影响啤酒过滤前酵母细胞浓度的因素

1. 前言 啤酒过滤前酵母细胞浓度,对改善啤酒过滤,提高啤酒质量,降低生产成本具有现实意义。影响过滤前酵母细胞浓度的关键因素是酵母凝聚性。凝聚性是酵母自身生理特性之一,受到工艺条件、外部环境的共同影响。     

啤酒酵母生产性状稳定性的实践

啤酒酵母生产性状的稳定性关系到啤酒正常发酵与产品质量的稳定问题 ,不能掉以轻心。保持啤酒酵母的良好性状应注意菌种保藏、酵母扩培、酵母使用与回收。以液氮超低温保藏最理想 ,酵母细胞存活率较高 ;酵母扩培从25℃起 ,分代逐渐降温 ,以保持其性能 ,扩培倍数以1∶5较理想 ,接种浓度为10×106～15×106 个/ml;生产使用时 ,满罐酵母接种浓度为10×106～12×106 个/ml为宜 ,以使用2～4代较理想 ,4代为限 ;酵母回收以低温(0℃左右)回收中间层较好 ,死亡率低、活力强 ,贮存时间不宜超过3天。(单雨)     

啤酒过滤性能探讨

影响啤酒过滤的主要因素有过滤前酵母细胞浓度、酒液粘度、固形物含量、稳定剂等;对β-葡聚糖、α-葡聚糖、酵母、颗粒物对啤酒过滤性的影响进行研究分析。改善啤酒过滤性的措施主要有降低麦汁和啤酒中β-葡萄糖的含量,降低过滤前酒液中的酵母细胞数,控制添加剂的添加,添加过滤助剂。(孙悟)     

精细化控制啤酒过滤,提升啤酒质量

啤酒过滤即把酒内悬浮的轻微小粒子,如蛋白质复合物、冷混浊物、酵母及其它的固体排掉以澄清成熟的啤酒。为保证过滤后的啤酒在最低保存期限内不出现外观变化,同时使泡沫、CO₂等损失最小,使啤酒的特性更加完美体现,必须严格控制过滤操作的关键点。1提高过滤后啤酒质量的基本要求——改善啤酒的可滤性、提高过滤速度和质量1.1过滤前的啤酒质量1)成熟发酵液采用两罐法倒酒降温至-1.0℃～0.0℃下冷贮一周以上,酵母浓度<2×10⁶     

板栗啤酒的研制

以板栗、大米为辅料,采用传统酿造技术和现代生物技术相结合,研制开发板栗啤酒。试验得出了板栗啤酒制作的主要技术参数:最佳原料配比为板栗:大米:麦芽=1:1:2,总料水比为1:4.5,酵母接种量为1.2×106个/mL￣50×106个/mL醪液,主发酵温度12℃,pH5.2￣5.5,发酵5d,添加100mg/L￣200mg/L二氧化硫以防止酒液褐变。可制得酒精度4%,具有浓厚板栗香气、口感独特的板栗啤酒。     

"安琪"啤酒活性干酵母酿造特性研究

啤酒活性干酵母是否真正适合于啤酒酿造,酿造性能如何,直接关系到该产品的应用推广.实验结果表明,安琪啤酒活性干酵母具有发酵速度快,3 d结束主发酵,4 d酒精发酵结束,最终酒精浓度3.9%(v/v)左右;双乙酰还原良好,发酵至第7天,双乙酰下降至0.14mg/L以下;适宜较高温度(10～22℃)发酵;凝聚性强,发酵至第6天,发酵液中的细胞浓度下降至1.0×106个/ml以下等特点.其质量和酿酒性能均达到或超过国外同类产品的水平.     

低醇啤酒的研制

采用跳跃式糖化法生产含低发酵性糖的麦汁 ,再用低醇啤酒酵母发酵 ,生产低醇啤酒。糖化工艺为 :采用1∶2.5的麦芽加水比 ,45℃保温30min,逐步升温至55℃ ,然后加沸水快速升温至72℃ ,最终麦芽加水比为1∶5.0 ,碘试反应完全后 ,逐步升温至82℃ ,保持5min,过滤。其他同普通麦汁糖化工艺。发酵工艺为 :发酵温度8℃ ,pH5.2～5.4 ,酵母接种量18×106～2.0×106 个/ml,发酵周期18天。中试结果表明 ,发酵度低于50 % ,酒精含量为普通啤酒的2/3 ,满足低醇啤酒的要求。低醇啤酒在风味上存在一定缺陷 ,有待完善。(庞晓)     

麦芽对酵母凝聚性的影响

酵母的凝聚性，直接决定着酵母的回收量、冷贮酒的过滤效果，同时也影响发酵液的降糖、双乙酰还原速度，以及啤酒的口味等。通过几年的实践探索，我们认为，麦芽是影响酵母凝聚性最主要的因素。     

鱼胶和啤酒的澄清

鱼胶在低pH值环境下能与酵母快速形成较大的颗粒而沉降到容器底部;使罐体内悬浮酵母数减少;也能沉降一些引起啤酒混浊或过滤问题的小颗粒。使用方法:将鱼胶缓慢加入pH2.4～3.0的酸化水中,酸化水温度5～10℃,并搅拌制得鱼胶溶液。添加量为5×10-6～1.0×10-5;可与带负电的多糖物质配合应用,效果更好。(孙悟)     

高浓度发酵酿制啤酒：实验室及小型制酒设备实验

前言传统的啤酒酿造工艺是采用11～12°P麦汁进行发酵,生产出的成品啤酒的酒精含量为4～5％(v/v)。酿造家发现,将麦汁浓度从12°P增加到18°P(高浓度),可以提高生产效率,减少劳动力,能源和资金的消耗,啤酒的风味和物理稳定性更好,单位体积可发酵物质生成的酒精更多。例如,已经证明,将麦汁浓度从12°P增加到15°P,可以使能量消耗降低14％,劳动生产率提高25～30％。但是,高浓度发酵时需要提高酵母添加率,建议酵母添加率为1～2×10~6个细胞/毫升、度(原麦汁浓度°P)。     

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.     

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.     

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