Roasting is an important postharvest process for enhancing the palatability of nuts. Canarium indicum (Burseraceae) is a tropical nut indigenous to lowland rainforests of Melanesia that has potential for commercialization. Three roasting regimes were investigated to indicate a suitable temperature/time relationship for roasting Canarium. 1) Roasting for the same time (10 min) at three different temperatures (115, 120 and 125°C) using fresh kernels (roasted within one month of harvest) and aged kernels (stored for three months after harvest); 2) Roasting for two different times (10 and 17 min) at the same temperature (120°C); 3) Roasting kernels of low, medium and high oily appearance at the same temperature (115°C). Kernel colour was rated from 1 (lightest) to 5 (darkest) using a paint colour swatch. Colours 3, 4 and 5 were considered dark enough to cause rejection. The mean colour of kernels was significantly darker when roasted at 125°C for 10 min compared with roasting at 115 and 120°C. Aged kernels were significantly darker when roasting at 120°C for 17 min than when roasted for 10 min. Roasting 'high' oily kernels produced significantly darker kernels compared with roasting 'shiny' and 'dull' kernels. These results indicate that aged Canarium kernels of inferior quality should be roasted at temperatures below 125°C for less than 17 min, but fresh, good quality kernels can be roasted at 125°C for 10 min. Kernels with very oily appearance are not suitable for roasting as oiliness indicates cellular damage, predisposing to excessive after-roast-darkening. Further research is required to provide clearer guidelines for roasting good quality Canarium kernels.
Acta Horticulturae / M. Wirthensohn (ed): Vol. 1109, pp.43-47