宣木瓜糯米酒发酵工艺优化

本研究以宣木瓜和糯米为主要原料,采用补料发酵工艺酿造宣木瓜糯米酒。筛选合适的酒曲和酵母,在此基础上设计Box-Behnken实验优化宣木瓜糯米酒发酵工艺条件,考察发酵温度、酵母添加量和初始p H对宣木瓜糯米酒酒精度和出酒率的影响。结果表明,酒曲3号适用于糯米糖化,获得的还原糖含量和糖化酶活力较高;酵母2号适用于宣木瓜糯米酒的发酵,其出酒率达到32.8%。经响应面实验优化得到的宣木瓜糯米酒最适发酵条件为:发酵温度17.9℃,发酵p H为4.50,酵母添加量为0.22 g/kg,在此条件下宣木瓜糯米酒酒精度为19.6%vol,出酒率可达45.3%。     

木瓜酒发酵过程中多酚类物质的高效液相色谱测定及含量变化分析

实验优化了高效液相色谱法同时测定木瓜酒中10种多酚类物质的测定条件,并分析各单体酚在发酵过程中的含量变化情况。结果表明,在优化的色谱条件下,木瓜酒中10种多酚物质能在60 min之内得到有效分离,各酚类物质在0.1~10 mg/L的质量浓度范围内相关系数R~20.993 6,线性关系良好,检出限在0.01~0.02mg/L之间,木瓜酒样品加标回收率在97.04%~107.32%之间,回收率高、准确可靠,适用于同时测定木瓜酒中没食子酸、原儿茶酸、香豆酸、绿原酸、槲皮苷、咖啡酸、儿茶素、芦丁、表儿茶素、山奈素10种酚类物质。经测定,3种木瓜酒中各单体酚含量在发酵过程中变化趋势与总酚含量基本一致,呈现先增加而后缓慢减少的趋势,发酵4个月后,3种木瓜酒中总多酚含量均显著增加(p0.05)。野木瓜酒(样品1)、皱皮木瓜酒(样品2)和光皮木瓜酒(样品3)的总多酚含量分别为903、1 178、1 057 mg/100 m L。3种木瓜酒中各酚类物质在发酵过程中变化趋势与总酚含量基本一致,主要含有的多酚物质有儿茶素、原儿茶酸和绿原酸;儿茶素含量在3种木瓜酒中含量最高且差异显著(p0.05),可用于区分上述3种木瓜品种。     

木瓜果醋发酵工艺的研究

研究以酿造木瓜果酒为原料,接种AS1.41醋酸菌,酿造木瓜果醋的工艺条件.试验结果表明,其最佳工艺条件为初始酒度6%vol,初始pH为4,AS1.41醋酸菌活化液的接种量为17.5%,发酵温度为31℃,装液量为20%,转为200r/min.发酵4d后所得木瓜果醋的醋酸含量为(6.557±0.06)g/100mL.     

宣木瓜酒发酵动力学和感官评价研究

对宣木瓜酒发酵动力学进行研究,提出拟合方程,利用origin6.1软件对实验数据进行处理,得到了酵母菌生长数量模型拟合方程,该方程较好地反映了宣木瓜酒发酵过程的动力学特征.采用模糊数学的方法对宣木瓜果酒感官评价结果进行分析,结果表明,模糊数学方法适用于宣木瓜酒感官评价.     

木瓜荞麦果酒制备工艺与品质分析

为改良传统木瓜果酒酿造工艺,提升木瓜果酒的品质,利用光皮木瓜酶解液和荞麦糖化液为混合原料,以酒精度、总黄酮含量以及感官评价为评价指标,通过单因素试验和正交试验优化木瓜荞麦果酒酿造工艺条件。结果表明,木瓜荞麦果酒的最佳酿造工艺条件为初始糖度24 °Bx、酵母接种量0.5%、发酵温度22 ℃、木瓜酶解液:荞麦糖化液质量比为1∶2、主发酵时间14 d。在此优化条件下,木瓜荞麦果酒液的酒精度为17.8%vol、总黄酮含量为0.54 mg/mL、总酸含量为3.78 g/L、总糖含量为24.31 g/L、还原糖含量为4.32 g/L,酒体色泽金黄、澄清透亮、香醇净爽,符合果酒品质要求。     

木瓜酒发酵工艺条件的初步研究

以新鲜木瓜为主要原料,研究了木瓜酒的发酵工艺.通过实验,在pH2.6～3.3、糖质量浓度180～250g/L,温度25～30℃的条件下发酵,得出其最佳发酵工艺条件为:发酵温度为25℃,糖的质量浓度250g/L,pH3.3,接种量0.18g/L.     

蓝莓酒发酵过程中主要成分变化规律研究

研究了蓝莓酒主发酵过程中总糖、总酸、挥发酸、花色苷、单宁、乙醇、甲醇、高级醇和酯等主要物质含量的变化。结果表明,蓝莓通过加糖9.6%发酵,原酒酒精度可达到11.8%(体积分数),总酸7.53g/L,pH2.95;花色苷含量逐渐减少,发酵结束后达0.615g/100g;单宁含量变化较小;挥发酸含量随着发酵时间的延长而逐渐上升,主发酵期间上升较快,但最终可控制在国标(≤1.2g/L)允许范围以内;甲醇在刚开始发酵时就存在,发酵前期略有上升,后略有下降,含量相对稳定;高级醇中的异丁醇和苯乙醇是蓝莓酒的主要香气成分,约占香气成分的60%以上,苯甲酸乙酯、乙酸乙酯、己酸乙酯、癸酸乙酯是蓝莓酒香气的主要成分,在发酵过程中高级醇和酯都不断增加,发酵过程中还检测到一些未知成分。     

木瓜红枣果酒的营养价值与保健作用研究

木瓜红枣果酒营养成分测定表明:木瓜红枣果酒中含有氨基酸、糖类、维生素、矿物质等人体必需的生理活性物质,其中谷氨酸、苏氨酸、脯氨酸、VB2、果糖、钾、钙、钠、铁含量较高。氨基酸总量高达465.10 mg/L,人体必需氨基酸有5种(24.86%);含矿质元素钾1 315.3 mg/L、钙129.4 mg/L、铁10.9 mg/L、硒6.2×10-3 mg/L等;含VB1 9.6×10-4 mg/100 g、VB2 0.078 mg/100 g、总糖40.4 g/L;还含有齐墩果酸7.18 mg/kg、0.48%的黄酮等活性物质。从这些生理活性物质的代谢过程,阐明了木瓜红枣果酒对人体的保健作用。     

建立反相高效液相色谱法测定宣木瓜中齐墩果酸的含量

建立反向高效液相色谱法测定宣木瓜中齐墩果酸的含量。采用PhenomenexC18色谱柱(250mm×4.6mmi.d.,5μm),流动相为V(甲醇)∶V(磷酸水溶液,pH=2.0)=85∶15,柱温27℃,流速0.8mL/min,进样量5μL,检测波长210nm。结果:齐墩果酸进样量在(0.5～3)μg范围内,线性关系良好,回归方程为:Y=4103095.714X-49564.000(R2=0.999)。齐墩果酸的平均回收率为93.59%,RSD为2.81%。方法操作简便,精密度高,重复性好,为宣木瓜中齐墩果酸的含量测定提供可靠的科学研究依据。     

木瓜中齐墩果酸的测定方法研究

本文比较了高氯酸-香草醛比色法和反相高效液相色谱法对木瓜中齐墩果酸测定效果。结果表明：高效液相色谱法测定方法快速、准确、适合木瓜中齐墩墩果酸的测定。测定条件：色谱柱Kramosil C18、流动相甲醇冰醋酸（100：0．1）、检测波长215nm。经测定鲜木瓜中齐墩果酸含量为0．06％。     

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.     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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.