直投式纳豆菌发酵剂制备工艺优化

为探索出一种工艺简便、成本低且活菌数高的直投式纳豆菌（Bacillus natto）发酵剂的制备方法，该研究以大米粉为基质替代传统的种子液培养基培养纳豆菌后直接将其烘干制成直投式纳豆菌发酵剂，通过单因素及正交试验优化直投式纳豆菌发酵剂的制备工艺。结果表明，用含1.5%蛋白胨的大米粉作为培养基，在接种量4.0%、加水量40%、培养温度43 ℃条件下培养纳豆菌28 h，菌体生长良好，将培养物烘干后制成的直投式纳豆菌发酵剂中的活菌数含量达4.71×109 CFU/g。此技术操作简便，可推广至工业生产中，简化生产过程。     

直投式酸奶发酵剂制备关键技术

酸奶发酵剂是影响整个酸奶生产和保证发酵乳产品质量稳定的关键因素,因而选择优良高效的乳酸菌发酵剂是酸奶生产过程中的核心问题之一.高效直投式酸奶发酵剂是一类新型的商品化生产菌种,在国外其制备技术已经较为成熟,但在国内尚处于起步阶段,市场长期被国外企业垄断,因此开发具有自主产权的直投发酵剂产品及制备技术显得尤为重要.该文综述了直投式发酵剂生产的国内外研究进展,指出了制备过程中决定其质量的各个技术环节,严控这些生产环节,才能保证产品质量,生产出具有我国自主产权的直投式发酵剂产品.     

5L立瓶发酵制备益生菌直投式发酵剂及应用试验

对长双歧杆菌、保加利亚乳杆菌、嗜热乳酸链球菌在5 L立瓶中分别进行培养,确定了各自的发酵最适收获期,菌体收集后经制备所获得冷冻浓缩直投式发酵剂活菌数大于1010mL-1,冷冻干燥直投式发酵剂活菌数大于1011g-1。以制备的冷冻浓缩、冷冻干燥直投式发酵剂,进行牛乳发酵应用试验,生产的益生菌酸奶风味纯正、品质良好。     

高效液相色谱法测定酸奶中四种有机酸

测定酸奶中风味有机酸,精确评价酸奶风味,并对比3种发酵剂的发酵性能。使用3种直投式发酵剂以半工业化方式生产酸奶,测定3种酸奶在发酵及冷藏过程中的酸度变化,感官评定酸奶成品,并通过高效液相色谱法(HPLC)分析酸奶中的4种有机酸成分(乳酸、柠檬酸、丙酮酸及甲酸)。结果表明:3种发酵剂产酸迅速,所产酸奶品质优良,M与自制发酵剂后酸化弱。冷藏期间3种酸奶中有机酸含量的变化存在细微差异。利用高效液相色谱法有效测定了酸奶中4种有机酸(乳酸、柠檬酸、丙酮酸及甲酸),成功评定了3种发酵剂的发酵性能。     

乳酸菌摇瓶增殖培养工艺研究

采用自行筛选的适用于作为高效冻干酸奶发酵剂的嗜热链球菌S.t-SY和保加利亚乳杆菌L.b-DR为出发菌株,在优化的麦芽复合汁增菌培养基上进行摇瓶增殖培养。通过研究培养温度、培养方式、基质起始pH值、接种量、中间补料方式等因素对乳酸菌摇瓶增殖培养的影响,优化乳酸菌摇瓶增殖培养的工艺条件。试验结果表明:在麦芽复合汁增菌培养基中乳酸菌增殖培养的最适条件是:培养温度37℃,基质起始pH值6.5～7.5,接种量0.2%～0.3%,静置培养16h,收获期S.t-SY和L.b-DR活菌数分别达到2.93×109、2.74×109cfu/mL。本试验结果为乳酸菌进一步应用麦芽复合汁增菌培养基生产高效浓缩直投式发酵剂提供了技术参数。     

一株产细菌素植物乳杆菌高密度发酵培养基的筛选及其在酸奶中的应用

目的:优化用于高密度发酵产细菌素的植物乳杆菌KLDS 1.0391的经济有效培养基,旨在生产具有益生作用的辅助发酵剂。方法:以发酵液中活菌数量和抑菌效果为指标,比较不同水解度的脱脂乳粉、乳清粉、麦麸,以及玉米浆粉的发酵效果,制备冻干形式的植物乳杆菌直投式发酵剂,将其添加至酸奶中,评价其对酸奶发酵时间、pH、滴定酸度、粘度和感官评价的影响,进而确定其在酸奶中应用的可行性。结果:确定脱脂乳粉、乳清粉和麦麸培养基的最佳水解度分别为15%、15%和20%;植物乳杆菌KLDS 1.0391在玉米浆粉培养基中获得的发酵效果最佳,活菌数量达到9.53 lg CFU/mL,抑菌圈直径达到12.69 mm。植物乳杆菌直投式菌种的添加对酸奶发酵时间和感官评价无显著影响(P>0.05),酸奶粘度下降,但可以缓解酸奶的后酸化程度。通过优化得到植物乳杆菌KLDS 1.0391高密度发酵的廉价培养基为:4%玉米浆粉,同时补充2%葡萄糖和0.1% Tween-80。结论:制得的植物乳杆菌直投式发酵剂可应用于酸奶生产中。     

直投式酸奶发酵剂的研究进展

本文概述了国内外制备直投式酸奶发酵剂的研究进展,以及进行直投式酸奶发酵剂研究的重要性.     

响应面优化酸浆豆腐直投式高效发酵剂配方

将酸浆乳酸菌与商业菌复合，以复合菌粉的冻干存活率为指标，通过优化复合菌粉保护剂配方制备直投式高效发酵剂。结果表明：以菌泥体积100 mL为基准，复合菌粉保护剂最优配方为酵母粉10 g、麦芽糖11.5 g、海藻糖5 g,此时复合菌粉存活率为83.07%;发酵后期直投式高效发酵剂的发酵能力优于菌液，且储存期间发酵性能不变；由二者制备的酸浆豆腐质构特性没有明显差异，说明直投式高效发酵剂可以代替菌液制作酸浆豆腐。     

康普茶直投式发酵剂的制备及其发酵性能的研究

目的 制备菌种成分明确的康普茶直投式发酵剂,并对直投式发酵剂的发酵性能进行探究,解析直投式发酵剂应用于康普茶生产的理论基础。方法 通过测定菌株存活率筛选适用于发酵康普茶的巴氏醋杆菌、木醋杆菌、拜耳结合酵母的冻干保护剂,再将冻干后的菌粉接种至红茶中发酵,以前期开发的康普茶混菌发酵剂为对照,通过测定康普茶发酵过程中糖类、乙醇、有机酸和感官等指标考察直投式发酵剂的发酵性能。结果 巴氏醋杆菌、木醋杆菌、拜耳结合酵母的最优冻干保护剂分别为30 g/100 mL的菊粉、20 g/100 mL的海藻糖、30 g/100 mL的海藻糖,存活率分别为92.41±1.33%、57.61±2.29%、52.95±1.67%。在康普茶发酵过程中,直投式发酵剂与未冻干的混菌发酵剂发酵的康普茶在主要成分、电子舌评测及感官评定等各个方面均呈现相似的变化趋势。直投式发酵剂发酵后的康普茶中以酸味柔和兼具健康功效的葡萄糖酸和葡萄糖醛酸为主,醋酸仅在第二天检测到;在发酵终点康普茶的乙醇含量符合饮料的标准（< 0.5% m/V）。结论 直投式发酵剂与实验室前期获得的混菌发酵剂发酵的康普茶品质相当,可以为康普茶直投式发酵剂的制备提供理论和技术支持。     

我国酸奶发酵剂的使用现状及发展趋势

酸奶发酵剂是制作酸奶所用的特定微生物培养材料.发酵剂的种类和酸奶的发酵方式对酸奶质量有着重要影响.本文比较了几种常见酸奶发酵剂的优缺点,并且指出直投式酸奶发酵剂是今后酸奶发酵剂的发展趋势.     

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.