小麦蛋白质含量对小麦芽质量的影响

本文通过对小麦蛋白质及其组分含量与小麦麦芽质量的关系的研究,发现：小麦芽蛋白酶活力的增长率与小麦总蛋白质含量存在显著负相关性相关系数r=-0.8468（P＜0.05）;小麦芽蛋白酶活力与库值呈极显著正相关性,相关系数r=0.9503（P＜0.01）;蛋白质含量低于15%、原小麦蛋白酶活力较高（大于20U）的小麦品种适合制小麦麦芽.小麦8号蛋白质含量14.60%,原小麦蛋白酶活力21.25U,常规制麦发芽7d得到的小麦芽,浸出物82.71%、其糖化力472.62WK、糖化时间9.0min、库值39.59%、α-AN140.23mg/100g、色度6.5EBC.小麦8号是比较优良的适合制麦芽小麦品种.     

小麦组分含量与小麦芽β-葡聚糖酶活力的相关性分析

跟踪测定了小麦芽常规制麦过程中β-葡聚糖酶活力的变化,分析了不同阶段小麦芽β-葡聚糖酶活与原小麦β-葡聚糖含量、蛋白质含量、淀粉含量之间的相关性.结果表明:绿麦芽β-葡聚糖酶与原小麦β-葡聚糖含量呈负相关(P<0.10);干麦芽β-葡聚糖酶与原小麦β-葡聚糖含量呈显著负相关(P<0.05).绿麦芽、干麦芽β-葡聚糖酶均与原小麦蛋白质含量呈显著负相关(P<0.05).干燥过程中小麦芽β-葡聚糖酶活力增加与小麦水溶蛋白含量成负相关(P<0.10)、与小麦醇溶蛋白含量成显著正相关(P<0.05).     

小麦籽粒在制麦过程中碳水化合物降解趋势的研究

以小麦品种扬麦13和皖麦38为研究对象,以啤酒大麦为对照,通过微型制麦工艺(断水浸麦方式、降温式发芽、低温干燥绿麦芽),较为系统的分析了制麦过程中小麦籽粒淀粉降解的趋势,讨论小麦品种的制麦特性以及淀粉降解的机理.结果表明,制麦过程中淀粉含量和直链淀粉含量下降较为缓慢;还原糖的含量变化总体为上升趋势;β-葡聚糖含量下降速度较快,且在发芽结束后小麦样品的β-葡聚糖含量小于啤酒大麦;戊聚糖含量在发芽的前3天内呈下降趋势,但发芽第4天有较大程度的增长,发芽结束后小麦样品中的戊聚糖含量小于啤酒大麦;浸出物在发芽初期以较高速度增加,在发芽后期上升较为缓慢;黏度在制麦中变化幅度较小,呈逐渐下降趋势;通过电子扫描电镜观察淀粉颗粒在制麦过程中的变化发现,小麦麦芽的胚乳结构越来越疏松,在发芽前期只要是蛋白质和大颗粒淀粉的降解,在发芽后期小颗粒淀粉的降解速度较快.由结果可知,小麦和啤酒大麦在制麦过程中碳水化合物的变化有较大差异;小麦发芽结束后除β-葡聚糖含量、戊聚糖含量小于啤酒大麦,其他指标均高于啤酒大麦;β-葡聚糖和戊聚糖含量不是造成小麦麦芽汁具有较高黏度的主要原因.     

小麦制麦对白啤酒胶体混浊的影响

小麦和小麦麦芽通常用于白啤酒的生产，尽管小麦和小麦麦芽的特性在很大程度上取决于小麦品种和制麦过程，但当前啤酒酿造者并未制定严格的小麦和小麦麦芽指标。最近的研究显示，小麦的蛋白质含量和各种分子量蛋白质的分布对白啤酒的最终混浊程度有着强烈的影响，因此本论文的目的就是研究小麦制麦对啤酒浊度的影响。不同改良程度的小麦麦芽由工业制备，麦芽指标，包括可溶性蛋白质含量和蛋白质降解状况等经过测定；小麦啤酒由实验室酿制并进行了标准的啤酒分析。实验发现小麦制麦对所期望的啤酒混浊有着积极的影响，增加蛋白质降解程度、减少沉淀物的生成等能形成稳定的浊度。     

添加不同发芽时间的小麦芽粉对面团及馒头品质的影响

以潍麦8号小麦为原料,采用常规制麦工艺分别制得不同发芽时间的小麦芽,后经125℃焙烤2 h磨粉,探究添加5%小麦芽粉对面粉糊化特性、面团粉质特性、拉伸特性及馒头品质的影响。结果表明,小麦芽经125℃焙烤2 h后,其α-淀粉酶的灭活率为82.2%~90.0%。添加小麦芽粉对面粉的峰值黏度、最低黏度、最终黏度、回生值和峰值时间均有显著影响(p≤0.05)。添加发芽第2~5天的小麦芽粉能显著降低面团的稳定时间,粉质指数,拉伸能量,拉伸比,拉伸阻力,升高面团的弱化度和延展度(p≤0.05)。添加发芽第2、4、5天的小麦芽粉制成馒头比容较大。添加发芽第2天的小麦芽粉制成馒头的感官评分最高。与空白对照组和添加其他发芽时间的小麦芽粉制成的馒头品质相比,添加发芽第2天的小麦芽粉制成的馒头外观呈咖啡色,比容较大,表面光滑,带有浓郁的焙烤麦芽香气。     

小麦啤酒酿造浅谈

小麦啤酒以小麦芽为主要原料酿制，无论是从口感上还是营养上都优于大麦啤酒。小麦啤酒的生产工艺流程与大麦啤酒基本一致：小麦经筛选、浸渍、发芽、干燥后制成干麦芽，添加辅料，延长蛋白质休止时间，经糖化、煮沸、过滤制成麦汁，再经发酵、灌装制成小麦啤酒。     

电解水在黑小麦发芽中的应用研究

本研究用电解水生产黑小麦芽,探究电解水对黑小麦发芽及生长的影响,并考察了电解水处理对黑小麦芽基本营养成分的影响,以期为电解水用于黑小麦的发芽提供科学依据。试验结果表明,电解水均可以促进黑小麦种子的萌发,其中p H值为4.55,有效氯浓度20.14 mg/L的酸性电解水处理组黑小麦发芽率比自来水对照组提高15.29%。但电解水处理组会不同程度的抑制黑小麦芽胚轴和胚根的生长,与自来水p H值相近的酸性或碱性电解水的抑制作用相对较弱。经p H值4.36~4.91,有效氯浓度10~30 mg/L的酸性电解水处理的黑小麦芽脂肪含量比自来水对照组降低27.06%~36.93%,还原糖含量降低21.84%~56.58%,总糖含量降低13.68%~27.11%,而蛋白质含量与对照组间无显著差异。因此在黑小麦芽的生产过程中,适宜在种子浸泡阶段使用电解水,而在芽苗淋浇阶段使用自来水,这样既促进了种子的萌发,也不会对黑小麦芽的生长产生抑制作用。     

制麦参数对过滤后啤酒形成浑浊的影响

制麦改变了大麦的化学和酶的成分。制麦期间合成酶、细胞壁(戊聚糖,蛋白质等)降解和淀粉分解。发芽程度决定最终啤酒以下几方面的质量:口感,泡沫和浑浊趋势(不同蛋白质),加工性能(如β-葡聚糖引起的粘度),发酵程度(FAN、糖含量)等。本文主要研究不同溶解度的麦芽对过滤后啤酒浊度的影响。通过分析不同发芽阶段的麦芽指标及其对最终啤酒成分的影响,主要是蛋白质含量和种类。运用Lab-on-a-Chip技术分析蛋白质部分,毛细管电泳测定分子量。使用双向凝胶电泳(2D-PAGE)来进一步支持Lab-on-a-Chip技术分析。此外,完成普通麦芽和啤酒分析、浊度和过滤性能的测定,跟踪测定麦芽到啤酒过程中蛋白质的组成。发现啤酒中的最终蛋白质组成未发生变化,高含量的25～28 kDa蛋白质部分能增加啤酒的浊度。     

用小麦酿造啤酒的讨论

小麦是酿造啤酒的原料之一，其分布主要在欧亚大陆和北美洲。品种因播种季节和皮色不同而呈多品种性：小麦营养比较丰富，经济价值较高；富含淀粉、蛋白质，还舍有脂肪、多种矿质元素和维生素B。小麦含蛋白质在11％～16％，比大麦含蛋白质高。小麦芽生产浸麦时间为大麦的2／3；浸麦度为37％～38％；发芽温度可升至17～20℃，结束温度为60℃；焙焦温度80℃。用小麦芽酿造啤酒对糖化和过滤、啤酒风味、酵母使用、啤酒过滤和啤酒抗冷都会产生一定的影响。     

不同蛋白质溶解度的小麦芽蛋白质组成及麦芽质量分析

为了研究小麦芽蛋白质溶解度与蛋白质组分及麦芽指标间的相关性,通过控制不同的浸麦度和发芽时间,制备了蛋白质溶解度分别为31.4％、33.1％、37.0％、37.6％、39.5％、40.9％、45.5％和54.2％的8种小麦芽,分析了小麦芽蛋白质组分、降解酶及麦芽基本指标.结果表明:随着小麦芽库值的增加,水溶性蛋白质含量成线性增加,醇溶性和碱溶性蛋白质呈现直线下降.小麦芽内肽酶活力与水溶性蛋白质含量、水分及浸出物呈现显著正相关(r分别为0.732、0.792和0.727),与醇溶性蛋白质含量呈现显著负相关(r=-0.734).因此小麦芽内肽酶活力的提高将有助于小麦芽浸出物的增加.小麦芽库值与水分、色度、浸出物、FAN、酸度均存在极显著正相关性(r=0.885、r=0.971、r=0.880、r=0.915和r=0.964);与浊度存在显著正相关(r=0.714);与有效酸度存在极显著负相关(r=-0.921).所以提高蛋白质溶解度小麦芽浸出物、浊度、FAN、酸度、色度等指标都会提高.比较8种小麦芽指标,蛋白质溶解度为39.5％时小麦芽指标较好.此时,浸出物为82.0％,FAN 166 mg/100 mg,糖化力为496 WK,黏度为1.61 cP,糖化时间为6 min.     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

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.     

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 of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.