Ultrasound-assisted extraction of phenolic compounds from mexican jackfruit (Artocarpus heterophyllus Lam.) pulp and their antioxidant activity

Abstract

In Mexico, jackfruit is one of the least known and underutilized fruits in the states of Jalisco and Nayarit; therefore, production is mainly exported. However, an estimated 10% of the total production does not meet the minimum requirement for quality standards. On the other hand, since jackfruit is not widely used, it represents an opportunity for research to provide an added value. Studies in this thesis showed that jackfruit and its by-products could promote the generation of functional ingredients with nutraceutical characteristics. Jackfruit pulp and peel’s nutritional and techno-functional characteristics showed that both have great potential as functional ingredients, depending on the application or food matrix. In recent years, the use of ultrasound (US) processing to extract bioactive compounds from plant matrices has increased. Thus, this research aimed to evaluate the effect of different ultrasonic treatments to assist the extraction process from jackfruit pulp powder, increase total phenolic compound content, and analyze their antioxidant capacity. A three-factor Box-Behnken design was used; here, processing time (5, 17.5, 30 min), solid/ liquid ratio (S/L; 1:5, 1:15, 1:25 g/mL), and the ultrasonic amplitude (40, 70, 100%) variables were considered to study the variations in the total phenolic content (TPC), and the antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS) techniques. In addition to physicochemical and nutritional characterization, results showed that the S/L ratio had the most significant effect on the TPC. However, there were no significant differences between the TCP values obtained from ultrasound-treated and untreated samples. The maximum phenolic compounds yield from the US-treated samples was 1.48 ± 0.02 mg GAE/g, achieved by using 100% amplitude for 17.5 min with an S/L ratio of 1:25 g/mL. Additionally, no correlation between the TPC and antioxidant capacity was determined. The highest antioxidant capacity determined by the ABTS assay was 1.29 ± 0.60 mg AAE/g, achieved by using 40% amplitude for 17.5 min with an S/L ratio of 1:25 g/mL. However, from the chromatograms, differences were observed between the treated and untreated samples since the peaks of the treated sample from fresh jackfruit pulp obtained a higher signal than the other samples. The phenolic compounds identified by HPLC in jackfruit pulp extracts were hydroxybenzoic acid, catechin, protocatechuic acid, chlorogenic acid, coumaric acid, and luteolin.