Open AccessFrequency, moisture content, and temperature dependent dielectric properties of potato starch related to drying with radio-frequency/microwave energy
Author(s) -
Zhuozhuo Zhu,
Wenchuan Guo
Publication year - 2017
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/s41598-017-09197-y
Subject(s) - water content , materials science , moisture , dielectric , microwave , radio frequency , starch , composite material , potato starch , analytical chemistry (journal) , food science , chemistry , electrical engineering , optoelectronics , chromatography , physics , geotechnical engineering , quantum mechanics , engineering
To develop advanced drying methods using radio-frequency (RF) or microwave (MW) energy, dielectric properties of potato starch were determined using an open-ended coaxial-line probe and network analyzer at frequencies between 20 and 4,500 MHz, moisture contents between 15.1% and 43.1% wet basis (w.b.), and temperatures between 25 and 75 °C. The results showed that both dielectric constant ( ε ′) and loss factor ( ε ″) were dependent on frequency, moisture content, and temperature. ε ′ decreased with increasing frequency at a given moisture content or temperature. At low moisture contents (≤25.4% w.b.) or low temperatures (≤45 °C), ε ″ increased with increasing frequency. However, ε ″ changed from decrease to increase with increasing frequency at high moisture contents or temperatures. At low temperatures (25–35 °C), both ε ′ and ε ″ increased with increasing moisture content. At low moisture contents (15.1–19.5% w.b.), they increased with increasing temperature. The change trends of ε ′ and ε ″ were different and dependent on temperature and moisture content at their high levels. The penetration depth ( d p ) decreased with increasing frequency. RF treatments may provide potential large-scale industrial drying application for potato starch. This research offers useful information on dielectric properties of potato starch related to drying with electromagnetic energy.