Food-Grade Chemical and Biological Agents Permeabilize Red Beet Hairy Roots, Assisting the Release of Betalaines

Abstract

Hairy root cultures of red beet, Beta vulgarisL., were permeabilized under the functions of food‐grade chemical and biological agents cetyl trimethylammonium bromide (CTAB), Triton X‐100, Tween‐80, Lactobacillushelveticus, Saccharomycescereviseae, and Candidautilis, as well as cell fractions of L. helveticus, for the recovery of betalaines with or without oxygen stress. Tween‐80 (0.15%), Triton X‐100 (0.2%), and CTAB (0.05%), in combination with oxygen stress, released 45%, 70%, and 90% pigment into the medium, respectively, with significantly lesser levels in agitated cultures receiving similar treatments. The release was rapid (1 h) in CTAB treatment with a much slower release in Tween‐80. CTAB (0.002%) was found to be also useful in effluxing betalaines (80%) from hairy roots grown in a bubble column reactor. Viability of permeabilized hairy roots, tested on agar medium, was not affected by any level of CTAB treatment and was significantly retarded at higher levels of Triton X‐100 and Tween‐80. An altogether new approach of pigment release using biological agents such as live cells of food‐grade microbes was used where C.utilis, L. helveticus, and S. cereviseaereleased 60%, 85%, and 54% betalaines, respectively, in 24 h, though lower level treatments also released similar levels of pigment by 48 h. Dried whole cell powder of L. helveticus, its total insoluble carbohydrate, and free lipid fractions released 10%, 0%, and 85% pigment, respectively. An extended study with a bubble column reactor using the free lipid fraction of L. helveticus showed 50% and 84% pigment release in 8 and 12 h, respectively, exhibiting good viability when plated on agar medium. Even in the bioreactor, replenishment of medium 8 h after treatment with free lipid of L. helveticus allowed regrowth of hairy roots. The high level of pigment release recorded here, using CTAB or lipid of L. helveticus, appears useful for developing processes for in situ recovery of betalaines. The live microbes, applicable only for batch cultures, are expected to impart improved sensory/nutraceutical effects to the recovered pigment and hence may add value to the product receiving the red beet pigment thus produced.