Quantitative Determination Of Carotenoids Research Articles

QUANTITATIVE DETERMINATION OF THE AMOUNT OF CAROTENOIDS IN THE FRUITS OF CHINESE LYCIUM CHINENSE MILL.

The objects of the study were Mature dried fruits of Chinese birch (Lycium chinense Mill., this. Solanaceae (Solanaceae)). Four samples were examined: No. 1 (Gifts of Pamir, Russia), No. 2 (Gullin Tianhe Pharmaceutical, China), No. 3 (A. J. Alliance, Russia), No. 4 (Globaltorg, Russia). The purpose of this work is to determine the amount of carotenoids in the fruits of Chinese by spectrophotometry.
 The quantitative determination of the amount of carotenoids in the raw material of Chinese Dereza was carried out. Thin-layer chromatography was used to confirm the presence of carotenoids in the fruits of Dereza. The expediency of using the spectrophotometric method for the detection and quantitative determination of carotenoids in extracts from the fruits of Chinese birch is substantiated. The electron spectra of hexane, acetone and acetone-hexane solutions in the wavelength range 400–500 nm have a maximum optical density at 450±2 nm, characteristic of β-carotene. The optimal conditions of extraction of carotenoids from the raw materials of this plant (extractant – hexane; ratio "raw material–extractant" – 1 : 5; extraction time – 90 minutes; the degree of grinding of raw materials – 0.5 mm). It was determined that the error of a single determination of the content of carotenoids in the fruits of Chinese Dereza with a confidence probability of 95% is ±3,49%. It was revealed that the content of carotenoids in the raw material of Chinese Dereza varies in the range of 33–39 mg%.

HPLC-UV/Vis-APCI-MS/MS Determination of Major Carotenoids and Their Bioaccessibility from "Delica" (Cucurbita maxima) and "Violina" (Cucurbita moschata) Pumpkins as Food Traceability Markers.

Carotenoids are a widespread group of fat-soluble pigments, and their major nutritional importance comes from their pro-vitamin A activity and their antioxidant capacity. In this study, two different pumpkin cultivars (Cucurbita maxima, also named ‘Delica’ and Cucurbita moschata, also known as ‘Violina’) from the southern Po Delta area were investigated in terms of carotenoid content and the influence of food processing on compositional changes and carotenoid bioaccessibility. Quali- and quantitative determination of carotenoids in sample extracts were performed on a C30 column by means of an online coupled HPLC-UV/Vis-APCI-MS/MS technique. The identification of separated compounds was tentatively achieved by merging (i) chromatographic data, (ii) UV-Vis spectra, and (iii) MS/MS fragmentation spectra. The chromatographic profiles for the two cultivars showed qualitative differences. Two major carotenoids were considered for quantification purposes and further investigations: lutein and -carotene. Quantification of target carotenoids was performed with external calibration through analytical standards. The concentration of lutein and -carotene was higher in C. maxima than in the other variety, C. moschata. Carotenoids are susceptible to degradation (isomerization and oxidation) during food processing (i.e., cooking), and the concentration of lutein and -carotene were monitored in oven-cooked and steam-cooked pumpkins. The steam-cooking process was superior in terms of limiting carotenoid loss. A complete functional profile of pumpkins as a source of carotenoids was gained with the evaluation of their in vitro bioaccessibility and their bioavailability after intake during human digestion. Bioaccessibility of lutein and -carotene were estimated by an in vitro static digestion model that involved salivary, gastric, and duodenal phases. Bioaccessibility values progressively increased from the salivary to the duodenal phase for both pumpkin varieties and cooking methods. Bioaccessibility of lutein was always lower than -carotene for both cultivars and for both cooking methods. Bioaccessibility values for lutein and -carotene changed from 1.93% to 2.34% vs. 4.94% and 8.83% in the salivary phase, from 2.7% to 4.63% vs. 7.83% and 15.60% in the gastric phase, and from 10.04% to 13.42% vs. 25.81% and 35.32% in the duodenal phase. For both target compounds, bioaccessibility in the duodenal phase was more than twice the gastric values, and it underlined that the type of cooking did not influence release from the initial matrix.

PHYSIOLOGICAL CHARACTERIZATION OF FLOWER SENESCENCE IN LONG LIFE AND EPHEMERAL HIBISCUS (HIBISCUS ROSA-SINENSIS L.)

PHYSIOLOGICAL CHARACTERIZATION OF FLOWER SENESCENCE IN LONG LIFE AND EPHEMERAL HIBISCUS (HIBISCUS ROSA-SINENSIS L.)

Assessment of the saponification step in the quantitative determination of carotenoids and provitamins A

The saponification step in the determination of carotenoids was reassessed. Synthetic carotenoids (β-apo-8′-carotenal, β-carotene) and food samples (tomato, kale, papaya) were used and different procedures were evaluated. Hot saponification resulted in greater losses and cis- and epoxycarotenoids were formed. The degradation was aggravated by a more direct contact between the carotenoids and the alkali. The AOAC procedure, performed in the presence of acetone, led to complete transformation of β-apo-8′-carotenal to citranaxanthin. Saponification was unnecessary for kale and tomato but was needed for good separation of papaya carotenoids which included carotenol esters. Saponification of the carotenoids dissolved overnight at room temperature in petroleum ether, with equal volume of 10% methanolic KOH, retained β-, γ-carotene, β-apo-8′-carotenal and lycopene and completely hydrolysed the carotenol esters. However, even with this mild saponification, lutein, zeaxanthin and violaxanthin degraded significantly. These losses could be reduced to insignificant levels by using an atmosphere of nitrogen or antioxidant.

Profiling and Quantitation of Bacterial Carotenoids by Liquid Chromatography and Photodiode Array Detection

An analytical method for the profiling and quantitative determination of carotenoids in bacteria is described. Exhaustive extraction of the pigments from four selected bacterial strains required treatment of the cells with potassium hydroxide or liquefied phenol or both before the addition of the extracting solvent (methanol or diethyl ether). The carotenoids in the extracts were separated by nonaqueous reversed-phase liquid chromatography in conjunction with photodiode array absorption detection. The identity of a peak was considered definitive only when both its retention time and absorption spectrum, before and after chemical reactions, matched those of a reference component. In the absence of the latter, most peaks could be tentatively identified. Two examples illustrate how in the analysis of pigmented bacteria errors may result from using nonchromatographic procedures or liquid chromatographic methods lacking sufficient criteria for peak identification. Carotenoids of interest were determined quantitatively when the authentic reference substance was available or, alternatively, were determined semiquantitatively.