Covalent anthocyanin-flavonol complexes from the violet-blue flowers of Allium 'Blue Perfume'.

Three covalent anthocyanin-flavonol complexes (pigments 1-3) were extracted from the violet-blue flower of Allium 'Blue Perfume' with 5% acetic acid-MeOH solution, in which pigment 1 was the dominant pigment. These three pigments are based on delphinidin 3-glucoside as their deacylanthocyanin and were acylated with malonyl kaempferol 3-sophoroside-7-glucosiduronic acid or malonyl-kaempferol 3-p-coumaroyl-tetraglycoside-7-glucosiduronic acid in addition to acylation with acetic acid. By spectroscopic and chemical methods, the structures of these three pigments 1-3 were determined to be: pigment 1, (6(I)-O-(delphinidin 3-O-(3(I)-O-(acetyl)-ß-glucopyranoside(I))))(2(VI)-O-(kaempferol 3-O-(2(II)-O-(3(III)-O-(ß-glucopyranosyl(V))-ß-glucopyranosyl(III))-4(II)-O-(trans-p-coumaroyl)-6(II)-O-(ß-glucopyranosyl(IV))-ß-glucopyranoside(II))-7-O-(ß-glucosiduronic acid(VI)))) malonate; pigment 2, (6(I)-O-(delphinidin 3-O-(3(I)-O-(acetyl)-ß-glucopyranoside(I))))(2(VI)-O-(kaempferol 3-O-(2(II)-O-ß-glucopyranosyl(III))-ß-glucopyranoside(II))-7-O-(ß-glucosiduronic acid(VI)))); and pigment 3, (6(I)-O-(delphinidin 3-O-(3(I)-O-(acetyl)-ß-glucopyranoside(I))))(2(VI)-O-(kaempferol 3-O-(2(II)-O-(3(III)-O-(ß-glucopyranosyl(V))-ß-glucopyranosyl(III))-4(II)-O-(cis-p-coumaroyl)-6(II)-O-(ß-glucopyranosyl(IV))-ß-glucopyranoside(II))-7-O-(ß-glucosiduronic acid(VI)))) malonate. The structure of pigment 2 was analogous to that of a covalent anthocyanin-flavonol complex isolated from Allium schoenoprasum where delphinidin was observed in place of cyanidin. The three covalent anthocyanin-flavonol complexes (pigment 1-3) had a stable violet-blue color with three characteristic absorption maxima at 540, 547 and 618nm in pH 5-6 buffer solution. From circular dichroism measurement of pigment 1 in the pH 6.0 buffer solution, cotton effects were observed at 533 (+), 604 (-) and 638 (-) nm. Based on these results, these covalent anthocyanin-flavonol complexes were presumed to maintain a stable intramolecular association between delphinidin and kaempferol units closely related to that observed between anthocyanin and hydroxycinnamic acid residues in polyacylated anthocyanins. Additionally, an acylated kaempferol glycoside (pigment 4) was isolated from the same flower extract, and its structure was determined to be kaempferol 3-O-sophoroside-7-O-(3-O-(malonyl)-ß-glucopyranosiduronic acid).

Effects of the amino-carbonyl reaction of ribose and glycine on the formation of the 2(or 5)-ethyl-5(or 2)-methyl-4-hydroxy-3(2H)-furanone aroma component specific to miso by halo-tolerant yeast.

The formation of HEMF[2(or 5)-ethyl-5(or 2)-methyl-4-hydroxy-3(2H)-furanone], the aroma component specific to miso and soy sauce, was promoted by cultivating the halo-tolerant yeast, Zygosaccharomyces rouxii, in a medium including the amino-carbonyl reaction products based on ribose and glycine. The glucose concentration in the medium influenced the HEMF formation by Z. rouxii.