Safe cooking optimisation by F-value computation in a semi-automatic oven

Cooking represents an important step in food processing for both sensorial and safety aspects. Aim of this study was to optimise the cooking cycles of a semi-automatic oven by definition and settling of minimum thermal conditions to guarantee safety while keeping sensorial quality of cooked foods. To this purpose, the heat penetration curves and the correspondent thermal lethality effect (FT) of cooking cycles conventionally adopted to prepare some foods and dishes characterised by different microbial risk (high: lasagne pie, meat minced roll, meat filled peppers; standard: spinach and salmon), were determined. On the basis of the microbial quality and the desired safety level, minimum thermal conditions (F71.1 = 5 min and T = 75 C at the slowest heating point of the food) were defined and settled in the electronics of the oven. These conditions were found to determine a sufficient number of log reduction of both total microbial count and coliforms able to guarantee safety as well as sensory quality at consumption. The oven with modified electronics during the heating step of cooking cycles records in real time the temperature in the product by a multipoint thermocouple, detects the slowest heat penetration curve and computes, by an internal computer the correspondent F71.1. After initial setting of the food category, this semi-automatic oven is able to find automatically the proper process conditions during cooking to obtain the correspondent FT, to let the cooking stop at the end of the recipe or to conduct the thermal treatment till the reaching of the set FT according to the risk category chosen before cooking start.