Adaption of an in vitro digestion method to screen carotenoid liberation and in vitro accessibility from differently processed spinach preparations

Pre-exposure of Lactobacillus acidophilus to stress conditions impacts the metabolites and bioaccessibility of calcium and carotenoids in fermented dairy products

This study evaluated the impact of fermentation with Lactobacillus acidophilus pre-subjected to acid, osmotic, and oxidative stress conditions on the production of metabolites and the bioaccessibility of nutrients and bioactive compounds in fermented milks and yogurts. The products were added with orange bagasse (additional calcium - Ca source) and buriti pulp (carotenoids source). Gas chromatography coupled with mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) were used to analyze the volatile and non-volatile compounds metabolites from fermentation, respectively. In vitro digestion assays (dialysis and micellization) evaluated the bioaccessibility of Ca and carotenoids. Results showed that fermentation with L. acidophilus, previously exposed to acid, osmotic, and oxidative stress conditions, increased the production of volatiles such as higher alcohols and compounds derived from amino acid catabolism (1-butanol, 1-decanol, 1-nonanol, nonanoic acid, 2-ethyl 1-hexanol, 1-methoxy-2-propanol). Also, when this microorganism was subjected to osmotic and oxidative stress, an increase in the bioaccessibility of Ca in natural fermented milks from 4.1 % to 13.3-15.5 % and in the same products fortified with orange bagasse from 5.3 % to 9.3-10.8 % (when compared to the non-stressed condition) were observed. Conversely, the use of L. acidophilus - non-stressed or subjected to oxidative stress - reduced the bioaccessibility of carotenoids in products containing buriti pulp from 9.6 % to 7.8 % and 4.1  % (in yogurts); and, from 4.1 % to 2.0 % (in fermented milks), when compared to control. Thus, the pre-exposure of probiotics to stress conditions may impact not only the sensory and biochemical characteristics of fermented products, but also the bioaccessibility of nutrients and bioactive compounds.

Dietary phytochemicals alleviate the premature skin aging: A comprehensive review

Skin aging, often called as premature skin aging, is the hastened deterioration of the skin resulting from multiple factors, including UV radiation, environmental contaminants, inadequate nutrition, stress, etc. Dietary phytochemicals, present in fruits, vegetables, and other plant-derived meals, have gained interest due to their efficiency to eradicate free radicals and lowering the release of inflammatory mediators which accounts for premature skin aging. Several dietary phytochemicals, i.e., carotenoids, polyphenols, flavonoids, terpenes, alkaloids, phytosterols, etc., exhibited potential anti-oxidant, anti-inflammatory, suppression of UV damage, and promote collagen synthesis. In addition, dietary phytochemicals include sulfur, present in various foods safeguard the skin against oxidative stress and inflammation. Thus, this article delves into the comprehension of various dietary phytochemicals investigated to alleviate the premature skin aging. The article further highlights specific phytochemicals and their sources, bioavailability, mechanisms, etc., in the context of safeguarding the skin against oxidative stress and inflammation. The present manuscript is a systematic comprehension of the available literature on dietary phytochemicals and skin aging in various database, i.e., PubMed, ScienceDirect, Google Scholar using the keywords, i.e., "dietary phytochemicals", "nutraceuticals", "skin aging" etc., via Boolean operator, i.e., "AND". The dietary guidelines presented in the manuscript is a unique summarization for a broad reader to understand the inclusion of various functional foods, nutrients, supplements, etc., to prevent premature skin aging. Thus, the utilization of dietary phytochemicals has shown a promising avenue in preventing skin aging, however, the future perspectives and challenges of such phytochemicals should be comprehended via clinical investigations.

Preliminary In Vitro Assessment of Whey Protein Isolate Hydrogel with Cannabidiol as a Potential Hydrophobic Oral Drug Delivery System for Colorectal Cancer Therapy

Colorectal cancer (CRC) is the second global cause of cancer morbidity. Often, potent CRC drugs fail to reach the market, due to the molecule having low solubility levels. Therefore, there is a need to develop a viable, targeted delivery system for hydrophobic drugs. Whey protein isolate (WPI), in the form of hydrogels, has demonstrated loadability with hydrophobic molecules. Hydrophobic cannabidiol (CBD) has demonstrated potential in inhibiting and suppressing CRC tumour growth. Therefore, in this study, WPI hydrogels were assessed as a novel oral hydrophobic drug delivery vehicle, using CBD as a model drug. The hydrogels were analysed in conditions consistent with the alimentary tract. The investigation was performed at pH 2 (stomach), pH 7 (small intestines) and pH 9 (large intestines) and using the enzymes pepsin (stomach) and protease (small and large intestines) to simulate the digestive environment. Polymer swelling assays demonstrated that the swelling potential of the hydrogels was strongly dependent on pH. At pH 2, hydrogels decreased in mass, losing around 10% of their initial mass, while hydrogels in a pH 9 environment increased in mass by approximately 50%. However, the enzymatic degradation of the hydrogels at pH 2 (pepsin, stomach), pH 7 (protease, small intestines) and pH 9 (protease, large intestines) was more pronounced in the neutral-alkaline pH range. Pepsin at pH 2 had no significant effect on the hydrogels. In contrast, protease at pH 9 significantly degraded the hydrogels, resulting in a mass loss of 30-40% from the initial mass. The results suggesting a higher rate of degradation in the intestines rather than in the stomach. Furthermore, CBD release, analysed with U.V. spectroscopy, demonstrated a higher release rate in pH conditions associated with the intestines (pH 7 and pH 9) rather than the stomach (pH 2), suggesting a higher rate of CBD release in regions of the digestive tract affected by CRC. Significantly, the hydrogels significantly reduced the viability of HT29 CRC cells. This study demonstrates the potential of the utilisation of WPI hydrogels as an oral hydrophobic drug delivery system.

Effect of In Vitro Gastrointestinal Digestion on Phytochemicals and Antioxidant Activities in Cherry Tomatoes (Solanum lycopersicum var. cerasiforme)

We investigated the impact of simulated in vitro gastrointestinal digestion on the levels of total polyphenols, total flavonoids, carotenoids, and antioxidant capacity in cherry tomatoes. The initial total polyphenol content of fresh tomatoes was 220.51 μg GAE/g, which decreased to 203.24 μg GAE/g after 120 min of stomach treatment and further decreased to 138.23 μg GAE/g after 120 min of small intestine treatment. Similarly, the initial total flavonoid content in fresh tomatoes was 43.28 μg QE/g, but after 120 min of small intestine digestion, it decreased by approximately 50.72% to 21.33 μg QE/g. Lycopene, lutein, and β-carotene also experienced a decrease of 69.71∼78.38% during the digestion process compared to fresh tomatoes. The antioxidant activity exhibited a reduction of 34.95∼37.67% compared to fresh tomatoes after digestion in the stomach and intestines. The bioactive compounds present in tomatoes undergo decomposition and conversion into other substances during digestion, and these degradation products are believed to inhibit the growth of SK-Hep1 human hepatoma cells while enhancing antioxidant activity within the intracellular environment.

Improvement in the Stability and Bioaccessibility of Carotenoid and Carotenoid Esters from a Papaya By-Product Using O/W Emulsions

The aim of the present work was to improve the stability and bioaccessibility of carotenoids from green oil extracts obtained from papaya by-products using oil-in-water (O/W) emulsions. The effects of different concentrations of pectin (1%, 2%, and 3%), a high-molecular-size emulsifier, together with Tween 20, a low-molecular-size emulsifier, high-speed homogenization conditions (time: 2, 3, 4, and 5 min; rpm: 9500, 12,000, 14,000, and 16,000 rpm), and high-pressure homogenization (HPH) (100 MPa for five cycles) were evaluated to determine the optimal conditions for obtaining O/W stable emulsions with encapsulated carotenoids. Soybean, sunflower, and coconut oils were used to formulate these O/W emulsions. The bioaccessibility of the main individual encapsulated papaya carotenoids was evaluated using the INFOGEST digestion methodology. In addition, the microstructures (confocal and optical microscopy) of the O/W carotenoid emulsions and their behavior during in vitro digestion phases were studied. Sunflower O/W carotenoid emulsions showed smaller mean particle size, higher negative ζ-potential, and higher viscosity than soybean O/W emulsions. Particle size reduction in the O/W emulsions using the HPH process improved the bioaccessibility of papaya encapsulated carotenoids. In these O/W emulsions, depending on the vegetable oil, lycopene was the carotenoid with the highest bioaccessibility (71-64%), followed by (all-E)-β-carotene (18%), (all-E)-β-cryptoxanthin (15%), and (all-E)-β-cryptoxanthin laurate (7-4%). These results highlight the potential of using green carotenoid papaya extracts to formulate O/W emulsions to enhance carotenoid bioactivity by efficiently preventing degradation and increasing in vitro bioaccessibility.

Immunomodulatory and Antioxidant Effects of Spray-Dried Encapsulated Kale Sprouts after In Vitro Gastrointestinal Digestion

The health-related compounds present in kale are vulnerable to the digestive process or storage conditions. Encapsulation has become an alternative for their protection and takes advantage of their biological activity. In this study, 7-day-old Red Russian kale sprouts grown in the presence of selenium (Se) and sulfur (S) were spray-dried with maltodextrin to assess their capacity to protect kale sprout phytochemicals from degradation during the digestion process. Analyses were conducted on the encapsulation efficiency, particle morphology, and storage stability. Mouse macrophages (Raw 264.7) and human intestinal cells (Caco-2) were used to assess the effect of the intestinal-digested fraction of the encapsulated kale sprout extracts on the cellular antioxidant capacity, the production of nitric oxide (NOx), and the concentrations of different cytokines as indicators of the immunological response. The highest encapsulation efficiency was observed in capsules with a 50:50 proportion of the hydroalcoholic extract of kale and maltodextrin. Gastrointestinal digestion affected compounds' content in encapsulated and non-encapsulated kale sprouts. Spray-dried encapsulation reduced the phytochemicals' degradation during storage, and the kale sprouts germinated with S and Se showed less degradation of lutein (35.6%, 28.2%), glucosinolates (15.4%, 18.9%), and phenolic compounds (20.3%, 25.7%), compared to non-encapsulated ones, respectively. S-encapsulates exerted the highest cellular antioxidant activity (94.2%) and immunomodulatory activity by stimulating IL-10 production (88.9%) and COX-2 (84.1%) and NOx (92.2%) inhibition. Thus, encapsulation is an effective method to improve kale sprout phytochemicals' stability and bioactivity during storage and metabolism.

Effect of Processing and In Vitro Digestion on Bioactive Constituents of Powdered IV Range Carrot (Daucus carota, L.) Wastes

Daucus carota L. is an important food crop utilized worldwide and a rich source of bioactive compounds. Carrot processing generates residues which are discarded or underused, for which using them as a source for obtaining new ingredients or products is an opportunity for the development of healthier and more sustainable diets. In the present study, the impact of different milling and drying procedures and in vitro digestion on the functional properties of carrot waste powders was evaluated. Carrot waste was transformed into powders by disruption (grinding vs. chopping), drying (freeze-drying or air-drying at 60 or 70 °C) and final milling. Powders were characterized in terms of physicochemical properties (water activity, moisture content, total soluble solids and particle size) nutraceuticals (total phenol content, total flavonoid content antioxidant activity by DPPH and ABTS methods, as well as carotenoid content (α-carotene, β-carotene, lutein, lycopene). Antioxidants and carotenoid content during in vitro gastrointestinal digestion were also evaluated; the latter in different matrices (directly, in water, in oil, and in oil-in-water emulsion). Processing allowed to reduce water activity of samples and obtain powders rich in antioxidant compounds and carotenoids. Both disruption and drying had a significant impact on powders' properties freeze-drying led to finer powders with higher carotenoid content but lower antioxidant values, whereas air-drying implied chopped air-dried powders exhibited higher phenols content and improved antioxidant activity. Simulated in vitro digestion studies revealed that digestion helps release bioactive compounds which are bound to the powder structure. The solubilization of carotenoids in oil was low, but fat co-ingestion notably increased their recovery. According to the results, carrot waste powders containing bioactive compounds could be proposed as functional ingredients to increase the nutritional value of foods, thus contributing to the concepts of more sustainable food systems and sustainable healthy diets.

The Bioaccessibility and Antioxidant Activities of Fermented Mango Cultivar Juices after Simulated In Vitro Digestion

The purpose of this study was to investigate the bioaccessibilities of total phenolic compounds, carotenoid profile, antioxidant activity, and Lactic acid bacteria (LAB) survival in fermented mango juice (MJs) obtained from three mango cultivars after exposure to an in vitro gastrointestinal digestion model. The MJs from three cultivars ('Sabre', 'Peach', and 'Tommy Atkins') were fermented using Lactiplantibacillus plantarum 75 (L75), Leuconostoc pseudomesenteroides 56 (L56), and their combination (L56 + 75). Fermented MJs were digested and fractions: gastric (GF), intestinal (IF), and dialysis (DF) were analyzed for total polyphenolic content (TPC), antioxidant activity (FRAP), 1-diphenyl-2-picrylhydrazyl (DPPH), and 2.2-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS). In addition, the carotenoid content and the LAB population were determined from the GF and IF. After digestion, TPC decreased while fermentation improved its bioaccessibility. L75-fermented 'Sabre' MJs had the highest bioaccessible TPC in the GF (75.65%), IF (50.10%), and DF (32.52%) while L56 'Peach' MJs increased the β-carotene bioaccessibility by 1.32-fold at GF and IF (1.21-fold). When compared to the other two juices, 'Sabre' and 'Peach' MJs fermented with L75 showed the highest IC₅₀ values for DPPH and ABTS. Generally, L75-fermented 'Sabre' MJs had the highest LAB survival at both GF (7.57 Log CFU/mL) and IF (7.45 Log CFU/mL) and hold potential as probiotic juices. L56-fermented 'Sabre' MJs would ensure the delivery of four times the carotenoid recommended dietary allowance (RDA) to a target site in the body while L75-fermented 'Peach' MJs could be used to effectively counteract oxidants in the body system.

Cooking African Pumpkin Leaves (Momordicabalsamina L.) by Stir-Frying Improved Bioactivity and Bioaccessibility of Metabolites-Metabolomic and Chemometric Approaches

The leaves of African pumpkins (Momordica balsamina L.) are a commonly consumed traditional vegetable. They are a good source of polyphenolic antioxidants and carotenoids, which are, however, affected by cooking or digestion. We investigated the effect of household cooking methods (stir-frying or boiling) on the changes in bioactive metabolites, antioxidant capacity, release and accessibility of β-carotene and also inhibition of inhibitory activity against α-amylase and α-glucosidase enzymes during in vitro digestion of African pumpkin leaves compared to the raw leaves. Compared to boiled or raw leaves, stir-frying improved the availability of bioactive metabolites at the gastrointestinal phase. Quercetin 3-galactoside and rhamnetin 3-O-glucoside (marker compounds) discriminated the stir-fried leaves from raw leaves and boiled leaves after digestion. Stir-frying improved the release and accessibility of β-carotene and enhanced the antioxidant activities compared to boiling. Dialysable fractions of stir-fried leaves exhibited the greatest inhibitory activity against α-amylase and α-glucosidase enzymes compared to the raw and boiled leaves, as well as acarbose. Stir-frying, therefore, is recommended for use in household cooking to benefit consumers by increasing the intake of phenolics and β-carotene.

High-Pressure Processing of Kale: Effects on the Extractability, In Vitro Bioaccessibility of Carotenoids & Vitamin E and the Lipophilic Antioxidant Capacity

High pressure processing (HPP) represents a non-thermal preservation technique for the gentle treatment of food products. Information about the impact of HPP on lipophilic food ingredients (e.g., carotenoids, vitamin E) is still limited in more complex matrices such as kale. Both the variation of pressure levels (200–600 MPa) and different holding times (5–40 min) served as HPP parameters. Whereas a slightly decreasing solvent extractability mostly correlated with increasing pressure regimes; the extension of holding times resulted in elevated extract concentrations, particularly at high-pressures up to 600 MPa. Surprisingly, slightly increasing bioaccessibility correlated with both elevated pressures and extended holding times, indicating matrix-dependent processes during in vitro digestion, compared to results of extractability. Moreover, the verification of syringe filters for digest filtration resulted in the highest relative recoveries using cellulose acetate and polyvinylidene difluoride membranes. The α-tocopherol equivalent antioxidant capacity (αTEAC) and oxygen radical antioxidant capacity (ORAC) assays of treated kale samples, chopped larger in size, showed increased antioxidant capacities, regarding elevated pressures and extended holding times. Consequently, one may conclude that HPP was confirmed as a gentle treatment technique for lipophilic micronutrients in kale. Nevertheless, it was indicated that sample pre-treatments could affect HP-related processes in food matrices prior to and possibly after HPP.

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.

Applying Pulsed Electric Fields to Whole Carrots Enhances the Bioaccessibility of Carotenoid and Phenolic Compounds in Derived Products

We propose the application of pulsed electric fields (PEF) to carrots to obtain derived products with increased phenolic and carotenoid bioaccessibility. For this purpose, juices, purees, and oil-added purees were obtained from whole PEF-treated carrots (five pulses of 3.5 kV cm-1; 0.61 kJ kg-1). In order to obtain shelf-stable products, the effect of a thermal treatment (70 °C for 10 min) was also studied. Carrot juices exhibited the highest carotenoid (43.4 mg/100 g fresh weight) and phenolic (322 mg kg-1 dry weight) contents. However, caffeic and coumaric acid derivatives were highly sensitive to PEF. The phenolic bioaccessibility reached 100% in purees obtained from the PEF-treated carrots, whereas the further thermally treated oil-added purees exhibited the greatest carotenoid bioaccessibility (7.8%). The increase in carotenoid bioaccessibility could be related to their better release and solubilization into micelles. The results suggest that food matrix aspects apart from particle size (e.g., pectin characteristics) are involved in phenolic bioaccessibility.

Interactions between Blackcurrant Polyphenols and Food Macronutrients in Model Systems: In Vitro Digestion Studies

Blackcurrant pomace, rich in fiber and polyphenols, can be used as added-value ingredient for food formulation. However, the bounding of polyphenols to pomace and the interactions that take place with food nutrients modify polyphenol bioaccessibility. This work studied the interactions between polyphenols and the main macronutrients in foods, and the changes that occurred during in vitro digestion, using model systems. Model systems were formulated with (i) water, (ii) wheat starch, (iii) olive oil, (iv) whey protein, and (v) a model combining all the ingredients. Polyphenols were added from two sources: as pomace and as a polyphenolic pomace extract. Interactions between polyphenols and macronutrients were studied using light microscopy; total phenolic content (TPC) and antioxidant capacity (AC) were determined before and after the in vitro digestion process. Lastly, the bioaccessibility of the samples was calculated. Polyphenols incorporated into the model systems as pomace increased their bioaccessibility if compared to polyphenols added as extract. For single-nutrient model systems formulated with pomace, the bioaccessibility was higher than when the system contained all the nutrients. Of all the components studied, the greatest effect on bioaccessibility was observed for proteins.

Effect of pulsed electric fields on carotenoid and phenolic bioaccessibility and their relationship with carrot structure

Phenolic compounds (PC) and carotenoids from carrots are bound to dietary fibre or stored in vacuoles and chromoplasts, respectively. To exert their antioxidant effects these compounds must be released during digestion, which is hindered by such barriers. Pulsed electric fields (PEF) modify cell membrane permeability, thus enhancing their bioaccessibility. The effect of PEF on the carrot carotenoid and PC content and bioaccessibility was investigated. With this purpose, PEF-treated carrots (5 pulses of 3.5 kV cm^-1) were stored for 24 h at 4 °C and microstructure was evaluated before subjecting them to in vitro digestion. PEF did not affect carotenoid content, whereas their bioaccessibility improved (11.9%). Likewise, PEF increased the content of some PC, e.g. coumaric acid (163.2%), probably caused by their better extractability. Conversely, caffeic acid derivatives decreased, which may be associated to greater contact with oxidative enzymes. Total PC bioaccessibility (20.8%) and some derivatives increased, e.g. caffeoylshikimic (68.9%), whereas some decreased (e.g. ferulic acid). Structural changes caused by PEF may improve bioaccessibility of carotenoids and PC by favouring their release and easy access to digestive enzymes. However, other antioxidants may be further degraded or entrapped during digestion. Therefore, PEF is an effective technology for obtaining carrots with enhanced carotenoids and phenolic bioaccessibility.

Influence of simulated food and oral processing on carotenoid and chlorophyll in vitro bioaccessibility among six spinach genotypes

Increasing the density of micronutrients and phytochemicals in vegetable foods through plant breeding and processing is of value for consumers. However, the extent to which interactions between genetics and processing (G × P) can be leveraged for green leafy vegetables to improve the delivery of such compounds is unknown. Using spinach as a model, a three-phase in vitro digestion method with and without simulated oral processing (mastication) and coupling to a Caco-2 human intestinal cell culture model was used to determine whether bioaccessibility and intestinal uptake of carotenoids and chlorophylls can be modified from six spinach genotypes, fresh or processed as blanched, sterilized, and juiced products. Carotenoid and chlorophyll bioaccessibility varied significantly with the genotype (p < 0.001) and processing treatment (p < 0.001), with processing having a more profound influence on the bioaccessibility, decreasing micellarization of phytochemicals from juiced (25.8-29.3%), to fresh (19.5-27.9%), to blanched (14.9-20.5%), and sterilized spinach (10.4-13.0%). Oral mastication had a significant influence on the carotenoid bioaccessible content of sterilized spinach (0.3-0.5 μmoles per g DW) as compared to fresh spinach (0.1-0.3 μmoles per g DW), most likely due to the additive effect of thermal processing and mastication on facilitating digestive breakdown of the spinach matrix. Caco-2 accumulation of carotenoid and chlorophyll was modestly but significantly (<0.001) lower in fresh spinach (2.4%) compared to other treatment samples (3.7-4.8%). These results suggest that the genotype, processing treatment, and genotype × processing (G × P) interaction may affect carotenoid and chlorophyll bioaccessibility in spinach and that food processing remains a dominant factor in modulating the bioavailability of these phytochemicals.

Effect of in-vitro digestion on the bio active compounds and biological activities of fruit pomaces

The effect of gastro intestinal digestion on total phenolic contents (TPC), total flavonoid contents (TFC), radical scavenging activity (RSA) and vitamin C levels of apple (Malus domestica) pomace and a local variety of jujube (Ziziphus mauritiana) pomace was evaluated after drying at 110 °C for 3 h in a hot air oven. The physicochemical properties and functional properties of apple and jujube pomaces were also assessed. Prior to digestion, apple pomace displayed greater levels of TPC, RSA and vitamin C (17.30 ± 0.59 GAE/g DW, 81.16 ± 3.27%, 0.078 ± 0.01 g/L, respectively) in comparison with jujube pomace (16.90 ± 0.66 GAE/g DW, 54.65 ± 2.09%, 0.069 ± 0.01 g/L, respectively), whereas, TFC level was found to be higher in jujube pomace (19.22 ± 0.87 QE/g DW). After digestion, both samples showed an increase in TPC (56.17 ± 2.14 and 52.01 ± 2.18 GAE/g DW for apple and jujube pomaces) and TFC levels (48.45 ± 1.87 and 53.82 ± 2.34 QE/g DW for apple and jujube pomaces) and it was perceived almost 3 to 4 times higher than the TPC and TFC of the samples before digestion. But, RSA of the fruit pomaces were found to be affected by the in vitro digestion which was observed as 54.65 ± 2.09 and 81.16 ± 3.27% respectively for apple and jujube pomaces. It may be suggested that the fruit powders may be incorporated in developing new functional foods rich in bio active compounds and thus can be utilized in different food applications.

Digestive Stability and Bioaccessibility of Antioxidants in Prickly Pear Fruits from the Canary Islands: Healthy Foods and Ingredients

Although prickly pear fruits have become an important part of the Canary diet, their native varieties are yet to be characterized in terms of betalains and phenolic compounds. To exert potential health benefits, these antioxidants must be released from the food matrix and be stable in the gastrointestinal tract. Our aim was to characterize the betalain and phenolic profile of four prickly pear varieties from the Canary Islands (Spain) and determine their digestive stability and bioaccessibility via in vitro gastrointestinal digestion. Digestive studies were performed considering the (i) importance of the edible fraction (pulps) and (ii) potential of fruit peels as by-products to obtain healthy ingredients. Betalains and phenolic profiles were analyzed by HPLC-DAD-ESI/MS and HPLC-DAD-MS/QTOF. Pulps in Colorada and Fresa varieties presented high indicaxanthin and betanin content, respectively. Despite low pH in the gastric phase, betalains were stable to reach the intestinal phase, although indicaxanthin presented a higher bioaccessibility. Blanco Buenavista peels contained a distinct flavonoid profile including a new isorhamnetin-hexosyl-rhamnoside. Phenolic compounds were abundant and highly bioaccessible in fruit peels. These findings suggest that prickly pear pulps are rich in bioaccessible betalains; and that their peels could be proposed as potential by-products to obtain sustainable healthy ingredients.

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

Lucuma is a starchy orange-yellow fruit native to the Andean region. It is widely consumed in Latin America and has been recently adapted to the agronomical characteristics of the south region of Spain. However, its carotenoid profile has never been reported. The aim of this study was to characterize the carotenoid and carotenoid ester composition of lucuma pulps (var. Molina and Beltran) and assess their bioaccessibility with an in vitro simulated gastrointestinal digestion according to the INFOGEST® methodology. The carotenoid profile in lucuma pulps revealed a high qualitative diversity composed of 33 compounds, corresponding to 9 free xanthophylls, 9 hydrocarbon carotenes and 15 xanthophyll esters. (13Z)-violaxanthin, (all-E)-violaxanthin and (all-E)-antheraxanthin were the most abundant carotenoids in lucuma fruits and were naturally present as xanthophyll esters: (all-E)-antheraxanthin 3-O-palmitate, (all-E)-violaxanthin laurate and (all-E)-violaxanthin palmitate. Carotenoids were stable during in vitro digestion; however, their release from the food matrix was limited which contributed to their low bioaccessibility.

Sea Buckthorn Oil as a Valuable Source of Bioaccessible Xanthophylls

Sea buckthorn oil, derived from the fruits of the shrub, also termed seaberry or sandthorn, is without doubt a strikingly rich source of carotenoids, in particular zeaxanthin and β-carotene. In the present study, sea buckthorn oil and an oil-in-water emulsion were subjected to a simulated gastro-intestinal in vitro digestion, with the main focus on xanthophyll bioaccessibility. Zeaxanthin mono- and di-esters were the predominant carotenoids in sea buckthorn oil, with zeaxanthin dipalmitate as the major compound (38.0%). A typical fatty acid profile was found, with palmitic (49.4%), palmitoleic (28.0%), and oleic (11.7%) acids as the dominant fatty acids. Taking into account the high amount of carotenoid esters present in sea buckthorn oil, the use of cholesterol esterase was included in the in vitro digestion protocol. Total carotenoid bioaccessibility was higher for the oil-in-water emulsion (22.5%) compared to sea buckthorn oil (18.0%) and even higher upon the addition of cholesterol esterase (28.0% and 21.2%, respectively). In the case of sea buckthorn oil, of all the free carotenoids, zeaxanthin had the highest bioaccessibility (61.5%), followed by lutein (48.9%), making sea buckthorn oil a potential attractive source of bioaccessible xanthophylls.

Co-ingestion of red cabbage with cherry tomato enhances digestive bioaccessibility of anthocyanins but decreases carotenoid bioaccessibility after simulated in vitro gastro-intestinal digestion

The effects of co-digestion of red cabbage with carrot, baby spinach and/or cherry tomato on the bioaccessibility of anthocyanins and carotenoids such as α-carotene, β-carotene, lutein and lycopene were examined using a simulated in vitro gastro-intestinal digestion model. The individual vegetables and their mixtures were digested with and without added a standardised salad dressing. Bioaccessibility of total anthocyanins was enhanced by 10-15% (p < 0.05) when red cabbage was co-digested with the carotenoid-rich vegetables, except with carrot. In contrast, the co-digestion of red cabbage with carrot decreased bioaccessibility of total carotenoids by 21-33% (p < 0.05), and with cherry tomato by 42-56% (p < 0.05). The bioaccessibility of a given carotenoid varied depending on the vegetable matrix. Among the tested vegetable mixtures, red cabbage and baby spinach when co-digested demonstrated that anthocyanins and carotenoids were equally bioaccessible (total anthocyanin bioaccessibility of 62-66% and total carotenoid bioaccessibility of 66%).

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%.

Component analysis of nutritionally rich chloroplasts: recovery from conventional and unconventional green plant species

A study of the literature indicates that chloroplasts synthesise a range of molecules, many of which have nutritional value for humans, but the nutritional credentials of chloroplasts recovered from plant cells are not established. Chloroplast-rich-fractions (CRFs) were prepared from green plant species and the macro- and micro-nutrient composition compared with the whole leaf materials (WLMs). The results indicated that, on a dry weight basis, CRF material from a range of green biomass was enriched in lipids and proteins, and in a range of micronutrients compared with the WLM. Vitamins E, pro-vitamin A, and lutein were all greater in CRF preparations. Of the minerals, iron was most notably concentrated in CRF. Spinach CRFs possessed the highest α-tocopherol [62 mg 100 g^-1, dry weight (DW)], β-carotene (336 mg 100 g^-1 DW) and lutein (341 mg 100 g^-1 DW) contents, whilst grass CRFs had the highest concentration of alpha-linolenic acid (ALA) (69.5 mg g^-1). The higher concentrations of α-tocopherol, β-carotene, lutein, ALA and trace minerals (Fe and Mn) in CRFs suggested their potential use as concentrated ingredients in food formulations deficient in these nutrients.