冷冻与酶解相结合澄清芦柑果汁的工艺研究及质量评价

研究冷冻法与果胶酶酶解法相结合对芦柑果汁的澄清作用,同时探讨此澄清方式对果汁品质的影响。实验以新鲜芦柑果肉为原料,先进行冷冻预处理,自然解冻榨汁、离心后再用果胶酶对果汁进行澄清。结果表明,芦柑果肉冷冻预处理的最佳温度为—20℃、时间为60 min,得到的果汁透光率和出汁率分别为80.57%、82.86%;果胶酶酶解的最优工艺参数为:酶添加量0.05 g/L、酶解温度45℃、酶解时间0.5 h,酶解处理后果汁的透光率和出汁率分别达到94.16%、90.38%;经冷冻与酶解相结合处理后汁液的Vc含量由26.77 mg/100 g降为25.48 mg/100 g,可溶性固形物及总糖下降较多,分别由9.6%、10.2 g/100 mL降为8.4%、7.8 g/100 mL,果胶和可溶性蛋白质几乎被完全分解;澄清汁储存稳定性良好。因此,该复合澄清工艺合理可行,可为芦柑果汁的深加工提供理论依据。     

果胶酶与半纤维素酶复合酶解制备费约果果汁的工艺优化

为减少费约果细胞壁中果胶和半纤维素等物质对果汁品质的负面影响,提高果汁出汁率,本文研究了复合酶(半纤维素酶和果胶酶)比例、加酶量、温度、时间对“Unique U-100”费约果果汁出汁率和可溶性固形物的影响。在单因素实验的基础上,进行四因素三水平的响应面优化。结果显示：在复合酶(半纤维素酶/果胶酶)比例为2.14:1,加酶量19.6 g/L,酶解温度56.8℃,酶解时间92 min的条件下,费约果果实出汁率最高,为79.5%,与模型预测值相对误差为5.67%;果汁中可溶性固形物含量为15.7%,与模型预测值相对误差为0.83%。此外,与直接压榨的费约果果汁相比,酶解后的果汁表现出更高的澄清度、总酚含量(24.4 mg GAE/100 g)和V_C含量(2.42 mg/100 g)。因此,本研究优化了复合酶酶解制备费约果果汁的工艺,提高费约果果汁出汁率和营养品质,可为后续费约果果汁深加工提供理论依据。     

沙田柚果浆酶解工艺条件的研究

以梅县沙田柚为原料,利用果胶酶处理柚果浆,考察酶解温度、酶解时间及酶添加量对果浆出汁率的影响,优化沙田柚果浆酶解工艺条件。结果表明,最佳酶解条件:酶解温度40～45℃,酶解时间3h,酶添加量75～100mg/L,此时出汁率在80%以上;比较酶解前后果汁的营养成分的变化,果汁可溶性固形物提高了0.6 oBix,还原糖含量由9.418g/L提高到10.30g/L,出汁率提高了18.23%,果汁黏度由30mPa.s显著下降至2mPa.s,VC损失率为28.2%,同时果汁透光率也显著提高,而对果汁总酸、pH值等基本无影响。     

果浆酶和果胶酶对猕猴桃出汁率的影响

为制取猕猴桃汁,通过单因素和正交试验,以出汁率、VC保存率和果汁色泽香气变化为指标,用果浆酶和果胶酶对猕猴桃进行酶解处理,探索更适合的猕猴桃制汁工艺条件。结果表明：两种酶都能大幅提高猕猴桃的出汁率,果胶酶酶解条件较剧烈,虽出汁率较高,但对VC含量和果汁色泽香气影响较大;果浆酶酶解条件较温和,总体指标较好,最佳酶解条件为酶解温度30℃、果浆酶加酶量10000U/kg、酶解时间2h、出汁率0.853mL/g,VC保存率67%。果浆酶更适合猕猴桃果汁的制取。     

响应面法优化猕猴桃果浆酶解工艺参数研究

本文研究果胶酶反应温度和作用时间及酶用量对猕猴桃果浆出汁率、果汁澄清度和乙醇不溶物的影响,采用通用旋转设计和响应面分析猕猴桃果浆酶解最优条件。结果表明,猕猴桃果浆的最佳酶解条件为:反应温度为45℃,作用时间为113min,果胶酶用量为0.013%,在此条件下,猕猴桃果浆预测出汁率达到83.30%,乙醇不溶物0.98g/100ml,果汁的澄清度为81.47%。验证试验表明,响应面优化后得到猕猴桃果浆出汁率、果汁澄清度和乙醇不溶物回归方程的相关系数分别为0.958、0.904和0.922。     

蓝靛果的酶解工艺优化及抗氧化特性研究

为充分利用蓝靛果,提高其经济价值,该文采用酶解法提高蓝靛果出汁率,研究蓝靛果汁中4种活性物质含量的变化,并用DPPH自由基、·OH、ABTS+自由基的清除率来评价蓝靛果汁的抗氧化能力。应用响应面法对蓝靛果的酶解工艺进行优化,结果表明,最优酶解工艺为果胶酶用量0.27%、纤维素酶用量0.92%、酶解温度47℃。在此工艺条件下,蓝靛果的出汁率为85.67%。酶解对蓝靛果汁中的VC、花色苷、总酚和总黄酮都有积极的影响,酶解后,蓝靛果汁中VC、花色苷和总黄酮的含量分别增加了1.78、1.13 mg/mL和2.54 mg/mL。酶解后的蓝靛果汁对DPPH自由基、·OH和ABTS+自由基的IC50值分别为0.285、6.37、11.62 mg/mL,具有较高的清除能力。当质量浓度为1.8 mg/mL时,蓝靛果汁对DPPH自由基的清除率为88.13%;当质量浓度为12 mg/mL时,蓝靛果汁对·OH的清除率为74.12%;蓝靛果汁在质量浓度为60 mg/mL时,ABTS+·的清除率达到最大为94.67%。     

8个梨品种非浓缩还原汁的特性分析

为筛选制备非浓缩还原梨汁的加工品种,以辽西的花盖梨、绥中白梨、晶白梨、锦丰梨、皇冠梨、水晶梨、雪花梨、酥梨8种品种为原料,通过测定梨汁的理化特性、褐变程度、稳定性等指标探究不同梨品种对梨汁品质的影响。结果表明:锦丰梨的出汁率高达85.39%,显著高于其他品种(P0.05);皇冠梨和雪花梨汁的褐变程度较小,而花盖梨和酥梨汁的褐变度显著高于其他品种(P0.05);晶白梨、锦丰梨汁的可溶性固形物含量显著高于其他梨汁(P0.05);不同品种梨汁的浊度在75.7 NTU～858.2 NTU之间,存在显著性差异(P0.05);各品种梨汁之间的pH值均在4.05～4.98之间。在稳定性方面,花盖梨显著低于其他品种梨汁(P0.05)。锦丰梨的出汁率和可溶性固形物含量高,果汁的酸度适中,褐变程度相对较轻,且外观无明显颜色变化,能较好的保持果汁的原有风味和营养成分,是较为理想的制汁材料。     

果胶酶ROHAPECT D5S对猕猴桃取汗和澄清的影响

研究了果胶酶ROHAPECTD5S对猕猴桃出汁率、粘度、澄清度和冷热稳定性的影响。结果表明,此酶可以极大地改进猕猴桃果浆的出汁率和降低果汁粘度,使果汁的澄清度加大,对冷冻和加热的稳定性加强,适合用作弥猴桃汁的加工,对猕猴桃浆的最佳应用条件为3PA/100g果浆（相当于干酶60g/1000kg果浆）,45℃下60min。     

酶解法提取蓝莓果汁的研究

为提高蓝莓果汁的提取率和营养品质,利用酶解技术,在单因素试验的基础上进行正交试验优化酶解工艺条件,并对果汁出汁率、总可溶性固形物、花青素含量进行测定。结果表明,酶解法提取蓝莓果汁最优工艺条件为果胶酶∶纤维素酶=3∶1,酶用量0.20%,酶解时间180 min,酶解温度50 ℃。在此最佳酶解工艺条件下,蓝莓果汁出汁率为73.37%,总可溶性固形物含量为11.8 °Bx,花青素含量为300.7 mg/kg。     

果胶酶ROHAPECT D 5S对猕猴桃取汁和澄清的影响

研究了果胶酶ROHAPECTD5S对猕猴桃出汁率、粘度、澄清度和冷热稳定性的影响。结果表明,此酶可以极大地改进猕猴桃果浆的出汁率和降低果汁粘度,使果汁的澄清度加大,对冷冻和加热的稳定性加强。适合用作猕猴桃汁的加工,对猕猴桃浆的最佳应用条件为3PA/100g果浆(相当于干酶60G/1000kg果浆),45℃下60min。     

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