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This study applied hot air‐assisted radio frequency (HA‐RF) as a new roasting method for almonds. Almonds roasted by HA‐RF at medium level (120–130°C, 15 min) had best quality compared with that roasted at light (110–120°C, 10 min) or heavy (120–130°C, 20 min) level. After medium level HA‐RF roasting, moisture content of almonds decreased to 3.4% from initially 4.2%, acid value and peroxide value of HA‐RF roasted almonds were significantly (p < .05) lower than those roasted by conventional oven. There were 61 and 87 volatile compounds in raw and HA‐RF roasted almonds, respectively, and 21 new volatile compounds were generated after storage of 18 weeks. Sensory attributes of HA‐RF roasted almonds were in well acceptable range and overall consumer acceptance (8.3) was comparable with that of oven roasted almonds (8.0). HA‐RF had great potential in roasting of almonds since it can obtain desired flavor and quality with lower roasting temperature and higher efficiency. Practical applications This study applied HA‐RF heating as a novel roasting method for almonds, research findings in this study indicated that HA‐RF roasting obtained good physicochemical and sensory quality of almonds when compared with conventional oven roasting, and HA‐RF roasting could obtain desired roasted flavor compounds. Due to rapid and volumetric heating characteristics of RF heating, HA‐RF roasting had high roasting efficiency and could obtain desired sample texture and flavor with low roasting temperature. And HA‐RF roasting is easily scale‐up for commercial application, thus HA‐RF holds great potential as an industrial roasting method for almonds.

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This study applied hot air-assisted RF (HA-RF) as second stage drying method for mango slices.Hot-air drying was used as first stage drying to reduce moisture content to about 40% (w.b.), then HA-RF drying was applied as second stage drying to further reduce moisture content to 18% within 45 min with 4.5 cm sample thickness (hot air temperature: 60 C, electrode gap: 7.5 cm). The time for the two-stage drying process was about 5 hr, which was clearly lower than that of hot-air drying (8 hr) or vacuum drying (7 hr). HA-RF as second stage drying maintained sample overall quality very well except for minor vitamin C degradation (retention rate: 91%);Overall quality of mango slices after the two-stage drying was better than that dried by hot-air drying, and close to that dried by vacuum drying. This study demonstrated HA-RF could be used as second stage drying method for mango slices. Practical applicationsThis study applied HA-RF heating as second stage drying method for mango slices, and research findings in this study indicated that HA-RF drying could reduce drying time and improve sample quality. This study proposed a new two-stage drying method for mango slices, and this technology can be easily scale-up for commercial application. And the two-stage drying efficiency and products quality could be further improved by other novel and efficient drying techniques as first stage drying.

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