Immobilization of Aspergillus ficuum tannase in calcium alginate beads and its application in the treatment of boldo (Peumus boldus) tea

• Published in: International journal of biological macromolecules 2018-10, Vol.118, p.1989-1994
• Main Authors: de Lima, Juliana Silva, Cabrera, Mariana Paola, Casazza, Alessandro Alberto, da Silva, Milena Fernandes, Perego, Patrizia, de Carvalho, Luiz Bezerra, Converti, Attilio
• Format: Article
• Language: English
• Subjects: Aspergillus ficuum; Boldo tea; Calcium alginate beads; Immobilization; Tannase
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2018.07.084

Tannase (tannin acyl hydrolase, E.C. 3.1.1.20) is an enzyme that catalyzes the hydrolysis of ester and depside linkages in hydrolysable tannins such as tannic acid, releasing gallic acid and glucose. It has several commercial applications in food industry, among which are gallic acid production, reduction of tannin content in fruit juices, and preparation of instantaneous tea. In this study we immobilized Aspergillus ficuum tannase in calcium alginate beads and then used it to treat boldo (Peumus boldus) tea. Such a technique allowed entrapping tannase with a 75% efficiency and appreciably increasing its thermal and pH stability compared with the free enzyme. Storage stability and reuse of the immobilized enzyme were very promising, in that about 60% of starting enzyme activity was retained after bead storage for 90 days at 4 °C or after six cycles of use. Boldo tea treatment with immobilized tannase for 120 min at 40 °C led to 31 and 60% removals of tannins and epigallocatechin gallate, an increase of about two orders of magnitude in gallic acid content, 56 and 109% increases in total flavonoids and epigallocatechin contents, a 42.8% increase in antioxidant activity and significant enhancements of tea color, clarity and pH. •Aspergillus ficuum tannase can be effectively entrapped in calcium alginate beads.•Tannase-containing beads succeed in the treatment of boldo (Peumus boldus) tea.•Tannase-containing beads are stable for a long time under shelf storage conditions.•The treatment improves the boldo tea quality in terms of clarity and color.•Tannin content of tea decreases, while antioxidant power and flavonoid content grow.