Effect of Moisture Content, Nut Size and Hot-Oil Roasting Time on the Whole Kernel “Out-Turn” of Cashew Nuts (Anacardium occidentale) During Shelling

Abstract

The effect of moisture content (MC), nut size and roasting time (RT) on the whole kernel out-turn (WKO) of cashew nuts during shelling was investigated in this study. Cashew nuts were graded into three sizes: small (18 – 22 mm), medium (23 – 25 mm) and large nuts (26 – 35 mm). About 3 kg of nuts from each grade was conditioned with water at 25oC to five moisture levels of 8.34, 11.80, 12.57, 15.40 and 16.84% (wb). The nuts were subjected to roasting in hot cashew nut shell liquid at a temperature range between 180 and 190oC for 0.75, 1.00, 1.25, and 1.50 min. The nuts were then shelled using a hand-operated shelling machine. The results showed that pre-shelling treatment of cashew nuts enhanced WKO. The single effect of MC, roasting time (RT) or nut size distribution is not enough for estimating WKO; it is rather by an interaction of these parameters. The average WKO of raw nuts was characteristically below
50% at all combinations of MC and RT. Pre-treatment by roasting was found to improve WKO considerably. The highest values were 96.96, 99.63 and 100% for large, medium and small-sized nuts at MC*RT of 16.84%*1 min, 16.84%*1 min and 15.4%*1.5 min respectively. As RT and MC increased, WKO increased within the experimental range.

Keywords: Moisture content, nut size, hot-oil roasting, whole kernel out-turn, cashew nuts.