Comparison of betalain extraction from beet (beta vulgaris) by low DC electrical field versus cryogenic freezing

A low DC electrical field (40 V/cm) applied to beet tissue as a novel method for extracting the naturally occurring betalain pigments removed soluble solids, minerals and pigment with almost no alteration of the gross textural properties of the tissue. Scanning electron micrographs revealed minor changes in the surface of the electrically treated tissue versus major changes in the tissue after freeze-thaw treatment. Cryogenic freezing (∼ 20 s) and thawing (one cycle) of the same tissue induced considerable damage, as evidenced by reduced values of stress at failure and loss of the tissue's elastic properties. Intact and DC-electrically treated tissue specimens had the same stress at failure (∼ 1500 kPa) and the same degree of elasticity (∼ 30%), in contrast to the tissue that passed throughfreeze-thawing (∼ 14%) and lost its elastic textural properties. Electrical extraction, which can be applied to thinly cut tissue, has a major advantage over other methods since the tissue remains almost intact, and thus can be used for other commercial applications, such as baking and filling.