RECENT ADVANCES ON STABILITY OF ANTHOCYANINS

Since Neolithic era, natural pigments have been added to foods and colour of food products is still one of the major concerns of food industry. Anthocyanins are the most noticeable group among coloured flavonoids, widely existing in the roots, stems and leaves as well as flowers and fruits of the vascular plants. They have a high potential for use as natural colorants instead of synthetic pigments because of their attractive colour and pharmacological properties. Stable and attractive colours are a highly valued attribute in competitive food industry. Considerable studies have been done on the effects of the most important chemical and physical factors involved in the stability of anthocyanins (temperature, light, pH, SO2, metal, sugar, ascorbic acid and oxygen), their concentrations, chemical structures, and matrix food compositions. Furthermore, the effects of separation technologies including microwave/ultrasound assisted extraction (MAE, UAE), and Colloidal Gaz Aphron (CGA) fractionation on the stability of anthocyanins are reviewed

Microwave assisted extraction of bioactive saponins from the starfish Echinaster sepositus: Optimization by response surface methodology and comparison with ultrasound and conventional solvent extraction

International audienceMicrowave assisted extraction (MAE) was investigated for the extraction of total saponins compounds from the starfish Echinaster sepositus. In order to achieve optimization of microwave extraction and to determine the influence of each operational variable (the solvent concentration (X1), irradiation time (X2), microwave power (X3), and liquid-solid ratio (X4)) on the extraction of saponins, response surface methodology (RSM) coupled with a Box–Behnken design (BBD) was applied. The optimized experimental conditions were 58.7 % aqueous methanol as solvent, 177 W as microwave power for 3 min irradiation time at 43.6 mL g−1 of liquid-solid ratio. The extraction yield under these conditions was 60.3 ± 0.6 mg g−1. The optimized MAE was compared with other methods, ultrasound assisted extraction (UAE) and with conventional solvent extraction (CSE). It was demonstrated that microwave produced saponins extraction 7.8 times as more as that produced by CSE and 3.3 as more as UAE has produced. From the in vitro hemolytic tests and electro-generated O2[rad]− quenching tests, we have noted that the microwave saponins extract was the most active one comparing with both UAE and CSE extracts

Removal of lead(II) from water using activated carbon developed from jujube stones, a low-cost sorbent

International audienceABSTRACT: The preparation of activated carbon from jujube stones with H2SO4 activation and its ability to remove lead from aqueous solutions were reported in this study. The surface structure of the activated carbon was characterized by various physico-chemical methods. Sorption studies were carried out by varying the initial metal ion and the pH: the amount of sorbed Pb(II) ions increased with increasing pH and initial Pb(II) ions concentration. The removal of lead ions was rapid and the kinetic of sorption can be well described by pseudo-second order modelling. The Langmuir model conveniently fits the data of isotherm experiments and the monolayer sorption capacity of Pb(II) ions was determined as 71.43 mg/g at pH 6.0 and 25°C. These results showed that activated carbon prepared from jujube stones could be considered for application as a potential sorbent for the removal of lead from wastewaters. © 2016 Taylor & Francis

Pistacia lentiscus leaves as a source of phenolic compounds: Microwave-assisted extraction optimized and compared with ultrasound-assisted and conventional solvent extraction

Microwave assisted extraction (MAE) was investigated for extraction of total phenolic compounds (TPC expressed as gallic acid equivalents GAE) from the leaves of Pistacia lentiscus L. with maximized total phenolic yield using response surface methodology (RSM) coupled with a Box-Behnken design. The optimal MAE processing parameters were 46% ethanol, extraction time 60s, potency density 17.86W/mL, and liquid/solid ratio 28:1, with an extraction yield of 185.69\ub118.35mgGAE/gdw. The optimized MAE was compared with another emerging technology (ultrasound assisted extraction, UAE) and with conventional solvent extraction (CSE) giving higher extraction yields of TPC, total flavonoids and tannins and comparable antioxidant capacity (according to the radical ABTS assay)

Valorization of Citrus limon residues for the recovery of antioxidants: Evaluation and optimization of microwave and ultrasound application to solvent extraction

Microwave and ultrasound-assisted extraction of phenolic compounds from C. limon peels were compared.\u2022Response surface methodology successfully employed to optimize the extraction processes.\u2022Better performance of microwave extraction than both ultrasound and conventional process. Ultrasound assisted extraction (UAE) and microwave-assisted extraction (MAE) were optimized (by response surface methodology, RSM) and compared for the recovery of total phenolic compounds (TPC expressed as gallic acid equivalents (GAE)) from Citrus limon peels. The optimized result for MAE was 48% ethanol as extraction solvent, 28:1. mL/g of solvent: solid ratio, 123. s and 400. W for irradiation time and power. The optimized result for UAE was 63.93% ethanol as extraction solvent, 40. mL/g of liquid/solid ratio, 15.05. min of holding time and 77.79% for amplitude. Maximum predicted TPC recoveries under the optimized conditions for MAE and UAE were 15.74 and 15.08. mg GAE/g respectively, which were close to the experimental values of 15.78. \ub1. 0.8 and 15.22. \ub1. 0.88. mg GAE/g, indicating suitability of the employed model and the success of RSM in optimizing the extraction conditions. The antioxidant activity determined by the DPPH and reducing power tests confirmed the suitability of MAE for the preparation of antioxidant-rich plant extracts

Optimization of Ultrasound-Assisted Extraction of Phenolic Compounds from Citrus sinensis L. Peels using Response Surface Methodology

The aim of this study was the optimization, by Response Surface Methodology (RSM), of Ultrasound Assisted Extraction (UAE) conditions for the recovery of phenolic compounds from C. sinensis peels with aqueous acetone at room temperature. A Central Composite Rotatable Design (CCD) was applied to determine the effects of extraction time (X1, 5-15 min), extraction amplitude (X2, 30-70%), and acetone concentration (X3, 30-70 %) on Total Phenolic Content (TPC expressed as Gallic Acid Equivalents GAE, according to the Folin\u2019s assay) of the extract. The independent variables were coded at five levels and their actual values were selected based on the results of single factor experiments. Results showed that acetone concentration and extraction amplitude were the most significant (p<0.05) factors affecting the TPC yield. The optimum extraction conditions were found to be 8.33 min extraction time, 65.94 % extraction amplitude and 75.79 % acetone concentration. Under the optimized conditions, a TPC yield of 13.57\ub10.71 mgGAE/gdw was obtained which resulted very close to the predicted value of 14.16 mgGAE/gdw

Saponin contents in the starfish Echinaster sepositus: Chemical characterization, qualitative and quantitative distribution

International audienceIn this study, we report the inter-organ, the sexual and the seasonal variability, of saponins contained in the common Mediterranean starfish Echinaster (Echinaster) sepositus. Saponins were extracted from five distinct body components namely the stomach, the pyloric caeca, the gonads, the oral body wall and aboral body wall. Of both sexes (males and females) collected at different seasons, the saponins mixtures were analyzed by Mass spectrometry (HR-ESI-MS and HR-ESI- MS/MS). Semi-quantitative approach was performed to estimate the variability of the saponin amounts. Our results demonstrated that the diversity of saponins in E. sepositus is higher than previously reported. We highlighted 11 different saponins, including 9 new congeners. Presumptive molecular structures are proposed for 6 molecules on the basis of key-fragmentations identified by HR-ESI-MS/MS. The comparison of the saponin contained in the five different body components revealed that minimum 3 saponins are common in all tissues. In addition, qualitative and quantitative variability of saponins compounds were linked to the organ, sex and the collecting season. The relative highest level of saponins was found in the stomach on the period of active feeding (winter). The significant higher levels of saponins were found in the gonads and oral body wall on the spawning period (summer). Generally, a great inter-organ, sexual and seasonal variability was found in both sexes. These results suggest that saponins probably fulfill several biological functions in E. sepositus. © 2021 Elsevier Lt

Removal of Methylene Blue from aqueous solutions by adsorption on Kaolin: Kinetic and equilibrium studies

International audienceRemoval of Methylene Blue (MB) from aqueous solutions is studied using a raw Algerian kaolin sample as a low-cost adsorbent. The effects of pH, contact time, dye concentration and temperature are all taken into consideration. The adsorption kinetics results are adjusted to best fit the pseudo-second order model. The experimental data are analyzed by Langmuir isotherms, revealing that the maximum adsorption capacity of MB on this kaolin sample equals 52.76 mg/g at T = 25 °C and pH = 6.0. The calculated thermodynamic data demonstrates that adsorption is spontaneous and enhanced at higher temperatures. Desorption studies with water indicate that the adsorbent could successfully retain MB, even after four cycles. From these results, it can be considered that the raw Algerian kaolin sample tested herein is effective in the removal of MB from aqueous solutions and moreover may be used as an alternative to high-cost commercial adsorbents. © 2017 Elsevier B.V