Phenolic antioxidants extraction from raspberry wastes assisted by-enzymes

Liza Laroze¹ · Carmen Soto² · María Elvira Zúñiga*^{1, 2}

¹Escuela de Ingeniería Bioquímica, Facultad de Ingeniería, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
²Centro Regional de Estudios en Alimentos Saludables, Valparaíso, Chile

*Corresponding author: mzuniga@ucv.cl

Financial support: Fondecyt Project 1070258; Mecesup UCV0206; CREAS-PUCV.

Keywords: antioxidant activity, enzymatic extraction, phenolic compounds.

The effect of enzymatic hydrolysis on phenolic antioxidant extraction was studied in raspberry solid wastes. This by-product possesses high content of crude fiber (60%) and low values of protein, oil and ash. Raspberry fiber composition suggests that biocatalysts with cellulase, hemicellulase and pectinase activities would be useful for carrying out an enzymatically assisted antioxidant extraction. Hydro-alcoholic extraction was done using different commercial enzymes. Total phenol content and antioxidant activity of enzyme-hydrolyzed residue extracts were measured and compared with those obtained without enzyme application.All biocatalysts evaluated increased soluble solids in comparison to the non-enzymatic control. Among them, Grindamyl and Maxoliva offered the best recovery of polyphenols. Enzymatic assisted extraction with an hydro-ethanolic mixture (75:25, v/v) during 18 hrs at 50°C increased phenolic content up to 35% and antioxidant capacity around 50%, 15% and 30% according to 2,2-diphenyl-1-picrylhydrazyl = 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl) (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) methods, respectively. Use of a higher enzyme concentration significantly improved extraction of phenolic antioxidants.