Convective drying of papaya seeds (Carica papaya L.) and optimization of oil extraction

• Papaya seeds were dried under different conditions in order to obtain oil.
• The best drying conditions were air temperature of 70 °C and air velocity of 2.0 m s−1.
• The seed oil yield (SOY) was 19.23%.
• SOY was related with structural modifications in the papaya seeds.
• Papaya seed oil presented 90% of oleic acid and 5% of linoleic acid.

The convective air drying of papaya seeds was studied in order to optimize the seed oil yield. Papaya seeds were dried under different conditions of air temperature and air velocity. The operation was characterized by drying rate and drying kinetic curves. Oil was extracted from the seeds, obtained in all drying conditions and, the yield was optimized. The results revealed that the constant rate and falling rate periods occurred during the convective air drying of papaya seeds. The Overhults kinetic model was suitable to represent the experimental drying curves. The optimal drying conditions, which provided the maximum seed oil yield, were: air temperature of 70 °C and air velocity of 2.0 m s−1. In these conditions, the seed oil yield was 19.23% and the final moisture content was 7.40% (w.b.). High quality oil, with about 90% of oleic acid, was obtained from papaya seeds.