Drying Characteristics and Processing Parameters for Microwave-Vacuum Drying of Kiwifruit (A ctinidia deliciosa ) Slices

Abstract

This study experimented on microwave-vacuum (MWV) drying of kiwifruit (Actinidia deliciosa) slices as a way to improve drying productivity and the quality of dried fruit. The effects of microwave power density, sample thickness and vacuum degree on the drying characteristics of kiwifruit slices were studied. The results showed that these three factors had significant effects on the vitamin C and chlorophyll contents and on the rehydration capacity of dried kiwifruit slices, as well as the total drying time. The processing parameters of MWV drying of kiwifruit slices were optimized by using Box-Behnken design with a quadratic regression model built by response surface methodology. The optimum processing parameters were experimentally determined as microwave power density at 7.7 W, sample thickness of 6.0 mm and MWV drying for 11.5 min at a vacuum degree of −90 kPa. High-quality dried kiwifruit slices can be created under these conditions using this drying process. PRACTICAL APPLICATIONSKiwifruit (Actinidia deliciosa) has become a popular fruit because of its bright green flesh, high level of vitamin C and because it contains a wide variety of phytonutrients, including carotenoids, lutein, phenolics, flavonoids and chlorophyll. It needs some form of preservation to extend its shelf life. Microwave-vacuum (MWV) drying is a novel alternative that combines the advantages of both microwave drying and vacuum drying. The objectives of this study were to investigate the effect of microwave power density, sample thickness and vacuum degree on the MWV drying characteristics and quality of MWV-dried kiwifruit slices, and to evaluate a suitable drying model for describing the drying process. In addition, the process parameters of MWV drying were optimized by response surface methodology. This present study provides the theoretical basis for industrial-scale production.

Continuous and intermittent microwave‐vacuum drying of apple: Drying kinetics, protein, mineral content, and color

“…This effect allows the driving force for mass transfer with evaporation of water from the materials, leading to a shorter drying time. However, damage to the product from electrical arcing in the oven or local overheating could be seen at higher vacuum levels (Tian et al, ). In the literature, Song, Zhang, Mujumdar, and Fan () investigated the effect of pressure levels on the drying kinetics during vacuum microwave drying at 240 W. They found that the drying time of potato decreased with increasing vacuum level.…”

Intermittent Microwave-Vacuum Drying Effects on Pears

“…Particles extracted from the dried samples were vertically cut into 1-mm-thick slices and coated with gold-palladium. All samples were examined under high vacuum (20 kV) (SCD-005, Baltec, Wetzlar, Germany), and then their microphotographs were taken [Tian et al, 2015].…”

Color change, ascorbic acid degradation kinetics, and rehydration behavior of kiwifruit as affected by different drying methods

“…In literature, most of the studies conducted on the drying of kiwi fruit includes only the HAD method and investigates the effect of HAD parameters (temperature, air velocity, relative humidity) or the sample properties (thickness, initial moisture content) on product quality (Chin, Siew, & Soon, 2015;Kaya, Aydın, & Kolayli, 2010;Mahjoorian et al, 2017;Mohammadi, Rafiee, Djomeh, & Keyhani, 2008). Ascorbic acid content of dried kiwifruit was determined by some authors (Chin et al, 2015;Kaya et al, 2010;Movagharnejad & Pouya, 2017;Orikasa et al, 2014;Tian et al, 2015). Kaya et al (2010) stated that increasing drying air temperature increased the degradation of vitamin C content of dried kiwifruit.…”