Evaluation of ultrasound‐assisted microwave hot air convective drying Chinese hickory—Drying kinetics and product's quality properties

Abstract

The fresh Chinese hickory nuts (Carya cathayensis sarg.) were exposed to airborne ultrasound‐assisted convective drying and microwave‐assisted convective drying, as well as their combination. We investigated the effect of different drying schemes on process kinetics and quality characteristics. The global model of drying kinetics based on coupled ordinary differential equations was used to describe the moisture and material temperature profiles during drying. Application of ultrasound and microwave in convective drying reduced drying time in the range of 14.0–56.6%, but the maximum savings was found for simultaneous exposure of convection, ultrasound, and microwave with the range of 73.6–84.2%. The globally mathematical model was successfully used to simulate the real drying kinetics processes. The quality properties about the content of heat‐sensitive bioactive substances such as phenolic, flavonoid, proanthocyanidin, individual phenolic compounds, as well as antioxidant capacity in convective drying assisted with microwave (100 W) and ultrasound (200 W; CU2M1) are found to be significantly higher than the other groups. The results allow stating ultrasound increase drying efficiency, as expected by reducing the drying time there is less damage to the product. Practical Application In this work, we designed an experimental scale hybrid dryer that equipped with hot‐air convective drying, ultrasound generator and microwave drying system to dehydrate Chinese hickory nut and the effect of different drying schemes on the drying kinetics and product characteristics were investigated. This is an innovative technology of microwave and ultrasound hybrid drying to produce dried hickory products. Application of ultrasound and microwave in convective drying reduced drying time in the range of 14–56.6%, but the shortest drying time was observed for simultaneous action of convection, ultrasound, and microwave. The results of qualitative analysis showed a product improvement due to ultrasound as compared to convective drying and microwave‐convective drying.

Effect of ultrasonic pretreatment on drying kinetics and physio‐mechanical characteristics of peach slices

“…increasing the pretreatment time, the time required for the samples to dry decreases; so that, the longest and shortest drying times belonged to the control samples with 320 min and the sample under ultrasound pretreatment (for 60 min) with a drying time of 240 min, respectively. The results were consistent with the results of ultrasound drying of kiwifruit (Wang et al, 2019), carrot slices (Yilmaz et al, 2019), potato slices Zhang et al (2021). When ultrasound is introduced into the environment, an enhancement of the mass transfer is governed by two important factors (Yao, 2016).…”

“…The results were consistent with the results of ultrasound drying of kiwifruit (Wang et al, 2019), carrot slices (Yilmaz et al, 2019), potato slices Zhang et al (2021). When ultrasound is introduced into the environment, an enhancement of the mass transfer is governed by two important factors (Yao, 2016).…”

“…Moreover, ultrasound would also result in micro streaming near the interfaces and, accordingly, affect the convection and diffusion of boundary layer. Consequently, during recent decades, food industry, that is, extraction, freezing, melting, and drying, has greatly applied this low‐frequency ultrasound technology (Zhang et al, 2021).…”

“…Souza da Silva et al (2019) who studied ultrasound‐assisted vacuum drying of nectarine aimed at evaluating the effect of ultrasound waves and vacuum on the drying kinetics (Souza da Silva et al, 2019). Zhang et al (2021) investigated the effect of different drying schemes on process kinetics and qualitative characteristics. The results showed that ultrasound increase drying efficiency, as expected by reducing the drying time there was less damage to the product (Zhang et al, 2021).…”

“…Zhang et al (2021) investigated the effect of different drying schemes on process kinetics and qualitative characteristics. The results showed that ultrasound increase drying efficiency, as expected by reducing the drying time there was less damage to the product (Zhang et al, 2021). Alizehi et al (2020) studied the effects of using various vacuum pretreatments and different ultrasound power levels on osmodehydration, diverse airdrying temperatures, infrared power, and the presence of teflon beads as inert particles of carrot cubes were investigated.…”