Kinetic and Compositional Study of Phenolic Extraction from Olive Leaves (var.Serrana) by Using Power Ultrasound

[EN] Power ultrasound is being used as a novel technique for process intensification. In this study, the feasibility of using power ultrasound to improve the phenolic extraction from olive leaves was approached taking both compositional and kinetic issues into account and also determining the influence of the main process parameters (the electric power supplied, emitter surface and temperature). For this purpose, the extraction kinetics were monitored by measuring the total phenolic content and antioxidant capacity and mathematically described by Naik's model, and HPLC DAD/MS MS was used to identify and quantify the main polyphenols. The electric power supplied and the emitter surface greatly affected the effective ultrasonic power applied to the medium, and hence the extraction rate. However, the influence of temperature on ultrasound assisted extraction was not clear. Compared with conventional extraction, ultrasound assisted extraction reduced the extraction time from 24 h to 15 min and did not modify the extract composition. Industrial relevance: Olive crop produces a significant quantity of byproducts (leaves, branches, solid and liquid wastes), coming from the tree pruning, fruit harvest and oil production, which are rich in phenolic compounds with bioactive properties. The extraction of the bioactive compounds could be an interesting option with which to increase the value of these byproducts, as it requires efficient extraction techniques in order to reduce processing costs and improve productivity. In this sense, ultrasound assisted extraction is considered a novel technique used as ameans of intensifying a slow process, such as the leaching of polyphenols fromvegetablematrices. In order to further address the industrial applications of ultrasound assisted extraction, a kinetic study should be carried out determining both the effective energy introduced into the medium, as well as its influence on the extract quality.The authors thank the Generalitat Valenciana (PROMETEO/2010/062 and PROMETEO/2012/007) for its financial support. M. H. Ahmad Qasem was the recipient of a fellowship from Ministerio de Educacion, Cultura y Deporte of Spain (Programa de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion).Ahmad-Qasem Mateo, MH.; Canovas, J.; Barrajon-Catalan, E.; Micol, V.; Cárcel Carrión, JA.; García Pérez, JV. (2013). Kinetic and Compositional Study of Phenolic Extraction from Olive Leaves (var.Serrana) by Using Power Ultrasound. Innovative Food Science and Emerging Technologies. (17):120-129. https://doi.org/10.1016/j.ifset.2012.11.008S1201291

Pre-treatment and extraction techniques for recovery of added value compounds from wastes throughout the agri-food chain

The enormous quantity of food wastes discarded annually force to look for alternatives for this interesting feedstock. Thus, food bio-waste valorisation is one of the imperatives of the nowadays society. This review is the most comprehensive overview of currently existing technologies and processes in this field. It tackles classical and innovative physical, physico-chemical and chemical methods of food waste pre-treatment and extraction for recovery of added value compounds and detection by modern technologies and are an outcome of the COST Action EUBIS, TD1203 Food Waste Valorisation for Sustainable Chemicals, Materials and Fuels

Optimization of Multistage Extraction of Olive Leaves for Recovery of Phenolic Compounds at Moderated Temperatures and Short Extraction Times

The aim of the present study was to improve the recovery of polyphenols from olive leaves (OL) by optimizing a multistage extraction scheme; provided that the olive leaves have been previously steam blanched. The maximum total phenol content expressed in ppm caffeic acid equivalents was obtained at pH 2, particle size 0.315 mm, solid-liquid ratio 1:7 and aqueous ethanol concentration 70% (v/v). The optimum duration time of each extraction stage and the operation temperature, were chosen based on qualitative and quantitative analysis of oleuropein (OLE), verbascoside, luteolin-7-O-glucoside and apigenin-7-O-glucoside performed by high performance liquid chromatography with diode array detector (HPLC-DAD). The optimum conditions for multistage extraction were 30 min total extraction time (10 min × 3 stages) at 85 °C. The 80% of the total yield of polyphenols was obtained at the 1st stage of the extraction. The total extraction yield of oleuropein was found 23 times higher (103.1 mg OLE/g dry weight (d.w.) OL) compared to the yield (4.6 mg OLE/g d.w. OL) obtained by the conventional extraction method (40 °C, 48 h). However, from an energetic and hence from an economical point of view it is preferable to work at 40 °C, since the total extraction yield of polyphenolic compounds was only 17% higher for a double increase in the operating temperature (i.e., 85 °C)