Whey protein and phenolic compound complexation: Effects on antioxidant capacity before and after in vitro digestion.

Whey protein isolate (WPI) interactions with (-)-epigallocatechin gallate (EGCG) and caffeic acid (CA) at pH 3.5 and 7.0 were investigated concerning complex formation and antioxidant capacity, before and after simulated digestion. Complex formation was evidenced by protein structural changes when WPI was associated with CA or EGCG. Reducing capacity and FRAP values increased as the phenolic compound concentration increased while ORAC values remained unchanged. In general, compared to the isolated compounds, complexation suppressed the antioxidant capacity possibly due to hydrophobic interaction and H-bonding between these compounds. Protein:phenolic complexation in 1:0.5 M ratio did not affect the digestibility compared to WPI (83%), except for WPI:CA at pH 7.0 (73%). The hydrophilicity profile of the digested samples suggested that pH of complexation and type of phenolic affected the protein cleavage pattern. Furthermore, the phenolic compounds were more stable when associated with the protein since they were protected from the simulated gastrointestinal environment.

Carotenoid esters analysis and occurrence: What do we know so far?

Carotenoids possessing hydroxyl groups can be found in nature both as free xanthophylls and as carotenoid esters, i.e. acylated with fatty acids. A single carotenoid can be acylated with different fatty acids, resulting in a high number of possible structures of carotenoid esters. The analysis of carotenoid esters can be challenging; although extraction techniques are essentially the same as those used for free carotenoids, depending on the sample composition, interfering compounds such as triacylglycerides are also present in the extract in significant amounts to cause high background noise and ionization suppression in mass spectrometric analysis. Besides analysis of UV-visible spectrum features, identification of carotenoid esters must include tandem mass spectrometry (MSn) because no changes in the carotenoid molecule chromophore occur due to acylation with fatty acids. Although carotenoid esters are widespread found in foods, especially in fruits, and their bioavailability is equivalent or even higher than that of the free carotenoid, occurrence of xanthophyll esters is very limited in human plasma and tissues. Challenges and further investigations needed on the topics above are given in this review.

Comparison of Two Static in Vitro Digestion Methods for Screening the Bioaccessibility of Carotenoids in Fruits, Vegetables, and Animal Products.

In vitro digestion methods are routinely used to assess the bioaccessibility of carotenoids and other dietary lipophilic compounds. Here, we compared the recovery of carotenoids and their efficiency of micellarization in digested fruits, vegetables, egg yolk, and salmon and also in mixed-vegetable salads with and without either egg yolk or salmon using the static INFOGEST method22 and the procedure of Failla et al.16 Carotenoid stability during the simulated digestion was ≥70%. The efficiencies of the partitioning of carotenoids into mixed micelles were similar when individual plant foods and salad meals were digested using the two static methods. Furthermore, the addition of cooked egg or salmon to vegetable salads increased the bioaccessibility of some carotenoids. Our findings showed that the two methods of in vitro digestion generated similar estimates of carotenoid retention and bioaccessibility for diverse foods.

Influence of salt on lipid oxidation in meat and seafood products: A review.

Sodium chloride, commonly known as salt, is a widely used additive in food industry due to its preservation and antimicrobial properties provided by its ability to reduce water activity. Moreover, the addition of salt to meat and seafood aims at improving water retention capacity and enhancing flavor due to its influence on the activity of some enzymes responsible for flavor development. On the other hand, salt added in meat and seafood can favor lipid oxidation, which is one of the main responsibles for quality losses in the food industry. In this review, the main mechanisms of fatty acids and cholesterol oxidation are described as well as the influence of salt on lipid oxidation in meat and seafood. Besides, the possible mechanisms of the pro-oxidant action of sodium chloride are presented and potential solutions to inhibit the salt action in lipid oxidation and decrease the salt content in food are discussed.

Microwave assisted direct saponification for the simultaneous determination of cholesterol and cholesterol oxides in shrimp.

A novel microwave-assisted direct saponification method for the simultaneous determination of cholesterol and cholesterol oxides in shrimp was developed and validated. Optimal saponification conditions, determined by means of an experimental design, were achieved using 500mg of sample and 20mL of 1mol/L KOH ethanol solution for 16min at 45°C at maximum power at 200W and magnetic stirring at 120rpm. Higher extraction of cholesterol oxides in a reduced saponification time (∼75 times) was achieved in comparison with the direct cold saponification method. The new method showed low detection (≤0.57µg/mL) and quantification (≤1.73µg/mL) limits, good repeatability (≤10.50% intraday and ≤8.56% interday) and low artifact formation (evaluated by using a deuterated cholesterol-D6 standard). Raw, salted and dried-salted shrimps were successfully analyzed by the validated method. The content of cholesterol oxides increased after salting and decreased after drying.

The Amazonian fruit Byrsonima crassifolia effectively scavenges reactive oxygen and nitrogen species and protects human erythrocytes against oxidative damage.

A hydrophilic extract of murici (Byrsonima crassifolia), a fruit native to the North and Northeast regions of Brazil, was evaluated in relation to its phenolic composition and in vitro antioxidant potential against some physiologically relevant reactive oxygen and nitrogen species. Additionally, the protective effect of murici extract against peroxyl radical (ROO)-induced toxicity to human erythrocytes was also determined. The major phenolic compound, determined by HPLC-DAD-MSn, was quercetin (2.72±0.35µg/mL). The extract was able to scavenge ROO (0.30±0.04µmoltroloxequivalent/mg), hypochlorous acid (IC50=10.0±0.1µg/mL), hydroxyl radical (IC50=7±1µg/mL) and peroxynitrite anion (IC50=21.0±0.6µg/mL and 17.0±1.6µg/mL, respectively, in absence and presence of NaHCO3). Human erythrocytes were subjected to oxidative damage, but murici extract was not able to inhibit hemolysis, even at the highest tested concentration. On the other hand, the extract inhibited hemoglobin oxidation (IC50=271±44µg/mL), lipid peroxidation (1000µg/mL) by 48±5%, depletion of glutathione (100µg/mL) by 49±2% and formation of its oxidized form (100µg/mL) by 96±4%.

Carotenoids and phenolic compounds from Solanum sessiliflorum, an unexploited Amazonian fruit, and their scavenging capacities against reactive oxygen and nitrogen species.

The composition of carotenoids and phenolic compounds from mana-cubiu (Solanum sessiliflorum), a fruit native to Amazonia, was determined by high-performance liquid chromatography coupled to diode array and mass spectrometry detectors (HPLC-DAD-MS(n)). The antioxidant capacities of the hydrophilic and carotenoid extracts against some reactive oxygen (ROO(•), H(2)O(2), HOCl, and HO(•)) and nitrogen (ONOO(-)) species were also determined. Seventeen carotenoids and three phenolic compounds were found in mana-cubiu. The major carotenoids were (all-E)-ß-carotene (7.15 µg/g of dry weight) and (all-E)-lutein (2.41 µg/g of dry weight). The 5-caffeoylquinic acid (1351 µg/g of dry weight) was the major phenolic compound, representing more than 78% (w/w) of the total phenolic compounds. Moreover, two dihydrocaffeoyl spermidines were found in the hydrophilic extract. Both mana-cubiu extracts were able to scavenge all the tested reactive species. The carotenoid extract was shown to be a potent scavenger of peroxyl radical, while the hydrophilic extract was a potent hydrogen peroxide and hypochlorous acid scavenger.

Microcapsules containing antioxidant molecules as scavengers of reactive oxygen and nitrogen species.

The antioxidant capacities of gum arabic and maltodextrin microcapsules containing antioxidant molecules (trolox, α-tocopherol, ß-carotene, apo-8'-carotenal and apo-12'-carotenal) against reactive oxygen and nitrogen species were evaluated. The scavenging capacities were influenced by the wall material, the reactive species, namely ROO(), H(2)O(2), HO(), HOCl and ONOO(-), and the antioxidant molecule. In general, a more pronounced enhancement of the antioxidant capacity due to incorporation of antioxidant molecules was observed in gum arabic microcapsules. The empty microcapsules showed capacity to scavenge all the studied ROS and RNS, being gum arabic a more potent antioxidant than maltodextrin. Apo-8'-carotenal incorporation promoted the highest increase in the scavenging capacities among the evaluated antioxidants, varying from 50% to 132% and from 39% to 85% for gum arabic and maltodextrin microcapsules, respectively, suggesting that this carotenoid presented the best balance between the molecule localization inside the microcapsules and the reactivity against the specific reactive species.

Development of a novel micro-assay for evaluation of peroxyl radical scavenger capacity: application to carotenoids and structure-activity relationship.

A micro-assay was developed and validated, using a microplate reader in 96-well format, C(11)-BODIPY(581/591) as fluorescent probe and AIBN as ROO() generator. The structure-activity relationship was established for 15 carotenoid standards, indicating that the opening of the ß-ionone ring and the increase of chromophore extension in the carotenoid structure were the major factors leading to the increase of ROO() scavenging capacity. The values for ROO() scavenging capacity were calculated using α-tocopherol as reference compound. Among the studied carotenoids, all-trans-lycopene was the most efficient ROO() scavenger (8.67±0.74) followed by all-trans-astaxanthin (6.50±0.62). All the carotenoids showed to be more effective ROO() scavengers than α-tocopherol and some hydrophilic compounds. Finally, the method was successfully applied to assay the ROO() scavenging capacity of carotenoid extracts from two Amazonian fruits, peach palm (7.83±0.21) and mamey (6.90±0.44).

Scavenging capacity of marine carotenoids against reactive oxygen and nitrogen species in a membrane-mimicking system.

Carotenoid intake has been associated with the decrease of the incidence of some chronic diseases by minimizing the in vivo oxidative damages induced by reactive oxygen (ROS) and nitrogen species (RNS). The carotenoids are well-known singlet oxygen quenchers; however, their capacity to scavenge other reactive species, such as peroxyl radical (ROO•, hydroxyl radical (HO•), hypochlorous acid (HOCl) and anion peroxynitrite (ONOO⁻), still needs to be more extensively studied, especially using membrane-mimicking systems, such as liposomes. Moreover, the identification of carotenoids possessing high antioxidant capacity can lead to new alternatives of drugs or nutritional supplements for prophylaxis or therapy of pathological conditions related to oxidative damages, such as cardiovascular diseases. The capacity to scavenge ROO•, HO•, HOCl and ONOO⁻ of seven carotenoids found in marine organisms was determined in liposomes based on the fluorescence loss of a fluorescent lipid (C11-BODIPY58¹/59¹) due to its oxidation by these reactive species. The carotenoid-bearing hydroxyl groups were generally more potent ROS scavengers than the carotenes, whilst ß-carotene was the most efficient ONOO⁻ scavenger. The role of astaxanthin as an antioxidant should be highlighted, since it was a more potent scavenger of ROO•, HOCl and ONOO⁻ than α-tocopherol.

Further insights on the carotenoid profile of the echinoderm Marthasterias glacialis L.

In this study, the carotenoid profile of the echinoderm Marthasterias glacialis L. was established using HPLC-DAD-APCI-MS/MS equipped with a C(30) column. This approach rendered the identification of 20 compounds, eight of them reported for the first time in this marine organism. Differentiation of carotenoid isomers was also achieved.

Optimization and validation of analytical conditions for cholesterol and cholesterol oxides extraction in chicken meat using response surface methodology.

The analytical conditions for the extraction of cholesterol and cholesterol oxides in chicken meat were optimized by means of response surface methodology. The separation and identification were performed by normal phase HPLC using UV and refractive index (RI) detectors, and the confirmation of the 11 cholesterol oxides identities in the samples was verified by HPLC-APCI-MS. The developed methodology showed good analytical performance, presenting recovery levels from 84 to 103% and detection limits varying from 0.01 to 0.06 microg/g for UV detection and from 1.98 to 2.12 microg/g for RI detection. The present study demonstrated the presence of 22 R-hydroxycholesterol, 24 S-hydroxycholesterol, and 22 S-hydroxycholesterol for the first time in chicken meat.