Heat transfer analysis of pasteurization of bottled beer in a tunnel pasteurizer using computational fluid dynamics

•The CFD model was developed for pasteurization of bottled beer.•Temperature dependent thermophysical properties of beer were used in this study.•The simulation results were validated with the experimental measurements.•The effectiveness of thermal processing of beer in a tunnel pasteurizer was investigated.•The effectiveness of pasteurization was investigated in terms of pasteurization unit.

Beer is one of the most widely consumed alcoholic beverages in the world. Pasteurization is an important unit operation in beer processing that inactivates the spoilage microorganisms present in beer thereby extending its shelf life. It is difficult to determine the temperature profile and slowest heating zone (i.e. minimum heating region) inside the bottle during industrial scale tunnel pasteurization. Computational fluid dynamics (CFD) modeling can be used as a tool to determine the temperature distribution pattern inside the bottled beer. This study is unique in terms of using the actual thermophysical properties of beer unlike in earlier published works. Further, CFD simulation prediction of the temperature profile in the bottled beer was validated with experimental measurements. The study was extended to investigate the effects of different zones' temperatures on inactivation of Saccharomyces cerevisiae, the most common beer spoilage organism. A tunnel pasteurizer with seven zones was selected to study the temperature profile inside the bottled beer and found to be in good agreement with the published temperature profiles in different zones. In addition, the effectiveness of pasteurization was investigated in terms of pasteurization unit (PU) and the resultant PU value (15 to 30 PU) was adequate for achieving the maximum sterility of beer.Industrial relevanceIn recent years, a rapid development in the application of CFD in food processing operations has been witnessed. The main need for CFD analysis of pasteurization is to determine the uniform and effective heat distribution inside the bottled beer and to examine the position of slowest heating zone (SHZ). Relatively few works have been published related to applications of CFD during beer pasteurization. However, all the studies were performed with water as a model fluid. So far no work has been published on the CFD simulation during the pasteurization process in bottled beer by using the thermophysical properties of beer. Hence, the present study was aimed at investigating the temperature distribution inside the beer bottle during the pasteurization process and in each zone of the industrial tunnel pasteurizer. This model can be used for the brewery industry to ensure that the required pasteurization temperature has been reached inside the beer bottle when conveyed through a tunnel pasteurizer. This is very essential to render a safe product with extended shelf life to the consumers.