Extração assistida por ultrassom e encapsulação de betacianinas de frutos de pitaya (Hylocereus spp.) em fibras ultrafinas de zeína pela técnica de electrospinning

Abstract

The pitaya is a cactus of tropical origin and is easily adapted to subtropical climates. Its cultivation and management are recent in some countries such as Brazil. The genus Hylocereus is cultivated for fruiting and the fruits of the species H. polyrhizus and H. undatus are easily found in the market. The peels, which represent 33% of the fruit weight, are discarded after consumption or pulp processing, increasing the amount of solid waste discarded in the environment. This material, as well as the pulp, has a high bioactive potential due to the presence of phenolic compounds and betacyanins, a major betalain subgroup in pitaya fruits. These pigments are sensitive to some factors such as temperature variations, changes in the pH scale, exposure to light and oxygen and, therefore, limit their applicability in the industry. One way to improve its resistance to deleterious factors is through encapsulation. This type of technology involves the application of a wall material that will envelop the bioactive and increase its resistance to degradation. Electrospinning encapsulation, a technique that uses electrostatic forces, can be used to encapsulate betacyanins from pitaya fruits. It has some advantages such as not using high temperatures and total solvent evaporation during processing. Therefore, the objective of this work was to extract betacyanins from the fruit skins of two pitaya species through the ultrasound-assisted extraction process and to evaluate the potential of betacyanin encapsulation from the pulp by the electrospinning technique. The dissertation was subdivided into two chapters, in the first an optimization of the ultrasound-assisted extraction process of betacyanin from the barks of H. polyrhizus and H. undatus was developed, and the extracts obtained through the optimum point were quantified in terms of color parameters, total phenolics and antioxidant activity. In the second, the extraction of betacyanins from the pulp,9 total phenolic compounds, antioxidant activity and encapsulation by electrospinning were studied. With the optimization of the extraction process (Chapter 1) it was possible to obtain a predictive linear model for the extraction of betacyanins from the skins of two species of pitaya fruits. Extracts from the optimal extraction point obtained similar betacyanins, coloration, total phenolic compounds and radical scavenging activity ABTS•+ and DPPH•, confirming that the model can be used for both species. In chapter 2, the same content was evaluated in the pulp extract (H. polyrhizus), where higher values of betacyanins, total phenolic compounds and ABTS•+ and DPPH• radical scavenging activity were obtained. Furthermore, it was possible to encapsulate different concentrations of betacyanins extracted from the pulp in ultrafine zein fibers by the electrospinning technique. This study can be used as a basis for future work