| 摘要 |
Extraction of purified plant anthocyanin colors particularly from dark grapes by treating impure materials to insure discrete monomeric anthocyanin molecules in solution and then passing the solution through ultrafiltration membranes to retain soluble and/or cloudy macromolecular, e.g., colloidal, impurities upstream that produce, an aging, haze and sediments, and pass the monomeric anthocyanins downstream for further concentration as liquid or powder to give a stable color concentrate that can be used as a color additive. For example, fruit solids may be treated with sulfur dioxide solutions to ionize, decolor and insure the monomeric state of the pigment molecules (change from anthocyanins to chromon 2-and 4-sulfonates), ultrafiltering the solution to pass the anthocyanins downstream while retaining upstream the macromolecular components such as pectins, tannins, proteins, complexes thereof, etc., optionally stripping the sulfur dioxide from the ultrafiltered solution to regenerate the original anthocyanins from the chromen sulfonates, and thereafter concentrating said anthocyanins by evaporation to a highly concentrated liquid from which unstable pigments with acyl groups in the molecule may optionally be removed by controlled precipitation at reduced temperatures. Alternatively, the liquid with or without the controlled precipitation may be further concentrated to powder. |
