Can hydro-thermo-mechanical treatment by instant controlled pressure-drop (DIC) be used as short time roasting process? Effect of processing parameters on sensory, physical, functional, and color attributes of Egyptian carob powder.

This study deals with the manufacture of a specific cocoa-like powder from Egyptian carob. The crucial unit operation consists of texturing/roasting unseeded carob kibbles, with the aim being to ensure perfect control of the chemical transformations that generate the desired flavor, drying to remove excess moisture, deodorizing to eliminate the undesirable flavor, and texturing to favor the physical/micro-mechanical changes that regulate the microstructure of the end product, in order to obtain an expanded-granule powder that can be used in many food formulations. The effect of saturated steam pressure of 0.30-0.60 MPa (133.5-158.8 °C) and processing time of 40-70 s, on the sensory attributes, physical and functional properties, and color characteristics were evaluated and optimized using response surface methodology (RSM). DIC-texturing/roasting could be used to improve the sensory and color characteristics, increase the expansion ratio and oil holding capacity, and decrease the bulk density of DIC-textured/roasted carob powder. The desired quality of textured/roasted carob powder was obtained at 0.60 MPa (158.8 °C) for 55 s (experimental conditions) with water holding capacity close to those of non-textured/unroasted sample. DIC can be used as a coupled process of texturing and roasting at 0.60 MPa for 68 s as predicted by RSM.