Pycnoporus cinnabarinus laccases: an interesting tool for food or non-food applications

The effects of the addition of ferulic acid and ethanol in P. cinnabarinus ss3 culture medium in fermentor were compared in 15-L fermentor. In the presence of 30 g l(-1) ethanol, laccase activity (270,000 U/L1) was 3-fold higher as compared with ferulic acid-induced cultures, and 150-fold higher as compared with non-induced cultures, respectively. High-quality flax pulp was bleached in a totally-chlorine free (TCF) sequence using a laccase-mediator system constituted by laccase from Pycnoporus cinnabarinus and 1-hydroxybenzotriazole (HBT) as mediator. Up to 90% delignification and strong brightness increase were attained after the laccase-mediator treatment followed by H2O2 bleaching. This TCF sequence was further improved by applying H2O2 under pressurized O2. In this way, up to 82% ISO brightness was obtained (compared with 37% in the initial pulp and 60% in the peroxide-bleached control) as well as very low kappa number. A positive evaluation of the laccase has been also performed in a food application. The colour of a tea-based beverage was significantly improved by incubating an infusion of green tea with the Pycnoporus laccase.