Development and evaluation of onion bulb descaler for removal and collection of surface dry peel

Abstract

Onion bulbs contain outer papery dry peel which is rich with industrially important high-value compounds. Removal of dry peel/scale of onion is the common practice during bulb processing, storage and marketing. A conventional manual method of scale removal involves huge labour, drudgery and means of environmental pollution. An onion descaler machine has been therefore developed to mechanize this operation, reduce drudgery and effectively collect the dry scales for industrial use. The operating parameters of the developed machine were optimized for its best performance using RSM. During optimization study, roller speed, roller slope and hopper opening were taken as independent variables. The performance of the machine was evaluated through descaling efficiency and descaling loss. During experimentation, descaling efficiency and descaling loss were obtained in the range of 35.92–98.55% and 0.82–9.07%. The optimum performance of the machine was obtained at 450 rpm roller speed, 2% roller slope and 380 mm of the hopper opening with maximum descaling efficiency (88.29%) and minimum descaling loss (3.65%). The optimization of the onion descaler parameters and their statistical relation provided the necessary information on the combination of material-machine alignment, and design parameters for enhanced descaling efficiency.