Alkaline Pressing of Electroporated Sugar Beet Tissue: Process Behavior and Qualitative Characteristics of Raw Juice

In this study, an alternative sugar beet processing method using alkaline pressing of electroporated cossettes was investigated. The cossettes were first treated by pulsed electric fields at ambient temperature (T = 12 °C) with a strength of E = 600 V/cm for tPEF = 10 ms. The electroporated cossettes were then subjected to a double pressing with intermediate lime impregnation. The lime quantity used was varied from 0 to 1 % (g CaO/100 g fresh cossettes). Liming of electroporated cossettes enhances the second pressing kinetics and improves the quality of raw juice. With lime addition in quantity of 0.6 % (g CaO/100 g fresh cossettes), the juice yield was increased by 12 %, the juice purity was higher (93.61 vs 93.07 %), the juice was less colored (2938 vs 4875 IU), and contained less colloids (1.96 vs 2.75 g/L) and proteins (197 vs 261 mg/L) comparing to the juice obtained from electroporated but nonlimed cossettes. The dryness of pulp was increased from 25.72 % without liming to 38.5 % using the optimal lime quantity. Results also suggest that a first pressing of 20 % was sufficient to impregnate the optimal lime quantity before the second pressing. The maximal juice yield estimated from the empirical compression model attained about 90 % under 15 bar.