Instrumentation of a semi-industrial oven to monitor non-enzymatic browning kinetics during baking

摘要

A semi-industrial convective oven was designed and characterized in this study to monitor the kinetics ofthermal reactions like Maillard and caramelization reactions occurring during baking. The thermalenvironment was characterized by measuring the heat fluxes received by the surface of the cakes underdifferent temperature (140, 170 and 200°C) and ventilation (min, max) conditions. Excellent reproducibilityof the convective heat transfer coefficient was obtained from one baking operation to another and the heatfluxes were shown to be uniform on the whole baking floor. Temperature and air humidity sensors were usedto observe heat and mass transfers during baking. Besides, the oven was equipped with two original samplingdevices enabling to acquire synchronous kinetic data on reaction products in the food matrix as well as in thevapors emitted by the product during baking and this, without disturbing the thermal environment. Theproduction of 5-hydroxymethylfurfural (HMF), which was used as an indicator of the development of nonenzymaticbrowning, was thus monitored synchronously in the sponge cake and vapors. A goodreproducibility of the reaction development was obtained with maximum 8.7 % variations of HMFconcentration at all sampling times of independent baking operations. Furthermore, the volatilization ofMaillard products in the oven chamber was proved to be proportional to the load of sponge cake being baked,showing the relevance of observing thermal reactions in the baking vapors. This oven should be of precioushelp for further kinetic modeling of complex thermal reactions occurring in solid food matrix baked underreal process conditions.