Atmospheric pressure chemical ionization mass spectrometry of retro-carotenoids.

RATIONALE: The single and double bonds of the polyene chain of the studied retro-carotenoids are located at the neighboring positions compared to those of regular carotenoids. Our mass spectrometry approach targeted at facilitating the characterization of retro-carotenoids as their structural diversity in nature is not yet fully elucidated. Moreover, extended π-electron systems endow several retro-carotenoids with exceptional colors from golden-orange to vibrant red that stimulate the food industry's interest. METHODS: Atmospheric pressure chemical ionization-quadrupole time-of-flight-high-resolution mass spectrometry (APCI-QTOF-HRMS) experiments of the three structurally related retro-carotenoids rhodoxanthin, eschscholtzxanthone, and eschscholtzxanthin were performed to elucidate the formation of specific ion species compared to those of the common carotenoids lutein and zeaxanthin. Mass fragmentations of the aforementioned retro-carotenoids were unraveled using APCI-tandem mass spectrometry (MS/MS) in the negative and positive ion modes. RESULTS: Abundant in-source fragment ions [M + H - H2 O]+ of eschscholtzxanthin and eschscholtzxanthone were formed in the positive ion mode owing to the loss of water at the hydroxylated ε-rings. Eliminations of the ε-rings at the characteristic exocyclic double bonds at C-6,7 and C-6',7' were observed after the resonance-stabilized loss of water. Distinct product ions were yielded for all retro-carotenoids assessed because of the cleavage at their typical central single bond at C-15,15'. CONCLUSIONS: Detailed APCI-QTOF-HRMS analyses enabled a highly accurate detection of the most abundant ion species and respective signal intensity ratios of retro-carotenoids, facilitating their further screening and reliable identification in natural sources. Mass fragmentations of the studied retro-carotenoids were found to be substantially impacted by the extraordinary configuration of their polyene backbone.

From Sugar to Nutritional Products - Product Form Development.

The formulation of active ingredients into emulsion- and suspension-based delivery systems offers a wide range of opportunities to produce stable and highly bioavailable product forms for their later application in human and animal nutrition. Recent trends in product form development have focused on using renewable and naturally-derived raw materials to meet the increasing consumer demand on sustainable value chains and nutritional products with 'clean labelling'. Therefore, we reviewed chemical fundamentals and application examples of plant-derived protective hydrocolloids with highly potent emulsifying capacity, in particular, modified starches, pectin, and lignosulfonates, for the formulation of vitamins, carotenoids, and other active ingredients.

Carotenoid profiles of red- and yellow-colored arils of cultivars of Taxus baccata L. and Taxus × media Rehder.

The botanical delimitation of Taxus species and cultivars may be facilitated by characterizing the pigment profiles of their red- and yellow-fleshed arils. Therefore, we determined genuine carotenoid profiles of differently colored arils of seven defined cultivars of Taxus baccata L. and Taxus × media Rehder. In-depth HPLC-DAD-ESI/APCI-MSn analyses revealed the presence of 43 carotenoids. Exceptional retro-carotenoids dominated the profiles of all samples assessed. Rhodoxanthin (E/Z)-isomers were predominant in the red-colored arils, resulting in a rather unusual abundance of carotenoid isomers as expressed by ratios of up to 1.3:2.0:0.9 between (all-E)-, (6Z)-, and (6Z,6'Z)-rhodoxanthin, respectively. By contrast, the uncommon yellow arils of Taxus baccata L. 'Lutea' mainly contained eschscholtzxanthin (E/Z)-isomers and esters. Total carotenoid concentrations ranged from 17.00 to 58.78 µg/g fresh weight across all samples assessed. Highest total rhodoxanthin concentrations of 51.33 ± 0.46 µg/g fresh weight were obtained from the red arils of Taxus × media Rehder 'Hicksii'. Overall, Taxus arils represent a promising source of carotenoids and, in particular, of retro-carotenoids with exceptional molecular structures and extraordinary absorption properties.

The impact of (E/Z)-isomerization and aggregation on the color of rhodoxanthin formulations for food and beverages.

Rhodoxanthin is a scarcely explored carotenoid with an extraordinarily large chromophore and high potential to function as red pigment. We report broad ranges of color shades accessible with rhodoxanthin across an unprecedented wide range of (E/Z)-ratios by thermal (E/Z)-isomerization, lyotropic aggregation, and two different formulation techniques, covering shares of the (all-E)-configured isomer of 19-91%. At (E/Z)-ratios of 75 and 23%, rhodoxanthin (E/Z)-isomer mixtures in acetone revealed color hues (CIE-h°) ranging from 20-44° to 36-54°. Lyotropic aggregation of rhodoxanthin (E/Z)-isomer mixtures in acetone/water yielded red (CIE-h° = 29°) to purple (-7°) and red-orange (44°) to pink (9°) color hues at (all-E)-proportions of 73 and 20%, respectively. Red and purple color hues were produced by micronization using solvent-based emulsification (CIE-h° = 33-37°) and high-performance wet-milling (-6°). The presented technological strategies for formulating nature-identical rhodoxanthin into water-dispersible forms showed its potential as promising pigment for imparting red, pink, and purple color to foods and beverages.

Kinetic and Thermodynamic Study of the Thermally Induced (E/Z)-Isomerization of the retro-Carotenoid Rhodoxanthin.

The hitherto scarcely investigated retro-carotenoid rhodoxanthin possesses high potential for coloration in the food and beverage industry using technofunctional formulations prepared thereof. Hence, we studied (E/Z)-isomerization pathways of rhodoxanthin, including seven (E/Z)-isomers comprising (Z)-configured double bonds at unusual exocyclic and inner polyene chain positions. A mathematical approach was developed to deduce kinetic and thermodynamic parameters of six parallel equilibrium reactions interconnecting (all-E)-rhodoxanthin with mono-, di-, and tri-(Z)-isomers using multiresponse modeling. At 40-70 °C in ethyl acetate, reaction rate constants regarding the rotation from (all-E)- to (6Z)-rhodoxanthin were 11-14 times higher than those of the common (E/Z)-isomerization reaction at C-13,14 of the non-retro-structured carotenoid canthaxanthin. Moreover, the equilibrium reaction between (all-E)- and (6Z)-rhodoxanthin was strongly product favored as indicated by negative Gibbs energies (-1.6 to -2.2 kJ mol-1), which is unusual for carotenoids within the studied temperatures. Overall, this study provides novel insights into structure-related dependencies of (E/Z)-isomerization reaction kinetics and thermodynamics of polyenes.

HPLC-DAD-APCI/ESI-MSn analysis of carotenoids and α-tocopherol in Costa Rican Acrocomia aculeata fruits of varying maturity stages.

Carotenoids and tocopherols were characterised in the meso- and exocarp of wild-growing Costa Rican Acrocomia aculeata fruits. Comprehensive profiling of these lipophilic micronutrients in fruits of three varying maturity stages was conducted for the first time. A method for the simultaneous extraction and quantitation of carotenoids and α-tocopherol was developed and validated. Detailed HPLC-DAD-APCI/ESI-MSn analyses enabled the identification of α-tocopherol and 25 carotenoids. The latter comprised antheraxanthin, ß-carotene, lutein, luteoxanthin, neoxanthin, phytoene, phytofluene, violaxanthin, zeaxanthin, and several (Z)-isomers of the aforementioned compounds. Quantitation by HPLC-DAD/FLD revealed total carotenoid concentrations of 872±178 and 3075±407µg/100g fresh weight in the meso- and exocarp of fully ripe fruits, respectively. In both fruit fractions, progressing maturation resulted in the accumulation of phytoene, phytofluene, (all-E)-zeaxanthin, (all-E)-antheraxanthin, and (all-E)-violaxanthin. Carotenoid profiling was supported by multivariate data analysis. Carotenoid precursors and xanthophyll cycle pigments characterised Macauba fruits of full maturity.