罐装啤酒与瓶装啤酒的巴氏杀菌过程数值模拟

以啤酒为研究对象,基于COMSOL Multiphysics软件建立二维传热模型来模拟同体积的罐装啤酒与瓶装啤酒的巴氏杀菌过程。得出在2种包装形式下啤酒的巴氏灭菌过程都存在明显的自然对流现象,最慢加热区(SHZ)在受热过程中逐渐下移。在杀菌初始时,金属罐中最大流速可达77.89 mm/s,明显大于此时玻璃瓶内的最大速度。采用60℃-20 min巴氏杀菌程序结束后,金属罐中啤酒的最小的巴氏杀菌单元值(PU值)为14.84,最大与最小的PU值的差值为5.16,而玻璃瓶中最小PU值只有6.09,最大最小PU值的差值为11.71,反映了500 mL啤酒采用金属罐装杀菌不仅可以缩短杀菌时间,且可以有效减少因传热不均匀引起的过杀菌现象。     

基于CFD技术的瓶装啤酒隧道式巴氏杀菌过程研究

通过数值模拟瓶装啤酒隧道式巴氏杀菌的过热阶段(巴氏杀菌加热部分的最后一个阶段),确定瓶中的冷核(slowest heating zone,SHZ),并运用L9(34)正交试验,分析喷淋水温度、喷口处喷淋水湍流强度以及瓶子的运行速度三因素对瓶中啤酒温度分布均匀性的影响。结果表明:冷核起先是位于瓶底,后向上移动,但不超过灌装高度的1/2;在加热至7min时,喷淋水温度、喷口处喷淋水湍流强度影响显著,瓶子的运行速度则不显著,试验的可能的最优条件:喷淋水温度为65℃,喷口处喷淋水湍流强度为3%,瓶子运行的速度为3mm/s。     

瓶装啤酒隧道式巴氏杀菌的数值模拟

为了保证啤酒的生物稳定性,需要对其进行巴氏杀菌。通过数值模拟瓶装啤酒隧道式巴氏杀菌的过热阶段,考察瓶内冷核(slowest heating zone,SHZ)的位置,分析在不同温度喷淋水条件下瓶内温度分布均匀情况。结果表明:在巴氏杀菌过程中,瓶中啤酒冷核位于1/3灌装高度;瓶内有明显的自然对流现象;当喷淋水温度为61℃时瓶中啤酒温度分布最为均匀,且温度越高瓶内啤酒温度分布越不均匀。     

啤酒巴氏杀菌控制

啤酒巴氏杀菌是生产熟啤酒的重要工序之一，杀菌不足或过度都将对啤酒的保质期和风味产生影响。PU值是巴氏杀菌的一个重要技术指标，作者就杀菌机PU值检测及PU仪的使用问题谈一谈自己的体会。     

巴斯德与巴氏杀菌法

都说,没有牛顿就没有现代物理学,同样,没有巴斯德就没有现代微生物学。科学的历史上,没有一个人的发现,能与人们日常生活如此地息息相关,也没有一个人的发明,能使人们的文明史取得如此飞跃的进步。     

巴氏杀菌后啤酒的双乙酰值反弹现象的分析及对策

巴氏杀菌后啤酒的双乙酰值反弹现象的分析及对策李英昌肖和云（黑龙江佳木斯啤酒厂；１５４０００）在啤酒销售的旺季，为了提高产量保证市场供应，常常缩短后发酵的时间。我厂夏季啤酒畅销时，也是采取缩短酒龄提前开桶的办法来提高产量，但却出现了这样一个怪现象，本来...     

激光红外线巴氏杀菌对啤酒质量的影响

啤酒杀菌有多种方法，现有的巴氏灭菌法和无菌过滤是比较常用的两种方法，但这两种方法对啤酒质量可能产生负面影响。高频激光近红外线称得上新型的、无破坏性的“巴氏灭菌法”，因为这种杀菌方法不会影响分子的离子化，对啤酒质量不会产生不利影响。研究显示：啤酒短期受激光红外线照射，可有效抑制酵母繁殖，并杀死细菌。经红外线照射过的啤酒，其酵母细胞的平均含量要比实际少3倍，细菌量要比实际少17倍。而且红外线光波穿透力强，可用于处理瓶装啤酒。“激光红外线巴氏杀菌”的显著特点是：对啤酒质量不会产生任何不利影响；它具有能耗低、价格低和高效性的特点，因此要比目前世界上啤酒厂所采用的其它工业方法价格要便宜。     

鸡蛋中微生物的污染与其巴氏杀菌的研究状况

21世纪的中国蛋品科技与工业生产历程，可以明显的分为3个阶段：1900～1949年为第1阶段，我国禽蛋生产产量极低，科技水平几乎没有发展，普通国民把吃鸡蛋作为一种奢侈的享受，“鸡蛋不是贫民物”更谈不上规模化工业生产；1950～1978年为第2阶段，禽蛋生产开始好转，年产量有所增加，一些省市相继成立传统蛋制品加工或鲜蛋     

浅谈啤酒杀菌--短时高温杀菌

目前国内啤酒均采用装瓶后杀菌方式,其设备大多采用隧道式杀菌机。本文论述了此工艺的不足及另一种杀菌方式,装瓶前杀菌,即短时高温杀菌的应用原理。     

超声波技术对食品杀菌效果及其与巴氏杀菌法的差异探究

近年来,超声波技术逐渐应用于食品工业领域,该项技术杀菌效果较好,较巴氏杀菌对食品品质和风味的损害性更低,被视为一种具有潜力的非热力杀菌技术.对超声波技术进行简单介绍并对其影响因素进行探究,同时与传统热力杀菌技术巴氏杀菌法进行对比,为超声波技术的广泛应用提供必要的理论背景.     

热泵型间歇式巴氏杀菌机的设计与性能分析

设计一种较适于工程应用的热泵型间歇式巴氏杀菌机,介绍其结构和工作过程,选择和设计杀菌罐、热水箱、冷水箱、热泵等关键部件,计算分析其工作周期、能耗等性能参数,并与普通间歇式巴氏杀菌机进行综合对比。结果表明,热泵型间歇式巴氏杀菌机的初投资与普通巴氏杀菌机相近,而电功率配置仅为其1/4,能耗仅为其1/5,且工作寿命长,安全性好,具有较大的综合优势。     

基于GSM的啤酒巴氏杀菌机温度远程监控系统设计

啤酒巴氏杀菌机喷淋水的温度是影响啤酒口味和质量的关键因素,设计基于MSP430单片机和GSM无线通讯的啤酒巴氏杀菌机温度远程监控及自动控制系统,控制核心采用MSP430单片机,温度实时检测采用DS18B20,其为数字式温度传感器,控制系统可以实时调节巴氏杀菌机各温区的温度,并实时地将各个测温区域的温度和温度异常报警信息,通过GSM网络传送到监控中心上位机和值班员手机。监控中心值班员也可以通过上位机对各个测温区进行温度设定。测试结果表明:系统具有调试方便、控制精度高、可靠性高、可远程集中监控等优点。解决了当前采用各个测温区有各自的温控仪,需要大量的值班员不断巡视等问题,节省了大量的人力、物力,提高了生产率。     

A preliminary study of the quality attributes of a cloudy wheat beer treated by flash pasteurization

Flash pasteurization (37 and 100 pasteurization units, PU) and conventional tunnel pasteurization (15 PU) processing of wheat beers were evaluated by examining their impacts on microorganisms, colour, colloidal haze and flavour stability during 84 days of storage at 20°C. The results revealed that the microbiological stability of 37 and 100 PU flash‐pasteurized beers was comparable with that of the 15 PU sample, and the development of both yeast and lactic acid bacteria was inhibited for 84 days of storage. The conventional tunnel‐pasteurized wheat beer resulted in a higher thermal load relative to the flash‐pasteurized samples based on the results of oxidative stability. These three pasteurized beers showed a similar decrease in haze intensity throughout the storage period. Meanwhile, flash‐pasteurized beers had better colour and colloidal haze stability than the tunnel‐pasteurized beer. It was also found by dynamic light scattering analysis that the temperature in the flash pasteurizer has the desired effect on the protein denaturation and particle size distribution. Therefore, flash pasteurization is a promising method to increase the shelf‐life of wheat beers instead of conventional tunnel pasteurization. Copyright © 2017 The Institute of Brewing & Distilling     

动力作用作为冷杀菌方法的可行性初探

通过鲜牛奶经纳米超高压均质机处理，取样，测定大肠菌群菌落数和细菌总数，结果表明，动力作用对牛乳中大肠菌群有致死效果；细菌总数最多可以降低3个对数单位，实验初步证实了动力杀菌作为一种冷杀菌的可行性。     

Preservation of protective capacity of hyperimmune anti-Stx2 bovine colostrum against enterohemorrhagic Escherichia coli O157:H7 pathogenicity after pasteurization and spray-drying processes

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major etiologic agent that causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Shiga toxin (Stx) is the main virulence factor of EHEC responsible for the progression to HUS. Although many laboratories have made efforts to develop an effective treatment for Stx-mediated HUS, a specific therapy has not been found yet. Human consumption of bovine colostrum is known to have therapeutic effects against several gastrointestinal infections because of the peptide and proteins (including antibodies) with direct antimicrobial and endotoxin-neutralizing effects contained in this fluid. We have previously demonstrated that colostrum from Stx type 2 (Stx2)-immunized pregnant cows effectively prevents Stx2 cytotoxicity and EHEC O157:H7 pathogenicity. In this study we evaluated the preservation of the protective properties of hyperimmune colostrum against Stx2 (HIC-Stx2) after pasteurization and spray-drying processes by performing in vitro and in vivo assays. Our results showed that reconstituted HIC-Stx2 colostrum after pasteurization at 60°C for 60 min and spray-dried under optimized conditions preserved specific IgG that successfully neutralized Stx2 cytotoxicity on Vero cells. Furthermore, this pasteurized/dehydrated and reconstituted HIC-Stx2 preserved the protective capacity against EHEC infection in a weaned mice model. The consumption of hyperimmune HIC-Stx2 bovine colostrum could be effective for HUS prevention in humans as well as in EHEC control in calves. However, further studies need to be done to consider its use for controlling EHEC infections.     

基于CFD技术的橙汁巴氏高温灭菌及冷却工艺研究

为了对橙汁灭菌及冷却工艺进行精确的研究,确保果汁品质的同时达到降低生产能耗、缩短生产时间的目的,在分析得到果汁中常见细菌灭杀温度及试验验证模型可靠性的基础上,对罐装橙汁高温灭菌及冷却工艺进行模拟计算。结果表明,在兼顾时间和能耗的原则下,最优灭菌工艺为95℃、1 020s,最优冷却工艺为10℃、720s。     

牛初乳巴氏杀菌工艺的优化研究

热处理是牛初乳加工中必不可少的工艺过程.通过对热处理强度对初乳中IgG保留率、微生物数量以及营养成分损失的影响进行研究,并对巴式杀菌工艺进行优化,得出以下结果:杀菌温度为60℃和63℃,加热时间超过30 min可以将微生物数量降低到安全数量.IgG的保留率随加热温度的升高而降低,随加热时间的延长而降低.加热温度对美拉德反应、脂肪氧化和蛋白质水解反应的影响均显著.通过优化得出,杀菌温度60℃和加热时间30 min,可以既保证微生物安全,同时最大保留IgG的浓度和营养成分损失较低.     

Evaluation of calf milk pasteurization systems on 6 Pennsylvania dairy farms

Waste milk has been fed to calves for many years, but concerns with bacterial contamination as well as possible transmission of diseases have discouraged widespread use of this feed. Pasteurization of waste milk is one option to reduce management risk while utilizing a valuable, low-cost, liquid feed source for calves. However, many farms currently pasteurizing waste milk lack a system to adequately monitor the efficiency of the process. A study was carried out to evaluate 6 on-farm pasteurization systems, including high-temperature, short-time pasteurizers and low-temperature, batch pasteurizers. Milk samples were taken pre- and postpasteurization as well as from the calf buckets and immediately frozen for later bacterial culture. Samples were collected twice daily for 15 d. Milk samples were examined for standard plate count (SPC), coagulase-negative staphylococci count, environmental streptococci count, coliform count, gram-negative noncoliform count, Streptococcus agalactiae count, and Staphylococcus aureus count. Before pasteurization, 68% of the samples had SPC <20,000 cfu/mL, and 39% of samples contained <100 cfu/mL of coliform bacteria. After pasteurization, 96% of samples had SPC <20,000 cfu/mL, and 92% had coliform counts <100 cfu/mL. Bacteria counts were significantly reduced by pasteurization, and pasteurized milk contained acceptable numbers of bacteria in >90% of samples. These results indicate that pasteurization can be very effective in lowering bacterial contamination of milk. However, bacteria numbers significantly increased after pasteurization and, in some cases, bacteria counts in milk fed to calves were similar to prepasteurization levels. Milk handling after pasteurization was identified as an important issue on the farms studied.     

基于CFD的回旋沉淀槽回旋沉降过程数值模拟

回旋沉淀槽是一个典型的固液分离设备,是啤酒酿造过程中必不可少的设备之一。研究考查了0~25°进冲角对回旋沉淀槽分离效果的影响,采用CFD技术对回旋过程进行模拟研究,寻找出了回旋沉降过程中的规律性。结果表明:在其他进料条件相同的情况下,随着进料管的进冲角的增大,回旋沉降效果先升高后降低,研究结果可为回旋沉淀槽的设计及优化提供参考依据。