发酵过程酵母对麦汁糖的吸收和代谢

麦汁中含有五种可发酵性糖葡萄糖、果糖、蔗糖、麦芽糖和麦芽三糖.在大多数麦汁中,麦芽糖的浓度最高,其次是麦芽三糖和葡萄糖.酵母对以上糖的吸收按一定顺序,葡萄糖抑制了麦芽三糖的吸收,酵母吸收葡萄糖不需要消耗其代谢的能量,而对麦芽糖和麦芽三糖的吸收需要能量(活性传递).各种糖的浓度和它们相关的比例会影响到酵母对总体麦汁的发酵速率和程度.Ale啤酒酵母菌株和Lager酵母菌株对麦汁糖的吸收各有不同的特性.例如,与Lager酵母菌株相比,Ale啤酒酵母菌株很少能利用麦芽三糖.此外,麦汁中葡萄糖和麦芽三糖的浓度会影响到啤酒的风味.特别是,用提高了葡萄糖浓度的麦汁酿造的啤酒其所含的酯浓度会升高(特别是乙酸乙酯和乙酸异戊酯).而用含高浓度麦芽糖的麦汁所酿造的啤酒,其酯的浓度大大减少了.高浓酿造(＞16°P)容易发生此现象.     

糖化酶对高粱Lager啤酒麦汁组成和糖酵解的影响

我们进行了一个置信度P〈0．05的三因子实验，利用大麦麦芽（BM）或高梁芽（SM），精选玉米（MZ）或腊质高梁（WXSOR）粉粒为辅料，添加或不添加糖化酶（AMG）生产Lager啤酒，研究其144h发酵过程中糖酵解和乙醇生成情况。在BM麦汁中，葡萄糖、麦芽糖、麦芽三糖分别占总可发酵糖的20％，68％和13％，而这个比例在SM麦汁中则分别为35％，48％和17％。添加AMG后，麦汁中葡萄糖含量从9．3g／L增加到24．5g／L，总可发酵性糖含量用g葡萄糖／L表示，从59．2g／L增加到72．6g／L。和BM麦汁相比，SM麦汁的葡萄糖含量约高50％，而初始麦芽糖则要低40％左右。用WXSOR或MZ作酿造辅料，生产的麦汁和啤酒具有相似的特性。AMG的添加使麦汁中葡萄糖量增加2．5倍以上，并使可发酵性糖量增加23％以上。线性回归分析表明发酵过程中可发酵性糖的消耗符合一级反应方程。葡萄糖、麦芽糖和麦芽三糖消耗50％的时间分别为49h，128h和125h，这清楚地表明酵母优先利用葡萄糖。和不添加AMG的麦汁相比，添加AMG麦汁中的麦芽糖和麦芽三糖的消耗速度分别加快和变慢了。发酵终了，BM啤酒的乙醇含量（5．1％，v／v）比SM啤酒（3．9％，v／v）要高。在添加AMG的啤酒生产中，用BM还是用SM及添加MZ辅料在最终的乙醇浓度上并无明显区别。研究结果表明，AMG可以降低糊精含量，增加初始葡萄糖量和总可发酵性糖量，特别是在利用SM为原料的时候，该现象更为明显。     

高效液相色谱法测定上面发酵法小麦啤酒麦汁中可发酵糖

用高效液相色谱法测定上面发酵法小麦啤酒麦汁中的葡萄糖、果糖、蔗糖、麦芽糖和麦芽三糖含量。结果表明:麦汁中5种可发酵糖的浓度与其峰面积在检测范围内呈良好的线性关系,相关系数0·9986～0·9997之间,样品的加标回收率在96·38%～98·95%,相对标准偏差1·87%～3·46%。     

改进酿酒酵母谷物发酵性能的诱变研究

酿酒酵母经诱变获得有效利用麦汁糖的优良性能。突变菌株经5d摇床培养使YNB基础培养基的麦芽三糖发酵度从32.4%提高到81.8%。薄层层析证明突变株麦芽三糖转运能力得到改善。模拟工业发酵实验证明突变菌株的麦汁糖发酵性能大大改善,而原有发酵优良性状未受到影响。说明该突变株益于工业啤酒生产和低热啤酒的生产。     

利用高效阴离子交换色谱串联脉冲安培检测方法对酒吧自酿啤酒的碳水化合物进行测定及特性描述

优化了高效阴离子交换色谱串联脉冲安培检测方法,以定量测定啤酒中甘露搪、麦芽糖、麦芽三糖、麦芽四糖、麦芽五糖、麦芽六糖和麦芽七耱的含量。本方法可以在一次色谱分离中检测上述低聚糖,而不需要任何前处理。检测限和定量限均适合啤酒,且准确性和重复性好。继优化了检测独特基质的高效阴离子交换色谱-脉冲安培方法之后,该研究的第二个目的是证实依据啤酒的类型来区分啤酒的可能性。酒吧自酿商业啤酒的碳水化合物含量,即便在同种类型的啤酒中也有很大变化,甘露糖、麦芽糖、麦芽三糖、麦芽四糖、麦芽五糖、麦芽六糖及麦芽七糖含量的变化范围分别为19.3mg/L~1469mg/L,4.5mg/L~2882mg/L,141.9mg/L~20731mg/L,168.5mg/L~7650mg/L,20.1mg/L~2537mg/L,22.9mg/L~3295mg/L,8.5mg/L~2492mg/L。事实上,主成分分析在证明啤酒差异时要考虑某些发酵条件和风格。     

干啤酒生产技术探讨

干啤酒生产方法有：①加糖法,加糖量为麦汁产量的15％一20％;②特种酵母生产法,选用能发酵单糖、双糖、麦芽糖等低分子糖和麦芽三糖等大分子糖类的酵母;③加酶法,如加霉菌糖化酶、植物普鲁兰酶。干啤生产控制要点为：①麦汁中麦芽糖含量在9．2％以上;②原料比,麦芽65％、大米35％,料水比1：4．25;③传统工艺主发酵温度9．5—10℃,露天发酵酒罐温度9—10℃。     

制麦和酿造过程中脱氧雪腐镰刀菌烯醇的初步研究

2008年江苏某农场的赤霉病感染相对严重的KA-4B大麦中,脱氧雪腐镰刀茵烯醇（DON）的含量为1．91mg/kg。以此大麦为原料,实验室规模下进行制麦和酿造实验,结果表明,浸麦可以洗去大麦本身含有的绝大部分DON;而大麦内部没有被洗掉的镰孢霉属真菌孢子在发芽阶段重新萌发、生长代谢,形成并积累大量的DON;焙燥阶段不能破坏DON,成品麦芽和麦根中DON的含量分别是原大麦中DON含量的51％和89％。麦芽中的DON可以经过糖化和发酵过程流入到啤酒中,啤酒中DON的总含量是麦芽粉中DON总量的86％。而同一年份相邻农场的基本未感染赤霉病的KA-4B大麦中,DON含量低于0．1mg/kg,绿麦芽和麦根中均检测到低于0．1mg／kg的DON,而成品麦芽、麦汁和啤酒中均未检测到DON。制麦及酿造实验表明,与基本未感染赤霉病的KA-4B大麦相比,赤霉病感染程度严重的KA-4B大麦微生物污染严重,DON含量相对高,大麦品质较差,发芽率较低,麦芽浸出率低,所制得麦汁的过滤速度快,麦汁和啤酒的色度均较高。     

麦汁制备工艺要点浅析

<正>麦汁制备是啤酒生产的重要环节。为保证啤酒发酵的顺利进行,通过糖化工序将麦芽中的非水溶性组分转化为水溶性物质,即将其转变为能被酵母利用的可发酵糖和营养物质。麦汁质量的好坏,将影响最终产品啤酒的风味稳定性。本文从工艺角度,对麦汁制备的要点进行简要分析。1控制好麦汁制备各阶段的温度、pH及时间从原料麦芽、水、酒花等得到定型麦汁,     

加拿大新品系麦芽酿造特性的研究

本文在无锡轻工大学生物工程学院的1m~3小型啤酒设备上以相同的糖化、发酵工艺对三种加拿大新品系麦芽进行了酿造比较试验。实验结果表明加拿大三个新品系大麦与哈林顿相比,均是优秀的制麦大麦。麦特卡夫的酿造特性与哈林顿基本相近。其麦汁或啤酒的各项指标不比哈林顿差,尤其是β-葡聚糖含量较低,优于哈林顿,其麦芽库值一般较高。斯泰托斯属溶解较慢品种,其麦芽库值一般较低,麦汁色度也较浅,β-葡聚糖含量较低。其麦芽在糖化时要稍微延长蛋白质休止时间,以提高定型麦汁中的总氮和α-氮含量,酿造特性比较接近哈林顿。肯德尔麦芽蛋白质含量较适中。其麦汁极限发酵度在三个新品种中最高,麦汁色度较哈林顿浅,在糖化时要控制蛋白质休止时间,容易制成爽口的啤酒。整个试验中以哈林顿为对照。     

麦芽及啤酒酿造过程中的农残分析

为了解麦芽和啤酒中主要农药的残留状况,采用固相萃取一气质联用法对进厂麦芽中16种主要农药的残留量进行了检测,并跟踪总结了啤酒酿造过程中农残的变化特点。结果显示,A厂加拿大麦芽可检出农残4种,B厂加拿大麦芽可检出农残3种,B厂国产麦芽可检出农残2种;制麦过程中,三唑醇和溴氰菊酯含量可降至检出限以下,抗蚜威、乙草胺、三唑酮和p．p,-DDT的含量也均有不同程度的降低;啤酒酿造过程农残进一步降低。麦芽中检出抗蚜成、三唑酮、p．p-DDT3种农残,麦汁只检出三唑酮,成品啤酒未检出。检出的农践在0．0001～0．02mg／kg范围。     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press