Effect of chlorogenic acid on spectral properties and stability of acylated and non-acylated cyanidin-3-O-glycosides.

Spectral characteristics and heat stability (90°C, 5h) of six isolated, structurally related cyanidin-3-O-glycosides from black carrot were investigated in aqueous solutions (pH 3.6 and 4.6) supplemented with chlorogenic acid (molar anthocyanin:co-pigment ratios 1:62.5-1:250). Chlorogenic acid supplementation generally increased absorbance of non-acylated anthocyanins by up to 97.9 and 122.9% at pH 3.6 and 4.6, respectively, being mainly attributed to the formation of intermolecular anthocyanin:co-pigment complexes. The effect significantly decreased when the chain length of the 3-O-linked non-acylated anthocyanins was increased from mono- to di- to triglycosyl moieties, possibly due to steric interferences of bound sugars and co-pigments. Intermolecular co-pigmentation was investigated for the first time for feruloylated and sinapoylated cyanidin-3-O-triglycosides. They exhibited weaker effects (10.8-16.0%) at pH 4.6, and no spectral response was observed at pH 3.6. Chlorogenic acid addition evoked weak enhancement of thermal pigment stability at pH 3.6, while it was highly detrimental for all anthocyanins at pH 4.6.

Anthocyanins from purple sweet potato (Ipomoea batatas (L.) Lam.) and their color modulation by the addition of phenolic acids and food-grade phenolic plant extracts.

Anthocyanin profiles and contents of three purple sweet potato provenances were investigated by HPLC-DAD-MSn. In contrast to widely uniform profiles, the contents of total (558-2477mg/100gDM) and individual anthocyanins varied widely. Furthermore, quantitative and qualitative effects of intermolecular co-pigmentation were studied by adding chlorogenic and rosmarinic acids, and food-grade phenolic apple and rosemary extracts at various dosages to a diluted purple sweet potato concentrate at pH 0.9, 2.6, 3.6, and 4.6. Addition of co-pigments generally increased pKH estimate-values of anthocyanins from 3.28 (without co-pigments) to up to 4.71, thus substantially broadening the pH range wherein colored forms prevail. The most pronounced hyperchromic shift by up to +50.5% at the absorption maximum was observed at pH 4.6. Simply by blending the co-pigments with purple sweet potato anthocyanins at pH-values ranging from 2.6 to 4.6, purplish-blue, light pink, magenta, brick-red, and intense red hues were accessible as expressed by CIE-L∗a∗b∗ color values.

Carotenoids, carotenoid esters, and anthocyanins of yellow-, orange-, and red-peeled cashew apples (Anacardium occidentale L.).

Pigment profiles of yellow-, orange-, and red-peeled cashew (Anacardium occidentale L.) apples were investigated. Among 15 identified carotenoids and carotenoid esters, ß-carotene, and ß-cryptoxanthin palmitate were the most abundant in peels and pulp of all samples. Total carotenoid concentrations in the pulp of yellow- and red-peeled cashew apples were low (0.69-0.73 mg/100g FW) compared to that of orange-peeled samples (2.2mg/100g FW). The color difference between the equally carotenoid-rich yellow and red colored samples indicated the presence of a further non-carotenoid pigment type in red peels. Among four detected anthocyanins, the major anthocyanin was unambiguously identified as 7-O-methylcyanidin 3-O-ß-D-galactopyranoside by NMR spectroscopy. Red and yellow peel color was chiefly determined by the presence and absence of anthocyanins, respectively, while the orange appearance of the peel was mainly caused by increased carotenoid concentrations. Thus, orange-peeled fruits represent a rich source of provitamin A (ca. 124 µg retinol-activity-equivalents/100g pulp, FW).

Effect of genuine non-anthocyanin phenolics and chlorogenic acid on color and stability of black carrot (Daucus carota ssp. sativus var. atrorubens Alef.) anthocyanins.

This work aimed at studying the color intensity and stability of black carrot anthocyanins as influenced by intermolecular co-pigmentation. For this purpose, purified anthocyanin solutions were supplemented with purified genuine black carrot phenolics, chlorogenic acid, and an aqueous phenolic-rich green coffee bean extract at various anthocyanin:co-pigment ratios (1:0-1:162; pH 3.6). The hyperchromic co-pigmentation effect depended on the concentration of added co-pigments, resulting in an absorbance increase of up to 22% at the absorption maximum. Anthocyanin stability during heating (90°C, 5h) was barely improved unless the concentrations of co-pigments exceeded those of their natural source. When adding co-pigments at ratios above 1:9.4, anthocyanin heat stability was significantly improved. As acylated anthocyanins were most stable, breeders might aim at increasing their content in the future, while breeding for high levels of colorless polyphenols may be unreachable. Nevertheless, we provided proof-of-concept for the successful color enhancement by the addition of a phenolic-rich green coffee bean extract, being useful for food-grade applications.

Chokeberry (Aronia melanocarpa (Michx.) Elliot) concentrate inhibits NF-κB and synergizes with selenium to inhibit the release of pro-inflammatory mediators in macrophages.

Black chokeberry has been known to play a protective role in human health due to its high polyphenolic content including anthocyanins and caffeic acid derivatives. In the present study, we first characterized the polyphenolic content of a commercial chokeberry concentrate and investigated its effect on LPS-induced NF-κB activation and release of pro-inflammatory mediators in macrophages in the presence or the absence of sodium selenite. Examination of the phytochemical profile of the juice concentrate revealed high content of polyphenols (3.3%), including anthocyanins, proanthocyanidins, phenolic acids, and flavonoids. Among them, cyanidin-3-O-galactoside and caffeoylquinic acids were identified as the major compounds. Data indicated that chokeberry concentrate inhibited both the release of TNFα, IL-6 and IL-8 in human peripheral monocytes and the activation of the NF-κB pathway in RAW 264.7 macrophage cells. Furthermore, chokeberry synergizes with sodium selenite to inhibit NF-κB activation, cytokine release and PGE2 synthesis. These findings suggest that selenium added to chokeberry juice enhances significantly its anti-inflammatory activity, thus revealing a sound approach in order to tune the use of traditional herbals by combining them with micronutrients.