Characterization and the impact of in vitro simulated digestion on the stability and bioaccessibility of carotenoids and their esters in two Pouteria lucuma varieties

Carotenoids in Paprika Fruits and Ajvar: Chemical Characterization and Biological Activity

In this study, carotenoids from four different paprika genotypes were analyzed at various maturation stages, as well as in Ajvar, a traditional Balkan product made from fully matured roasted paprika fruits. For this purpose, the HPTLC analytical method was used, and five dominant carotenoids were analyzed: β-carotene, lutein, zeaxanthin, capsanthin, and β-cryptoxanthin. Additionally, total carotenoids were analyzed spectrophotometrically, antioxidant capacity was determined, and their bioavailability was assayed using in vitro digestion. Finally, Raman spectroscopy, a non-destructive analytical method, was used to estimate the total carotenoid content. The results showed that the amount of all investigated carotenoids is the highest in the final maturity stage (0.38 g/100 g DM to 1.55 g/100 g DM). On the other hand, the lowest concentration of all investigated carotenoids was detected at the first stage of maturation, ranging from 0.01 g/100 g DM to 0.25 g/100 g DM. However, the analysis of carotenoid content in Ajvar showed a tendency for a decrease in concentration compared to their quantity in fresh fruits, although this was also dependent on the genotype (1.9-66.98% according to HPTLC results and 16.14-82.36% according to spectrophotometry). Antioxidant tests indicated an increase in antioxidant capacity with the ripening of paprika fruits, confirming the role of carotenoids as compounds capable of neutralizing harmful oxygen species (DPPH ranged from 0.21 to 1.50 µmol/g TEAC, CUPRAC ranged from 0.185 to 0.297 mg AsA/g DM, FRP ranged from 9.33 to 25.66 mg AsA/g DM). Quantification of total carotenoids by Raman spectroscopy showed that results were highly correlated with those obtained by HPTLC and the spectrophotometric method, highlighting the potential of Raman spectroscopy for carotenoid quantification. Based on the obtained results, it can be concluded that the traditional product Ajvar represents an important source of carotenoids, which are preserved after heat treatment with high biological activity relative to the final ripening stage of the paprika. Furthermore, the bioavailability of carotenoids from Ajvar is significantly higher compared to the results from fresh paprika analysis.

Valorization of Pumpkin Byproducts: Antioxidant Activity and Carotenoid Characterization of Extracts from Peel and Filaments

Pumpkin (Cucurbita sp.) represents an unquestionable source of valuable nutrients and bioactive compounds having a broad spectrum of health-promoting effects. The goal of this work was to characterize the byproducts (peels and filaments) of different pumpkin varieties belonging to C. moschata (Butternut, Lunga di Napoli, Moscata di Provenza, and Violina rugosa) and C. maxima (Delica, Delica vanity, Hokkaido, and Mantovana) species in terms of total carotenoid content, antioxidant activity, and carotenoid profiling. The research revealed that peels and filaments were a good source of β-carotene and other non-esterified carotenoids, as well as esterified carotenoids. Considering the growing market demand for safe and healthy food products, pumpkin byproducts, having also an interesting antioxidant bioactivity, could be useful in the development of novel functional products.

Ultrasonic-assisted binding of canistel (Lucuma nervosa A.DC) seed starch with quercetin

In order to provide a reference for improving the physicochemical properties of starch, the study of starch polyphenol complex interaction has aroused considerable interest. As a common method of starch modification, ultrasound can make starch granules have voids and cracks, and make starch and polyphenols combine more closely. In this research, canistel seed starch was modified by ultrasonic treatment alone or combined with quercetin. The molecular structure, particle characteristics and properties of starch were evaluated. With the increase of ultrasonic temperature, the particle size of the dextrinized starch granules increased, but the addition of quercetin could protect the destruction of starch granule size by ultrasonic; X-ray diffraction and infrared spectra indicated that quercetin was bound to the surface of canistel seed starch through hydrogen bonding, and the complex and the original starch had the same crystal structure and increased crystallinity; by molecular simulation, quercetin bound inside the starch molecular helix preserved the crystalline helical configuration of starch to some extent and inhibited the complete unhelicalization of starch molecules. Meanwhile, hydrogen bonding was the main driving force for the binding of starch molecules to quercetin, and van der Waals interactions also promoted the binding of both. In the physicochemical properties, as the temperature increased after the combination of ultrasonic modified starch combined with quercetin, the solubility, swelling force and apparent viscosity of the compound increased significantly, and it has higher stability and shear resistance.

Micelle separation conditions based on particle size strongly affect carotenoid bioaccessibility assessment from juices after in vitro digestion

For assessing the carotenoid bioaccessibility during in vitro digestion, obtaining the micelle fraction that can diffuse through the mucin layer according to the particle size is an important step. However, the accuracy of the various approaches to obtaining the right fraction of micelles described in literature has not been investigated. In many studies the reported bioaccessible fraction might therefore be over- or underestimating the real bioaccessibility. The present study aimed to fill this gap and give approaches to get accurate data on the bioaccessible fraction from samples with different properties. Results illustrated that optimizing the centrifugal speed and duration of the digesta are essential in obtaining the micelle fraction. Different digesta have different optimum centrifugal parameters to obtain the bioaccessible fraction. 6,000 rpm and 40 min was selected as the optimum centrifugal parameter for combined juice (CJ). 6,000 rpm and 60 min was the optimum centrifugal parameter for CJ with oil, and CJ with emulsion using non-ionic emulsifier. 8,000 rpm and 20 min was the optimum centrifugal parameter for CJ with emulsion using ionic emulsifier. Polygalacturonanase (PG)-digested systems required higher centrifugal speed (10,000 rpm) compared with CJ-based systems (6,000 rpm or 8,000 rpm). A prediction model to determine the optimal centrifugation speed/time from the properties of the intestinal digesta was developed. Sample preparation conditions strongly affect carotenoid bioaccessibility assessment from juices during in vitro digestion. Based on these results, it is highly recommended to perform an optimized preparation procedure for bioaccessible fraction prior to carotenoid bioaccessibility analysis.

Effect of High Hydrostatic Pressure on the Extractability and Bioaccessibility of Carotenoids and Their Esters from Papaya (Carica papaya L.) and Its Impact on Tissue Microstructure

High hydrostatic pressure (HHP) is a non-thermal technology widely used in the industry to extend food shelf-life and it has been proven to enhance the extractability of secondary metabolites, such as carotenoids, in plant foods. In this study, fresh-cut papaya pulp of varieties (Sweet Mary, Alicia and Eksotika) from the Canary Islands (Spain) were submitted to the HHP process (pressure: 100, 350 and 600 MPa; time: come-up time (CUT) and 5 min) to evaluate, for the first time, individual carotenoid and carotenoid ester extractability and to assess their bioaccessibility using an in vitro simulated gastrointestinal digestion assay, following the standardized INFOGEST® methodology. In addition, changes in papaya pulp microstructure after HHP treatments and during the different phases of the in vitro digestion were evaluated with optical light microscopy. HPLC-DAD (LC-MS/MS (APCI+)) analyses revealed that HHP treatments increased the carotenoid content, obtaining the highest extractability in pulp of the Sweet Mary papaya variety treated at 350 MPa during 5 min (4469 ± 124 μg/100 g fresh weight) which was an increase of 269% in respect to the HHP-untreated control sample. The highest carotenoid extraction value within each papaya variety among all HHP treatments was observed for (all-E)-lycopene, in a range of 98-1302 μg/100 g fresh weight (23-344%). Light micrographs of HHP-treated pulps showed many microstructural changes associated to carotenoid release related to the observed increase in their content. Carotenoids and carotenoid esters of papaya pulp submitted to in vitro digestion showed great stability; however, their bioaccessibility was very low due to the low content of fatty acids in papaya pulp necessary for the micellarization process. Further studies will be required to improve papaya carotenoid and carotenoid ester bioaccessibility.

Bioaccessibility of microalgae-based carotenoids and their association with the lipid matrix

The composition of microalgae can contribute to nutritious and functional diets. Among the functional compounds, carotenoids are in focus since positive effects on human health have been established, which are in turn related to their bioaccessibility. In addition to essential nutrients, our hypothesis was that microalgae biomasses could be used as sources of bioaccessible carotenoids. Thus, this study determined for the first time the bioaccessibility of carotenoids from biomass of Scenedesmus bijuga and Chlorella sorokiniana and their possible relationship with the lipid composition of the matrix. The samples were submitted to in vitro digestion protocol, and carotenoids were determined by HPLC-PDA-MS/MS. Individual bioaccessibility of carotenoids was ≥ 3.25%. In general, compounds in their cis conformation were more bioaccessible than trans; and total carotenes more than total xanthophylls. Twelve compounds were bioaccessible from the biomass of S. bijuga, and eight in C. sorokiniana. In S. bijuga, the bioaccessibility of total carotenoids was 7.30%, and the major bioaccessible carotenoids were 9-cis-β-carotene (43.78%), 9-cis-zeaxanthin (42.30%) followed by 9-cis-lutein (26.73%); while in C. sorokiniana, the total bioaccessibility was 8.03%, and 9-cis-β-carotene (26.18%), all-trans-β-carotene (13.56%), followed by 13-cis-lutein (10.71%) were the major compounds. Overall, the total content of lipids does not influence the bioaccessibility of total carotenoids. Still, the lipid composition, including structural characteristics such as degree of saturation and chain length of the fatty acid, impacts the promotion of individual bioaccessibility of carotenes and xanthophylls of microalgae. Finally, the results of this study can assist the development of microalgae-based functional food ingredients and products.

In vitro bioaccessibility of macular xanthophylls from commercial microalgal powders of Arthrospira platensis and Chlorella pyrenoidosa

The bioaccessibility of the major carotenoids present in two commercial microalgal supplements in powder form was investigated through a standardized in vitro digestion method. The dried biomass of Arthrospira platensis contained β-carotene (36.8 mg/100 g) and zeaxanthin (20.8 mg/100 g) as the main carotenoids as well as a high content of saturated fatty acids (61% of total fatty acids), whereas that of Chlorella pyrenoidosa was rich in lutein (37.8 mg/100 g) and had a high level of unsaturated fatty acids (65% of total fatty acids). In the case of the latter, lutein bioaccessibility was not statistically enhanced after the replacement of porcine bile extract with bovine bile extract in the in vitro digestion protocol and after the addition of coconut oil (17.8% as against to 19.2% and 19.2% vs. 18.5%, respectively). In contrast, the use of bovine bile extract along with co-digestion with coconut oil significantly enhanced the bioaccessibility of zeaxanthin from A. platensis, reaching the highest bioaccessibility of 42.8%.

Carotenoid and Carotenoid Ester Profile and Their Deposition in Plastids in Fruits of New Papaya (Carica papaya L.) Varieties from the Canary Islands

The carotenoid profile of non-saponified and saponified extracts of different tissues (pulp and peel) of fruits of three new papaya varieties, Sweet Mary, Alicia, and Eksotika, was characterized for the first time, and almost all carotenoid compounds were quantified. Carotenoids and carotenoid esters were analyzed and characterized using HPLC-photo diode array (PDA-MS with atmospheric pressure chemical ionization with positive ion mode (APCI+) with a C30 reversed-phase column. The carotenoid deposition in collenchyma and chlorenchyma cells of papaya pulp and peel tissues was assessed by optical microscopy, confocal laser scanning microscopy, and transmission electron microscopy. The most abundant carotenoids in the fruit of the three papaya varieties (pulp and peel) were (all-E)-lycopene (230.0-421.2 µg/100 g fresh weight), (all-E)-β-carotene (120.3-233.2 µg/100 g fresh weight), and (all-E)-β-cryptoxanthin laurate (74.4-223.2 µg/100 g fresh weight. Moreover, high concentrations of (all-E)-lutein (922.5-1381.1 µg/100 g fresh weight) and its esters, such as (all-E)-lutein-3-O-myristate and (all-E)-lutein dimyristate, were found in peel extracts. The optical microscopy study of papaya pulps showed that carotenoid deposition in all papaya varieties, including Maradol, was mainly localized close to the cell walls, showing the presence of some crystalloids and round-shaped structures, with different sizes and distribution due to the different carotenoid content among varieties. No crystalloids or globular depositions were found in any of the peel sections, and no remarkable differences were found in the papaya peel microstructure of the different papaya varieties.

A Brief Overview of Dietary Zeaxanthin Occurrence and Bioaccessibility

As it exhibits no provitamin A activity, the dietary intake of zeaxanthin is not considered essential. However, its contribution to ocular health has long been acknowledged. Numerous publications emphasize the importance of zeaxanthin alongside lutein in ocular diseases such as cataracts and age-related macular degeneration which constitute an important health concern, especially among the elderly. Considering that the average dietary ratio of lutein to zeaxanthin favors the first, more bioaccessible food sources of zeaxanthin that can hinder the development and progression of the above-mentioned disorders are of great interest. In this paper, a brief overview of the more recent state of knowledge as regards dietary sources together with their respective zeaxanthin bioaccessibility assessed through a standardized in vitro digestion method was provided.