Development of a green procedure of citrus fruits waste processing to recover carotenoids

In this study, an original and green procedure of processing waste of the citrus fruits was developed using the concept of bio-refinery, innovative techniques “ultrasound” and “micro-wave”, and a green solvent “limonene” to recover carotenoids. Essential oil extraction was performed by Solvent Free Microwave Extraction (SFME) and compared to steam distillation (SD). The essential oil yields were comparable for both processes: 4.02 ± 0.23% for SFME and 4.16 ± 0.05% for SD. After that, carotenoid extraction from citrus peels was performed by ultrasound-assisted extraction (UAE) and conventional extraction (CE) using d-limonene obtained starting from essential oil, as a solvent, and then compared to n-hexane extract. Response surface methodology (RSM) using central composite designs (CCD) approach was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE). The statistical analysis revealed that the optimized conditions of ultrasound power, temperature and time were 208Wcm−2, 20 °C and 5 min giving carotenoid content of 11.25 mg L−1. Compared to the conventional extraction, (UAE) gave an increase of 40% in carotenoid content. The comparison to n-hexane extract gave no significant changes in carotenoid content. Combination of microwave, ultrasound and d-limonene obtained from a bio-refinery of a by-product of citrus fruits industry allow us to develop a very good environmental green approach giving high added values compounds, with a saving of time, and a complete valorisation of waste

Extraction des huiles essentielles riches en anti-oxydants à partir de produits naturels et de co-produits agroalimentaires

De manière générale, l extraction des huiles essentielles préalable à l analyse chimique se compose de deux étapes : extraction et analyse. Alors que l étape analytique requiert en général quelques minutes, l étape d extraction nécessite plusieurs heures. C est le cas de la méthode de Clevenger, inventée en 1928 (Clevenger, 1928), qui est la procédure de distillation de référence. Depuis la découverte des effets thermiques des micro-ondes par Spencer en 1946, l impact des micro-ondes sur la matière a été largement caractérisé et validé par la communauté scientifique. Rapidement, les micro-ondes ont été utilisées pour l extraction dans le but de contrecarrer les limites des techniques d extraction conventionnelles. Notre travail a consisté en la conception, l optimisation et la valorisation d une technique d extraction des huiles essentielle pour les matrices végétales et co-produits alimentaires : l Hydrodiffusion assistée par micro-ondes et gravité (MHG). Une première partie du document est consacrée aux fondements et considérations théoriques des procédés conventionnelles et innovantes d extraction des molécules aromatiques. Une seconde partiedu manuscrit rappelle les techniques employées pour la conception et valorisation de la MHG.Enfin, la dernière partie du manuscrit traite des résultats obtenus et s articule selon trois sections distinctes : dans un premier chapitre, la mise au point, et l application du nouveau dispositif de laboratoire sont décrites. L originalité de l appareillage réside en une extraction rapide, non destructrices et généralisables à divers matrices végétales discutées dans un second chapitre. La compréhension du phénomène mis en jeu dans l extraction et l approche écologique de l invention fait l objet d un troisième et dernier chapitre.In most cases, sample preparation can be divided in two distinctive steps : extraction andanalysis. While analytical step requires few minutes, the extraction step requires severalhours. This applies to clevenger method, invented in 1928, which today is the reference fordistillation extraction. Since the discovery of thermal effects of microwaves by Spencer in1946, the impact of microwaves on the matter has been widely characterized and validated bythe scientific community. Quickly, microwaves were used for extraction to coutercatlimitations of conventional extraction procedures. Our work consisted of design, optimizationand development of a new extraction technique of essential oils in vegetables matrices andby-products of food industry. The first part of the document is devoted to understanding thetheorical foundations and considerations of conventional and innovative extractionprocedures. A second part of the manuscript refers to the techniques used for the design andoptimization of micowaves hydrodiffusion and gravity. Finally, the last part of the manuscriptdeals with the results obtained and is divided into three distinct sections: in the first chapter,the development, optimization and implementation of the new device and described. Theapparatus allows rapid and non destructive extractions that can generalized for variousvegetables matrices. This topic is discused in a second chapter. A phenomenoncomprehension of process extraction and the ecological approach of the invention, is thesubject of a third and final chapterAVIGNON-Bib. numérique (840079901) / SudocSudocFranceF

Extraction of green absolute from thyme using ultrasound and sunflower oil

Absolute is the plant aroma isolate mostly used in the food and fragrance sectors. The use of organic solvents constitutes the most commonly used method for obtaining this aroma. However, this technique may leave trace amounts of solvents which are considered undesirable for these industries. In this work, a new green extraction approach was implemented using ultrasound (US) with sunflower oil (SO) as a natural solvent to produce green absolute from thyme (Thymus vulgaris). US optimal conditions for absolute yield were investigated using response surface methodology (RSM) and compared to conventional SO (SO-CV) and hexane (Hex-CV) extractions. The absolutes were analyzed by GC-MS for their chemical composition and tested for their antioxidant activities (total phenols, DPPH and frying test). Optimized conditions obtained by RSM for absolute yield were T = 50 °C, t = 22 min, P = 98 W. The US using SO as solvent offers important advantages: shorter extraction time, increase of 47% in absolute yield compared to SO-CV extraction. Although the absolute obtained by hexane extraction provided improved yield (8.64 g/100 g DW), it contained around 75% of waxy materials. GC-MS analysis showed no remarkable variation of the chemical composition of the absolutes compared to those obtained by hexane extraction. Moreover, the US extraction allowed the highest recovery of monoterpene phenols thymol and carvacrol (86.2%). The absolute obtained by SO-US was free from waxes and organic solvent residues and exerted the highest antioxidant activity. Results show that ultrasound extraction using SO is a good alternative. It suggests the possibility of the production of green absolutes on pilot and industrial scale

Antioxidant activity, phenolic and flavonoid content in leaves, flowers, stems and seeds of mallow (Malva sylvestris L.) from North Western of Algeria

The nutraceutical composition (phenolics and flavonoids) of all leaves, flowers, stems and seeds of mallow, Malva sylvestris L., as well as their antioxidant properties were studied using in vitro methods: ferric reducing antioxidant power (FRAP) assay, by scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and total antioxidant capacity (TAC) based on the reduction of molybdenum (VI) to molybdenum (V). Results show that all extracts possessed concentration-dependant antioxidant activity. Leaf extracts have a highest amount of total phenolics with 24.123 ± 0.718 mg GAE/g, and total flavonoids with 0.694 ± 0.017 mg RE/100 g. However, the seed extracts presented the lowest amount in the two assays used. In addition, the AcOEt (EC50 = 3.10 mg/ml) fraction showed the highest value of antioxidant activities for almost all parts of leaves.Keywords: Malva sylvestris L., antioxidant activity, ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1- picrylhydrazyl (DPPH), total antioxidant capacity (TAC).African Journal of Biotechnology, Vol. 13(3), pp. 486-491, 15 January, 201