Convective Heat Transfer to Fluid Foods in Cans

The chapter explains about the convection heating of foods in cans. Canning is the effective means to preserve large part of food supply. Heating characteristics of food products based on conduction and convection are illustrated. Conduction heated products exhibit slower heating rates and longer lag times and convection-heated products exhibit faster heating rates and shorter lag times. Methodologies to study convective heat transfer to foods are explained. The heat transfer rates to liquid foods are influenced by flow conditions such as viscosity, geometry, velocity of flow, and physical and thermal properties of liquid. Flow properties of Non-Newtonian fluids and viscoelastic fluids are also discussed. Heat transfer by natural convection takes place by conduction through a stagnant film of liquid on the inside surface of the can. Various factors affecting heat transfer by forced convection are explained in details. Methods of heat transfer in orbitor retorts, spin cooker, flame sterilization etc. are clearly illustrated. The process of heat transfer by convection in the presence of particulate matter is explained in detail. Heat is first transferred to the fluid and then to the particle. The presence of particulate matter will alter the flow patterns and contribute to the mixing of the can's contents due to their motion. The chapter also emphases the need for experimental studies that are applicable to non-Newtonian foods. It also illustrates the importance of dimensionless correlation in the field of heat transfer.