Residue from Passion Fruit Processing Industry: Application of Mathematical Drying Models for Seeds

The objective of this research was to study the drying kinetics of passion fruit seeds, a byproduct of the industrial processing of passion fruit with the potential to elaborate food products such as oil and flour. After drying, the seeds were directed for cold press oil extraction, and the quantification of fatty acids was performed. Following the oil extraction, the residues underwent a grinding process to produce flour, which was characterized in terms of its nutritional aspects. The drying process was conducted using an experimental forced convection dryer with controlled temperatures of 40, 50, 60, and 70 °C, and a drying air velocity of 1.5 m s−1. This work introduced a novel approach using mathematical models, all derived from Fick’s equation. For each model, the activation energy and thermodynamic properties related to the drying procedure were determined. Fatty acids in the oils and physicochemical characteristics of the defatted residue’s flour were also analyzed. The Cavalcanti Mata, Henderson and Pabis, and Page models modified by Cavalcanti Mata were found to best fit the experimental data. The highest proportions of unsaturated fatty acids in passion fruit oil were linoleic acid (Omega-6) at 68.8% and oleic acid (Omega-9) at 16.1%. The predominant saturated fatty acid was palmitic acid at 10.61%, with no significant differences observed in relation to the drying temperatures. It can be concluded that the composition of the flour from the residue of passion fruit grain oil extraction varies in terms of crude fiber content, ranging from 56.36% to 58.8%, and protein content, ranging from 15.6% to 18.26%, with significant differences observed concerning the drying temperatures. The lipid content varied from 13.5% to 13.76%, with no significant differences observed across the evaluated drying temperature variations.