白首乌酵素发酵工艺的优化

为了开发一款白首乌酵素产品,本文以白首乌为原料,采用乳酸菌和酵母菌复合发酵制备酵素,对乳酸菌和酵母菌的单因素实验条件进行优化,并确定两菌种复合发酵时的接种顺序和发酵时间。结果表明:采用先接种酵母菌后接种乳酸菌发酵的方式最优,该接种顺序下的最佳复合发酵工艺条件为:梅山酵母菌(S4)在初始pH5.0、装瓶量30 mL(250 mL)、蛋白胨添加量1.2%、接种量0.2%、发酵温度30 ℃的条件下,发酵24 h,酵母菌发酵结束后,接种3%的复合乳酸菌(嗜酸乳杆菌(LA)和植物乳杆菌(LP)以1:1混合(v:v)),37 ℃静置发酵36 h,然后在4~8 ℃下后发酵12 h,使发酵液产香。在此条件下,白首乌酵素中乳酸菌活菌为2.61×108 CFU/mL,酵母菌活菌数为7.9×107 CFU/mL,超氧化物歧化酶(superoxide dismutase,SOD)活力为4.23×104 U/L。采用发酵的方法制备白首乌产品,为白首乌资源的开发利用提供了新的思路,对促进白首乌产业的发展具有重要意义。     

复合菌种发酵法制备玫瑰酵素工艺研究

研究了复合菌种发酵法制备玫瑰酵素最佳工艺。采用响应面法优化酵母菌和乳酸菌双菌种发酵法制备玫瑰花酵素的最佳工艺,建立玫瑰花酵素SOD酶活性与各自变量的回归方程。结果表明,最优双菌种发酵条件为酵母菌接种量1.99%,酵母菌发酵时间9.13 d;乳酸菌接种量1.27%,乳酸菌发酵时间10.98 d,此优化条件下SOD酶活性为245.3 U/mL,接近理论值246.45 U/mL。在双菌种优化条件下,接种醋酸菌联合发酵,增加酵素口感和风味,通过三种菌的复合发酵,得到具有玫瑰红色和玫瑰花味,淡淡酒香,酸甜适宜,口味及营养丰富的酵素饮品。     

酸马奶中乳酸菌与酵母菌的共生发酵特性

对内蒙古锡盟地区酸马奶中分离出的1株乳酸菌和1株酵母菌进行混合培养,初步确定双菌混合发酵的最佳培养条件：双菌发酵计数乳酸菌活菌数的最佳发酵温度为30℃摇床培养12h再转到37℃静置培养,最佳发酵时间为20h,脱脂乳中添加的营养成分最优配方为蛋白胨1g/100mL、蔗糖0.5g/100mL、酵母浸粉0.5g/100mL;双菌发酵计数酵母菌活菌数的最佳发酵温度为37℃静置培养8h再转到30℃摇床培养,最佳发酵时间为32h,脱脂乳中添加的营养成分最优配方为蛋白胨0.5g/100mL、蔗糖0.5g/100mL、酵母浸粉0.5g/100mL;选用乳酸菌与酵母菌质量比1:1作为菌种配比。 同时在最佳生长条件下探讨乳酸菌与酵母菌的相互作用关系以及后发酵对二者共生作用的影响,结果表明,促进乳酸菌生长的活性物质生成的时间为12h以前(即将酵母菌在5号配方中30℃摇床培养),促进酵母菌生长的活性物质生成的时间应为16h以前(即将乳酸菌在1号配方中37℃静置培养),在后发酵过程中,乳酸菌与酵母菌双菌培养的活菌数都极显著高于单菌培养(P＜0.01)。     

蓝莓酵素复合菌种发酵工艺优化及品质分析

该研究以蓝莓为主要原料,以酵母菌、植物乳杆菌(Lactobacillus plantarum)、干酪乳杆菌(Lactobacillus casei)为发酵菌种制备蓝莓酵素,以超氧化物歧化酶(SOD)酶活性为考察指标,首先通过均匀设计试验确定复合菌种的最佳接种量;其次通过单因素试验,考察发酵时间、发酵温度、初始总可溶性固形物含量及料液比对SOD活力的影响;最后通过响应面试验获得最佳发酵工艺条件。结果表明,酵母菌、植物乳杆菌、干酪乳杆菌三种菌株的最佳接种量分别为0.1%、2%、0.47%,蓝莓酵素的最佳发酵工艺条件为发酵时间41.5 h,发酵温度31℃,初始总可溶性固形物含量12°Bx,料液比1∶5(g:m L),在此优化条件下,蓝莓酵素的pH值为3.14,酒精度为0.2%vol,总酚含量为3.14 mg/mL,花色苷含量为26.06 mg/mL,乳酸菌活菌数为1.01×10⁷CFU/m L,SOD酶活性为103.01 U/m L。     

混合菌种发酵大豆黄浆水的工艺优化

采用干酪乳杆菌、发酵乳杆菌、酿酒酵母对大豆黄浆水进行发酵,以乳酸菌和酵母菌活菌数为指标,研究糖蜜添加量、初始pH、接种量、接种比例、培养转速、发酵温度、发酵时间对发酵液中活菌数的影响。在单因素实验的基础上,采用响应面法优化大豆黄浆水发酵的工艺参数。结果表明最佳工艺参数为：接种量6%、接种菌种比例1∶1∶1、培养转速120 r/min、培养时间48 h、糖蜜添加量5%、初始pH 6.80,培养温度31 ℃,在此条件下大豆黄浆水发酵液中乳酸菌活菌数为3.18×109 CFU/mL,酵母菌菌数为4.1×108 CFU/mL。     

复合菌株发酵胡萝卜饮料的工艺研究

以胡萝卜渣为原料,研究猴菇菌、乳酸菌和酵母菌复合发酵生产胡萝卜活菌饮料的工艺,通过正交试验设计、感官评价等方式对猴菇菌种子培养基的配方、猴菇菌发酵工艺条件、发酵液的前处理以及乳酸菌和酵母菌复合发酵工艺条件进行了优化。结果表明,猴菇菌种子培养基的配方是胡萝卜汁30%,麦芽糖2%,豆浆6%,柠檬酸0.02%,磷酸二氢钾0.1%,硫酸镁0.15%。猴菇菌的最佳发酵参数为发酵温度25℃,发酵时间78 h,接种量12%,干渣添加量2%。淀粉酶的最佳添加量为0.05%。乳酸菌和酵母菌复合发酵的最佳工艺参数为发酵温度36℃,发酵时间12 h,接种量4%,酿酒酵母与乳酸菌配比为1︰2。     

蓝莓酵素发酵工艺优化

以新鲜蓝莓为原料,植物乳杆菌（Lactobacillus plantarum）和酵母菌作为发酵菌种,以蛋白酶活力及超氧化物歧化酶（SOD）活力为评价指标,通过单因素试验和正交试验优化最佳发酵工艺条件。结果表明,植物乳杆菌（Lactobacillus plantarum）单独发酵蓝莓酵素时,发酵工艺条件为植物乳杆菌接种量为4%,39 ℃条件下发酵1 d。在此条件下蛋白酶活力及SOD酶活力分别为39.44 U/mL和84.17 U/g。植物乳杆菌（Lactobacillus plantarum）和酵母菌复合菌种发酵工艺条件为同时接入4%植物乳杆菌与0.15%的酵母菌,34 ℃条件下培养4 d,蛋白酶活力及SOD酶活力分别达到了55.76 U/mL和81.27 U/g,该方式是最佳的蓝莓酵素制备工艺。     

红茶菌发酵条件的控制研究

将分离筛选得到的乳酸菌、醋酸菌和酵母菌进行配比得到红茶菌复合菌种,分别讨论培养基pH值、溶氧量、温度和时间对培养结果的影响。结果表明：乳酸菌、醋酸菌、酵母菌按质量配比2:2:1,即总接种量5%、最适初始pH值为5.5、装液量为40%(即装液量100mL/250mL),在30℃、传统培养基培养5d的条件下,发酵效果最好。     

蓝莓果渣酵素发酵工艺优化

以蓝莓果渣为主要原料,优化最佳发酵工艺条件,提高酵素产品质量。选取工艺参数为酵母菌和干酪乳酸菌的最佳接种量、发酵温度、初始pH值、发酵时间,分析其对酵母菌的蛋白酶活力和浓度及对干酪乳酸菌浓度的影响。按照单因素试验和正交试验法设计上述工艺参数的优化试验。确定最佳酵母菌发酵工艺条件为：发酵液初始pH 3.5、发酵温度30 ℃、接种量0.15%、发酵时间16 h。酵母菌发酵16 h后在37 ℃条件下,发酵液pH 4.0,干酪乳杆菌接种量0.50%,静置发酵24 h,温度保持在18～20 ℃左右,静置进行24 h的后发酵,使发酵液产香,品质优良,将浓缩后的发酵液通过真空冷冻干燥,制成蓝莓果渣酵素粉状产品。     

银耳酵素发酵及体外消化对活性物质影响

为研究银耳酵素发酵工艺和体外消化对其活性物质的影响,以银耳为主要原料,通过单因素试验和正交试验,以SOD酶活性、总酸含量和菌落总数为指标,优化酵母菌发酵、乳酸菌发酵、混合菌种发酵的三种银耳酵素的工艺参数,分析它们在体外消化中多糖、多酚和黄酮含量的变化规律。酵母菌发酵最佳工艺:蔗糖10.00%、酵母菌1.00%、35℃发酵20 h;乳酸菌发酵最优工艺:脱脂乳粉5.00%、蔗糖6.00%、乳酸菌1.75%、33℃发酵20 h;混合菌种发酵最优工艺:酵母菌发酵15 h时接种乳酸菌,再发酵20 h。经体外模拟胃肠消化后,三种银耳酵素的多糖、多酚和黄酮含量有提高。混合菌种发酵银耳酵素发酵效果最好,更易于在胃肠消化中释放活性物质,尤其是多酚类物质,这为研究其抗氧化活性提供了基础。     

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.