瑞士乳杆菌TUST005发酵干酪乳清产物的工艺条件优化

以瑞士乳杆菌TUST005、干酪乳清为原料,在单因素实验基础上,采用四因素三水平的正交实验方法研究了不同的接种量、培养时间、培养温度和初始pH值对游离氨基酸质量浓度的影响。结果表明,瑞士乳杆菌TUST005制备发酵干酪乳清的最佳工艺条件:新鲜干酪乳清经灭菌后,接种3%(体积分数)的发酵剂,培养时间为30 h,发酵液初始pH值为6.5,36℃静止培养,游离氨基酸的质量浓度为1.74μg/mL。     

瑞士乳杆菌高活力蛋白酶发酵条件的优化

本研究采用正交试验的方法对瑞士乳杆菌TS6024发酵乳清蛋白相关发酵条件进行优化,以达到瑞士乳杆菌分泌高水平蛋白酶能力的目的。实验结果表明,优化的发酵条件为:温度35℃、发酵初始pH6.5、接种量2.0%、静置发酵16h后,发酵液中生成游离氨基酸的水平达到994.170×10-5mol/L,分泌蛋白酶的活力达到62.136U。     

大豆抗氧化活性肽固态发酵工艺优化

为优化大豆抗氧化活性肽固态发酵的工艺条件,以总抗氧化活性为指标,对大豆抗氧化肽固态发酵的培养基组成、发酵温度、接种量、初始pH值、加水量等因素进行了单因素试验,并用二次回归通用旋转组合设计对反应温度和pH进行了优化.获得了优化的大豆抗氧化肽固态发酵的工艺条件培养基中豆粕与麸皮的比例为41,培养基的水分含量66.7%,接种量25.0%,种龄48 h,发酵温度33.7℃,起始pH 8.49,发酵时间36 h.在此条件下发酵产物总抗氧化活性为568.89 U/g豆粕,比最初的436.14 U/g豆粕提高了30.44%,实验值与预测值基本相符.     

微生物发酵法制备乳清抗氧化肽的研究

通过筛选得到发酵法生产乳清抗氧化肽的最适乳酸菌菌株,同时以氧自由基清除率为指标研究了接种量、菌种比、发酵温度、初始pH值和时间对液态发酵法生产乳清多肽的影响,并采用正交试验确定了最佳发酵工艺条件.结果表明,接种量5%,菌种比1:1,发酵温度37℃,初始pH值6.4,时间16 h,此时测得乳清水解产物O2-清除率为39.45%,肽质量浓度为2.62 g/L.     

基于高活菌数的瑞士乳杆菌和鼠李糖乳杆菌混合发酵工艺优化

以瑞士乳杆菌和鼠李糖乳杆菌混合发酵培养,利用两菌株细胞代谢的差异,以静置发酵24 h后得到的活菌数目为指标,通过单因素实验和正交实验,研究了瑞士乳杆菌和鼠李糖乳杆菌高活菌数混合发酵的最适发酵条件。结果表明,瑞士乳杆菌和鼠李糖乳杆菌高活菌数混合发酵的最优条件为:发酵温度37℃,初始pH=6.8,接种量6%,瑞士乳杆菌:鼠李糖乳杆菌=1∶2,瑞士乳杆菌优先接种3 h。最终得到乳酸菌总活菌数为7.2×10~9m L~(-1)。与在相同条件下单独发酵的瑞士乳杆菌和鼠李糖乳杆菌活菌数相比,分别提高了1∶8倍和10.2倍。为乳酸菌的高活菌数发酵奠定了基础。     

发酵乳清蛋白制取抗氧化肽的研究

为研究乳清蛋白发酵产物的抗氧化能力,采用益生菌对其进行发酵。以DPPH自由基清除率为指标,通过单因素试验和正交试验对发酵条件进行优化,得到发酵工艺的最佳参数为:10%乳清蛋白复原乳在37℃,初始pH值6.8,接种量4%条件下发酵24h。在该条件下,发酵产物对DPPH自由基的清除率为66.95%。     

凝固型蜂蜜酸奶发酵工艺条件对还原糖转化率的影响

本实验探索了发酵时间、发酵温度和初始pH值对蜂蜜酸奶还原糖转化率的影响,通过单因素试验和正交试验确定了最佳的发酵工艺参数。结果表明:在蜂蜜8%、脱脂奶粉10%、按1:1接入保加利亚乳杆菌和嗜热链球菌,总接种量为2%的基本条件下,当发酵时间为4h、发酵温度为42℃、初始pH值为6.8时,原料中还原糖转化率达到36.18%。     

植物乳杆菌发酵红枣汁的工艺条件优化及体外抗氧化活性

为研究植物乳杆菌发酵红枣汁的工艺条件及抗氧化活性,采用正交试验法对植物乳杆菌的发酵温度、发酵p H、发酵时间和接种量进行考察,通过多指标(酸度、活菌数和感官评价)综合加权评分方法优化红枣汁的发酵条件,并对发酵红枣汁清除DPPH·、ABTS·+和FRAP能力进行评价。结果表明,植物乳杆菌发酵红枣汁的最优工艺为发酵温度37℃,pH 5.5,发酵时间36 h和接种量5%,在此条件下,发酵红枣汁的综合评分最高(99.73)。方差分析结果表明,接种量对红枣汁的综合评分有显著影响,而发酵温度、发酵pH和发酵时间对红枣汁综合评分没有显著影响。与未发酵的红枣汁相比,经植物乳杆菌发酵后的红枣汁FRAP能力显著增加,DPPH·清除能力没有显著变化,ABTS·+清除能力显著降低。经植物乳杆菌发酵的红枣汁具有一定的抗氧化和自由基清除活性。     

产超氧化物歧化酶乳酸菌的筛选及发酵条件优化

从不同地区的传统发酵食品中筛选出104株菌落形态各异的乳酸菌,通过过氧化氢抗性试验筛选出20株具有抗氧化能力的乳酸菌,并测定其产SOD的能力。结果表明,20株乳酸菌中C8的SOD活性最高,达349.62 U/mg。通过革兰氏染色、过氧化氢酶试验和16S rRNA基因序列分析,构建系统发育树,根据同源性分析确定C8为乳酸乳球菌。为提高菌株产SOD的能力,通过单因素实验探究培养温度、初始接种量、初始pH值和灌装量对乳酸乳球菌产SOD的影响,并通过正交试验进一步优化菌株的发酵条件。最终确定最佳发酵条件为:发酵温度37℃,初始接种量3%,初始pH 7.5,灌装量75mL。在此培养条件下,乳酸乳球菌的SOD活性达93.95 U/mL,与优化前相比提高了2.2倍,为后期乳酸乳球菌在发酵产业的应用奠定基础。     

响应面法优化开菲尔乳制品的发酵条件

以开菲尔粉、乳酸乳球菌乳酸亚种和戊糖乳杆菌为发酵剂,通过单因素试验研究发酵剂添加比例、接种量、发酵时间、发酵温度对开菲尔发酵乳品质的影响。以感官评分为响应值,用响应面法分析获得最佳发酵条件是:开菲尔粉接种量0.175 g/L,乳酸乳球菌乳酸亚种与戊糖乳杆菌菌液体积比1.73∶1,接种量3.21%(体积分数),发酵温度42.8℃,发酵时间7.8 h。在此条件下开菲尔发酵乳组织状态较黏稠,乳清析出少,香气较好,酸甜适宜。其多肽含量2.125 g/L,抗氧化活性EC5019.928 g/L,具有较高的营养价值和保健功效。     

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.     

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.     

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.