Effects of hot air-assisted radio frequency roasting on nutritional quality and aroma composition of cashew nut kernels

Hot air-assisted radio frequency (HA-RF) heating has great potential in roasting of cashew nut kernels with high roasting efficacy. This study further investigated HA-RF roasting effects on nutritional quality, malondialdehyde (MDA) and aroma compounds of cashew nut kernels. After HA-RF roasting, crude fiber content of kernels increased from 2.49 g/100 g to 3.18 g/100 g while ash and protein content did not change significantly (p > 0.05). In raw and roasted kernels, 14 fatty acids were detected including 7 saturated fatty acids and 7 unsaturated fatty acids. Fatty acid composition and individual amino acid content were not affected by HA-RF or conventional hot air (HA) roasting. MDA content increased from 0.36 mg/kg to 0.48 mg/kg and 0.64 mg/kg after HA-RF roasting and HA roasting. The types of aroma compounds of cashew nut kernels roasted by HA-RF and HA were similar, but HA-RFK had lower furan content and higher ketone and terpene contents. This study indicated HA-RF roasting was comparable or even better than HA roasting in improving nutritional quality and flavor. •Crude fiber content increased after hot air-assisted radio frequency (HA-RF) roasting.•HA-RF roasted kernels had lower MDA content than those roasted by hot air.•Nutritional qualities were comparable in HA-RF and hot air roasted kernels.•HA-RF roasted kernels had higher ketone and terpene contents.•HA-RF roasting had comparable or even better quality of cashew nut kernels.