Recovery of bioactive compounds from beet leaves through simultaneous extraction: Modelling and process optimization

Extraction of bioactive compounds from beet leaves was studied for the valorization of this by-product. The objective of this work was to optimize the extraction of total phenolic compounds (TPC), betacyanins (BC) and betaxanthins (BX) from beet leaves through a liquid:solid process with low environmental impact. For this propose, kinetic aspects of the extraction process at 30 and 80 degrees C were evaluated, finding that times higher than 60 min were unfavourable for betalainic pigments since degradation was observed. Thereafter a Plackett-Burman design was applied to study the effect of several extraction variables on the efficiency of the process. Accordingly, temperature, %EtOH and solid:liquid ratio were selected as the most significant variables for a further optimization. Finally, Response Surface Methodology was employed in order to simultaneously maximize the three responses. The extraction conditions that achieve this goal were: 61 degrees C, 80% EtOH and r of 1:10, under which the bioactive concentrations were: 31.7 mg AG/g DM, 0.78 mg/g DM, 2.17 mg/g DM for TPC, BC and BX, respectively. The study proposes a simple and reasonably efficient method to produce a rich in phenolics, bright red purple extract, which can be later processed to be used in several applications for the food industry. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.