Pulsed electric field treatment applied to microbreweries for processing craft beer

热处理方法，如热巴氏灭菌，主要用作使腐败微生物失活的手段。然而，热处理方法是能量密集型的，并对腌制食品的营养和感官质量产生不利影响。近年来，像脉冲电场（PEF）技术这样的非热工艺已被研究用于商业应用。PEF装置由一对导电金属电极组成，由已知的间隙距离隔开。高压脉冲施加在一个电极上，同时使另一个电极保持地电位。由此产生的电场导致细胞膜的不可逆破坏；因此微生物失活。加拿大的酿酒法规不要求对精酿啤酒进行巴氏灭菌；因此，PEF处理在酿造工业中有潜在的应用。PEF处理是一种非热处理，与传统的热巴氏杀菌相比，其鲜味和营养价值得到了更好的保留。然而，由于PEF处理过程中的电流，金属离子从电极中释放出来。金属的释放量取决于产品的类型、电极的具体组成和使用的脉冲类型。本研究通过设计用于消除大多数金属离子释放的加压处理室，调查了PEF处理在精酿啤酒中的适用性。通过滑铁卢大学和Innocente酿酒公司之间的紧密合作，我们有信心证明PEF巴氏灭菌对精酿啤酒的有效性，使用改进的UW'sPEF设备。正在考虑进行系统测试，精确控制施加的脉冲、处理时间和其他参数，如介质温度和能量，以评估pef加工过程中释放的金属离子及其对味道和保质期的影响（如果有的话）。这项研究的成果所期望的知识和技术将直接有利于小啤酒厂推广其新的优质产品。

Heat treatment methods such as thermal pasteurization are predominantly utilized as a means to inactivatespoilage microbes. However, heat treatment methods are energy intensive and adversely affect nutritional andorganoleptic quality of the preserved food. In the recent years non-thermal processes like pulsed electric field(PEF) technology has been investigated for commercial applications. PEF devices consist of a pair ofelectrically conductive metal electrodes, separated by a known gap distance. High voltage pulses are applied toone of the electrodes while keeping the other electrode at ground potential. The resulting electric field causesirreversible breakdown of cell membrane; hence microbial inactivation.Brewery regulations in Canada do not necessitate pasteurization of craft beer; hence, PEF processing finds apotential application in the brewing industry. PEF treatment being a non-thermal, the fresh like taste and thenutritional value are better retained than with conventional thermal pasteurization. However, due to the flow ofcurrent during the PEF processing, metal ions are released from the electrodes. The amount of metal releaseddepends on the type of product, the specific composition of electrodes and the type of pulses used. Thisproposed research investigates the applicability of the PEF processing to craft beer, through a pressurizedprocessing chamber that has been designed to eliminate release of most metal ions.With a strong cooperation between the University of Waterloo and Innocente Brewing Company, we areconfident in demonstrating the effectiveness of the PEF pasteurization for craft beer, using the modified UW'sPEF facility. Systematic tests with precise control of the applied pulse, treatment time, and other parameters,like medium temperature and energy are being considered to evaluate metal ions released during the PEFprocessing and their consequent effect, if any, on the taste and the shelf life. The knowledge and technologythat are expected as outcome of this research are of direct benefit for microbreweries in promoting their newpremium products.