Enzymatic Release of Antioxidants for Human Low-Density Lipoprotein from Grape Pomace

Enzyme-assisted release of phenolic antioxidants from grape pomace from wine production was examined. The enzymes used were Grindamyl pectinase from Aspergillus niger and Celluclast from Trichoderma reesei. Total phenols released ranged from 820 to 6055 mg/L gallic acid equivalents (GAE) and varied in response to enzyme type, time of enzyme treatment, particle size of the pomace, and type of extraction solvent employed. The yield of total phenols was correlated to the degree of plant cell wall breakdown of grape pomace (r > 0.6, P < 0.01). Grindamyl pectinase catalyzed degradation of grape pomace polysaccharides (P < 0.001), whereas Celluclast did not. Reduction of the particle size of grape pomace to 125−250 μm increased the enzymatic polysaccharide hydrolysis and the recovery of phenols. The grape pomace extracts significantly retarded human low-density lipoprotein oxidation in vitro. When evaluated at 3.0 μM GAE, phenolic extracts of Grindamyl pectinase treated pomace of small particle size (125−250 μm) appeared to release more active antioxidant phenols than the other types of enzyme treatments tested (P < 0.05). Keywords: Pectinase; cellulase; phenols; plant cell wall degradation; LDL oxidation