Farshad Bolourchifard
Politecnico di Milano, Italy
Title: Impact of preheating on solid-liquid food temperature distribution after ohmic sterilization process and multi-objective optimization
Biography
Biography: Farshad Bolourchifard
Abstract
The ohmic heating is a non-traditional process of food sterilization; application of an external electric field through the target medium can raise its temperature to the desired sterilizing value. Unlike its traditional counterparts, the result is a remarkably efficient process due to the fact that the energy is released directly through the body of the product (fruits, vegetables, foods, mixtures etc.) rather than at its surface. Industrial applications of the process are particularly advanced in the food, pharmaceutical and biotechnological sectors, where remarkable results have been obtained for a wide variety of products. However, non-homogeneity and variation of local electrical conductivity may cause hot and cold spots inside the sterilizing food product. Since, the cold and hot spots can affect the final quality of the sterilized product as well; the non-uniform temperature gradient is the main short-comings of the ohmic heating food sterilization. In the current study, a combination of preheating and ohmic heating techniques is used as an effective hybrid sterilization method to make the temperature profile inside the product more uniform and eventually to prevent the occurrence of the hot and cold spots as much as possible. Without loss of generality, the proposed method is applied to two specific case studies to prove its effectiveness. The results show that the regulated preheating by applying a quality based optimization will substantially reduce the required voltage of ohmic heating and also the temperature difference between the hot and cold spot so that can satisfy the sterilization temperature limits and guarantee more acceptable quality and safety of sterilized product.