Non-lethal secondary product release from transformed root cultures of Beta vulgaris

Transformed root tissue of Beta vulgaris (Detroit Dark Red) was permeabilized to stimulate the release of intracellularly stored betanin without adverse affects on tissue viability as measured by biomass accumulation. Product release of up to 15% (w/w) was achieved by heat treatment at 42 degrees C for 45 min with minimal effect on viability. Higher levels of product release were obtained with increasing temperature and exposure, but at the expense of viability. Viability was measured by comparing dry weight increases of permeabilized tissue 3 days after treatment vs non-permeabilized tissue over the same time interval. Recovery of heat-treated tissue was improved by addition of CaCl2 (20 mM for 10 min) post-heat treatment. Betanin release up to 15% was also obtained at ambient temperature (25 degrees C) by addition of up to 20 mM (NH4)2SO4 in the presence of 1 mM ethylenediaminetetraacetic acid (EDTA).