1.5%。由此工艺制得的山芹调味粉色泽鲜绿,风味突出、浓郁,且滋味清爽鲜美,甜咸适宜。     

工业化宫保鸡丁产品中莴笋前处理加工品质关键技术研究

以莴笋茎干为原料,色泽和脆度为感官考核指标,通过对比漂烫温度、漂烫时间、漂烫液浓度和保护液的浓度对宫保鸡丁中配菜莴笋颜色及脆度的影响,确定工业化宫保鸡丁中莴笋最优护绿保脆参数。结果表明:漂烫温度85℃,漂烫时间1.5min,漂烫液的浓度为0.03%碳酸钠,保护液浓度为0.3%氯化钙,该参数条件处理后的莴笋能够在工业化宫保鸡丁中保持良好的颜色及脆度,使得其口感、风味、脆度和色泽几种品质最佳。     

香鱼清蒸即食产品的加工工艺

该文以感官品质为指标,通过正交实验确立了清蒸香鱼的调味配方。以微生物指标、感官品质和质构为指标,研究了漂烫工艺和121℃下的杀菌时间。结果表明,最佳调味配方为:食盐100 g/kg、味精7.5 g/kg、料酒150 mL/kg、白醋25mL/kg;最佳漂烫工艺为:漂烫温度90℃、漂烫时间10 s;杀菌时间为15 min。产品肉质软嫩,具有香鱼独特的香气。     

芒果真空冷冻干燥工艺的研究

以百色象牙芒为原料,采用真空冷冻干燥的方法,对芒果干燥过程的漂烫工艺、护色工艺以及真空冷冻干燥的参数控制等问题进行研究。结果显示:沸水烫的温度为95℃,漂烫时间为45s时,漂烫效果最好;0.30mol/L×10-3苹果酸和0.20mol/L×10-3抗坏血酸的复合液,护色时间10min,复合液pH3.5,此时的护色效果最佳;干燥过程分为升华干燥阶段和解析干燥阶段,升华干燥阶段,真空度为45~55Pa,加热板温度为35℃;解析干燥阶段,真空度为45~55Pa、加热板温度为55℃,此时干燥的产品品质最优。     

泡小米辣护色保脆工艺研究

研究小米辣泡制前处理的护色保脆工艺.单因素试验表明小米辣烫漂温度为55℃、时间20 min、pH 4.0;正交试验表明最佳护色保脆液配方为焦亚硫酸钠0.02%、柠檬酸0.10%、氯化钙0.10%、D-异抗坏血酸钠0.05%.泡制后的小米辣保留了天然脆性、自然色泽和优良口感.     

茭白叶护绿工艺研究

研究护绿液配方、护绿工艺、温度、时间对茭白叶护绿效果的影响.实验表明:采用浓è度为300 mg/kg的CuCl2、ZnCl2、柠檬酸和浓度为250 mg/kg的CaCl2作为护绿液,烫漂加工工艺,在温度为100℃、时间为1.5 min 的状态下处理获得的茭白叶,效果最好且能较好地保持原有质地.     

低糖苦瓜果脯的加工工艺

以苦瓜为原料,对影响苦瓜果脯品质的烫漂、护色、温度、渗糖等关键工艺进行研究。结果表明:苦瓜最佳切分厚度为0.7 cm～0.8 cm;烫漂时间为3 min;烫漂温度为90℃。最佳护色和硬化工艺配方为:氯化钙0.5%、亚硫酸氢钠0.5%、氯化钠0.2%、醋酸锌0.3%。最佳渗糖工艺为:CMC浓度为2.0%、β-环状糊精的添加量3%、浸泡液浓度梯度为30%-40%-50%、每次冷浸时间8 h。制成的低糖苦瓜果脯风味好、色泽自然。     

速冻小松菜加工贮运中护绿技术研究

为探索出口速冻小松菜加工贮运中适宜的护绿保鲜措施,以莎莉品种小松菜为试材,研究其速冻前复合液烫漂处理中碳酸氢钠和氯化钠浓度、烫漂温度和时间等因素对小松菜冻藏贮运(-18℃)中色泽的影响;同时对处理条件进行优化。结果表明,小松菜速冻加工中适宜的护绿处理条件为:0.10%碳酸氢钠+0.10%氯化钠复合液,在90℃条件下漂烫1.2min,并结合0.20%氯化钙溶液室温浸泡30 min+PE包装+速冻等综合措施,对产品冻藏期色泽护绿效果较好。     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.