Tartaric and citric acid solutions were used to extract anthocyanins from fresh grape skins, in a non continuous process. The type of solvent and concentration were significant factors in the extraction operation, and tartaric acid was more efficient than citric acid in the extraction yield. Comparative trials were conducted using sulphur dioxide and acidified ethanol as solvents. The extraction yields using the optimal tar taric acid solution differed slightly from those obtained with acidified ethanol but were higher than those obtained with sulphur dioxide. Total amounts of polyphenols, proanthocyanidins and flavans were determined in the extracts obtained from the tartaric acid solutions. Solvent concentration was not a significant factor for flavan extraction yield but was highly significant for the extraction of the other compounds. The stability of the anthocyanins was evaluated at four different storage temperatures and atmospheric conditions. The combined effects of low pH of the extract (2.4), low temperature (2.0degreesC) and modified atmosphere (N-2) provided a long shelf-life. Based on the results, a 0.75% tartaric acid solution is recommended for anthocyanin extraction from fresh grape skin, and could substitute the widely used sulphur dioxide.
|Titolo:||A METHOD FOR ANTHOCYANIN EXTRACTION FROM FRESH GRAPE SKIN|
|Data di pubblicazione:||2003|
|Appare nelle tipologie:||1.1 Articolo in rivista|