406: Ultrasound Technology for the Optimization of Antioxidant Extracts From Red Beetroot

Introduction

Ultrasound (US) technology provides a promising approach for valorizing co-products, such as waste beetroot, to produce extracts with high antioxidant properties. This efficient extraction method, with its short processing times, offers the potential to generate new ingredients at reduced production costs, making them suitable for food industry applications. However, careful optimization is essential to ensure the highest extract quality. Therefore, the aim of this study was to optimize the production of antioxidant extracts from red beetroot using US technology.

Methods

US extraction process was optimized employing a Box-Behnken experimental design with three factors and three levels, resulting in 15 experimental trials. The independent variables were the solvent-to-solid ratio (fixed as 20, 30, and 40), amplitude percentage (fixed as 40, 70, and 100%) and time (fixed as 1, 2, and 3 min). Dried beetroot powder was employed as the raw material, and acidified ethanol (pH = 3) served as the extraction solvent. Total phenolic content (TPC) and antioxidant capacity (using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2-2’-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS), ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) assays) were determined. These were treated as dependent variables in the model. Response surface methodology was employed to optimize the independent variables and maximize the responses of dependent variables.

Results

The solvent-to-solid ratio was the only variable to have a significant impact on the extraction of bioactive compounds from beetroot using US. This factor notably influenced the TPC, ABTS, FRAP, and ORAC values. Through the application of this design, the optimal extraction conditions were established, which included a solvent-to-solid ratio of 30, an amplitude of 100%, and a processing time of 3 min. Under these optimal conditions, the predicted concentrations of bioactive compounds were 971.65 mg gallic acid equivalents/100 g for TPC, and the predicted antioxidant capacities were 1229.44 mg ascorbic acid equivalents/100 g for ABTS, 13532.89 µmol Fe2+/100 g for FRAP, and 63.27 mg trolox/g for ORAC.

Significance

The solvent-to-solid ratio was the only variable that significantly influenced US extraction, demonstrating that higher ratios enhance the production of extracts with greater antioxidant capacity in 3-min processing times.

Authors: Noemí Echegaray, Rubén Agregán, Mirian Pateiro, José Ángel Pérez-Álvarez, Juana Fernández-López, Roberto Bermúdez, Rubén Domínguez-Valencia, José Manuel Lorenzo