Transfer Of Carotenoids Research Articles

Effect of Novel Processing Techniques on the Carotenoid Release during the Production of Red Guava Juice.

Red guava, distinguished by its elevated lycopene content, emerges as a promising natural source of carotenoids. This study systematically evaluates the impact of diverse processing techniques on the efficient release of carotenoids. The primary objective is to facilitate the transfer of carotenoids into the juice fraction, yielding carotenoid-enriched juice seamlessly integrable into aqueous-based food matrices. The untreated guava puree exhibited a modest release of carotenoids, with only 66.26% of β-carotene and 57.08% of lycopene reaching the juice. Contrastly, both high-pressure homogenization (HPH) at 25 MPa and enzyme (EM) treatment significantly enhanced carotenoid release efficiency (p < 0.05), while high hydrostatic pressure (HHP) at 400 MPa and pulsed electric field (PEF) of 4 kV/cm did not (p > 0.05). Notably, HPH demonstrated the most substantial release effect, with β-carotene and lycopene reaching 90.78% and 73.85%, respectively. However, the stability of EM-treated samples was relatively poor, evident in a zeta-potential value of -6.51 mV observed in the juice. Correlation analysis highlighted the interactions between pectin and carotenoids likely a key factor influencing the stable dissolution or dispersion of carotenoids in the aqueous phase. The findings underscore HPH as a potent tool for obtaining carotenoid-enriched guava juice, positioning it as a desirable ingredient for clean-label foods.

Distributions of Carotenoids and α-Tocopherol among Lipoproteins Do Not Change when Human Plasma is Incubated In Vitro

Carotenoids and α-tocopherol are dietary, lipophilic antioxidants which may protect plasma lipoproteins from oxidation, a process believed to contribute to atherogenesis. In this study, the quantities and distributions of carotenoids, α-tocopherol and major lipids in the plasma and lipoproteins of seven normolipidemic humans were determined. Experiments were also conducted to determine if these antioxidants redistribute among lipoproteins when plasma is incubated in vitro. Virtually all of the total carotenoid in plasma associated with lipoproteins, primarily LDL [73 ± 10% (mean ± SD)], as did the more non-polar individual carotenoids, β-cryptoxanthin (68 ± 9%), lycopene (79 ± 9%), and β-carotene (72 ± 12%), in patterns which closely resembled the distribution of total cholesterol. Xanthophyll, the most polar carotenoid examined, distributed equally between LDL (44 ± 11%) and HDL (38 ± 14%), whereas α-tocopherol associated with LDL (43 ± 12%), HDL (26 ± 10%), and VLDL (27 ± 13%). These patterns closely resembled that of phospholipid. Approximately four carotenoid molecules associated with each VLDL and one with each LDL particle, whereas only 25 of every 1000 HDL particles contained carotenoid. Approximately 145 molecules of α-tocopherol associated with VLDL, 12 with LDL, and one with each HDL particle. Unlike triglyceride and cholesteryl ester, known to transfer among lipoproteins through the action of cholesteryl ester transfer protein, net transfer of carotenoids and α-tocopherol among lipoproteins did not occur. While these results suggest that the relative polarities of these antioxidants influence their distributions among lipoproteins, the extent to which carotenoids and α-tocopherol associate with specific lipoproteins does not appear to be governed by some of the mechanisms which lead to the establishment of major lipid distributions.

The Lutein and Zeaxanthin in Pregnancy (L-ZIP) study\u2014carotenoid supplementation during pregnancy: ocular and systemic effects\u2014study protocol for a randomized controlled trial

BackgroundLutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ), collectively called the macular pigment (MP), are dietary carotenoids that preferentially localize in the macula of the human eye. MP protects the macula from photo-oxidative damage and enhances visual function. Inadequate maternal intake of carotenoids, coupled with the placental transfer of maternal carotenoids to support fetal brain and retina development, potentially put mothers at risk of depletion systemically and in their ocular tissues. Presently, maternal carotenoid status throughout pregnancy remains poorly characterized, and no prospective randomized controlled trial of L and Z supplementation via prenatal vitamins has assessed maternal and infants’ systemic and ocular carotenoid status during pregnancy. We hypothesize that prenatal maternal carotenoid supplementation will counteract maternal carotenoid depletion during pregnancy and will improve biomarkers of carotenoid status of both mothers and infants.MethodsLutein and Zeaxanthin in Pregnancy (L-ZIP) is a phase 2, single-center, prospective, double-masked, randomized active-controlled clinical trial conducted at the John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA. Participants consume a daily standard prenatal multivitamin with no added carotenoids and are randomized (1:1 allocation) to receive either a capsule containing 10 mg L and 2 mg Z in safflower oil (Carotenoid group) or a capsule containing only safflower oil with no added carotenoids (Control group) for a period of 6 to 8 months. Skin, serum, and ocular carotenoids are measured at every study visit (i.e., within the first trimester [baseline], second trimester, third trimester, and 0–2 weeks postpartum). Skin carotenoid assessment is by resonance Raman spectroscopy (RRS); serum carotenoid status is quantified using high-performance liquid chromatography (HPLC); and MP is measured with the dual-wavelength autofluorescence. Infants’ MP and foveal anatomy are assessed using RetCam retinal camera and Bioptigen SD-OCT, respectively. The primary outcomes are changes in maternal systemic and ocular carotenoid status during pregnancy.DiscussionL-ZIP is the first prospective RCT to investigate maternal carotenoid status throughout pregnancy and to determine whether prenatal maternal carotenoid supplementation will offset maternal carotenoid depletion and improve biomarkers of maternal and infant’s carotenoid status. Findings from L-ZIP will strengthen recommendations regarding prenatal carotenoid supplementation and consequently inform policy decisions.Trial registrationClinicalTrials.gov NCT03750968. Registered on November 23, 2018

Characterization of Processing Influences on In Vitro Bioaccessibility of Carotenoids and Chlorophylls from Six Spinach Genotypes

Abstract Objectives Spinach is a rich source of bioactives including carotenoids and chlorophylls. Ultimate delivery, or bioavailability, of these bioactives to consumers varies depending on pre-/post-harvest factors that impact the food matrix. The interaction between food processing, oral processing (mastication), and spinach genotype have not been explored. Insights into these factors hold the potential to identify interaction effects between genotype and processing (GxP). Methods Six genotypes of spinach selected based on previous bioaccessibility screening were greenhouse grown in Salisbury, NC (Fall 2019), harvested, and stored fresh at 4C (24 hr) or at −80C after processing by blanching (2 min, 100C), thermal sterilization (121C for 15 min), or juicing. All genotypes were subjected to all processing methods, and a portion of each sample was subjected to simulated mastication while another was homogenized (30 sec) into a puree. All samples were subjected to a three-phase in vitro digestion to assess the transfer of carotenoids and chlorophyll derivatives from the food matrix to the aqueous micellar fraction (bioaccessibility). Results Processing method, genotype, and GxP had a significant influence on total bioactive content (P &amp;lt; 0.01), relative bioaccessibility (P &amp;lt; 0.01), and bioaccessible content (P &amp;lt; 0.01). Average bioactive content decreased in the order of juiced (26.2–36.9 μmol/g), blanched (23.3–30.0 μmol/g), thermally sterilized (22.5–27.3 μmol/g), and fresh spinach (18.6–25.0 μmol/g). Bioaccessible content decreased from juiced (6.8–9.8 μmol/g), to fresh (4.0–6.9 μmol/g) and blanched (4.6–5.6 μmol/g), and then thermally sterilized (2.4–3.3 μmol/g). Bioaccessible content from masticated samples was similar for thermally sterilized (0.9–1.5 μmol/g) and fresh samples (0.7–1.3 μmol/g). Conclusions Results indicate that heat treatment preserves bioactives in these six spinach genotypes and may modestly decrease their bioaccessibility. Influence of mastication on bioaccessible content of bioactives supports the notion that oral processing is a critical factor impacting ultimate bioaccessibility from vegetables. Together, these results provide valuable information for optimization of bioactive delivery. Funding Sources Foundation for Food and Agriculture Research.

In vitro digestibility kinetics of oil-in-water emulsions structured by water-soluble pectin-protein mixtures from vegetable purées

The potential use of water-soluble biopolymers from vegetable-origin in structuring oil-in-water emulsions and the influence on their digestion was investigated. The aqueous/serum phase, containing water-soluble biopolymers, of processed carrot and broccoli purées were isolated, lyophilized and then used either as the emulsifier or component in the continuous phase of carotenoid-loaded o/w emulsions. The kinetics of lipid digestion, micelle formation and carotenoid bioaccessibility of such emulsions were monitored during the in vitro small intestinal phase.The vegetable sera were characterized by a mixture of pectin and protein, in which free proteins and/or proteins-linked to pectin were probably present. Such pectin-protein mixtures exhibited an emulsion stabilizing capacity that determined the rate and extent of lipolysis, micelle formation, and carotenoid bioaccessibility. Emulsion destabilization during the gastric phase caused larger droplets in the emulsion formulated with broccoli serum containing high protein content and low Mw pectin compared to carrot serum with low protein content and high Mw pectin. In turn, a broccoli serum-emulsion presented slower rate and lower extent of lipolysis, micelle formation and consequently carotenoid bioaccessibility. By contrast, broccoli serum as a component in the continuous phase had no effect on lipolysis, micelle formation and carotenoid bioaccessibility, while, carrot serum limited the extent of carotenoid bioaccessibility without affecting the lipolysis and micelle formation. Carrot serum in the continuous phase hindered the transfer of carotenoids into mixed micelles. Water-soluble vegetable-based biopolymers (which can be tuned by processing) can be potentially used as natural emulsifiers that might modulate lipolysis and bioaccessibility of lipophilic bioactive compounds.

Health Effects of Carotenoids during Pregnancy and Lactation.

Adequate nutrition is particularly important during pregnancy since it is needed not only for maintaining the health of the mother, but also determines the course of pregnancy and its outcome, fetus development as well as the child’s health after birth and during the later period of life. Data coming from epidemiological and interventions studies support the observation that carotenoids intake provide positive health effects in adults and the elderly population. These health effects are the result of their antioxidant and anti-inflammatory properties. Recent studies have also demonstrated the significant role of carotenoids during pregnancy and infancy. Some studies indicate a correlation between carotenoid status and lower risk of pregnancy pathologies induced by intensified oxidative stress, but results of these investigations are equivocal. Carotenoids have been well studied in relation to their beneficial role in the prevention of preeclampsia. It is currently hypothesized that carotenoids can play an important role in the prevention of preterm birth and intrauterine growth restriction. Carotenoid status in the newborn depends on the nutritional status of the mother, but little is known about the transfer of carotenoids from the mother to the fetus. Carotenoids are among the few nutrients found in breast milk, in which the levels are determined by the mother’s diet. Nutritional status of the newborn directly depends on its diet. Both mix feeding and artificial feeding may cause depletion of carotenoids since infant formulas contain only trace amounts of these compounds. Carotenoids, particularly lutein and zeaxanthin play a significant role in the development of vision and nervous system (among others, they are important for the development of retina as well as energy metabolism and brain electrical activity). Furthermore, more scientific evidence is emerging on the role of carotenoids in the prevention of disorders affecting preterm infants, who are susceptible to oxidative stress, particularly retinopathy of prematurity.

Photo-induced electron transfer of carotenoids in mesoporous sieves (MCM-41) and surface modified MCM-41: The role of hydrogen bonds on the electron transfer

Abstract Two types of hydrogen bonds (H-bond) can be formed when a carotenoid containing a hydroxy group, such as retinol, interacts with a silanol group on the surface of MCM-41. H-bond 1, the oxygen atom of the carotenoid interacts with the proton of the SiOH group on the surface of MCM-41, and H-bond 2, the proton of the OH group of the carotenoid interacts with the oxygen atom of SiOH group on the surface of MCM-41. DFT calculations show that the formation of the H-bond 1 decreases the LUMO of the carotenoid and stabilizes the neutral species more than the radical cation, and thus disfavors the photo-induced electron transfer (ET) from the carotenoid to MCM-41. The opposite is true for the formation of H-bond 2. This conclusion is confirmed by the EPR study of the photo-induced ET of retinol imbedded in MCM-41 and the surface modified MCM-41. Although the formation of H-bond 1 results in low ET efficiency, the efficiency is much higher than that of the same carotenoid physisorbed on the surface of MCM-41. These results are relevant for improving the low solar-light-to-energy conversion efficiency in dye-sensitized solar cells.

Carotenoid transfer to oil upon high pressure homogenisation of tomato and carrot based matrices

The transfer of carotenoids into the oil phase during digestion is limited by matrix related factors that hamper carotenoid release and the conditions of low gastric acidity that limit carotenoid solubility. Therefore, the aim of this study was to investigate the use of high pressure homogenisation (HPH) as a driving force to favour carotenoid transfer to oil before digestion. The level of bio-encapsulation and carotenoid hydrophobicity were investigated as factors that may influence carotenoid transfer from tomato and carrot based matrices to oil upon HPH. The results indicated that the selective transfer of a particular carotenoid depended on its hydrophobicity. The cell wall in tomato cell clusters represents a limiting factor for carotenoid transfer. Overall, the findings indicate that HPH is efficient in transferring carotenoids to the oil phase and this can be crucial to improve the nutritional quality of carrot and tomato-based products.

Effect of different microalgal n−3 PUFA supplementation doses on yolk color and n−3 LC-PUFA enrichment in the egg

To examine the effect of different omega-3 polyunsaturated fatty acid (n−3 PUFA) doses on the long chain (LC) n−3 PUFA enrichment in the egg yolk, Isochrysis galbana was supplemented in nine different doses (from 0 to 400mg n−3 PUFAs per 100g feed) to the diet of laying hens. A linear increase of the n−3 LC-PUFA enrichment was observed up to a dose of 120mg n−3 PUFAs per 100g feed. Higher n−3 PUFA supplementation doses resulted in a decreased efficiency of n−3 LC-PUFA incorporation into the egg yolk. Pronounced color changes were observed due to transfer of carotenoids from the microalgal biomass to the egg yolk. However, a corresponding linear trend in yolk color changes was not observed for the low supplementation doses when compared to the n−3 LC-PUFA changes in the egg yolk. The a*-value increased remarkably with supplementation of 3% Isochrysis (150mg n−3 PUFAs per 100g feed) and remained stable with the higher supplementation doses.

Prevention of Solvent‐Mediated Isomer Transfer of Carotenoids

AbstractDuring industrial manufacturing, formulation, and storage, the tendency towards isomerization of astaxanthin (AXT) may affect its bioavailability. Potential additives like potassium carbonate, potassium acetate, dipotassium hydrogen orthophosphate, potassium hydroxide, and cesium carbonate were mixed to solutions of AXT and chloroform in order to increase the stability of all‐trans AXT while present in solution. The additives should not cause any damage to neither the dissolved nor the crystalline substance. Concentration changes in the course of time were measured and monitored by HPLC and a photometer. The additives exerted different effects on the dissolved AXT, either enhancing or weakening the isomerization processes and/or decomposition. Potassium carbonate and dipotassium hydrogen orthophosphate insufficiently affected the preservation of the all‐trans AXT structure. In contrast, potassium acetate, potassium hydroxide, and cesium carbonate led to satisfying results and can be recommended as additives.

Impact of feed supplementation with different omega-3 rich microalgae species on enrichment of eggs of laying hens

Four different omega-3 rich autotrophic microalgae, Phaeodactylum tricornutum, Nannochloropsis oculata, Isochrysis galbana and Chlorella fusca, were supplemented to the diet of laying hens in order to increase the level of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) in egg yolk. The microalgae were supplemented in two doses: 125mg and 250mg extra n-3 PUFA per 100g feed. Supplementing these microalgae resulted in increased but different n-3 LC-PUFA levels in egg yolk, mainly docosahexaenoic acid enrichment. Only supplementation of Chlorella gave rise to mainly α-linolenic acid enrichment. The highest efficiency of n-3 LC-PUFA enrichment was obtained by supplementation of Phaeodactylum and Isochrysis. Furthermore, yolk colour shifted from yellow to a more intense red colour with supplementation of Phaeodactylum, Nannochloropsis and Isochrysis, due to transfer of carotenoids from microalgae to eggs.This study shows that besides Nannochloropsis other microalgae offer an alternative to current sources for enrichment of hen eggs.

Impact of microalgal feed supplementation on omega-3 fatty acid enrichment of hen eggs

In many Western countries, the average intake of the health beneficial omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is below the recommended level, raising interest in food enrichment with n-3 LC-PUFA. To that end, the impact of feed supplementation with EPA rich autotrophic microalgal biomass on n-3 L-PUFA enrichment of eggs was studied. Hens were divided in three groups receiving different diets for 28days: a standard diet (C) for laying hens, (C) supplemented with 5.0% spray dried Nannochloropsis gaditana, and (C) to which 10.0% of these microalgae were added. Microalgal EPA was hardly accumulated in yolk lipids, but preferentially converted to DHA and deposited in yolk phospholipids. The efficiency of deposition of microalgal n-3 LC-PUFA to eggs was rather low. Switching back to standard feed ensured that the n-3 LC-PUFA level obtained in enriched eggs decreased back to that of the control eggs. Moreover, the colour of egg yolk shifted from yellow to more orange-red, which is presumably due to transfer of microalgal carotenoids to egg yolk. Thus, the use of autotrophic microalgae as supplement for standard feed offers an alternative to current sources for the production of DHA enriched eggs.

Eggshell Spottiness Reflects Maternally Transferred Antibodies in Blue Tits

Blue-green and brown-spotted eggshells in birds have been proposed as sexual signals of female physiological condition and egg quality, reflecting maternal investment in the egg. Testing this hypothesis requires linking eggshell coloration to egg content, which is lacking for brown protoporphyrin-based pigmentation. As protoporphyrins can induce oxidative stress, and a large amount in eggshells should indicate either high female and egg quality if it reflects the female's high oxidative tolerance, or conversely poor quality if it reflects female physiological stress. Different studies supported either predictions but are difficult to compare given the methodological differences in eggshell-spottiness measurements. Using the blue tit Cyanistes caeruleus as a model species, we aimed at disentangling both predictions in testing if brown-spotted eggshell could reflect the quality of maternal investment in antibodies and carotenoids in the egg, and at improving between-study comparisons in correlating several common measurements of eggshell coloration (spectral and digital measures, spotted surface, pigmentation indices). We found that these color variables were weakly correlated highlighting the need for comparable quantitative measurements between studies and for multivariate regressions incorporating several eggshell-color characteristics. When evaluating the potential signaling function of brown-spotted eggshells, we thus searched for the brown eggshell-color variables that best predicted the maternal transfer of antibodies and carotenoids to egg yolks. We also tested the effects of several parental traits and breeding parameters potentially affecting this transfer. While eggshell coloration did not relate to yolk carotenoids, the eggs with larger and less evenly-distributed spots had higher antibody concentrations, suggesting that both the quantity and distribution of brown pigments reflected the transfer of maternal immune compounds in egg yolks. As yolk antibody concentrations were also positively related to key proxies of maternal quality (egg volume, number, yellow feather brightness, tarsus length), eggshells with larger spots concentrated at their broad pole may indicate higher-quality eggs.

Environmental effects shape the maternal transfer of carotenoids and vitamin E to the yolk

IntroductionMaternal effects occur when the phenotype of the offspring is influenced by the phenotype of the mother, which in turn depends on her heritable state as well as on influences from the current and past environmental conditions. All of these pathways may, therefore, form significant sources of variation in maternal effects. Here, we focused on the maternal transfer of carotenoids and vitamin E to the egg yolk, using canaries as a model species. Maternal yolk carotenoids and vitamin E are known to generate significant phenotypic variation in offspring, representing examples of maternal effects. We studied the intra-individual consistency in deposition patterns across two years and the mother-daughter resemblance across two generations in order to estimate the level of heritable variation. The effects of the current environmental conditions were studied via a food supplementation experiment, while the consequences of past environmental conditions were estimated on the basis of the early growth trajectories.ResultsThere was a significant effect of the current environmental conditions on the yolk carotenoid and vitamin E deposition, but this effect varied between antioxidant components. The deposition of yolk carotenoids and vitamin E were linked to the process of yolk formation. Past environmental conditions did not contribute to the variation in yolk carotenoid and vitamin E levels nor did we find significant heritable variation.ConclusionsThe transfer of carotenoids or vitamin E may be an example where current environmental variation is largely passed from the mother to the offspring, despite the numerous intermediate physiological steps that are involved. Differences in the effect of the environmental conditions as experienced by the mother during laying may be due to differences in availability as well as physiological processes such as competitive exclusion or selective absorption.

Maternal effects and β-carotene assimilation in Canary chicks

Carotenoids are pigments responsible for the red, orange and yellow coloration of plants and animals. They may be beneficial in two ways; they have a powerful antioxidant activity, and they can behave as an immunostimulant. Animals however cannot synthesize carotenoids de novo, they must obtain them through their diet. In our experiments on Canaries, we investigated how mothers transfer their dietary carotenoid-related benefits to their offspring; either through the egg, or through the diet (during chicks' feeding). Female Canaries were allowed to access β-carotene enriched food during egg formation and/or chicks' feeding. We sorted the chicks into four groups using the period when they assimilated the beta-carotene as a variable. The four groups were: (i) before hatching (from yolk), (ii) after hatching (from maternal feeding), (iii) before and after hatching, or (iv) never. Colorimetry and HPLC analysis from sub-samples of yolks confirmed the maternal transfer of dietary carotenoids to the yolk. Our results show that benefits from maternal dietary carotenoids are transferred to the chicks, but according to the period when they are assimilated by the chicks, the physiological effects are different. It was found that the chicks' growth was enhanced when carotenoids were assimilated both before and after hatching. However an increase in cellular immunity efficiency only occurs when the assimilation takes place after hatching.

Bioavailability of Non-Provitamin A Carotenoids

The role of carotenoids in human nutrition has gained increased interest, especially due to their associated health-beneficial effects for a number of chronic diseases, including certain types of cancer and cardiovascular disease. Whereas data is available on the intake and presence of carotenoids in foods, limited information exists on factors influencing their bioavailability, especially for the non-provitamin A carotenoids. However, carotenoid absorption strongly depends on a number of factors which are not entirely understood. These include mainly the release of carotenoids from the food matrix, their incorporation into mixed bile micelles, the transfer of carotenoids from micelles to the mucosa for passive or facilitated absorption (via SR-BI proteins), and the sequestration into chylomicrons. Thus, dietary compounds influencing carotenoid micelle incorporation, e.g. the amount fat present in an ingested meal or components competing for uptake, such as phytosterols and other carotenoids, can have a considerable impact on carotenoid bioavailability. However, the effect of many dietary factors, including dietary fiber, type of fat, or minerals on carotenoid absorption is not well understood. In addition, bioavailability also depends on the carotenoid structure; in general, polar carotenoids are preferably incorporated into mixed micelles and tend to be of higher bioavailability, as may be the case for free vs. esterified xanthophylls, and cis-isomers vs. their trans-form, due to apparent shorter chain-lengths. Whereas their importance as part of a healthy diet warrants an improved understanding of carotenoids, their dietary fate following ingestion, including their stability, efficiency of micelle-incorporation, and pathway of absorption are still marginally understood.

Carotenoid Bioaccessibility from Whole Grain and Degermed Maize Meal Products

Although yellow maize (Zea mays) fractions and products are a source of dietary carotenoids, only limited information is available on the bioavailability of these pigments from maize-based foods. To better understand the distribution and bioavailability of carotenoid pigments from yellow maize (Z. mays) products, commercial milled maize fractions were screened for carotenoid content as were model foods including extruded puff, bread, and wet cooked porridge. Carotenoid content of maize fractions ranged from a low of 1.77-6.50 mg/kg in yellow maize bran (YCB) to 12.04-17.94 mg/kg in yellow corn meal (YCM). Lutein and zeaxanthin were major carotenoid species in maize milled fractions, accounting for approximately 70% of total carotenoid content. Following screening, carotenoid bioaccessibility was assessed from model foods using a simulated three-stage in vitro digestion process designed to measure transfer of carotenoids from the food matrix to bile salt lipid micelles (micellarization). Micellarization efficiency of xanthophylls was similar from YCM extruded puff and bread (63 and 69%), but lower from YCM porridge (48%). Xanthophyll micellarization from whole yellow corn meal (WYCM) products was highest in bread (85%) and similar in extruded puff and porridge (46 and 47%). For extruded puffs and breads, beta-carotene micellarization was 10-23%, but higher in porridge (40-63%), indicating that wet cooking may positively influence bioaccessibility of apolar carotenes. The results suggest that maize-based food products are good dietary sources of bioaccessible carotenoids and that specific food preparation methods may influence the relative bioaccessibility of individual carotenoid species.

Carotenoids in a food chain along a pollution gradient

Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their diet. They function in pigmentation and as antioxidants. We studied the carotenoid profiles in a model food chain (plant–insect–bird) in an air pollution gradient to find out whether heavy metal pollution affects the transfer of carotenoids across the trophic levels. Birch leaves showed higher β-carotene and, one of the birch species ( Betula pendula), higher total carotenoids levels in the polluted area. There was no difference in the lutein concentration of caterpillars’ food source, birch leaves, between the study areas. Autumnal moth larvae accumulated lutein more efficiently than β-carotene while sawfly larvae accumulated β-carotene over lutein. Because of different antioxidant profiles in different leaf chewing insects their sensitivity to pollution stress may differ. The lutein concentration of plasma and feathers of Great tit nestlings did not differ along the pollution gradient. The lack of difference in lutein concentration of autumnal moth larvae along pollution gradient may partly explain the lutein concentrations of Great tit nestlings, since the abundance of autumnal moth larvae peak during the nestling phase of Great tit. The lutein concentration of autumnal moth larvae was positively associated to circulating plasma lutein level of Great tit indicating the importance of carotenoid rich diet during the nestling phase. In addition, the higher the plasma lutein concentration the more lutein was deposited to feathers, irrespective of the other possible functions of lutein in nestlings. We found that carotenoid levels differed between the polluted and the unpolluted area especially at lower levels of food chain: in birches and in caterpillars.

Environmental Pollution Affects the Plumage Color of Great Tit Nestlings through Carotenoid Availability

Birds need to acquire carotenoids for their feather pigmentation from their diet, which means that their plumage color may change as a consequence of human impact on their environment. For example, the carotenoid-based plumage coloration of Great tit, Parus major, nestlings is associated with the degree of environmental pollution. Breast feathers of birds in territories exposed to heavy metals are less yellow than those in unpolluted environments. Here we tested two hypotheses that could explain the observed pattern: (I) deficiency of carotenoids in diet, and (II) pollution-related changes in transfer of carotenoids to feathers. We manipulated dietary carotenoid levels of nestlings and measured the responses in plumage color and tissue concentrations. Our carotenoid supplementation produced the same response in tissue carotenoid concentrations and plumage color in polluted and unpolluted environments. Variation in heavy metal levels did not explain the variation in tissue (yolk, plasma, and feathers) carotenoid concentrations and was not related to plumage coloration. Instead, the variation in plumage yellowness was associated with the availability of carotenoid-rich caterpillars in territories. Our results support the hypothesis that the primary reason for pollution-related variation in plumage color is carotenoid deficiency in the diet.

Micellarisation of Carotenoids from Raw and Cooked Vegetables

The efficiency of carotenoid micellarisation from plant foods can be used as an effective tool for the initial screening of carotenoid bioavailability. Therefore, the objectives of the present study were to assess the effects of cooking on the micellarisation of beta-carotene, lycopene, beta-cryptoxanthin and lutein from courgette (zucchini), red pepper and tomato; and, to a minor extent, investigate uptake of lutein by Caco-2 cells from micellar fractions obtained from raw and cooked courgettes. Both raw and cooked vegetables were subjected to an in vitro digestion procedure. beta-Carotene levels were significantly decreased in the digesta from each vegetable after boiling, grilling, microwave-cooking, or steaming, however all of the cooking methods enhanced beta-carotene transfer to micelles. Carotenoid micellarisation ranged from 1.7% to 100% depending on the food, carotenoid, and the cooking method tested. Grilling and microwave-cooking were generally the most detrimental on the transfer of xanthophyll carotenoids, namely beta-cryptoxanthin, to the micelles. Caco-2 cells absorbed greater amounts of lutein from the micelles of microwave-cooked courgettes than those that were raw, boiled, grilled, or steamed. Depending on the cooking methods used, carotenoid retention as well as micellarisation varied for each carotenoid among the different vegetables and different carotenoids present in each particular food.