Cordia dichotoma: Estudo do comportamento térmico e avaliação da composição nutricional

Abstract

The present study aimed to evaluate the thermal behavior and nutritional content of the lyophilized peel and pulp of Cordia dichotoma fruit. Fruits were collected in Campo Grande (MS), sanitized, and separated into peel and pulp fractions. The samples were frozen and lyophilized to obtain dry and stable material. Subsequently, each fraction was ground using a knife mill to improve homogeneity. For Thermal Analysis (TG/DTG), samples were subjected to heating rates of 5, 10, 15, and 20 °C.min-1 from ambient temperature up to 900 °C under air and nitrogen atmospheres, with a flow rate of 60 mL.min-1. Differential Scanning Calorimetry (DSC) was also performed at a heating rate of 10 °C.min-1 from ambient temperature up to 500–550 °C to identify endothermic and exothermic events. Nutritional composition was determined in duplicate: moisture by oven drying (105 °C), ash by incineration, protein by modified Kjeldahl method, lipids by Soxhlet extraction, and carbohydrates by difference. TG/DTG assays demonstrated high reliability with confirmed reproducibility in triplicate. In air atmosphere, the peel showed adjusted R² values between 0.8609 and 0.8872, and angular coefficients (β₁) ranging from −0.6818 %.min-1 to −2.8280 %.min-1, reflecting initial moisture removal and gradual decomposition of organic components. Under nitrogen, these parameters improved slightly (R² from 0.8845 to 0.8966; β₁ from −0.6989 %.min-1 to −2.6046 %.min-1). For the pulp, the linear models fit even better: in air, R² ranged from 0.9269 to 0.9447 and β₁ from −0.6096 %.min-1 to −2.5245 %.min-1; in nitrogen, R² was 0.9144 with β₁ from −0.6189 %.min-1 to −2.2765 %.min-1, indicating a faster pyrolysis kinetics for the pulp. DSC curves revealed endothermic peaks between 500 and 550 °C, attributable to the cleavage of cellulose and hemicellulose bonds, with energy absorption characteristic of lignocellulosic materials, corroborating previous studies on phase transitions in biomaterials. Nutritional analysis showed that the pulp had a higher moisture content (76.16%) compared to the peel (60.55%). However, the peel contained higher amounts of carbohydrates (6.68% vs. 1.71%), protein (4.53% vs. 2.48%), lipids (16.36% vs. 1.42%), and ash (2.98% vs. 2.60%) in the fresh fruit. In summary, the experimental protocol proved robust and reproducible, allowing differentiation of thermal behavior between peel and pulp under distinct atmospheres. The thermal and nutritional characterization provides valuable insights for industrial, pharmaceutical, and waste valorization applications of C. dichotoma, contributing to sustainable processes and innovations in biotechnological materials.