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。     

皮状丝孢酵母产油脂的研究

本文对皮状丝孢酵母的生长发育和油脂合成进行了研究,监测和分析了酵母菌生长发育、油脂合成和脂肪酸成分及数量,检测了形态、OD值、糖氮代谢、p H、生物量、油脂含量和脂肪酸组分。结果表明:皮状丝孢酵母生长80 h左右时镜检测得菌细胞体内含油脂情况与80 h左右时实际提油获得的油脂量相一致,其油脂产量为3.66 g/L,含油率约为39.20%。皮状丝孢酵母生长0~6 h为适应期,此时糖氮的消耗明显,细胞数量缓慢增加;6~25 h为对数期,氮消耗非常显著,细胞数量急剧增加,细胞变大;25~120 h为稳定期,糖的消耗明显,消耗速度显然大于氮的消耗,细胞内开始慢慢积累油脂;之后为衰退期,氮的消耗基本趋于平稳。皮状丝孢酵母所产脂肪酸主要以C16、C18为主,此类脂肪酸适于进行脂交换制备生物柴油。     

利用皮状丝孢酵母对甘蔗渣酶解液产油脂的研究

本试验旨在研究碱和高温液态水2种预处理方式对发酵的影响。甘蔗渣分别利用碱和高温液态水(LHW)预处理,然后使用纤维素酶进行酶解。在LHW和碱预处理后的酶解液中,分别含22.06和39.28 g/L总糖。不经过浓缩,也不需要添加任何营养物质,酶解液被用于皮状丝孢酵母的油脂发酵试验。经过3 d的培养,在LHW预处理的酶解液中,皮状丝孢酵母的生物量达到了8.08 g/L,油脂质量分数为52.00%,油脂系数高达19.03%。在碱预处理的酶解液中,经过8 d的培养,皮状丝孢酵母的生物量为13.67 g/L,油脂质量分数为43.20%,油脂系数为15.03%。脂肪酸组成分析表明所产油脂与棕榈油的组成相似。试验结果表明,甘蔗渣是一种有前景的产油脂原料,LHW是一种良好的预处理方式。该研究为利用甘蔗渣发酵产油脂提供了新思路。     

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。     

一株丝孢酵母属菌株发酵产油脂的研究

通过摇瓶发酵,比较丝孢酵母属菌株JM-B在不同营养和发酵条件下的产油脂情况。以菌体生物量、油脂产量、油脂含量及油脂系数为指标,优化碳源质量浓度、氮源组成与质量浓度、磷酸盐质量浓度等发酵培养基组成,优化接种量、发酵温度、摇床转速、发酵时间等发酵条件,利用气相色谱法测定油脂脂肪酸组成。结果表明:最适培养基组成为葡萄糖100 g/L,硫酸铵1.0 g/L,酵母膏10 g/L,磷酸二氢钾4 g/L,p H自然;最适发酵条件为发酵温度25℃,摇床转速160 r/min,种子液种龄36 h,接种量10%(以发酵液体积计),发酵时间144 h。在最适培养条件下,得到的菌体生物量和油脂产量最高,分别为16.14、6.64 g/L,油脂产量较优化前提高了161.4%,油脂中饱和脂肪酸含量比优化前降低了28.1%。可以认为丝孢酵母属菌株JM-B是一株很有开发潜力的产油脂菌株。     

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。     

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.     

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.     

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％。     

菊芋菊糖、山楂、菊花复合饮料的研制

采用热水浸提法对菊糖进行提取,通过正交试验确定了提取菊糖的最佳条件为:料水比1∶25(g/g),温度90℃,提取时间60 min,菊糖提取率为79.98%。以菊芋菊糖、山楂、菊花为主要原料,添加白砂糖、蜂蜜等辅料。针对其关键技术进行了探讨,采用单因素和正交试验设计,以产品感官评价为指标,确定菊芋菊糖、山楂、菊花复合饮料的最佳工艺配方。结果表明:山楂和菊花提取液比为2∶3(m L/m L)、菊芋菊糖2%、白砂糖4%、蜂蜜3%、最佳稳定剂为0.05%海藻酸钠和0.1%CMC-Na。该复合饮料具有营养、保健的功能,色泽、香味、口感俱佳。     

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.     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.