Title:Increased Content of Free Phenolic Compounds and Antioxidant Activity of Grape Pomace Cultivated with Three Different β-glucosidase Fungi Producers
VOLUME: 11 ISSUE: 2
Author(s):Natália G. Graebin, Plinho F. Hertz and Marco A. Z. Ayub
Affiliation:Biotechnology & Biochemical Engineering Laboratory (BiotecLab), Federal University of Rio Grande do Sul, Av. Bento Gonçalves, 9500, P.O. Box 15090, ZC 91501-970, Porto Alegre, RS, Brazil.
Keywords:β-glucosidase activity, bioactive compounds, grape pomace, phenolic glycosides, phytochemicals, solid-state cultivation.
Abstract:In this research, we tried to recover the antioxidant activities of grape pomace by means of using solid-state
cultivation (SSC) of Aspergillus niger BLAn1, Phanerochaete chrysosporium BLPc1, and Penicillium sp. BLPen1, three
GRAS strains of fungi. We measured the enzymatic activities of β-glucosidase, responsible for liberating the aglycone
forms of the phenolic compounds, as well as their total content. The highest β-glucosidase activities were approximately
17.2, 8.3, and 13.5 U · g-1 pomace for the 3 strains, respectively. The enzyme activity was considerably reduced with
moisture-saturated air injection in the system. The total phenolic content obtained were 21.15, 12.13, and 10.08 mg GAE
(Acid galic equivalent) · g-1 pomace, whereas the highest antioxidant activities released were 16.30, 11.35, and 10.57
mmol TEAC (Trolox equivalent antioxidant capacity) · g-1 pomace (by DPPH assay), and 158.61, 104.68, and 102.55
mmol TEAC · g-1 pomace (by ABTS assay), for BLAn1, BLPc1, and BLPen1, respectively. These results suggest that the
enzyme hydrolysis of phenolic glycosides leads to increased concentrations of free phenolic compounds, enhancing radical-
scavenging potential of pomace.
