双菌混合发酵丢糟生产微生物油脂的研究

探索利用假丝酵母和皮状丝孢酵母混合发酵丢糟生产微生物油脂的最佳工艺条件.在对假丝酵母和皮状丝孢进行驯化培养的基础上,设定假丝酵母和皮状丝孢酵母的比例、接种量、培养温度、培养时间为4个因素,进行L9(34)正交试验,通过测定油脂含量,获得油脂生产的最佳工艺条件.研究结果表明,双菌发酵丢糟生产微生物油脂的最佳工艺条件:假丝酵母和皮状丝孢酵母的比例为1:1,接种量为9％,培养温度为32℃,培养时间为4d,在该条件下测得每1000g丢糟发酵物中油脂含量为21.14g.     

皮状丝孢酵母在酶法水解丢糟生产微生物油脂中的应用

以大曲丢糟为主要原料,利用纤维素酶为催化剂,以皮状丝孢酵母为生产菌,采用正交试验进行微生物油脂发酵研究。结果表明,丢糟酶解的最佳工艺条件为：纤维素酶添加量为0．5％,水解温度为55℃,水解时间1．5h,所得丢糟水解液还原糖含量为9．83％;皮状丝孢酵母发酵丢糟水解液生产微生物油脂的最佳工艺条件为：皮状丝孢酵母接种量为11％,培养温度为26℃,培养时间为7d,培养基的糖度为9。P。在最佳条件下测得皮状丝孢酵母生物量为0．3549g／100mL,油脂含量为23．89％。     

皮状丝孢酵母发酵丢糟水解液的应用研究

采用正交试验研究了硫酸水解丢糟的最佳工艺与皮状丝孢酵母发酵丢糟水解液生产微生物油脂的最佳工艺.结果表明:最佳丢糟酸水解工艺条件为硫酸添加量8％ (9 mol/L),水解温度90℃,水解时间1.5 h;在最佳水解条件下,丢糟水解液中还原糖含量为1.51％.最佳皮状丝孢酵母发酵丢糟水解液生产微生物油脂的工艺条件为接种量8％,发酵温度32℃,蔗糖添加量0.8％,发酵时间3d;在最佳发酵条件下,菌体的油脂含量可达24.86％.     

皮状丝孢酵母菌发酵菊粉产油脂的研究

因皮状丝孢酵母是一株高产油脂酵母,对皮状丝孢酵母发酵菊粉产油脂进行了研究。考察了盐酸水解、菊粉酶水解及菊粉酶添加量对皮状丝孢酵母发酵菊粉产油脂的影响,实验结果表明:酶解菊粉的方法优于酸解,当菊粉酶添加量为80U/50mL发酵液时,皮状丝孢酵母生物量和油脂含量最高,分别达到13.49g/L和5.26g/L,油脂得率达到39%。皮状丝孢酵母发酵菊粉产的油脂中脂肪酸成分以含16和18个碳原子的长链脂肪酸为主,其中80.5%以上是C16:0、C18:1和C18:2,尤其是C18:1(53.1%)。因此,皮状丝孢酵母发酵菊粉生产的油脂可作制备生物柴油的替代原料。     

圆红冬孢酵母发酵玉米秸秆水解液产油脂的研究

以玉米秸秆为原料,圆红冬孢酵母As 2.1389为实验菌株,研究了玉米秸秆稀酸水解的条件及该菌种在水解液中发酵产油脂的特性.结果表明,玉米秸秆的最佳水解条件为:硫酸体积分数2％,固液比1∶10,121℃高压水解20 min;在此条件下,水解液中的还原糖含量为38.77 g/L.圆红冬孢酵母在经Ca(OH)2脱毒处理后的水解液中进行发酵产油脂,最佳发酵条件为:pH 5,接种量15％,发酵时间5d,得到的生物量为13.5 g/L,油脂产量4.71 g/L,油脂含量为34.89％,还原糖利用率95.73％.气相色谱-质谱分析表明其油脂的脂肪酸组成与植物油脂相似,可作为制备生物柴油的原料油脂.     

玉米秸秆水解液发酵产生物油脂试验研究

对发酵性丝孢酵母IFFI01368发酵玉米秸秆水解液产脂的培养基组成和发酵条件进行了探索,并对油脂的脂肪酸组成进行了鉴定.结果表明最佳条件为:补加4%的蔗糖,酵母膏、硫酸铵为氮源,碳氮比100:1,pH 5.5,发酵摇瓶装液量为300 mL三角瓶装玉卷秸秆水解液50 mL,时间4d.在最佳条件下于27℃、150 r/min振荡发酵培养,所得生物量为23.5 g/L,油脂含量42.7%,产脂能力为10.03 g/L.所产生物油脂的脂肪酸主要为棕榈酸、油酸和硬脂酸.     

响应面法优化皮状丝孢酵母产油脂发酵培养基

以皮状丝孢酵母（Trichosporon cutaneum）为出发菌株,对其产油脂的发酵培养基进行研究。以油脂产量为评价指标,通过单因素试验研究发酵培养基中的碳源、氮源、外源因子对油脂产量的影响,然后利用响应面试验对培养基进行优化。结果表明,最佳培养基配方为葡萄糖97.6 g/L、玉米浆干粉4.4 g/L、乙酸钠0.09 g/L。在该优化条件下,皮状丝孢酵母的油脂产量达到了14.4 g/L。     

含乙酸玉米芯水解液中四株油脂酵母联产多糖与油脂的研究

为了研究木质纤维素水解液中高浓度乙酸的存在对油脂酵母发酵的影响,本研究以4株油脂酵母(皮状丝孢酵母、浅白隐球酵母、Trichosporon dermatis与Trichosporon coremiiforme)为研究对象,在玉米芯水解液中添加高浓度乙酸(15 g/L)作为发酵底物,研究发酵的底物代谢与产物积累规律。结果表明:发酵培养基中的糖与乙酸几乎可被皮状丝孢酵母与T.dermatis完全代谢;而T.coremiiforme与浅白隐球酵母对糖与有机酸的代谢效果不佳。皮状丝孢酵母与T.dermatis在高效降低高底物浓度培养基的COD的同时,可在胞外合成一定浓度的多糖产品。四株油脂酵母的油脂脂肪酸组成以C16、C18系列为主,其中油酸(C18:1)比例最高;除合成微生物油脂外,它们还能在胞内大量积累多糖类物质以及少量的蛋白质与灰分。本文可为油脂酵母利用廉价原料联产酵母多糖与微生物油脂这两种高附加值食品提供参考。     

以绿色木霉Trichodermaviride NUA-051及产朊假丝酵母Candida utilis发酵酸解玉米秸秆生产单细胞蛋白的艺研究

以蛋白质得率为目标,综合考虑绿色木霉(Trichodermaviride NUA-051)与产朊假丝酵母(Candida utilis)2.281的共生特性及营养竞争,通过木霉发酵产物还原糖对菌体生长抑制的实验研究及发酵条件实验,确立了以酸解玉米秸秆为原料生产单细胞蛋白的发酵工艺酸解玉米秸秆150g/L,木霉发酵40h接种酵母2%,(NH4)2SO4 25.0g/L,KH2PO4 6g/L、MgSO4·7H2O 0.4g/L,通风量为4.5L/L·min为,搅拌转速为600r/min,pH5～6,温度35℃.木霉发酵时间40h,酵母发酵时间24h,发酵总周期64h.     

菊芋提取液的皮状丝孢酵母发酵产油脂试验研究

以皮状丝孢酵母为产油脂菌种,研究其发酵菊糖提取液产油脂情况。首先研究了从菊芋中提取菊糖的条件,获得最适提取条件为:温度85℃,时间80 min,菊芋粉质量浓度70 g/L,在此最优提取条件下,菊糖提取率达95%;然后考察了pH值、接种量、培养温度和氮源对皮状丝孢酵母发酵菊糖提取液产油脂的影响,获得最优条件为:初始pH值5.5、培养温度30℃、接种量10%。在此优化条件下,5 L发酵罐分批扩大培养,其生物量、出油率和油脂得率分别达到13.93 g/L、34.73%和4.89 g/L。补充添加氮源对生物量、出油率和油脂得率的提高不显著。气相色谱法测定脂肪酸成分主要是C16和C18系列,其中80.2%以上是C16:0、C18:1和C18:2,尤其是C18:1(43%),其油酸、棕榈酸和亚油酸占总脂肪酸的比例和植物油脂非常接近。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

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.