Profiling phenolic compounds in underutilized mango peel by-products from cultivars grown in Spanish subtropical climate over maturation course.

Nutraceutical market has undergone an exponential growth worldwide due to its health link-up. With the purpose of evaluating nutraceutical value, the phenolic composition of underutilized mango peel by-products of three cultivars ('Keitt', 'Kent' and 'Osteen') grown in Spanish subtropical climate was monitored at three maturation stages (green, ripe and overripe). Tracking the total phenol content, mango peels were figured out to have until twenty-seven fold higher than edible fraction. Mango peels comprised a wide range of phenolic compounds such as mono- and di-galloyl compounds, gallotannins, phenolic acids, benzophenones and flavonoids. The influence of both factors, cultivar and maturation degree, on the phenolic composition was the main outcome of the research. 'Keitt' mango peel was revealed as the cultivar with the highest phenolic content mainly due to the great quantities of galloyl glucose, 5-galloylquinic acid, digalloylquinic acid, hexagalloyl glucose and macluring galloyl glucoside detected. Regarding to the effect of maturation degree, green mango peels showed the highest amounts of polyphenols, although this behaviour could be dependent on the mango cultivar. Therefore, mango peels resulted to be a promising and low-cost resource of phenolic compounds to be exploited in food industry, but to enhance the nutraceutical value, factors such as cultivar and maturation degree should be taken into account.

HPLC-DAD-Q-ToF-MS profiling of phenolic compounds from mango (Mangifera indica L.) seed kernel of different cultivars and maturation stages as a preliminary approach to determine functional and nutraceutical value.

Mango seed kernel is a by-product which is usually discarded. However, it has been confirmed in this study that seed kernel exhibits more phenolic compounds with bioactive properties than edible fraction of mango. The influence of factors such as cultivar and maturation degree on the phenolic composition has been studied to evaluate nutraceutical value. The comprehensive analysis of phenolic composition by HPLC-DAD-Q-ToF-MS seed kernel from different cultivars ('Keitt', 'Kent'and 'Osteen') at five maturation stages was conducted. Results evidenced that 'Keitt' samples exhibited higher quantities of iriflophenone glucoside, maclurin C-glucoside, maclurin digalloyl glucoside, mangiferin, 5-galloyl quinic acid and trigalloyl glucose at the first three ripening stages. However, seed kernel from 'Osteen' variety showed higher amounts of hexa- and hepta-gallotannins whose concentrations diminished over the maturation course. Therefore, cultivar and maturation stage factors should be take into account due to their influence on the phenolic composition and subsequently on the nutraceutical value.

Pressurized GRAS solvents for the green extraction of phenolic compounds from hibiscus sabdariffa calyces.

An environmental friendly extraction procedure has been tested to extract phenolic compounds from H. sabdariffa calyces using pressurized GRAS solvents. A central composite rotatable design (CCRD) was performed to evaluate the influence of the main operational conditions: temperature (40-200 °C) and solvent composition based on aqueous hidroalcoholic solutions (0-100% ethanol). Phenolic composition of experimental extracts analyzed by HPLC-ESI-QTOF-MS showed that higher temperatures and greater ethanol percentages drove to solvents with lower dielectric constants, which resulted in extracts with major quantities of phenolic compounds. An exception was the extraction of cyanidin-3-sambubioside that could only be quantified in extracts performed at the lowest temperature (40 °C) due to its thermal sensibility. In addition, a RSM was carried out with the aim to maximize the extraction of total phenolic content. To this end, the predicted optimal extraction conditions by RSM were 200 °C and 100% (v/v) of ethanol. Results showed that temperature and ethanol percentage had a significant influence on the extraction of total phenolic compounds (p value < 0.05). The mathematical model pointed out 200 °C of temperature and 100% of ethanol as the optimum conditions to perform the isolation of phenolic compounds by means of pressurized GRAS solvents.

Implementation of subcritical water extraction with natural deep eutectic solvents for sustainable extraction of phenolic compounds from winemaking by-products.

In attempt to recover valuable phenolic compounds from grape pomace by-products, a new implemented methodology has been proposed. The subcritical water extraction technique has been implemented with the use of emerging eco-solvents such as natural deep eutectic solvents (NADESs). The extraction efficiency of different NADESs were screened. Among them, choline chloride containing urea as hydrogen bond donor was selected (ChClU). However, due to pressurised system and the viscosity of NADESs, ChClU could not be used as truly solvent but as a solvent modifier in an promising percentage of 30%. The optimum extraction temperature for the isolation of phenolic compounds was 100 °C since extractions above this temperature implied the loss of the original composition of grape pomace due to thermaldegradation reactions and neoformation of Maillard compounds. The employ of subcritical water combined with 30% of ChClU led to a significant rise of extracted phenolic compounds quantities in comparison with the solely use of subcritical water. Among them, the extraction of catechin and epicatechin suffered an increase of 45.05 and 47.98% respectively, so this implementation led to highly efficient and truly eco-friendly extraction method. The implementation of subcritical water with NADESs to extract valuable compounds from winery by-products has not been applied until now.

Acute study of dose-dependent effects of (-)-epicatechin on vascular function in healthy male volunteers: A randomized controlled trial.

BACKGROUND & AIMS: There is convincing clinical evidence to suggest that flavanol-containing foods/beverages are capable of inducing improvements in human vascular function. However, whilst (-)-epicatechin has been tested for efficacy, a full dose-dependency has yet to be established, particularly at doses below 1 mg/kg BW. The current study examined the dose-dependent effects of (-)-epicatechin on human vascular function with concurrent measurement of plasma (-)-epicatechin metabolites and levels of circulating nitrite and nitrate species, NOx. METHODS: An acute, double-blind, placebo-controlled, crossover intervention trial was conducted in 20 healthy males with 4 treatment arms: water-based (-)-epicatechin (0.1, 0.5 and 1.0 mg/kg BW) and a water only as control. Vascular function was assessed by flow-mediated dilatation (FMD) measured at the brachial artery, laser Doppler imaging with iontophoresis (LDI) at the subcutaneous capillaries of the forearm (response to Ach and SNP) and peripheral blood pressure (BP) at baseline, 1, 2, 4 and 6 h post-intervention. Plasma analysis of epicatechin metabolites was conducted by LC-MS and circulating plasma of nitrite and nitrate species were performed using an HPLC-based system (ENO-30). RESULTS: Significant increases in % FMD were found to occur at 1 and 2 h following intake of 1 mg/kg BW, and at 2 h for the 0.5 mg/kg BW intake. There were no significant changes in LDI or BP at any time-points or intake levels. Increases in FMD over the 6 h timeframe were closely paralleled by the appearance of total plasma (-)-epicatechin metabolites. Non-significant changes in circulating NOx was observed. CONCLUSIONS: Our data add further evidence that (-)-epicatechin is a causal vasoactive molecule within flavanol-containing foods/beverages. In addition, we show for the first time that intake levels as low as 0.5 mg/kg BW are capable of inducing acute improvements in vascular function (FMD) in healthy volunteers.

Oak wood extracts as natural antioxidants to increase shelf life of raw pork patties in modified atmosphere packaging.

The use of antioxidants and refrigeration storage in modified atmosphere packaging, MAP, are the main strategies to slow down the oxidative and microbial deterioration of fresh meat. Synthetic antioxidants are commonly used for this purpose, however due to their controversial health effects, natural alternatives for their replacement are being looked for. The main aim of this work is the evaluation of pressurised aqueous extracts from oak wood as natural preservative of pork patties. The effect of different amounts of oak wood extracts (0.05, 0.5 and 1.0%) on the self-life of pork patties packed in MAP in refrigeration during 12 days were studied in comparison with the use of sodium ascorbate as synthetic preservative. Samples treated with oak wood extracts showed lower lipid oxidation, higher antioxidant capacity and an inhibitory effect on the enterobacteria growth. Furthermore, the addition of oak wood extracts resulted in a dramatically decrease of the volatile compounds coming from the lipid oxidation reactions. On the other hand, it is noteworthy that the use of oak wood extracts modified sensorial characteristics. Intensity colour was higher and new sensorial features such as oak wood and sweet spices appeared which were well appreciated.

Enhanced and green extraction of bioactive compounds from Lippia citriodora by tailor-made natural deep eutectic solvents.

Natural deep eutectic solvents (NADESs) have been postulated as alternative green solvents for the isolation of valuable bioactive compounds from Lippia citriodora. Thus, 11 different NADESs, based on choline chloride (ChCl) as the hydrogen bond acceptor in combination with different hydrogen bond donors (organic acids, polyalcohols, sugars, and urea) were tested. According to the results obtained, ChCl-lactic acid exhibited the highest extraction yield for iridoids, 7.25 mg g-1, phenylpropanoids, 17.23 mg g-1, and flavonoids, 9.02 mg g-1 being significantly greater than phenylpropanoid and flavonoid yields, 15.63 and 5.43 mg g-1 respectively, extracted with methanol as conventional solvent. Subsequently, in order to optimise the most influential microwave assisted extraction (MAE) parameters, a Box-Behnken design paired with a response surface methodology were implemented. Temperature and water content showed a strong effect on the extraction of polyphenol sub-classes, while the effect of irradiation time was less noticeable on extraction yields. Temperature of 63.68 °C, a water content of 32.19% and a microwave irrdiation time of 17.08 min were the optimum conditions provided by the statistical program. The use of NADESs showed potential to facilitate the design and customisation of green tailor-made solvents which have greater extraction capacity than conventional organic solvents.

Alternative amendment for vineyards from by-products of pyro-bituminous shale: Effect on wine amino acids and biogenic amines.

With the aim of looking for a model of agroecological production, the use of by-products from pyro-bituminous shale as amendment, and its effect on wine amino acids and biogenic amines has been evaluated. Field trials aimed to compare the effect of different doses of conventional and limestone shale from by-products of pyro-bituminous. Four replicates for six different fertilization treatments were arranged in a split plot design during 2009/2010 and 2010/2011 vintage. A chromatographic analysis was carried out to evaluate the impact of fertilization treatments on the amino acid and biogenic amine content of wines produced. Results showed few significant differences among fertilization treatments tested according to the amino acids composition of wines, although it seemed that a combination of conventional and pyro-bituminous shale could be the best option. By-products of pyro-bituminous shale seem to be a good partial substitutive amendment for Brazilian vineyards. This research seems to be a new approach for sustainable revalorization of domestic fertilizers to enable minor environmental impacts and lower production costs without detriment to quality.

Assessment of flavanol stereoisomers and caffeine and theobromine content in commercial chocolates.

Assessment of the flavanol composition of 41 commercial chocolates was by HPLC-DAD. Among individual flavonols ranged from 0.095 to 3.264mgg(-1), epicatechin was the predominant flavanol accounting for 32.9%. Contrary to catechin, epicatechin was a reliable predictive value of the polyphenol content. Conversely the percentage of theobromine used as a proxy measure for nonfat cocoa solids (NFCS) was not a good predictor of epicatechin or flavanol content. In a further chiral analysis, the naturally occurring forms of cocoa flavanols, (-)-epicatechin and (+)-catechin, was determined joint the occurrence of (+)-epicatechin and (-)-catechin due to the epimerization reactions produced in chocolate manufacture. (-)-Epicatechin, the most bioactive compound and predominant form accounted of 93%. However, no positive correlation was found with% cocoa solids, the most significant quality parameter.

Comparison of extraction methods for volatile compounds of Muscat grape juice.

Typical flavour of Muscat d'Alexandrie wines is mainly due to volatile compounds coming from grapes of this variety. Therefore, the choice of grapes is crucial to obtain musts with a great aromatic potential, which will contribute to the final aroma of wines derived from those musts. In this study, three sampling techniques, liquid-liquid extraction (LLE), solid phase extraction (SPE) and simultaneous distillation-extraction (SDE), were compared for the analysis of volatile compounds in Muscat grape juice. Results showed that although the three techniques can be recommended for the quantitative analysis of volatile compounds from musts, LLE and SPE are better sample preparation techniques than SDE, mainly for determination of polar compounds such as acids or alcohols.