Study of the kinetics of drying brewer's spent grain
The kinetics of drying of the crude brewer's spent grain - a secondary product of LLC «Belorechensky brewery» (Russian Federation, Krasnodar region) has been studied. Drying is carried out in two temperature modes - 60 and 55°C. The speed of the drying agent under forced convection was 4,5 m/s. The dry matter content was determined according to GOST 31640-2012 in laboratory conditions and was 12,9%. Measurement of mass loss during drying was performed at an interval of 5 min. The total drying time of the brewer's spent grain sample in the amount of 50 g is 420 min at 50°C, 360 min - at 60°C. The average value of the final moisture content of brewer's spent grain made up 11,85%. Curves of drying and drying speed are constructed. Drying speed when removing free moisture in the first drying period, min-1: at 60°C - 3,5, at 55°C - 3,0. It was found that the content on average of bound moisture is 57% of the mass of moisture in brewer's spent grain, free moisture - 43%. Analysis of the structure sample of brewer's spent grain a microscope before and after drying confirmed the fact that the amount of bound moisture in the studied material is greater than the amount of free moisture. The presence of particles of 5-7 mm in size indicates a significant amount of cellular moisture in undisturbed capillaries. Further improvement of the technology for processing brewer's spent grain should be aimed at destroying the cellular structure of the material after its mechanical dehydration.