Microwave decontamination processing of tahini and process design considerations using a computational approach

Tahini, as a low moisture food product, is linked to several outbreaks of Salmonella recently even though a high temperature roasting (of sesame seeds) through its production is involved. Therefore, a final decontamination approach might be required for safety. Considering its higher oil content and lower thermophysical properties, conventional approaches are not easy to apply while preserving the quality attributes. Therefore, microwave heating was used for decontamination purpose. For this purpose, a computational mathematical model was developed first to determine the temperature distribution of tahini during microwave heating, and microbial inactivation studies for Salmonella enteritidis (ATCC 13076) were carried out. Changes in color and peroxide values were evaluated, and the experimentally validated model was further used to design an industrial process to achieve a 5-log cycle reduction as an efficient decontamination processing. The target temperature over 80 °C within the sample was demonstrated to achieve such a process, and industrial scale process conditions were presented for 262 kg/h process capacity.