Thermal degradation of phenolic compounds and water adsorption isotherms of flours from jenipapo peel, pulp, and seeds

Abstract Jenipapo ( Genipa americana L.) is a Brazilian fruit known for its abundance of phenolic compounds, which have potential nutritional and technological applications. This study investigated the production of flours from the pulp (FP), peel (FC), and seeds (FS) of jenipapo, dried at 70 °C, by evaluating the degradation kinetics of total phenolic compounds (TPC), thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), and hygroscopic behavior through the determination of water adsorption isotherms. The results indicated that first-order models were effective in predicting the degradation of TPC in all flours, with a reduction in these compounds as storage temperature increased. The peel flour (FC) demonstrated a higher content of TPC and lower susceptibility to degradation at 30 and 40 °C, while the seed flour (FS) showed lower TPC content and shorter half-life times. Thermogravimetric analysis revealed three mass loss events in the flours, related to dehydration, decomposition of components such as proteins and lipids, and the formation of fixed mineral residue, with the greatest loss observed during the third event. Endothermic peaks were observed in all three flours during the gelatinization process. FTIR analysis confirmed the presence of various functional groups, highlighting the similarity between the samples. The water adsorption isotherms of all flours were well fitted by the GAB model and classified as type II at the studied temperatures. The peel flour stood out for having a higher content of phenolic compounds and greater stability during storage, favoring its bioactive potential. These findings highlight the potential application of jenipapo flours, particularly peel flour, as ingredients with relevant bioactive stability and hygroscopic behavior, supporting strategies for product development in the food industry. The demonstrated retention of phenolic compounds at lower storage temperatures and the defined water adsorption patterns reinforce their technological viability and potential functional contribution.