Characterisation of acylated anthocyanins from red cabbage, purple sweet potato, and Tradescantia pallida leaves as natural food colourants by HPLC-DAD-ESI(+)-QTOF-MS/MS and ESI(+)-MSn analysis.

Anthocyanins in red cabbage, sweet potato, and Tradescantia pallida leaves were characterised. A total of 18 non-, mono-, and diacylated cyanidins was identified in red cabbage by high performance liquid chromatography-diode array detection coupled to high-resolution and multi-stage mass spectrometry. Sweet potato leaves contained 16 different cyanidin- and peonidin glycosides being predominantly mono- and diacylated. In T. pallida leaves, the tetra-acylated anthocyanin tradescantin prevailed. The large proportion of acylated anthocyanins resulted in a superior thermal stability during heating of aqueous model solutions (pH 3.0) coloured with red cabbage and purple sweet potato extracts as compared to that of a commercial Hibiscus-based food dye. However, their stability was still outperformed by that of the most stable Tradescantia extract. Comparing vis spectra from pH 1-10, the latter had an additional, uncommon absorption maximum at approx. 585 nm at slightly acidic to neutral pH values, yielding intensely red to purple colours.

Vitamin E and carotenoid profiles in leaves, stems, petioles and flowers of stinging nettle (Urtica leptophylla Kunth) from Costa Rica.

BACKGROUND: Local leafy vegetables are gaining attention as affordable sources of micronutrients, including vitamins, pro-vitamin carotenoids and other bioactive compounds. Stinging nettles (Urtica spp.) are used as source of fibers, herbal medicine and food. However, despite the relatively wide geographical spread of Urtica leptophylla on the American continent, little is known about its content of vitamin E congeners and carotenoids. We therefore investigated the particular nutritional potential of different plant structures of wild Costa Rican U. leptophylla by focusing on their vitamin E and carotenoid profiles. RESULTS: Young, mature and herbivore-damaged leaves, flowers, stems and petioles were collected and freeze-dried. Vitamin E and carotenoids were determined by high-performance liquid chromatography after liquid/liquid extraction with hexane. α-Tocopherol was the major vitamin E congener in all structures. Flowers had a high content of γ-tocopherol. Herbivore-damaged leaves had higher contents of vitamin E than undamaged leaves. Lutein was the major and ß-carotene the second most abundant carotenoid in U. leptophylla. No differences in carotenoid profiles were observed between damaged and undamaged leaves. CONCLUSION: The leaves of U. leptophylla had the highest nutritional value of all analyzed structures; therefore, they might represent a potential source of α-tocopherol, lutein and ß-carotene. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Influence of surface roughness on the spectroscopic characterization of jadeite and greenstones archaeological artifacts: The axe-god pendants case study.

Spectroscopic techniques are commonly used for the non-invasive characterization of the molecular and elemental composition of greenstone archaeological artifacts. The surface topography of these artifacts is greatly influenced by the crafting and polishing techniques employed in their making. However, no study of the effect of roughness on spectra has ever been reported for greenstones. Here we show that infrared, Raman and X-ray fluorescence spectra are strongly influenced by the sample's surface roughness. Spectral changes were seen in both geological (45 jadeite and green stone samples) and archaeological artifacts (12 axe-God pendants); in every case, the variations were more prominent in samples with higher arithmetic average height values. The results show that these changes can affect the interpretation of the spectroscopic data and limit the efficacy of statistical analysis. Consequently, any spectroscopic characterization of this type of samples should be performed preferably in areas with lower values of roughness parameters. Overall, FT-IR appears to be the most advantageous technique to distinguish the differences in mineral composition of this type of samples during in situ studies; its performance was evaluated with an innovative statistical analysis that treats the spectra as functional data. Additionally, the results suggest that confocal Raman spectroscopy is an ideal complementary technique that enhances mineralogical characterization, nevertheless its applicability is limited to laboratory settings.

Carotenoids and xanthophyll esters of yellow and red nance fruits (Byrsonima crassifolia (L.) Kunth) from Costa Rica.

Carotenoid profiles, by means of HPLC-PDA-MSn, and CIE-L*C*h° colour values of yellow and red nance fruits from Costa Rica were elucidated. Among 16 carotenoids detected, (all-E)-lutein was the most abundant accounting for >80% of the total carotenoids, followed by (all-E)-zeaxanthin (9-11%) and (all-E)-ß-carotene (2-9%). Minor constituents were (Z)-isomers of lutein and ß-carotene, as well as diverse lutein diesters. Among the esters, lutein dimyristate was the most abundant as substantiated by the comparison with a marigold flower extract. Total carotenoids in the peel (616.2 µg/100 g of FW in yellow nance and 174.2 µg/100 g of FW in red nance) were higher than in the pulp (39.4 µg/100 g of FW in yellow nance and 31.4 µg/100 g of FW in red nance). Since carotenoid profiles of yellow and red varieties were qualitatively similar, although the colour values showed significant differences (77.2 and 88.6 h° in peel and pulp of yellow nance, versus 32.7 and 67.3 h° in peel and pulp of red nance, respectively), pigments other than carotenoids may impart the colour of red nance. High lutein content renders nance fruit as a nutritionally relevant source of this micronutrient.

Characterization of Mesocarp and Kernel Lipids from Elaeis guineensis Jacq., Elaeis oleifera [Kunth] Cortés, and Their Interspecific Hybrids.

Morphological traits, total lipid contents, and fatty acid profiles were assessed in fruits of several accessions of Elaeis oleifera [Kunth] Cortés, Elaeis guineensis Jacq., and their interspecific hybrids. The latter featured the highest mesocarp-to-fruit ratios (77.9-78.2%). The total lipid contents of both E. guineensis mesocarp and kernel were significantly higher than for E. oleifera accessions. Main fatty acids comprised C16:0, C18:1n9, and C18:2n6 in mesocarp and C12:0, C14:0, and C18:1n9 in kernels. E. oleifera samples were characterized by higher proportions of unsaturated long-chain fatty acids. Saturated medium-chain fatty acids supported the clustering of E. guineensis kernels in multivariate statistics. Hybrid mesocarp lipids had an intermediate fatty acid composition, whereas their kernel lipids resembled those of E. oleifera genotypes. Principal component analysis based on lipid contents and proportions of individual fatty acids permitted clear-cut distinction of E. oleifera, E. guineensis, and their hybrids.