黑蒜类黑精的超声提取工艺优化及其稳定性和抗氧化性研究

以黑蒜为原料,采用超声法提取黑蒜中的类黑精,并对提取工艺条件进行优化。选取乙醇体积分数、料液比、超声时间和超声温度四个影响因素进行单因素实验,在此基础上,采用正交试验优化最佳提取工艺,同时对黑蒜类黑精的稳定性和抗氧化活性进行研究。结果表明,超声法提取黑蒜类黑精的最佳工艺参数为:乙醇体积分数为10%、料液比为1:7、超声时间为40 min、超声温度为70℃,此条件下得率为3.465%。稳定性研究结果表明,温度高于50℃时,类黑精稳定性不好,而-15℃冷冻和4℃冷藏条件下,类黑精呈现较好的稳定性。氧化剂H₂O₂和还原剂Na₂SO₃、甜味剂、暗光对黑蒜类黑精稳定性无显著影响,直射光、酸味剂、强酸pH2～4和弱碱pH8～10,则会使其稳定性降低,而金属离子Zn²⁺和Fe²⁺会与其发生络合反应。质量分数小于2%时的山梨酸钾和苯甲酸钠会降低类黑精的稳定性,而0.05%的苯甲酸钠和0.1%的山梨酸钾对类黑精稳定性影响很小,可作为类黑精食品的防腐剂。黑蒜类黑精的DPPH·...     

食品中类黑精的研究进展

类黑精是指碳水化合物与带有自由氨基的含氮化合物反应产生的棕色的高分子量美拉德反应产物,在烘培产品、啤酒、酱油、醋等食品中普遍存在。近年来,类黑精抗氧化、抗诱变、抗癌、抗菌、抗高血压等功能逐渐成为人们关注的焦点。本文综述了目前国内外关于类黑精结构、理化性质及分离纯化方法等方面的研究,并综述了其对人类健康有影响的生理活性,以期为进一步研究食品中类黑精的营养保健功能奠定基础,也为食品中类黑精的检测方法建立提供科学依据。     

类黑精研究进展

该文叙述类黑精的特性、制备、提取,重点阐述类黑精抗氧化、抗肿瘤、抗菌、类似食物纤维等生理活性。     

黑蒜药食功能研究进展

黑蒜是大蒜经高温高湿发酵制得的一种食品,具有较高的营养价值,近年逐渐受到青睐。研究表明,黑蒜含有类黑精、蛋白质、多酚、含硫化合物、多糖等活性化学成分,有抗氧化、抗炎、抗肿瘤、降血脂等药理作用,具有较好的开发前景。本文对黑蒜的化学成分、药理作用、加工工艺及相关产品品类等相关内容进行综述,并对黑蒜未来的开发应用进行展望。     

美拉德反应产物类黑精的研究进展

美拉德反应是食品加工、贮藏及烹饪过程中普遍存在的重要反应,其终产物类黑精是一类结构复杂的高分子量化合物,其不但赋予食品色泽和风味品质,且具有多种功能活性,多年来始终是食品科学领域研究的热点。因此,本文在阐述美拉德反应过程的基础上,综述了类黑精的来源、制备过程、分离纯化、理化特性与结构表征以及功能活性的研究进展,并对其研究价值进行了展望,以期为食品类黑精的相关研究及应用开发提供参考。     

小磨香油芝麻渣中类黑精的提取及抗氧化活性分析

以小磨香油芝麻渣为原料,利用不同溶液辅助超声提取芝麻渣中的类黑精,并采用电子舌对类黑精的滋味进行检测、傅里叶红外对其结构进行初步分析、及类黑精抗氧化活性的检测和分析。结果表明,以p H 10.0碱溶液为提取液中的类黑精含量最高,其次是60%乙醇溶液,且醇提类黑精有更强的苦味;p H 10.0碱提组分的蛋白含量最高,60%醇提组分的总糖含量最高,分别为47.58%和25.18%,芝麻渣类黑精主要是蛋白结合型;芝麻渣类黑精最突出的滋味是苦味,最高苦味值达到7.28±0.03,其次是鲜味;随着类黑精浓度的增加,几种抗氧化活性指标有增加的趋势,其中用水提取的有最好的·OH清除效果,达到56.52%,60%醇提类黑精在浓度为1 mg/mL时,DPPH·清除率已高达95%;芝麻渣类黑精中具有芳族胺和呋喃等杂芳环结构。本研究说明芝麻渣类黑精适合用p H10碱溶液和60%醇溶液提取且具有较好的抗氧化活性,为芝麻渣类黑精的初步探索以及芝麻渣的开发利用提供了一定理论依据。     

黑蒜加工中类黑精相关成分变化及其组成分析

以黑蒜为原料,采用DNS法、苯酚-硫酸法、全自动氨基酸分析仪及高效液相色谱法,对黑蒜加工不同时间点还原糖、总糖、氨基酸、5-羟甲基糠醛(5-HMF)等类黑精形成相关成分的含量进行分析。同时提取黑蒜类黑精,采用热裂解-气相色谱-质谱(pyrolysis-gas chromatography-mass spectrometry,Py-GC-MS)联用技术分析黑蒜类黑精的化学组成:结果表明:加工过程中总糖呈下降趋势,还原糖含量逐渐升高;共检出13种氨基酸,除组氨酸外,其他氨基酸均有不同程度的降低,其中降幅最为明显的有精氨酸、赖氨酸、天冬氨酸和苯丙氨酸;5-HMF有一个先升后降的过程;Py-GC-MS结果表明:黑蒜类黑精中相对含量最高的为呋喃类,其次为吡咯类、噻吩类、烷烃、糠醛类、酚类等。     

咖啡类黑精提取工艺优化及结构表征

本研究以云南小粒咖啡为研究对象，优化咖啡类黑精提取工艺，利用100、50、30 kDa的滤膜分级，基于分子形貌、光谱学特性表征不同分子量段的咖啡类黑精结构。结果表明：咖啡类黑精最佳提取工艺为：料液比1:16(g/mL)，提取温度80℃，提取时间60 min。凝胶渗透色谱结果表明咖啡类黑精在溶液中呈现紧密球形结构，分子量大小主要为4.56×10⁴和2.94×10⁴ Da，占比分别为72.5%和27.5%。X-射线衍射表明咖啡类黑精内部结晶性很弱，属无定形结构。微观形貌特征分析表明未经分级处理的咖啡类黑精呈表面粗糙且存在孔隙的不规则团聚球形，分级处理后聚合结构消失，呈不规则片状和长条状。黑褐色程度及基础成分含量随分子量的减小而降低。紫外可见光谱研究表明不同分子量组分在285和320 nm处呈现出弱吸收峰。傅里叶红外光谱显示可能存在羧基、羟基、氨基及甲基等基团。三维荧光谱图中荧光峰位在λex=400 nm，λem=480～490 nm，表明咖啡类黑精有芳香环、杂环，存在刚性结构。通过对咖啡类黑精进行优化提取、分级及结构表征，为进一步研究云南小粒咖啡...     

黑蒜提取物的抗氧化性与抗炎活性比较研究

目的对分离纯化黑蒜多糖的过程中得到6种黑蒜提取物,进行成分分析,并比较研究它们的抗氧化活性和抗炎活性。方法黑蒜经热水提取获得黑蒜水提物(hot water extract,HWE),经乙醇分离得到乙醇上清(ethanol supernatant extract,ESE)和沉淀(ethanol precipitate extract,EPE)提取物,并再经脱蛋白和乙醇分离得到脱蛋白的乙醇上清(deproteinized ethanol supernatant extract,d ESE)和沉淀(deproteinized ethanol precipitate extract,d EPE)提取物,再经DEAE 52纤维素层析纯化得到多糖提取物(purified polysaccharide extract,PPE)。首先采用薄层层析法分析了6种黑蒜提取物的单糖组成,还测定了总糖含量、还原糖含量、硫含量。再比较分析了6种多糖提取物的抗氧化与抗炎活性。结果 6种黑蒜提取物对DPPH自由基和ABTS自由基均具有良好的清除作用。6种黑蒜提取物对脂多糖(lipopoly saccharides,LPS)(20?g/mL)所致的RAW264.7细胞生长抑制均有显著性保护作用(P0.05)。6种黑蒜提取物对LPS(1?g/mL)诱导RAW264.7细胞NO,IL-1?,IL-6和TNF-?等细胞炎性因子的释放均有显著的抑制作用(P0.05)。结论黑蒜多糖提取物具有良好的抗氧化作用和抗炎活性,研究结果为黑蒜的进一步研发提供了理论依据和实际参考价值。     

微波辅助萃取黑蒜大蒜素及对小鼠血糖值影响

本实验主要研究微波辅助萃取黑蒜大蒜素,以及对黑蒜大蒜素溶液进行GC-MS分析。与普通大蒜提取大蒜素比较,对小鼠进行降血糖动物实验。实验表明,黑蒜大蒜素具有降血糖功能。将黑蒜用有机溶剂萃取法提取出来,采用同时蒸馏萃取黑蒜大蒜素溶液中的挥发性物质,通过气相色谱-质谱联用技术对其化学成分进行了分析。鉴定出黑蒜大蒜素溶液中含有7种含硫物质。     

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.     

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.     

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.     

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.     

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.     

Analysis on Economic Indicators from 62 Enterprises in Printing Machinery Industry in Q1 2014

Operation of printing machine industry was still unsatisfactory in the first quarter of 2014.Analysis on operation of printing machine industry.a.Market demand was not strong;sales of product undulated and declined.According to the statistics,the total industrial output value fell by 19.28% in the first quarter of 2014 than the average quarter value in 2013; industrial added value decreased by 4.16%; sales revenue dropped by 22.83%. h. Business operation of enterprises was in poor condition. c. R＆D of new products is an important transformation guarantee for enterprises. d. To take self explore new ways upgrading advantages,and explore new ways.