comparison of pulse electric field and thermal processing on mass transfer in sugar extraction from sugar beet

the effect of pulse electric field on mass transfer in sugar beet cossettes with different thicknesses were investigated and compared with traditional thermal processing. two kinds of sugar beet cossettes 3±0.5 cm and 2±0.5 thicknesses with 3–5 cm long subjected to pulse electric field (3kv, 8 µf, and 20 pulse) and compared with heat treated samples (80ºc for15 minutes) as conventional thermal processing. all treated samples were pressed at 20 bar (2mpa) using laboratory press. brix, electrical conductivity as mass transfer index, yield and drying rate of pulp for each treatment were evaluated. further to statistical analysis, the results showed that the brix and electrical conductivity as well as juice yield in pef treated samples especially in thin cossettes were two times higher than thermal treated samples. the majority of juice extracted in the first step of pressing process. in addition, the drying rate of pulp amount in pef treated samples was significantly higher than thermal treated one. this phenomenon can be due to keeping of physical structure of cossettes and increasing of porosities of pef treated beet cells versus decomposed cell structure and lump formation which led to prevent the moisture release in thermal treated samples.