Screening of critical factors influencing the efficient hydrolysis of zeaxanthin dipalmitate in an adapted in vitro- digestion model.

As hydrolysis of carotenoid esters is believed to be highly efficient in vivo, their insufficient hydrolysis in in vitro-digestion models, particularly, regarding zeaxanthin diesters, is a current issue. Therefore, in this study, several factors related to the enzymatic hydrolysis were investigated in an adapted version of the standardized INFOGEST in vitro-digestion model, using zeaxanthin dipalmitate (ZDP) as a substrate. The results showed that pancreatic lipase was able to hydrolyze ZDP, whereas carboxyl ester lipase (CEL) substantially contributed to ZDP cleavage. Replacement of commonly used porcine with bovine bile extracts and the substitution of coffee creamer for soybean oil at identical fat contents both significantly improved hydrolysis efficiency and bioaccessibility of total zeaxanthin to better mimic in vivo conditions. Thus, bile and lipids selection for in vitro digestion of carotenoid esters was crucial. The combined use of coffee creamer, pancreatin, CEL, and bovine bile led to the highest hydrolysis efficiency of 29.5%.

Effect of aggregation form on bioavailability of zeaxanthin in humans: a randomised cross-over study.

Carotenoid bioavailability from plant and animal food is highly variable depending on numerous factors such as the physical deposition form of carotenoids. As the carotenoid zeaxanthin is believed to play an important role in eye and brain health, we sought to compare the human bioavailability of an H-aggregated with that of a J-aggregated deposition form of zeaxanthin encapsulated into identical formulation matrices. A randomised two-way cross-over study with sixteen participants was designed to compare the post-prandial bioavailability of an H-aggregated zeaxanthin and a J-aggregated zeaxanthin dipalmitate formulation, both delivering 10 mg of free zeaxanthin. Carotenoid levels in TAG-rich lipoprotein fractions were analysed over 9·5 h after test meal consumption. Bioavailability from the J-aggregated formulation (AUC=55·9 nmol h/l) was 23 % higher than from the H-aggregated one (AUC=45·5 nmol h/l), although being only marginally significant (P=0·064). Furthermore, the same formulations were subjected to an internationally recognised in vitro digestion protocol to reveal potential strengths and weaknesses of simulated digestions. In agreement with our human study, liberation of zeaxanthin from the J-aggregated formulation into the simulated duodenal fluids was superior to that from the H-aggregated form. However, micellization rate (bioaccessibility) of the J-aggregated zeaxanthin dipalmitate was lower than that of the H-aggregated zeaxanthin, being contradictory to our in vivo results. An insufficient ester cleavage during simulated digestion was suggested to be the root cause for these observations. In brief, combining our in vitro and in vivo observations, the effect of the different aggregation forms on human bioavailability was lower than expected.

Carotenoids from gac fruit aril (Momordica cochinchinensis [Lour.] Spreng.) are more bioaccessible than those from carrot root and tomato fruit.

Using a simulated digestion procedure in vitro, liberation and bioaccessibility of ß-carotene (29.5±1.7% and 22.6±0.9%, respectively) and lycopene (51.3±2.6% and 33.2±3.1%, respectively) from gac fruit aril were found to be significantly higher than from carrot root (ß-carotene, 5.2±0.5% and 0.5±0.2%, respectively) and tomato fruit (lycopene, 15.9±2.8% and 1.8±0.5%, respectively). Gac fruit aril naturally contained significantly more lipids (11% on fresh weight base) than carrot root and tomato fruit (<1%). However, when test meals were supplemented with an O/W emulsion to match the content of gac fruit aril, carotenoid bioaccessibility was still considerably lower than that from genuine gac fruit aril. Carotenoids in gac fruit aril were found to be stored in small, round-shaped chromoplasts. Despite the high lipid content, these carotenoids are unlikely to occur in a lipid-dissolved state according to simple solubility estimations, instead being possibly deposited as submicroscopic crystallites. In contrast, carotenoids of carrot root and tomato fruit were stored in large, needle-like crystallous chromoplasts. Consequently, we hypothesized the natural deposition form to be majorly responsible for the observed differences in bioaccessibility. A favorable surface-to-volume ratio of the deposition form in gac fruit aril might have allowed a more rapid micellization during digestion, and thus, an enhanced bioaccessibility. Irrespective of the ultimate reason, gac fruit aril provided a highly bioaccessible form of both lycopene and provitamin A (ß-carotene), thus offering a most valuable dietary source of both carotenoids. Currently, gac is majorly grown in Southeast Asia, where its consumption might help to diminish the 'hidden hunger' namely the insufficient supply with vitamin A. Ultimately, gac fruit might thus contribute to alleviating most severe health implications of vitamin A deficiency, such as anaemia and xerophthalmia, the prevailing cause of preventable childhood blindness, as well as mortality from infectious diseases.

Carotenoids and Carotenoid Esters of Red and Yellow Physalis (Physalis alkekengi L. and P. pubescens L.) Fruits and Calyces.

Carotenoid profiles of fruits and calyces of red (Physalis alkekengi L.) and yellow (P. pubescens L.) Physalis were characterized by HPLC-DAD-APCI-MSn. Altogether 69 carotenoids were detected in red Physalis, thereof, 45 were identified. In yellow Physalis, 40 carotenoids were detected and 33 were identified. Zeaxanthin esters with various fatty acids were found to be the most abundant carotenoids in red Physalis, accounting for 51-63% of total carotenoids, followed by ß-cryptoxanthin esters (16-24%). In yellow Physalis, mainly free carotenoids such as lutein and ß-carotene were found. Total carotenoid contents ranged between 19.8 and 21.6 mg/100 g fresh red Physalis fruits and 1.28-1.38 mg/100 g fresh yellow Physalis fruits, demonstrating that Physalis fruits are rich sources of dietary carotenoids. Yellow Physalis calyces contained only 153-306 µg carotenoids/g dry weight, while those of red Physalis contained substantially higher amounts (14.6-17.6 mg/g dry weight), thus possibly exhibiting great potential as a natural source for commercial zeaxanthin extraction.

Ultrastructural deposition forms and bioaccessibility of carotenoids and carotenoid esters from goji berries (Lycium barbarum L.).

Goji berries (Lycium barbarum L.) have been known to contain strikingly high levels of zeaxanthin, while the physical deposition form and bioaccessibility of the latter was yet unknown. In the present study, we associated ripening-induced modifications in the profile of carotenoids with fundamental changes of the deposition state of carotenoids in goji berries. Unripe fruit contained common chloroplast-specific carotenoids being protein-bound within chloroplastidal thylakoids. The subsequent ripening-induced transformation of chloroplasts to tubular chromoplasts was accompanied by an accumulation of up to 36mg/100g FW zeaxanthin dipalmitate and further minor xanthophyll esters, prevailing in a presumably liquid-crystalline state within the nano-scaled chromoplast tubules. The in vitro digestion unraveled the enhanced liberation and bioaccessibility of zeaxanthin from these tubular aggregates in goji berries as compared to protein-complexed lutein from spinach. Goji berries therefore might represent a more potent source of macular pigments than green leafy vegetables like spinach.

Carotenoids, carotenoid esters, and anthocyanins of yellow-, orange-, and red-peeled cashew apples (Anacardium occidentale L.).

Pigment profiles of yellow-, orange-, and red-peeled cashew (Anacardium occidentale L.) apples were investigated. Among 15 identified carotenoids and carotenoid esters, ß-carotene, and ß-cryptoxanthin palmitate were the most abundant in peels and pulp of all samples. Total carotenoid concentrations in the pulp of yellow- and red-peeled cashew apples were low (0.69-0.73 mg/100g FW) compared to that of orange-peeled samples (2.2mg/100g FW). The color difference between the equally carotenoid-rich yellow and red colored samples indicated the presence of a further non-carotenoid pigment type in red peels. Among four detected anthocyanins, the major anthocyanin was unambiguously identified as 7-O-methylcyanidin 3-O-ß-D-galactopyranoside by NMR spectroscopy. Red and yellow peel color was chiefly determined by the presence and absence of anthocyanins, respectively, while the orange appearance of the peel was mainly caused by increased carotenoid concentrations. Thus, orange-peeled fruits represent a rich source of provitamin A (ca. 124 µg retinol-activity-equivalents/100g pulp, FW).

Lipid-dissolved γ-carotene, ß-carotene, and lycopene in globular chromoplasts of peach palm (Bactris gasipaes Kunth) fruits.

MAIN CONCLUSION: High levels of ß-carotene, lycopene, and the rare γ-carotene occur predominantly lipid-dissolved in the chromoplasts of peach palm fruits. First proof of their absorption from these fruits is reported. The structural diversity, the physical deposition state in planta, and the human bioavailability of carotenoids from the edible fruits of diverse orange and yellow-colored peach palm (Bactris gasipaes Kunth) varieties were investigated. HPLC-PDA-MS(n) revealed a broad range of carotenes, reaching total carotenoid levels from 0.7 to 13.9 mg/100 g FW. Besides the predominant (all-E)-ß-carotene (0.4-5.4 mg/100 g FW), two (Z)-isomers of γ-carotene (0.1-3.9 mg/100 g FW), and one (Z)-lycopene isomer (0.04-0.83 mg/100 g FW) prevailed. Approximately 89-94 % of total carotenoid content pertained to provitamin A carotenoids with retinol activity equivalents ranging from 37 to 609 µg/100 g FW. The physical deposition state of these carotenoids in planta was investigated using light, transmission electron, and scanning electron microscopy. The plastids found in both orange and yellow-colored fruit mesocarps were amylo-chromoplasts of the globular type, containing carotenoids predominantly in a lipid-dissolved form. The hypothesis of lipid-dissolved carotenoids was supported by simple solubility estimations based on carotenoid and lipid contents of the fruit mesocarp. In our study, we report first results on the human bioavailability of γ-carotene, ß-carotene, and lycopene from peach palm fruit, particularly proving the post-prandial absorption of the rarely occurring γ-carotene. Since the physical state of carotenoid deposition has been shown to be decisive for carotenoid bioavailability, lipid-dissolved carotenoids in peach palm fruits are expected to be highly bioavailable, however, further studies are required.