Nisin及纳他霉素生物保鲜剂对干豆腐保鲜效果的研究

以干豆腐为原料,研究Nisin、纳他霉素和Nisin-纳他霉素复配对干豆腐的保鲜效果,通过感官评定、挥发性盐基氮(total volatile basic nitrogen,TVB-N)、菌落总数、pH值、电子鼻和色差值对干豆腐的新鲜程度进行评价。结果表明,在贮藏过程中,其他试验组相比,Nisin-纳他霉素复配处理的干豆腐TVB-N值、菌落总数均最小;颜色没有明显变化,并有效减缓干豆腐的风味腐败。因此,Nisin-纳他霉素复配可在37℃条件下有效延长干豆腐保鲜期,其保鲜效果明显优于Nisin和纳他霉素单独保鲜。     

响应面法优化符离集烧鸡复合生物防腐剂的研究

为延长符离集烧鸡的货架期,将乳酸链球菌素(Nisin)、溶菌酶、茶多酚、壳聚糖、纳他霉素和ε-聚赖氨酸等6种生物防腐剂加入到符离集烧鸡中,以菌落总数、挥发性盐基氮、硫代巴比妥酸值和pH值为指标,研究生物防腐剂对符离集烧鸡的保鲜作用。单因素实验结果表明,和壳聚糖、纳他霉素、ε-聚赖氨酸相比,Nisin、溶菌酶、茶多酚3种生物防腐剂具有更好的抑菌效果,并能显著提高符离集烧鸡的品质;在此基础上,采用响应面优化法对3种生物防腐剂进行复配,经分析后建立多元回归模型,确定复合生物防腐剂最优添加浓度为Nisin 0.03 g/kg、茶多酚0.09 g/kg、溶菌酶0.10 g/kg。     

防腐剂及二次杀菌对熟肉制品保藏性的影响

为延长熟肉制品保质期,使用纳他霉素、乳酸链球菌素(Nisin)、双乙酸钠、脱氢乙酸钠、山梨酸钾五种防腐剂处理熟肉制品,真空包装后在4℃下保藏并观察其感官和微生物变化。选择保藏效果较好的防腐剂并结合二次杀菌处理熟肉制品,以保温检验结果结合感官评分为评价指标,确定用于熟肉制品保藏的最佳防腐剂配方及二次杀菌条件。结果表明:4℃贮藏条件下,单一防腐剂处理对熟肉制品保藏效果最好的是Nisin,用量为0.32 g/kg时保质期可达74 d;熟肉制品采用复合防腐剂(Nisin 0.08 g/kg+双乙酸钠0.5 g/kg)结合二次杀菌处理,产品可达到商业无菌要求。     

复合防腐剂对低硝中式香肠贮藏期品质的影响

为减少亚硝酸盐在中式香肠中的用量,以山梨酸钾、Nisin、纳他霉素作为复合防腐剂,采用正交试验设计确定各因素水平的比例,对中式香肠贮藏期间挥发性盐基氮、菌落总数、亚硝酸盐残留量、质构指标进行测定。结果表明:复合防腐剂可以部分取代亚硝酸盐,三种添加剂的最优组合为山梨酸钾0.3g/kg、Nisin0.2g/kg、纳他霉素0.03g/kg、亚硝酸钠0.04g/kg,且按此量进行复配时,防腐效果明显优于对照组(亚硝酸钠0.15g/kg)。     

即食湿面条的保鲜研究

即食湿面条因水分含量高,常温下易腐败变质,研究了浓度为250 mg/L纳他霉素酒精溶液应用于即食湿面条的保鲜效果,结果表明其对细茵、霉茵和酵母茵均有较好的抑制作用,可较好地保持即食湿面条的品质.     

复合型天然防腐剂在乳化型香肠中的作用研究

为了提高乳化型香肠的抗腐败能力,研究纳他霉素、Ni8in、乳酸钠3种食品添加荆复配后对乳化型香肠的各种作用,比较它们之间的强弱,并与亚硝酸钠的抑菌效果作比较.采用L9(34)正交试验设计确定各因素和水平,对乳化型香肠进行感官指标、pH、菌落总数的测定.研究结果表明:复合防腐剂在感官品质、pH等方面比亚硝酸钠要好.3种添加剂的最优组合为:纳他霉素100 g/kg、乳酸钠2.4 g/kg、Nisin O.5 g/kg.3种添加剂中Nisin和乳酸钠对延长货架期有显著性影响(p<0.05).抑菌效果依次是Nisin＞乳酸钠＞纳他霉素.     

保鲜剂对鲜湿面保鲜效果的影响

研究了几种保鲜剂对鲜湿面的保鲜作用,结果表明:添加富马酸二甲酯、Nisin、纳他霉素都有一定的保鲜作用,尤其以复配保鲜剂对鲜湿面中微生物抑制作用最强,使鲜湿面的品质保证长达一年以上。     

乳酸链球菌素协同纳他霉素在豆腐保鲜中的应用

以豆腐为研究对象,通过添加乳酸链球菌素（nisin）和纳他霉素以提高豆腐的保鲜时间,以感官评分和菌落总数为评价指标,考察了乳酸链球菌素与纳他霉素添加量、杀菌温度和杀菌时间等对其的影响,通过正交试验得出最佳的优化条件为：nisin与纳他霉素添加量0.12 g/kg、杀菌温度90 ℃和杀菌时间20 min。此工艺条件处理后,冷却并在37 ℃恒温培养箱中保存7 d,测得试样的感官评分为93分,菌落总数为0.53×104 CFU/g。没有添加乳酸链球菌素和纳他霉素的对照组在同样条件下保存1 d,测得感官评分在50分以下,这为延长豆腐的保质期提供了实验基础和理论依据。     

天然复合保鲜涂膜液对卤鸭脖的保鲜效果研究

为研究天然复合保鲜涂膜液对卤鸭脖品质的影响,首先以菌落总数、挥发性盐基氮(TVB-N)、pH和硫代巴比妥酸值(TBARS)为检测指标,通过单因素实验分别考察海藻酸钠、乳酸链球菌素(Nisin)和纳他霉素对卤鸭脖品质的影响,再通过L₉(34)正交试验法比较3种不同比例天然保鲜剂对卤鸭脖品质的影响,筛选最优组合的保鲜涂膜液。结果表明:3种天然保鲜剂的保鲜效果均优于空白组,其中Nisin显示出较强的抑菌效果,海藻酸钠形成的薄膜具备较好的抗氧化效果。当3种天然保鲜剂浓度配比为海藻酸钠1.0 g/100 mL、Nisin 0.9 g/100 mL、纳他霉素0.18 g/100 mL时,涂膜液对卤鸭脖品质的保鲜作用最佳,涂膜后4 ℃冷藏第15 d菌落总数、TVB-N、pH、TBARS和色差值分别为(5.37±0.08)lg CFU/g、(20.86±0.79) mg/100 g、(5.85±0.06)、(2.68±0.08) mg/kg、(1.51±0.07),均显著优于对照组(p<0.05),能够有效延长卤鸭脖冷藏的货架期。     

纳他霉素与乳酸链球菌素复合防腐剂在酱油防霉中的应用

研究了纳他霉素 (Natamycin)与乳酸链球菌素 (Nisin)在传统酿造酱油中的防霉应用情况 ,以及不同浓度纳他霉素与乳酸链球菌素的复合使用情况 .结果表明 :纳他霉素防止传统酿造酱油霉变的最小抑菌浓度 (MIC)为 2 0 μg/kg ,而通过与乳酸链球菌素复合 ,可以有效降低MIC至 8μg/kg ,符合食品添加剂的卫生要求 .     

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.