Thermal Processing Equipment for Heating and Cooling

Chapter 5 describes the role of heating and cooling systems in aseptic processing, presenting the current methods and equipment used. Heating and cooling are essential parts of aseptic processing, playing a critical role in final food product safety and quality. The selected heating and cooling systems should result in rapid heat transfer, minimizing any food quality losses (color, texture, etc.) and maintaining the required food safety level of the finished product. The heating and cooling systems used in aseptic processing depend on food product characteristics (viscosity, homogenous, or multiphase products). For liquid, low-viscous homogeneous foods, where direct steam heating systems are used, a flash evaporating cooling system is used for the initial cooling stage. In most cases, flash evaporative cooling is used after the hold tube to provide an initial rapid cooling while also removing the excess condensed water added from the steam. In systems that use indirect heat exchangers for heating and cooling, the systems will consist of plate, tubular, or scraped surface heat exchangers depending on product viscosity and characteristics. Liquid homogeneous products, low or medium viscosities, can be processed in any indirect system. Highly viscous and multiphase foods are typically processed in scraped surface heat exchangers, while advanced heating technologies are also an excellent option for this type of product.