Optimisation of an ultrasound-assisted extraction method for the simultaneous determination of phenolics in rice grains

Fifteen phenolic compounds were determined in rice grains by ultrasound assisted extraction and ultra-performance liquid chromatography with photodiode array detection. Primarily, an UAE method has been developed and validated for the extraction of phenolics from rice grains. For the optimization, a Box–Behnken Design based on six factors including extraction temperature (10–70 °C), solvent composition (0–50% methanol in water), cycle (0.2–0.7 s−1), ultrasound amplitude (30–70%), and solvent to sample ratio (2.5:1 to 5:1) was employed. Multi-response optimization (MRO) was performed to develop a simultaneous extraction method of 15 phenolics. The optimal UAE conditions were: extraction temperature 45 °C, time 25 min, cycle 0.4 s−1, ultrasoundamplitude 47%, solvent composition 80% methanol in water at pH 4.25, and sample to solvent ratio1:5. Linearity, LODs, LOQs, precision and recovery were determined. In addition, the method was successfullyapplied to analyse a number of rice samples with different varietie

A comparison study between ultrasound-assisted and enzyme-assisted extraction of anthocyanins from blackcurrant (Ribes nigrum L.)

Blackcurrant (Ribes nigrum L.) is a fruit rich in vitamins, fatty acids, minerals, essential oils and phenolic com-pounds, including anthocyanins. In the present work, two anthocyanin extraction methods from blackcurrant samples based on Ultrasound-Assisted Extraction (UAE) and Enzyme-Assisted Extraction (EAE) have been developed. A Plackett-Burman design with seven variables has been preliminary used for both UAE and EAE in order to determine the most influential variables in each methodology. After that, a Box-Behnken design was employed to optimize the extraction methods. The composition of the extraction solvent (% EtOH in water) has been the most influential variable for both UAE and EAE. The optimal extraction times have been 5 min for UAE and 10 min for EAE. No differences have been observed in anthocyanin extraction with both methodologies. Both methods have been applied to blackcurrant-derived products and proven their suitability for quality control analysis.This work has been supported by the project "EQC2018-005135-P" (Equipment for liquid chromatography by means of mass spectrometry and ion chromatography) of the State Sub-program of Research In-frastructures and Technical Scientific Equipment

Ultrasound-assisted extraction of amino acids from grapes

Recent cultivar techniques on vineyards can have a marked influence on the final nitrogen content of grapes, specifically individual amino acid contents. Furthermore, individual amino acid contents in grapes are related to the final aromatic composition of wines. A new ultrasound-assisted method for the extraction of amino acids from grapes has been developed. Several extraction variables, including solvent (water/ethanol mixtures), solvent pH (2–7), temperature (10–70 C), ultrasonic power (20–70%) and ultrasonic frequency (0.2–1.0 s 1), were optimized to guarantee full recovery of the amino acids from grapes. An experimental design was employed to optimize the extraction parameters. The surface response methodology was used to evaluate the effects of the extraction variables. The analytical properties of the new method were established, including limit of detection (average value 1.4 mmol kg 1), limit of quantification (average value 2.6 mmol kg 1), repeatability (average RSD = 12.9%) and reproducibility (average RSD = 15.7%). Finally, the new method was applied to three cultivars of white grape throughout the ripening period

Multiresponse optimization of a UPLC method for the simultaneous determination of tryptophan and 15 tryptophan-derived compounds using a Box-Behnken design with a desirability function

A Box–Behnken design was used in conjunction with multiresponse optimization based on the desirability function to carry out the simultaneous separation of tryptophan and 15 derivatives by Ultra Performance Liquid Chromatography. The gradient composition of the mobile phase and the flow rate were optimized with respect to the resolution of severely overlapping chromatographic peaks and the total run time. Two different stationary phases were evaluated (hybrid silica and a solid-core-based C18 column). The methods were validated and a suitable sensitivity was found for all compounds in the concentration range 1–100 lg L–1 (R2 > 0.999). High levels of repeatability and intermediate precision (CV less than 0.25% and 1.7% on average for the retention time and the signal area, respectively) were obtained. The new method was applied to the determination tryptophan and its derivatives in black pigmented glutinous and non- lutinous rice grain sample

Fast Determination of Phenolic Compounds in Rice Grains by Ultraperformance Liquid Chromatography Coupled to Photodiode Array Detection: Method Development and Validation

There are several phenolic compounds in rice grains providing benefits for human health. The concentration of phenolic compounds in rice is strongly affected by the polishing steps during rice production. A new sensitive ultraperformance liquid chromatography−ultraviolet−visible spectroscopy method with a photodiode array detection protocol has been developed and validated for the quantitation of phenolic compounds in rice grains. Several working variables and two different columns were evaluated. Finally, a less than 3 min analysis time was developed to achieve enough resolution for the simultaneous determination of the 20 most common phenolic compounds in rice. The analytical properties for the separation method produced an adequate sensitivity for all phenolic compounds in the regular range for phenolics in rice, 0.5−100 mg L−1 (R2 > 0.997), with high precisions for both repeatability and intermediate precisions (coefficients of variation less than 0.4 and 2.5% for the retention time and area of the peaks, respectively)

Valorization of microalgae biomass as a potential source of high-value sugars and polyalcohols

In the current context of global warming and fossil fuel depletion, the aim of the EU Blue Growth concept is to support sustainable growth in the marine and maritime sectors. A crucial issue under this initiative is the valorization of microalgae biomass. The production of sugar and polyalcohols from microalgae Nannochloropsis gaditana, Arthrospira platensis, and Pyrocystis lunula has been studied in the context of this initiative. Using fresh and/or atomized samples, several extraction methods were assayed. In brief, two types of lysis (mechanical and ultrasonic), variations in temperature and treatments times, and treatments with HCl and maceration. The obtained mono-saccharides, di-saccharides and polyalcohols were analyzed by HPLC. Best obtained results were for saccharose with the HCl treatment and mannitol with maceration treatment extracted from N. gaditana biomass (160250 and 72148 mg/L respectively). These results may open new routes for the commercial exploitation of microalgae biomass as a completely novel raw material for the food, drinks and pharmaceuticals manufacturing industries

Optimization of the ultrasound-assisted extraction of anthocyanins and total phenolic compounds in mulberry (Morus nigra) pulp

New ultrasound-assisted extraction methods for the determination of anthocyanins and total phenolic compounds present in mulberries have been developed. Several extraction variables, including methanol composition (50–100%), temperature (10–70 C), ultrasound amplitude (30–70%), cycle (0.2–0.7 s), solvent pH (3–7) and solvent-solid ratio (10:1.5–20:1.5) were optimized. A Box–Behnken design in conjunction with a response surface methodology was employed to optimize the conditions for the maximum response based on 54 different experiments. Two response variables were considered: total anthocyanins and total phenolic compounds. Extraction temperature and solvent composition were found to be the most influential parameters for anthocyanins (48 C and 76%) and phenolic compounds (64 C and 61%). The developed methods showed high reproducibility and repeatability (RSD < 5%). Finally, the new methods were successfully applied to real samples in order to investigate the presence of anthocyanins and total phenolic compounds in several mulberry jams

Extraction of Anthocyanins and Total Phenolic Compounds from Açai (Euterpe oleracea Mart.) Using an Experimental Design Methodology. Part 3: Microwave-Assisted Extraction

In this work, two methods based on microwave-assisted extraction techniques for the extraction of both anthocyanins and total phenolic compounds from acai have been developed. For that, a full factorial design (Box-Behnken design) has been used to optimize the following four variables: solvent composition (25-75% methanol in water), temperature (50-100 degrees C), pH (2-7), and sample/solvent ratio (0.5 g: 10 mL-0.5 g: 20 mL). The anthocyanins and total phenolic compounds content have been determined by ultra high-pressure liquid chromatography and Folin-Ciocalteu method, respectively. The optimum conditions for the extraction of anthocyanins were 38% MeOH in water, 99.63 degrees C, pH 3.00, at 0.5 g: 10 mL of ratio, while for the extraction of total phenolic compounds they were 74.16% MeOH in water, 99.14 degrees C, pH 5.46, at 0.5 g: 20 mL of ratio. Both methods have shown a high repeatability and intermediate precision with a relative standard deviation lower than 5%. Furthermore, an extraction kinetics study was carried out using extraction periods ranging from 2 min until 25 min. The optimized methods have been applied to acai-containing real samples. The results with such real samples have confirmed that both methods are suitable for a rapid and reliable extraction of anthocyanins and total phenolic compounds

Optimization by Means of Chemometric Tools of an Ultrasound-Assisted Method for the Extraction of Betacyanins from Red Dragon Fruit (Hylocereus polyrhizus)

Betacyanins have been reported to provide prominent health-promoting effects, in addition to contributing to the exotic color and pleasant palate of red dragon fruit that has been attracting universal interest for over a decade. An accurate determination of betacyanins in dragon fruit is important if we are to benefit from the nutraceutical features of these compounds. Seven betacyanin pigments have been identified and extracted by means of ultrasound-assisted techniques from red dragon fruit. Chemometric tools such as Box-Behnken Design (BBD) in conjunction with response surface methodology (RSM) have been successfully used to evaluate and optimize the relevant extraction variables i.e., temperature (A: 10, 35, 60 degrees C), solvent composition (B: 20, 50, 80% methanol in water), sample to solvent ratio (C: 0.1:10, 0.2:10, 0.3:10 g/mL), power (D: 20, 45, 70%), and cycle (E: 0.3, 0.5, 0.7 s(-1)). The results obtained from the analysis of variance (ANOVA) suggest that the solvent composition (p 0.0063), sample to solvent ratio (p 0.0126), and cycle (p 0.0302) are the most influential variables in betacyanin extraction. The optimal variable settings for ultrasound-assisted extraction (UAE) were a 54.6 degrees C extraction temperature, 0.3 s(-1) cycle, 20% ultrasound power, 21.4% methanol in water solvent composition, 0.2:10 sample to solvent ratio, and a 5 min extraction time. The validation of the method for repeatability and intermediate precision provided excellent results at 1.56% and 2.94% respectively. Furthermore, the novel UAE method was successfully used for the determination of betacyanins content in red dragon fruit from different geographic origins.This work has been supported by the project "EQC2018-005135-P" (Equipment for liquid chromatography by means of mass spectrometry and ion chromatography) of the State Subprogram of Research Infrastructures and Technical Scientific Equipment

How Different Cooking Methods Affect the Phenolic Composition of Sweet Potato for Human Consumption (Ipomea batata (L.) Lam)

In recent years, there has been increasing interest in the functional components of sweet potato because of its nutritional and medicinal value. The aim of this study is to analyse how much sweet potato phenolic compounds composition (derived from caffeoylquinic acids) varies as a result of cooking. Traditional techniques such as: boiling, oven roasting and more recent processing techniques such as microwave cooking were tested. Three sweet potato varieties were cooked for different periods of time and under different conditions. Ultrasound-assisted extraction (UAE) was used to extract the compounds of interest and then, a chemometric tool such as Box-Behnken design (BBD) was successfully used to evaluate and optimise the most influential factors in the extraction, i.e., temperature, solvent composition and sample-to-solvent ratio. The optimal settings for UAE were: solvent 100% methanol, a temperature of 39.4 degrees C and a mass/volume ratio of 0.5 g per 10 mL solvent. Oven roasting of sweet potatoes resulted in increased levels of caffeoylquinic acids, whereas prolonged cooking times in water resulted in decreasing levels of the same.This work has been supported by the project "EQC2018-005135-P" (Equipment for liquid chromatography by means of mass spectrometry and ion chromatography) of the State Subprogram of Research Infrastructures and Technical Scientific Equipment