Abdolmajid Maskooki; Mohammad Naghi Eshtiaghi
Abstract
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, ...
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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.
Keywords: Pulse electric fields, Mass transfer, Sugar beet, Brix, Electrical conductivity
Abdolmajid Maskooki; Mohammad Naghi Eshtiaghi
Abstract
The effects of pulsed electric field (PEF) on the cell disintegration of sugar beet were studied. Field strength (0.5kV/cm to 6kV/cm), pulse number (1 to 100 pulses) and capacity of capacitors (0.5 F to 32 F) were evaluated on degree of cell disintegration and consumed energy in PEF treatment. ...
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The effects of pulsed electric field (PEF) on the cell disintegration of sugar beet were studied. Field strength (0.5kV/cm to 6kV/cm), pulse number (1 to 100 pulses) and capacity of capacitors (0.5 F to 32 F) were evaluated on degree of cell disintegration and consumed energy in PEF treatment. The field conditions of 1 and 2 kV/cm, 8 F with 20 and 10 pulses respectively disintegrated the cell membrane in less than 1 minute. The most important parameters during cell permeabilization were the total energy input followed by field strength. At energy input of 3.2 kJ/kg, the higher the field strength resulted the higher cell permeabilization. Mass transfer with determination of sugar and ion leaching for PEF pretreated sugar beets at room temperature were compared to moderate and high heat treatment (50, 75 and 80C, 15minutes). Comparison between PEF pretreatment and conventional thermal cell disintegration (average 75C) method showed that high values of sugar may extracted after PEF pretreatment (2kV/cm, 8µF) at ambient temperature while 75C or more with long time thermal duration is needed to achieve the same extracted sugar. In addition, the energy consumption for thermal treatment is approximately 20 times more than PEF pretreatment. Optimization of field condition (Field strength, capacity of condensers, and number of pulses) as well as treatment chamber conditions are very important factors to achieve high yield of sugar from sugar beet when using PEF.
Keywords: Nonthermal, Pulse electric fields, Sugar beet, Cell disintegration
