Rapid, extensive extraction of polyphenols from red grapes
Special Symposium - Innovations in Food Technology (LMC Congress)
White BioTech & Related Processes (Food-2b)
Keywords: phenolics, grapes, quality
Assessment of the phenolic content of red grapes is an important prerequisite for understanding how grape phenols impact wine quality. In the search for a rapid and robust extraction method we have investigated the influence of selected factors on extraction efficiency of phenols from eight different red wine grape cultivars. The effects of solvent contact time, extraction temperature, solvent levels of ethanol and hydrochloric acid on the extraction of total phenols and anthocyanins were investigated in a series of statistically designed factorial experiments. The results were bench-marked versus the “total” content as measured by a modified, 1 hour “total” extraction protocol and the data were expressed as relative extraction degrees. Both extraction temperature and solvent levels of ethanol and hydrochloric acid were found to have highly significant effects on the extraction of both total phenols and anthocyanins. By applying optimized extraction conditions: 50 % v/v acidified aqueous ethanol (0.1 M HCl) and 1:1 solvent:grape v/w ratio at 40 ºC, followed by sample neutralization and workup we found that it was possible to extract an average of 82.1 % total phenols and 91.5 % of the anthocyanins from the grapes with only five minutes of solvent contact time.
Presented Wednesday 19, 17:15 to 17:20, in session White BioTech & Related Processes (Food-2b).
