Bioavailability of β-carotene isomers from raw and cooked carrots using an in vitro digestion model coupled with a human intestinal Caco-2 cell model

Not only is there limited information in the literature regarding the β-carotene (BC) isomer profile of micelles from digested foods; few studies have looked at their subsequent uptake and transport by human intestinal Caco-2 cells. Therefore, the aims of the present study were, first, to assess the profile of BC isomers in micelles from digested raw and cooked carrots; and, second, to determine their cellular uptake and transport. Greater amounts of all-trans-, 13-cis- and 15-cis-BC isomers were present in the micelles of cooked carrots compared with raw carrots. Furthermore, micelle fractions obtained from the most highly processed (pureed) carrots had greater (P < 0.05) amounts of all-trans-, 13-cis- and 15-cis-BC compared with those derived from raw and boiled carrots. A similar trend was seen with BC isomer uptake and transport. Our data suggest that the food matrix and degree of processing play important roles on carotenoid isomerization and bioavailability.     

Analysis of Anabaena vaginicola and Nostoc calcicola from Northern Iran,as rich sources of major carotenoids

Four major carotenoids of high nutritional significance, including β-carotene, lycopene, lutein and zeaxanthin were determined in three isolates of heterocystous cyanobacteria, belonging to the genera Anabaena and Nostoc, isolated from Iranian terrestrial and aquatic ecosystems, for the first time. The ultrasonically extracted carotenoids were identified and quantified by a rapid and sensitive isocratic HPLC method and identification was further confirmed by spiking authentic standards and the pattern of the UV–Vis spectra obtained from photo-diode array detector. The results showed that these isolates contain large amounts of four major carotenoids, especially lycopene (up to 24570 μg/g dry weight, DW) which appears to be the highest reported amount until present; and β-carotene (up to 8133 μg/g DW) which is comparable with the best natural sources of β-carotene. Meanwhile, they are rich in the cis-isomers of lycopene and β-carotene which is important in their bioavailability and health benefits.     

Spatial distribution of dry matter in yellow fleshed cassava roots and its influence on carotenoid retention upon boiling

Understanding retention of carotenoids after different processing methods is important. This study was conducted to quantify dry matter content and carotenoids found in different sections of the cassava roots from six clones and to assess true retention of carotenoids after 30 min of boiling. Retention was quantified in normalized prisms taken from proximal, central and distal sectors of the root. Dry matter content (DMC) was measured along and across the roots and varied from 14.1 to 51.0%. DMC tended to be lower at the center of the root and in distal sections. DMC affected the homogeneity of the food matrix and, therefore, contributed in spatial variation in retention of carotenoids. Average true retention (dry matter basis) was 86.6% and ranged from 76.0 and 96.7% (averages per clone and section of the root, respectively). Retention was positively associated with carotenoid content in unprocessed samples, although the relationship was weak. The study shows that during boiling weight of samples changed from slight losses to gains of up to 40% (depending on original DMC of the uncooked root), resulting in an “apparent dilution” of the carotenoids. Results suggested the occurrence of some isomerization. All-trans β-carotene losses (13%) were partially explained by increases in the 13-cis (34%) and 15-cis (8%) isoforms, as well as lixiviation (< 1%) into the boiling water.     

Relation between in vitro lipid digestion and β-carotene bioaccessibility in β-carotene-enriched emulsions with different concentrations of l-α-phosphatidylcholine

In view of consumer health, it is desirable to promote the bioaccessibility of lipid-soluble compounds like carotenoids, while limiting the lipid intake. The objective of this work was to examine the relation between in vitro lipid digestion and β-carotene bioaccessibility of carrot-based model food emulsions containing water, 5% olive oil enriched with β-carotene (from carrots) and different concentrations (1–2–3–4%) of l-α-phosphatidylcholine (PHC), as an emulsifier. The lipid digestion (hydrolysis of triacylglycerols (TAGS) and incorporation of free fatty acids (FFAs) and monoacylglycerols (MAGs) in the micelles) and the β-carotene bioaccessibility (incorporation of β-carotene in the micelles) were studied after an in vitro digestion procedure wherein the stomach phase was mimicked for 2.0 h (37 °C) and the small intestinal phase was mimicked for 1.0 h, 1.5 h and 2.0 h (37 °C) (both end-over-end rotations). As a consequence, not only the influence of the emulsifier concentration, but also the influence of the duration in the small intestinal phase was investigated in this study. The oil droplet size distributions of the emulsions at different stages of digestion were shown to be dependent on the phosphatidylcholine concentration, but independent on the duration in the small intestinal phase (1.0 h–2.0 h). Furthermore, all TAGs were already hydrolysed into FFAs and MAGs after 1.0 h small intestinal phase and the incorporation of FFAs and MAGs into micelles seemed to reach a maximum for all emulsions (approximately 26.5%), independent on the phoshpatidylcholine concentration and thus on the particle size distributions. Finally, the β-carotene bioaccessibility increased with increasing phosphatidylcholine concentration, ranging from 33.2% to 79.8% for a 1% and 4% PHC emulsion respectively. No significant differences in β-carotene bioaccessibility were however noticed for the different durations in the small intestinal phase tested. In conclusion, a higher phosphatidylcholine concentration in emulsions leads to higher β-carotene bioaccessibility while the incorporation of lipids into micelles did not increase.     

Determination of thermal oxidation and oxidation products of β-carotene in corn oil triacylglycerols

A reversed phase HPLC-DAD coupled to APCI-MS method is reported for the determination of the degradation of β-carotene and characterization of the oxidation products in corn oil. Corn oil containing β-carotene was oxidized in the Rancimat at 110 °C from 1 to 14 h. A significant degradation of β-carotene was observed in corn oil during accelerated thermal oxidation. A total of eight different oxidized products of β-carotene were identified, which includes 8′-apo-β-carotenal, 6′-apo-β-carotenal, 5,6-epoxy-8′-apo-β-carotenal, β-carotene-2,2′-dione, 13-Z-5,6,5′,6′-diepoxy-β-carotene, all-E-5,8-epoxy-β-carotene, all-E-5,6-epoxy-β-carotene, and 15-Z-5,6-epoxy-β-carotene. Corn oil triacylglycerols (TAGs) oxidation products were also identified using isocratic HPLC–ESI-MS. It was found that β-carotene promoted oxidation of TAGs especially at longer exposure times. For the first time two new classes of oxidized TAGs have been identified in corn oil, which were epidioxy bis-hydroperoxides and hydroxy bis-hydroperoxides. Other oxidation products of TAGs were mono-epoxides, mono-hydroperoxides, and epoxy hydroperoxides. It was found that complementing the HPLC-DAD method for β-carotene with ESI-MS method for TAGs oxidation provides a comprehensive set of analytical tools to characterize carotenoids and triacylglycerols oxidation and degradation in edible oils.     

Suppressive effect of carotenoid extract of Dunaliella salina alga on production of LPS-stimulated pro-inflammatory mediators in RAW264.7 cells via NF-κB and JNK inactivation

The carotenoid extract from Dunaliella salina was used to evaluate the suppressive effects on lipopolysaccharide (LPS)-induced pro-inflammatory mediators in RAW264.7 cells. The extract composed all-trans forms of α-carotene (28.8 mg/g extract), β-carotene (471.1 mg/g extract), lutein (7.1 mg/g extract) and zeaxanthin (7.2 mg/g extract), 13- or 13′-cis-β-carotene (12.1 mg/g extract), 9- or 9′-cis-α-carotene (19.1 mg/g extract) and 9- or 9′-cis-β-carotene (440.3 mg/g extract) dose-dependently reduced the production of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α), the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the secretion of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in LPS-activated RAW264.7 cells. Its attenuation of LPS-induced inflammatory responses was closely related to inhibition of the nuclear NF-κB p50 subunit translocation by blocking inhibitor of κBα (IκB) phosphorylation and degradation correlated with suppressing IκB kinase (IKK) α/β phosphorylation, as well as down-regulation of the c-Jun NH₂-terminal kinase (JNK) activation.     

Transport of bovine milk-derived opioid peptides across a Caco-2 monolayer

The transepithelial transport of μ-opioid (MOP) receptor agonists, i.e., bovine β-casomorphin-5 and -7 (derived from β-casein) and an antagonist, i.e., casoxin-6 (derived from κ-casein) were investigated using a human intestinal cell (Caco-2) monolayer. To determine the transport pathway of the peptides across Caco-2 monolayers, two directions of the transport (apical-to-basolateral and basolateral-to-apical) were studied. All investigated peptides were transported across Caco-2. The cumulative fractions of transported peptides were increased linearly in time in each case. The permeability coefficients (P_aap) calculated for all peptides in two transport directions ranged between 0.57 and 9.21 × 10^?6 cm min^?1. These data suggest the possibility of transport of opioid peptides derived from food across human intestinal mucosa.     

Mastication effects on carotenoid bioaccessibility from mango fruit tissue

The release of carotenoids from fresh fruits or vegetables is determined by the encapsulating plant tissue matrix, intracellular carotenoid location within the cell, and the mastication process. The objectives of this study were to assess the particle sizes obtained after mastication of mango fruit tissue, and how the resulting degree of plant tissue rupture affects carotenoid bioaccessibility. A fine and a coarse chewer were selected after screening 20 healthy volunteers for in vivo human mastication, and the collected chewed boluses were subjected to wet sieving fractionation, followed by an in vitro gastric and small intestinal digestion model. Confocal micrographs show that the smallest particle size fraction (0.075 mm) consists mostly of fragmented cells and the largest size fraction (2.8 mm) contains bulky clusters of whole cells and vascular fibers. Higher amounts of total carotenoids (211–320 μg/100 g) were observed in the larger particle size fraction (2.8 mm) relative to the 1 mm (192–249 μg/100 g) and 0.075 mm fractions (136–199 μg/100 g). Smaller particles showed a greater % release of total carotenoids after in vitro digestion. Xanthophyll derivatives are more bioaccessible than β-carotene for all particle sizes. The effects of particle size or degree of fine vs coarse chewing are unexpectedly small (p > 0.05), but the process of chewing substantially reduced the release of β-carotene and xanthophylls by 34% and 18%, respectively. While there is a (small) particle size effect, this appears to not be the primary factor controlling bioaccessibility for soft tissues such as mango, in contrast to previous reports that a single cell wall appears to be enough to prevent bioaccessibility of carotenoids in more robust carrot tissues.     

The effect of pectin concentration and degree of methyl-esterification on the in vitro bioaccessibility of β-carotene-enriched emulsions

Soluble fibers, like pectin, are known to influence the physicochemical processes during the digestion of dietary fat and may therefore affect the absorption of lipophilic micronutrients such as carotenoids. The objective of the current work was to investigate whether the pectin concentration and degree of methyl-esterification (DM) influence the bioaccessibility of carotenoids loaded in the oil phase of oil-in-water emulsions. The in vitro β-carotene bioaccessibility was determined for different oil-in-water emulsions in which 1 or 2% citrus pectin with a DM of 99%, 66% and 14% was present. Results show that pectin concentration and DM influence the initial emulsion properties. The most stable emulsions with the smallest oil droplets (D(v,0.9) of 15–16 μm) were obtained when medium or high methyl-esterified pectin was present in a 2% concentration while gel-like pectin structures (D(v,0.9) of 114 μm), entrapping oil droplets, were observed in the case where low methyl-esterified pectin was present in the aqueous emulsion phase. During in vitro stomach digestion, these gel-like structures, entrapping β-carotene loaded oil droplets, significantly enlarged (D(v,0.9) of 738 μm), whereas the emulsion structure could be preserved when the medium or high methyl-esterified pectin was present. Initial emulsion viscosity differences, due to pectin concentration and especially due to pectin DM, largely disappeared during in vitro digestion, but were still significant after the stomach digestion phase. The observed differences in emulsion structure before and during in vitro digestion only resulted in a significant difference between emulsions containing low methyl-esterified pectin (β-carotene bioaccessibility of 33–37%) and medium/high methyl-esterified pectin (β-carotene bioaccessibility of 56–62%).     

Milk enhances intestinal absorption of green tea catechins in in vitro digestion/Caco-2 cells model

The effect of milk on the absorption of polyphenols is still controversial so far. In order to determine the impact of milk addition on green tea catechins bioaccessibility and intestinal absorption an in vitro digestion/Caco-2 cell model was applied. Green tea extract (GTE) was solubilized in distilled water at 23 °C and 100 °C, combined with skimmed milk (GTE + 10% milk and GTE + 25% milk) and subjected to simulated gastric and intestinal digestion, followed by transepithelial absorption in Caco-2 cells monolayers. In the mixture with milk, gallated catechins: ECG and EGCG showed binding to milk proteins while EC and EGC seemed to have weaker affinity. Catechins were stable during gastric incubation and very sensitive to intestinal digestion. Bioaccessibility of green tea catechins brewed at 100 °C was higher than brewed at 23 °C. Catechins from digested GTE with 10% and 25% milk exhibited enhanced intestinal permeability in Caco-2 model in comparison to non-digested GTE and digested GTE without milk. Apparent permeability coefficients (P_app) of EGCG and ECG in digested GTE with 25% milk were significantly higher compared to those in GTE with 10% milk, and amounted to 2.41 × 10^− 6 cm/s and 1.39 × 10^− 6 cm/s. The recoveries of all catechins in GTE with milk in Caco-2 cells after 2 h incubation were significantly higher than that without milk. To summarize, these data suggest that milk addition may increase catechin bioavailability by enhancing their transepithelial absorption and uptake from green tea extract.     

Human Serum Vitamin A and β-Carotene Contents in Relation to Locally Consumed Foods,Social Status and Gender in Kano Metropolis

Determination of the levels of vitamin A (as retinol) and β-carotene in locally consumed foods in relationship to their occurrence in the serum of individuals grouped according to different social groups and sexes was carried out in Kano metropolis. Both raw and prepared foods (meals/snacks) investigated showed the presence of β-carotene while vitamin A was only present in the latter. The levels of β-carotene in foods/snacks ranged from 2.00 – 3.40 and 88 – 1120 iu/kg in raw foods while that of vitamin A in the former was 13.00 – 23.50 iu/kg. Food/snacks derived from animal products and those made from vitamin A fortified foods showed marginally higher vitamin contents. The mean serum β-carotene and retinol concentrations of the individual grouped according to sex and social class showed significant differences between the three social groups (P < 0.05). The higher the income class, the higher the value of vitamin A and its precursor. There was no significant difference in the β-carotene and retinol concentration between males and females of low income and high income class (P > 0.05). However, there was significant difference between males and females of the medium income class (P < 0.05). These results are discussed in terms of an apparent relationship between income and serum vitamin A content.     

Carotenoid content,its stability during drying and the antioxidant activity of commercial coriander (Coriandrum sativum L.) varieties

Although populations of several tropical countries are under severe vitamin-A deficiency, traditional sources of pro-vitamin-A carotenoids have not been exploited due to the lack of relevant research data. In this study, ten commercial varieties of coriander (Coriandrum sativum L.), grown at identical conditions, were evaluated for carotenoids, their bio-efficacy and stability during drying, with the main emphasis on β-carotene (vitamin-A precursor) analysis by HPLC-MS. In all varieties, β-carotene content was higher in foliage at mature stage, than in seedlings and seeds. Variety GS4 Multicut produced highest biomass (6.18 ± 0.73 g/plant), total carotenoids (217.50 ± 5.6 mg/100 g DW) and β-carotene (73.64 ± 0.3 mg/100 g DW) at pre-flowering stage. Carotenoids extract showed a high antioxidant activity with IC₅₀ value of 14.29 ± 1.68 μg/ml, scavenging hydroxyl radicals and rendering higher protection to DNA than by standard gallic acid (IC₅₀ = 357.21 ± 4.29). Microwave drying of foliage was rapid with better retention of pigments, high intactness of trans-β-carotene and higher extractability of pigments when compared with oven drying.     

Analysis of carotenoids with emphasis on 9-cis β-carotene in vegetables and fruits commonly consumed in Israel

Recent epidemiological studies have directed the attention from the synthetic all-trans β-carotene to natural carotenoids predominant in fruits and vegetables as possible active ingredients for prevention of cancer and cardiovascular diseases. Seventeen fruits and 17 vegetables commonly consumed in Israel and the β-car-otene-rich alga, Dunaliella bardawil, were analysed for their content of carotenoids with emphasis on 9-cis β-carotene by reversed-phase, 3D photodiode array HPLC. Fourteen carotenoids were eluted in order of decreasing polarity, from polar oxycarotenoids to lipophilic hydrocarbons, and quantified in μg carotenoid per gram freeze-dried plant sample. The richest sources of total carotenoids (>100μg/g dry weight) in Israeli fruits were pittango, mango and papaya while, in vegetables, the predominant types were carrot, dill, parsley, tomato, lettuce, sweet potato and red pepper. Red fruits and vegetables contained mainly lycopene. Yellow and orange fruits and vegetables had high contents of hydrocarbon carotenes with substantial levels of cryptoxanthins and xanthophylls. The green vegetables had high contents of both xanthophylls and hydrocarbon carotenes. Relatively high ratios (9-cis to all-trans β-carotene) of above 0.2 g/g were noted in sweet potato, papaya, parsley, lettuce, dill, apricot, pepper, prune and pumpkin, compared to the high ratio of 9-cis to all-trans β-carotene in the alga Dunaliella (~ 1.0 g/g). The high content of 9-cis β-carotene in certain fruits and vegetables and the wide variety of carotenoids and stereoisomers of carotenoids in all plants should shift nutritional and medical attention from the synthetic all-trans β-carotene toward natural carotenoids as potential candidates for chemoprevention.     

Major carotenoid composition of Brazilian Valencia orange juice: Identification and quantification by HPLC

The carotenoid composition of Brazilian Valencia orange juice was determined by open column chromatography (OCC) and high-performance liquid chromatography. Carotenoid pigments were extracted using acetone and saponified using 10% methanolic potassium hydroxide. Sixteen pigments were isolated by OCC and identified as α-carotene, ζ-carotene, β-carotene, α-cryptoxanthin, β-cryptoxanthin, lutein-5,6-epoxide, violaxanthin, lutein, antheraxanthin, zeaxanthin, luteoxanthin A, luteoxanthin B, mutatoxanthin A, mutatoxanthin B, auroxanthin B and trollichrome B. Thirteen carotenoid pigments were separated using a ternary gradient (acetonitrile–methanol–ethyl acetate) elution on a C₁₈ reversed-phase column. Among these, violaxanthin, lutein, zeaxanthin, β-cryptoxanthin, ζ-carotene, α-carotene, and β-carotene were quantified. The total carotenoid content was 12 ± 6.7 mg/l, and the major carotenoids were lutein (23%), β-cryptoxanthin (21%), and zeaxanthin (20%).     

Pasteurization of citrus juices with ohmic heating to preserve the carotenoid profile

This study was carried out to assess, for the first time, the effect of ohmic heating on the carotenoid profile of two citrus fruit juices: grapefruit and blood orange. Two heat treatments were designed to obtain pasteurization values of 50 and 150 min (Tref = 70 °C and z-value = 10 °C) with ohmic heating as compared to conventional heating. The results showed that xanthophyll losses could reach 70% for epoxyxanthophylls (cis-violaxanthin and cis-antheraxanthin) and 40% for hydroxyxanthophylls (β-cryptoxanthin, lutein, and zeaxanthin) with conventional heating, but losses were under 30% and 20%, respectively, with ohmic heating. Carotene species (lycopene and β-carotene) were stable regardless of the treatment. No negative non-thermal effects of ohmic heating were shown on carotenoids. Loss simulations of the studied carotenoids showed that the high temperatures reached with ohmic heating during pasteurization could substantially increase the organoleptic and nutritional quality of acid carotenoid-rich juices.Industrial relevanceCitrus are the top fruit crops in terms of world trade. This craze for them -particularly orange and grapefruit- is notably due to their high content in organoleptic and nutritional compounds of interest and among them carotenoids. About 50% of the Citrus production is processed in juice. From the growing variety of products, minimal processed juices now have a significant market share. This work assessed for the first time the effect of ohmic heating, a thermal method for stabilizing juices while minimizing the impact on the juice quality, on the carotenoid profiles of blood orange and grapefruit juice. Pasteurization with ohmic heating was proven to be a very good alternative for protecting carotenoids and especially xanthophylls compared to conventional heating. These results will help in designing ohmic heating process parameters for optimizing the overall quality of carotenoid-rich fruit juices.     

Evaluation of extraction method for the analysis of carotenoids in fruits and vegetables

This study evaluated a suitable extraction method for a wide range of sample matrices in carotenoid analysis. Using canned tomato juice as a representative sample, it is shown that two solvents of low biological hazard, ethanol and hexane are the most suitable for extracting carotenoids from the matrix. The use of double extraction, each with 35 ml of ethanol:hexane mixture (4:3, by volume), resulted in good recoveries of carotenoids (lycopene 96%, α-carotene 102% and β-carotene 93–100%). Coefficients of variation conducted on different days were: lycopene 5% and β-carotene 7%. An application of the established method to various kinds of fruit and vegetable matrices is also shown, using carrot and spinach as representative samples of root and leafy vegetables, for determining recoveries of added carotenoids. The average percent recoveries of added carotenoids from canned tomato juice, carrot and spinach were: 101, 99.8 and 101% for α-carotene (12.4, 24.8, 49.6 and 99.2 μg/10 ml of added α-carotene); and 98.1, 99.7 and 96.1 percent for β-carotene (25.5, 50.9, 101 and 201 μg/10 ml of added β-carotene). These similar recoveries over the explored concentration ranges confirm that the application of established extraction method is unaffected by differences in matrix composition of the samples.     

In vitro study of anti-oxidative effects of β-carotene and α-lipoic acid for nanocapsulated lipids

In this study we attempted to assess the efficacy of the in vitro activities of β-carotene and α-lipoic acid in conjugation with an encapsulated lipid. Nanoemulsion was prepared and freeze-dried to get nanocapsules. Highest encapsulation efficiency 84.32 ± 1.08% was achieved for α-lipoic acid nanocapsules, whereas for β-carotene nanocapsules it was 79.63 ± 1.41%. Morphology study showed that the dried capsules had an irregular, rough surface. Both anti-oxidants were equally effective in releasing core materials. Complete release of the total lipid occurred within 210 min from both β-carotene and α-lipoic acid bearing nanocapsules. Stability study revealed that β-carotene nanocapsules showed decrease in oil content from 79.63 g lipid to 72.8 g lipid for every 100 g lipid encapsulated, in 3 months, whereas α-lipoic acid nanocapsules retained oil much better, the oil retention being from 84.32 g lipid to 78.08 g lipid per 100 g lipid encapsulated. DPPH radical scavenging activity of β-carotene and α-lipoic acid ranged from 62.75% and 44.13% to 32.94% and 36.95% (after 90 days) respectively. Reducing activity of β-carotene was higher (absorbance 0.492 to 0.291 at 90 days) compared to α-lipoic acid (absorbance 0.243 to 0.109 after 90 days). Again β-carotene and α-lipoic acid metal-chelation activity ranged from 47.65% and 48.59% to 32.315% and 39.29% after 90 days.     

Carotenoid composition of two Brazilian genotypes of acerola (Malpighia punicifolia L.) from two harvests

Acerola fruit is native to Central America and adapted very well to Brazil, which in turn became the major worldwide acerola producer, consumer and exporter. Two acerola genotypes were harvested from a Brazilian plantation during the 2003 and 2004 summer harvests. Both genotypes presented β-carotene (265.5–1669.4 μg/100 g), lutein (37.6–100.7 μg/100 g), β-cryptoxanthin (16.3–56.5 μg/100 g) and α-carotene (7.8–59.3 μg/100 g) as the major carotenoids. In both harvests, the β-carotene, β-cryptoxanthin and α-carotene levels were higher in the Olivier genotype, whereas the lutein content was higher in the Waldy Cati 30 genotype. Due to higher sunlight exposure, the fruits harvested in 2004 showed higher total carotenoid contents than those from the 2003 harvest. Acerola, especially the Olivier genotype, with 148–283 RE/100 g, can be considered as a good source of provitamin A.     

Composition and characterization of cordyxanthins from Cordyceps militaris fruit bodies

Fruit bodies of Cordyceps militaris are widely used as functional food in China, Southeast Asia and North America. Cordyceps carotenoids are the important active components in the fruit bodies. However, chemical composition and property of the cordyceps carotenoids are still unknown. In this study, the novel carotenoids from C. militaris fruit bodies were separated and identified as xanthophylls and named as cordyxanthin-I (2, 3, 2′, 3′-tetradehydro-18, 16′, 17′, 18′-tetranor-ε, ε-carotene-5, 5′, 1′ -triol), cordyxanthin-II (2, 3, 2′, 3′-tetradehydro-18, 1′, 16′, 17′, 18′-pentanor-ε, ε-carotene-5, 5′, -diol), cordyxanthin-III (2, 3, 2′, 3′-tetradehydro-18, 17′, 18′-trinor-ε, ε-carotene-5, 5′, -diol) and cordyxanthin-IV (2, 3, 2′, 3′-tetradehydro-18, 18′-dinor-ε, ε-carotene-5, 5′, -diol). The four cordyxanthins proved to be highly water-soluble and could be directly quantified at 447 nm with β-carotene as a standard. Compared with traditional cultivation, the contents of the four cordyxanthins could be significantly increased by treatment of pink light (2/3 of 620–630 nm + 1/3 of 450–460 nm).     

Effect of cyclodextrins on the thermodynamic and kinetic properties of cyanidin-3-O-glucoside

In this study, the effect of α and β-cyclodextrin on cyanidin-3-O-glucoside color was investigated by UV–visible absorption techniques. The equilibrium and kinetic constants of the network of chemical reactions taking place in cyanidin-3-O-glucoside were also studied in water at 25 °C by UV–visible absorption techniques. The results showed that the addition of β-cyclodextrin resulted in the fading of anthocyanin solution, and this fading effect was greater at higher pH. This anti-copigmentation effect is caused by the selective inclusion and stabilization of the anthocyanin colorless forms into the β-cyclodextrin cavity. Oppositely, no changes were observed in the cyanidin-3-O-glucoside absorption spectra with the addition of α-cyclodextrin.Direct pH jump, from thermally equilibrated solutions at pH = 1.0 (flavylium cation, AH⁺), shows three kinetic processes: formation of the base A, hydration reaction to form the hemiketal B and the chalcone cis–trans isomerization (Cc–Ct). The results obtained clearly indicated that the equilibrium and kinetic constants of the network of chemical reactions taking place in cyanidin-3-O-glucoside were affected by the presence of β-cyclodextrin. Molecular inclusion in the β-cyclodextrin cavity resulted in the increase of the isomerization observed rate constant (k_obs) at pH 5.3 and in the increase of the hydration equilibrium constant K_h which is in agreement with the fading of the anthocyanin solution. For the macrocycle α-cyclodextrin, no significant changes were observed on the equilibrium and kinetic constants, which suggests that the inclusion of cyanidin-3-glucoside in the α-cyclodextrin's cavity is not favored.