Individual and combined impacts of water immersion, steaming at 100 °C and hot air drying on the cashew nut shelling process

Abstract

Shelling cashew nuts is a highly labour-intensive process that often results in broken kernels, reducing efficiency and economic value. Improving shelling techniques is crucial for increasing whole kernel yield, reducing waste, and enhancing sustainability in the cashew industry. In this study, the aim was to investigate the impact of pre-treatments (water immersion, steaming and artificial drying) applied alone or in combination to weaken the nut and facilitate shelling. An experimental approach incorporating microtomography was used to identify the importance of each step and the factors controlling the process. The results show that water content is the main factor influencing whole kernel yield, shelling rate and shell toughness. Hydration during soaking makes the shell more flexible and reduces kernel cracking, while steaming intensifies this effect. Rapid drying keeps the kernel hydrated and makes the shell brittle, improving the production rate. The study suggests that steaming alone might sufficiently saturate the shell, eliminating the need for soaking. In addition, artificial drying reduces the duration of the process. The results obtained provided a better understanding of the process control variables with a view to its improvement. Further studies on process modelling could provide insights into optimising the yield of whole kernels