2015 Volume 62 Issue 2 Pages 69-78
Purple sweet potato rich in acylated anthocyanin (YGM) pigments was used to develop a vinegar with a deep color and high functionality. The addition of purple sweet potato to the acetic acid fermentation process, together with seed vinegar and pure ethanol, was more effective than the use of a saccharification source, utilized previously. Furthermore, use of concentrated pigment extract instead of purple sweet potato provided a brewing method for ‘red vinegar’ exhibiting twofold higher YGM concentration. This red vinegar was expected to have high functionality since it contains acetic acid, purple sweet potato-derived components, and brewing ingredients. Isolation and structural determination of the brewing components resulted in the identification of new acylated polyphenols. A two-step purification method using an adsorption resin column was established for the large-scale preparation of the major component, 6-O-caffeoylsophorose (CS). A single oral administration of CS to maltose-loaded SD rats caused an effective anti-hyperglycemic effect via the acute inhibition of α-glucosidase in the small intestine. In addition, CS was found to be transported across Caco-2 monolayers by the monocarboxylate transporter. Absorbed CS may promote glucose uptake into skeletal muscle cells. Taken together, CS or the brewed vinegar developed in this study could serve as new functional foods and help prevent lifestyle-related diseases, for example by exhibiting an anti-diabetic effect.
