鸡蛋清蛋白磷酸化改性及功能性的研究

为了进一步改善蛋清蛋白的加工特性,采用三聚磷酸钠(STP)对鸡蛋清蛋白进行磷酸化改性,并针对其一些功能性质进行了探讨.主要以磷酸化程度为考察指标,通过单因素和正交实验,确定了最佳的蛋清蛋白的磷酸化工艺参数为温度30℃、pH为8.0、加热时间为3.5h,STP添加量为2.0％;此条件下磷酸化程度达到60mg/g.对比磷酸化改性前后的鸡蛋清蛋白的功能特性表明:磷酸化改性后,鸡蛋清蛋白的水溶性、保水性、乳化性和乳化稳定性都有一定程度地提高,但SEM对其微观聚集态结构观察,改性前后两者之间微观结构区别不是很明显.     

虾蛄肌原纤维蛋白磷酸化工艺及其在虾蛄肉制品中的应用

研究多聚磷酸盐磷酸化虾蛄肌原纤维蛋白的最佳工艺条件,并探究复合磷酸盐在虾蛄肉制品中的应用。采用三聚磷酸钠(STP)、焦磷酸钠(SPP)、三偏磷酸钠(STMP)分别对虾蛄肌原纤维蛋白进行磷酸化改性,在单因素实验的基础上,利用响应面法优化虾蛄肌原纤维蛋白磷酸化条件,结果表明:STP最佳工艺条件为:反应pH8.0、STP添加量4%、反应时间2.0 h,所得磷酸化程度为102.87 mg/g;SPP最佳磷酸化条件为:反应pH7.5、SPP添加量2%、反应时间2.0 h,所得磷酸化程度为96.41 mg/g;STMP最佳磷酸化条件为:反应pH8.0、STMP添加量4%、反应时间2.5 h,所得磷酸化程度为76.53 mg/g。在此基础上,探究4组不同比例复合磷酸盐对新型果蔬虾饼品质的影响,结果表明:复合磷酸盐可显著降低虾饼的蒸煮损失和在加工过程中抗坏血酸含量的损失(p<0.05),并提高其质构特性;当STP:SPP:STMP比例为2:1:2时,能显著改善虾蛄肉制品的品质(p<0.05),证实了磷酸化改性的可行性。     

响应面法优化水酶法结合磷酸化提取大豆蛋白的生产工艺

为了提高大豆水酶法的总蛋白提取率,在酶解过程中利用三聚磷酸钠(STP)进行磷酸化改性。通过研究加酶量、料液比、STP添加量、酶解时间和改性时间对总蛋白提取率的影响,并利用响应面分析优化出了最佳改性工艺参数:5000U·g-1底物,料液比为1∶8(w/v),STP添加量为4%(w/w),酶解时间为3.37h,改性时间为35.68min,此时总蛋白提取率为94.05%左右。     

虾蛄盐溶蛋白磷酸化工艺及其功能性质的研究

为了改善虾蛄盐溶蛋白的功能特性,采用三聚磷酸钠(STP)对虾蛄盐溶蛋白进行磷酸化修饰。在单因素实验的基础上,应用响应面法优化虾蛄盐溶蛋白磷酸化工艺的条件,确定最佳磷酸化工艺条件为:反应p H为8.5,STP用量为4%,反应温度为30℃,反应时间为2.5 h,响应值磷酸化程度为4.715μg/mg,与预测值(4.722μg/mg)的相对误差为0.15%。磷酸化改性后,虾蛄盐溶蛋白的乳化活性、乳化稳定性、起泡性及泡沫稳定性与未磷酸化相比分别提高了61.90%、23.99%、88.57%、25.42%。     

磷酸化改性提高蛋清粉凝胶性的研究

为了提高蛋清粉的凝胶性,文中采用三聚磷酸钠(STP)对蛋清粉蛋白进行磷酸化改性,通过研究三聚磷酸钠添加量、加热时间、温度三因素对蛋清粉凝胶强度的影响,在单因素试验的基础上,采用响应面分析法对改性条件进行优化。结果表明:磷酸化对蛋清粉最适改性条件是STP添加量0.5%,反应温度35℃,反应时间4 h。该条件下生产的蛋清粉与未改性的蛋清粉相比,其凝胶强度由308 g/cm2提高到730.392 g/cm2。     

化学磷酸化改性小麦面筋蛋白

采用三聚磷酸钠(STP)对小麦面筋蛋白进行磷酸化改性,确定最佳工艺条件为三聚磷酸钠浓度与样品浓度之比为3:13,反应时间0.5h,反应温度20℃以及pH9.5。研究了磷酸化对小麦面筋蛋白功能特性的影响。结果表明,用三聚磷酸钠对小麦面筋蛋白进行磷酸化改性,小麦面筋蛋白的功能性质显著改善,改性后可使乳化性、溶解性、起泡性及其稳定性都有极大的提高。     

磷酸化改性提高松仁分离蛋白乳化性研究

松仁分离蛋白是从红松松籽仁中提取出的一种蛋白质产品。本实验对松仁蛋白进行磷酸化化学改性,利用三聚磷酸钠(STP)对松仁蛋白进行磷酸化处理,改性后松仁蛋白的乳化能力显著增加,并确定了最佳的改性条件为STP浓度6.0%,提取时间为0.5h,提取温度为40℃。     

磷酸化大豆蛋白功能特性的研究

采用三聚磷酸钠(STP)对大豆分离蛋白进行化学改性,得出3％大豆分离蛋白磷酸化程度最大的工艺条件为pH8.0,STP浓度为3％,35℃下保温3.5小时,此时的磷酸化程度为57％。测定了改性前后,不同改性程度下大豆分离蛋白的水溶性、乳化能力、发泡能力、持水能力以及流变特性等的变化。结果表明改性后大豆蛋白的等电点由pH4.5漂移到3.9,与此同时,大豆蛋白的功能特性也有了很大的改善。用红外光谱,证实了STP与大豆蛋白反应的实质就是赖氨酸残基进行氨基磷酸酯化反应。     

响应面法对磷酸化改性红松仁分离蛋白溶解性工艺参数的优化

红松仁分离蛋白是从红松籽仁中提取的一种蛋白质产品.以红松籽为原料,采用三聚磷酸钠(STP)对红松仁分离蛋白进行改性.在单因素试验的基础上,利用centre-composition中心复合设计,通过响应面分析法对改性后红松仁分离蛋白的溶解性工艺进行优化,研究不同反应温度,pH值,STP浓度和反应时间下改性的红松仁蛋白的溶解性.研究发现:对红松仁分离蛋白溶解性的影响条件依次为STP浓度>pH值>反应时间>反应温度,其中STP浓度和pH值对红松仁分离蛋白溶解度影响高度显著,pH值影响显著,反应温度影响不显著;磷酸化改性红松仁分离蛋白的最佳溶解条件是:反应温度45℃,pH值8.5,STP浓度7%,反应时间为75min.在此条件下红松仁分离蛋白的溶解度可达:80.2%.     

大豆分离蛋白的磷酸化改性及功能性质的研究

采用三聚磷酸钠 (STP)对大豆分离蛋白 (SPI)进行化学改性 ,运用三因素二次饱和试验设计 ,得出最优试验回归方程为 :Y =2 8 2 6+5 89X1+0 93X2 +0 83X3-0 1 5 7X12 -1 2 6X2 2 +2 2 6X32 +0 65X1X2 -0 1 5X1X3+0 3 8X2 X3。并得出 6%大豆分离蛋白磷酸化程度最大的工艺条件是 pH 8 0 ,STP浓度为 3 %,45℃下反应 4h。同时研究了改性前后不同程度下SPI的功能性的变化 ,结果表明 ,改性后的SPI的溶解性、乳化能力、持水能力以及粘度等均有很大的提高 ,而发泡性无明显改善。通过红外光谱检测证明 ,STP与SPI反应是赖氨酸残基所进行的磷酸酯化反应。     

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.