An experimental study on cryogenic spice grinding system for black pepper grinding

Abstract

In this paper, an experimental study on cryogenic spice grinding system for black pepper grinding has been presented. Black pepper was ground in developed cryogenic spice grinding system at varying temperatures (10°C and -50°C) and varying conveyor screw speeds (5, 10 and 15 rpm) in its pin mill (6500 rpm). Average particle size increased with increasing conveyor screw speed irrespective of temperature. A higher particle size was obtained at 10°C irrespective of conveyor screw speed in comparison to that obtained at -50°C. A more bright and light colour was obtained at -50°C in comparison to that at 10°C. The variation of a, b, chroma value, hue angle and browning index were significant (p  0.05) with varying speed at -50°C and that of non significant with varying speed at 10°C. The maximum values of piperine (2.65 %), total phenol-alcohol extract (1.00 %) and total phenol-water extract (0.87 %) were obtained at -50°C and 5 rpm. The maximum values of DPPH activity-alcohol extract (23.85 %) and DPPH activity-water extract (22.66 %) were obtained at -50°C and 5 rpm whereas minimum values of DPPH activity-alcohol extract (19.40 %) and DPPH activity -water extract (18.89 %) were obtained at 10°C and 15 rpm. It was observed that developed cryogenic spice grinding system yields better quality of black pepper powder under cryogenic conditions (at -50°C) as compared to that at ambient conditions (³10°C) in terms of average particle size, colour attributes, essential oil components, piperine, total phenolics and DPPH scavenging capacity.