Optimization of freeze drying of oyster mushroom and composition of extruded snack incorporated with oyster mushroom flour using response surface methodology

Abstract

Mushroom is a highly perishable product, so various methods were developed for the preservation and storage of it. In our study the optimizing conditions for the freeze drying of oyster mushroom and incorporating this oyster mushroom flour in addition with either the rice flour or corn flour to develop an extruded product. For obtaining the optimizing conditions Central Composite Design is employed that comes under the Response Surface Methodology. With coefficient of determination R 2 , the significant regression models are describing the changes on the physical characters, with respect to the independent variables that were established. For the freeze drying the parameters of the processing conditions are varied like for temperature of -30 ºC to -50ºC and time from 27 to 35 hrs. The independent variables that had an effect on the processing conditions are colour, particle density and porosity. The optimum processing conditions obtained according to Response surface methodology for freeze drying are -40ºC at 31 hrs. In the development of extruded product incorporated with the oyster mushroom flour to that of the corn flour or rice flour the compositions are varied from 5 to 20%. The response variables that had an impact due to the varying composition in raw material where speed, pressure and temperature. The optimum percent of oyster mushroom flour to that of the corn flour or rice flour are 10 and 12.5 respectively.