Optimization of a process for enzyme-assisted pigment extraction from grape (Vitis vinifera L.) pomace.

Publication Type

Journal contribution (peer reviewed)

Authors

MAIER, T., GÖPPERT, A., KAMMERER, D.R., SCHIEBER, A., CARLE, R.,

Year of publication

2008

Published in

European Food Research and Technology

Band/Volume

227/

Series/labeling

DOI: 10.1007/s00217-007-0720-y

Page (from - to)

267-275

A process for enzyme-assisted extraction of polyphenols from grape pomace was developed on laboratory and pilot-plant scale. After resuspending grape pomace in water, the skins were ground and the resulting mash was pasteurized to inactivate the deteriorative enzymes responsible for polyphenol degradation, and then pre-extracted with hot water. Subsequently, cell wall polysaccharides were hydrolyzed. The extract was separated from the solid residue by pressing, and finally spray dried. Before scaling-up, enzymatic hydrolysis was optimized on laboratory scale using a D-optimal design and analyzed by response surface methodology. A mixture of pectinolytic and cellulolytic enzyme preparations (ratio 2:1) yielded the highest amounts of phenolic compounds after 2 h of treatment, applying a dosage of 4500 mg/kg (based on dry matter) at T= 40 °C and pH 4.0. Aqueous pre-extraction of the pomace followed by enzymatic treatment resulted in significantly improved extraction yields reaching 91.9%, 92.4% and 63.6% for phenolic acids, non-anthocyanin flavonoids and anthocyanins, respectively. As the yields obtained were comparable to those from sulfite-assisted extraction, this process can be considered a suitable alternative to the application of sulfite.