Extraction, encapsulation, and evaluation of the thermal properties of Grumixama (Eugenia brasiliensis)

Keywords: Eugenia brasiliensis; Encapsulated; Polyvinylpyrrolidone; Thermal.

Abstract: Grumixama is a native fruit of the Atlantic Forest that is still underexplored. The aim of this study was to investigate the thermal properties of pure and encapsulated extracts from the pulp of Eugenia brasiliensis. The extract was obtained from 8.75% of the fruit, using a mixture of ethanol and water (80:20 v/v), processed in an Ultraturrax at 12,000 rpm for 15 minutes. Encapsulation was carried out by adding polyvinylpyrrolidone (PVP, 0.5%) and Tween 80 (0.05%) to the same extract concentration. Differential Scanning Calorimetry (Shimadzu, model DSC-60 Plus) was performed by placing approximately 10 mg of sample in an aluminum pan (6.0 mm diameter). The analysis was conducted from 25 to 550 °C with a heating rate of 10 °C/min under a nitrogen flow of 50 mL/min. The DSC curves reveal significant changes in the thermal profile of the grumixama extract after its incorporation into the polymeric matrix, evidencing the formation of a solid dispersion. The thermogram of the free extract (A) exhibits marked thermal events, notably a broad endothermic dehydration event between 100 and 140 °C, followed by a sharp endothermic peak at 160 °C, associated with the melting or thermal decomposition of lower molecular weight compounds. In contrast, the profile of the encapsulated extract (B) shows the complete disappearance of the peak at 160 °C, indicating the transition from a crystalline state to a predominantly amorphous state. Furthermore, curve B showed a baseline stability plateau between 200 and 350 °C, with main thermal degradation shifts occurring only above 380 °C, featuring peaks at 460 °C and 495 °C. The absence of isolated extract thermal events in curve B demonstrates that the bioactive compounds were molecularly dispersed in the PVP (polyvinylpyrrolidone) matrix, which confirms the success of encapsulation in forming a homogeneous solid dispersion. Therefore, the encapsulated extract exhibits higher thermal stability up to approximately 350 °C when compared to the free grumixama extract.

The authors acknowledge the Graduate Program in Food Technology (PPGTA) of the Federal Technological University of Paraná (UTFPR), Campo Mourão campus, the National Council for Scientific and Technological Development (CNPq). CNPq Call No. 49/2024 – Junior Postdoctoral Fellowship – PDJ 2024, process No. 151797/2025-0, and CNPq Research Productivity Fellowship (302986/2025-1), and the Coordination for the Improvement of Higher Education Personnel (CAPES) No 001.