Developing Hot Air-Assisted Radio Frequency Drying for In-shell Macadamia Nuts

Developing hot air-assisted radio frequency drying for in-shell walnuts

“…Finally, the sample temperature began to decline slowly due to reduced RF power absorbed by the walnut samples with the reduced MC. Similar trends were also observed by Wang et al (2014b) who used HARF drying for in-shell macadamia nuts. To obtain the required drying rate and avoid nut quality degradation, a process that combined an electrode gap of 18.0 cm with 50 °C hot air was selected for further drying tests.…”

“…In addition, with the increase of the drying time, the drying rate was gradually reduced due to the continuous moisture loss in walnut samples. A similar result was found in RF drying of in-shell almonds and macadamia nuts (Gao et al, 2010;Wang et al, 2014b).…”

“…5b) was faster when compared to HA drying alone (Fig. 6), since a positive temperature gradient remained due to RF heating and thus the vapour pressure gradient from the sample centre towards the surface enhanced the drying process (Feng et al, 2001;Wang et al, 2014b).…”

Validation of top electrode voltage in free-running oscillator radio frequency systems with different moisture content soybeans

“…Two types of RF systems, including 50 U and free-running oscillator, are widely used for laboratory researches and industrial applications. Since 50 U units are expensive, the free-running oscillator RF system has been widely applied for thawing (Farag, Lyng, Morgan, & Cronin, 2008, post-baking (Koral, 2004;Koray, Cos ‚ kun, Kocada glı, & G€ okmen, 2012), disinfestation (Lagunas-Solar et al, 2007;Shrestha & Baik, 2013;Wang, Monzon, Johnson, Mitcham, & Tang, 2007a, 2007bWang, Tiwari, Jiao, Johnson, & Tang, 2010), drying (Lee, Li, Zhao, & Park, 2010;Marshall & Metaxas, 1999;Wang, Zhang, et al 2013) and pasteurisation (Gao, Tang, Villa-Rojas, Wang, & Wang, 2011;Kim, Sagong, Choi, Ryu, & Kang, 2012). However, the major challenges for commercial RF applications are non-uniform and run-away heating, such as overheating in corners and edges (Fu, 2004;Tiwari, Wang, Tang, & Birla, 2011;Uyar, Erdogdu, & Marra, 2014;Wang et al, 2010;Wang, Tang, Johnson, & Cavalieri, 2013).…”

Dielectric properties of chili powder in the development of radio frequency and microwave pasteurisation

“…Most water was bounded by protein and fat. [31] With the increase of moisture content, single bound water became into muti-layer combined water or free water, and more free water could be used to dissolve ions. Similar trend of moisture-dependent dielectric properties of chili powder were also observed at other temperatures, densities, and frequencies.…”