Harvest date affects aronia juice polyphenols, sugars, and antioxidant activity, but not anthocyanin stability.

The goal of this work was to characterize how the date of harvest of 'Viking' aronia berry impacts juice pigmentation, sugars, and antioxidant activity. Aronia juice anthocyanins doubled at the fifth week of the harvest, and then decreased. Juice hydroxycinnamic acids decreased 33% from the first week, while proanthocyanidins increased 64%. Juice fructose and glucose plateaued at the fourth week, but sorbitol increased 40% to the seventh harvest week. Aronia juice pigment density increased due to anthocyanin concentration, and polyphenol copigmentation did not significantly affect juice pigmentation. Anthocyanin stability at pH 4.5 was similar between weeks. However, addition of quercetin, sorbitol, and chlorogenic acid to aronia anthocyanins inhibited pH-induced loss of color. Sorbitol and citric acid may be partially responsible for weekly variation in antioxidant activity, as addition of these agents inhibited DPPH scavenging 13-30%. Thus, aronia polyphenol and non-polyphenol components contribute to its colorant and antioxidant functionality.

Underutilized chokeberry (Aronia melanocarpa, Aronia arbutifolia, Aronia prunifolia) accessions are rich sources of anthocyanins, flavonoids, hydroxycinnamic acids, and proanthocyanidins.

Polyphenols from underutilized black, purple, and red aronia (Aronia melanocarpa, Aronia prunifolia, and Aronia arbutifolia) and 'Viking' (Aronia mitschurinii) berries were characterized. Anthocyanin and nonanthocyanin flavonoids were quantitated by UHPLC-DAD-MS and proanthocyanidins by normal-phase HPLC. On a dry weight basis, anthocyanins were mainly cyanidin-3-galactoside, highest in black aronia (3.4-14.8 mg/g) and lowest in red aronia (0.5-0.8 mg/g) as cyandin-3-galactoside equivalents. Berries from 'Viking' and the red accession UC021 had substantially more proanthocyanidins than the other accessions, with 3.3 and 3.8 mg catechin equiv/g, respectively. Chlorogenic acids and quercetin glycosides were most abundant in purple UC047 berries, at 17.3 and 1.3 mg/g, respectively. In contrast to anthocyanin content, total phenol values were highest in berries from red and purple accessions and attributed to phenolic acid and proanthocyanin content. Thus, red, purple, and black aronia berries are rich sources of polyphenols with various levels of polyphenol classes.

Aronia melanocarpa (chokeberry) polyphenol-rich extract improves antioxidant function and reduces total plasma cholesterol in apolipoprotein E knockout mice.

We hypothesized that a polyphenol-rich chokeberry extract (CBE) would modulate hepatic lipid metabolism and improve antioxidant function in apolipoprotein E knockout (apoE(-/-)) mice. ApoE(-/-) mice were fed diets containing 15% fat with 0.2% cholesterol alone or supplemented with 0.005% or 0.05% CBE for 4 weeks. CBE polyphenol content was determined by the total phenols, 4-dimethylaminocinnamaldehyde, and ultra high-performance liquid chromatography-mass spectrometry methods. The 0.05% CBE diet provided mice with mean daily doses of 1.2 mg gallic acid equivalents of total phenols, 0.19 mg anthocyanins, 0.17 mg phenolic acids, 0.06 mg proanthocyanidins (as catechin-equivalents), and 0.02 mg flavonols. The 0.05% CBE group had 12% less plasma total cholesterol concentrations than the control. Despite the hypocholesterolemic effect of CBE, hepatic mRNA levels of low-density lipoprotein receptor, hydroxyl-3-methylglutaryl coenzyme A reductase and cholesterol 7α-hydroxylase in CBE-fed mice were not significantly different from controls. Dietary CBE did not alter hepatic lipid content or the hepatic expression of genes involved in lipogenesis and fatty acid ß-oxidation such as fatty acid synthase, carnitine palmitoyltransferase 1 and acyl-CoA oxidase. Plasma paraoxonase and catalase activities were significantly increased in mice fed 0.05% CBE. Both CBE diets increased hepatic glutathione peroxidase (GPx) activity but the 0.05% CBE group had 24% less proximal intestine GPx activity relative to controls. Thus, dietary CBE lowered total cholesterol and improved plasma and hepatic antioxidant function at nutritionally-relevant doses in apoE(-/-) mice. Furthermore, the CBE cholesterol-lowering mechanism in apoE(-/-) mice was independent of hepatic expression of genes involved in cholesterol metabolism.