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。     

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。     

啤酒巴氏杀菌过程的CFD数值分析

以瓶装啤酒为研究对象,建立巴氏杀菌过程的CFD数值模型,基于Fluent对热传递过程进行数值分析,建立固液耦合的复合共轭传热系统,得到完整受热周期中瓶内啤酒温度场变化情况;通过CFD数值分析,得到Ⅰ~Ⅺ温区的变温过程,在总生产能力为3.6万瓶/h的工况下,设计总过程时间为60min,保温时间为11min,该条件下啤酒出口温度为30℃(≤35℃),出酒温度明显降低,有利于在保质的同时提高啤酒新鲜度,达到了啤酒生产的PU值标准;最后通过实验验证了提出的11温区杀菌过程数值模型的正确性,为生产工艺参数提供了数据依据。     

基于COMSOL Multiphysics模型的液态罐头食品热杀菌过程模拟研究

以水和CMC溶液为研究对象,通过无线实时温度传感器检测热杀菌过程中罐中心温度的变化,并以COMSOL Multiphysics软件为基础建立传热模型。对比模拟结果与实际数据发现模型能很好地模拟罐中心点温度的变化。在此基础上,进一步用COMSOL Multiphysics软件模拟整罐空间的温度分布、速度分布及致死率值,得出在50 s与4 000 s时,水的最大流动速度分别为6.36 mm/s和5.05 mm/s,1%CMC溶液的最大流动速度分别为0.394 mm/s与1.124 mm/s,罐内最慢加热区(SHZ)位于罐体高度10%~30%处,与文献一致。杀菌结束时,水的最大、最小致死率值相差0.6min,而1%CMC与2.5%CMC溶液最大、最小致死率相差分别为12.4 min和18.86 min,这表明对于较高黏度的食品应采用旋转杀菌。     

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。     

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。     

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...     

瓶装啤酒杀菌工艺的研究

瓶装熟啤酒杀菌值的掌握直接影响啤酒的风味和生物稳定性，若杀菌过头啤酒易产生杀菌味，氧化聚合加剧；若杀菌不彻底，啤酒将很快出现生物混浊。本文从工艺制订，过程控制及常见的问题等三方面进行了探讨。     

基于COMSOL Multiphysics的金枪鱼罐头热杀菌过程数值模拟

以COMSOL Multiphysics软件为基础,建立纯传导和固液混合两种模型来模拟金枪鱼罐头的热杀菌过程。通过无线温度传感器检测热杀菌过程中130 g金枪鱼与55 g,4%Na Cl卤水罐头中心温度的变化,结果发现:固液混合模型的预测结果与试验数据十分吻合,而纯传导模型明显低估了罐内温度传递。在此基础上,用固液混合模型模拟工业杀菌条件(10 min-60 min-10 min/116℃)下金枪鱼罐头内的温度分布、速度分布及致死率值,结果发现最慢加热区(SHZ)位于罐高的22.9%~50%之间,最慢冷却区(SCZ)位于罐高的50%~81%处。在升温和降温阶段,罐内液体流速可达4.41 mm/s。杀菌结束时罐内最大与最小致死率值相差4.93 min,而中心点致死率与最小致死率相差很小。本文建立的模型可为金枪鱼罐头的热杀菌优化提供参考。     

高径比与倾斜角对液态圆柱罐头食品热杀菌过程的影响

以0.85%CMC溶液为研究对象,基于COMSOL Multiphysics软件建立三维传热模型来模拟液态罐头食品的热杀菌过程。采用无线温度传感器检测热杀菌过程中罐内CMC溶液中心温度的变化进行验证,发现模型能很好地模拟罐中心点温度的变化。在此基础上,模拟等体积不同高径比与不同倾斜角对热杀菌过程的影响。结果表明,液态圆柱罐头的杀菌时间随高径比与倾斜角的增大先增加后减少,在高径比为0.75~1时,杀菌时间出现大值。当高径比小于0.75时,罐体垂直放置杀菌时间小;当高径比大于0.75时,罐体水平放置杀菌时间小;高径比等于0.75时,罐体垂直放置与水平放置杀菌时间相近。慢加热区(SHZ)达到100℃时,高径比为0.75,倾斜角为0°的罐内流动为激烈,大流速为2.83 mm/s,高径比为0.25,倾斜角为45°时,罐内流动为缓慢,大流速为1.22 mm/s。     

Free radical reactions in beer during pasteurization

Oxidative reactions during beer pasterization were studied using chemiluminescence (CL) and electron spin resonance (ESR) analyses. the CL production of beer was acclerated by pasteurization and the maximum CL intensity appeared sooner than that in non-pasteurized beer. Beers pasteurized with 15–30 pasteurization units (P.U) had the same CL producing activities as the non-pasteurized beers stored at 20°C for 6–10 days. Free radicals were produced and some of them were consumed by beer oxidation during pasteurization. It seems that free radicals were consumed by beer oxidation during pasteurization. It seems that free radical reactions occur in beer during pasteurization and that the degree of oxidation during pasteurization generally corresponded to that of non-pasteurized beer stored at room temperature for about 1 wee.     

PET啤酒瓶的阻隔性检测

简要介绍了现在常用的几种塑料容器的制造材料,详述了PET容器在啤酒包装上的应用以及现有的容器透氧性检测手段。     

高技术啤酒瓶——聚酯瓶

<正> 毫不夸张地说,每个人几乎都饮用过啤酒和PET瓶装饮料。这种由聚酯物吹塑而成的瓶子以优异的性能,正逐步稳定地取代金属和玻璃容器,而且相应的制造设备和工艺也不断地发展。     

A suitable model of microbial survival curves for beer pasteurization

Published isothermal inactivation data indicated that beer can undergo under- or over-processing depending on the target log reduction and the shape of the survival curve of a microorganism if traditional first-order model is used. This was demonstrated for a mold, yeasts and lactic acid bacteria by use of a more flexible and convenient model than the first-order model, namely Weibull model. The parameters of the Weibull model can be reduced from two to one with a very a slight loss of goodness-of-fit. The validity of the proposed model should also be checked for mixed populations of microorganisms in beer and non-isothermal treatments for beer. Beer can be the first product to validate the proposed model in industrial base since it has been free from problems with pathogenic microorganisms. If the model provides the requirements then it can also be used in other food products. This will minimize the energy expenditure for pasteurization and provide minimal processing to achieve a better food quality.     

Modelling and simulation of bottle rinsing

This study describes newly developed mathematical models of bottle rinsing. Our approach is based on 3D‐CFD models of turbulent two‐phase flow (water and air), which have been implemented based on the freely available open source software OpenFOAM. The models are validated using data obtained with a standard injection nozzle and then used to evaluate the performance of two fictitious modified nozzle types w.r.t. cleaning efficiency, water consumption and water drainage. Maps of the interior walls of the bottles showing the distribution of important parameters such as wall shear stresses or water coverage were derived from the simulations. The simulations suggest that rotating or pulsating injection nozzles may perform better than standard nozzle configurations.     

Computational study for microwave pasteurization of beer and hypothetical continuous flow system design

Beer pasteurization is carried out in conventional systems where low temperature and long time process (56 min process with 13 min pre-heating, 14 min heating, 6 min holding time and 23 min cooling time) is applied for bottled or canned products. Longer process times lead to losses in the sensory properties. Another approach is flash pasteurization where the beer is first pasteurized and then filled into bottles or cans. For flash pasteurization, microwave (MW) process with rapid heating feature might be an innovative alternative. Therefore, the objective of this study was to explore the MW processing for beer pasteurization. For this purpose, a computational mathematical model was developed to determine the temperature change of beer during MW process and experimentally validated in a 2450 MHz lab-scale system. Following the validation, process design studies for a continuous flow system were carried out. These studies demonstrated the MW application as a rapid process (e.g. 60 s of total MW heating time at 5000 W with a short holding time of 27 s) to achieve the required pasteurization unit at a flow rate of 50.4 kg/h. This confirmed the MW process as a possible industrial application. Using these results, continuous flow process optimization studies for industrial process considerations might be planned.