Extração de compostos antociânicos de frutos de jambolão (Syzygium cumini L.) e sua incorporação em fibras ultrafinas de zeína

Abstract

Jambolan is a fruit rich in bioactive compounds, especially anthocyanins. Anthocyanins are non-toxic natural pigments belonging to the group of flavonoids, which have several biological properties, such as antioxidant and antimicrobial activity. The anthocyanins present in jambolan fruits are promising compounds for replacing synthetic dyes for the elaboration of active and intelligent packaging for food. The aim of this study was to optimize the extraction of anthocyanins from jambolan, using a 2³ multivariate design, with central and axial points, having as variables temperature, time and concentration of ethanol/water. The jambolan extract obtained at the optimal point of extraction was characterized and added to the polymeric solution of zein at concentrations of 0, 20, 30 and 40% (w/w) for the production of fibers by the electrospinning technique. The extraction conditions (temperature from 30 to 95 ºC, time from 5 to 120 minutes and ethanol/water ratio from 0 to 100%) allowed the identification of the following anthocyanins: delphinidin 3,5-diglycoside (Del3,5D(1) and Del3,5D(2)), petunidin 3,5-diglycoside (Pet3,5D(1) and Pet3,5D(2)), malvidin 3,5-diglycoside (Mal3,5D) and petunidin 3-glycoside (Pet3G) . The optimal condition for the extraction of anthocyanins was 30 ºC for 5 minutes of extraction, using only acidified water (0% ethanol). The total content of anthocyanins present in the extract was 142.88 mg/100g, with delphinidin 3,5- diglycoside as the major compound, representing 39.05% of the anthocyanins identified. The fibers obtained were ultra-fine, uniform and continuous with a diameter ranging from 472 to 622 nm, encapsulation efficiency of up to 66.8%, contact angle ranging from 94.4° to 64.4° and high antioxidant activity (58.8% inhibition by the ABTS•+ method). The colorimetric profile of jambolan anthocyanins extract at different pH proved to be a viable option for application as an indicator of pH change in smart packaging. Therefore, the ultra-fine fibers produced in this study have promising characteristics for the development of active/intelligent food packaging.