Goldenberry (Physalis peruviana L.) seed oil: press extraction, optimization, characterization, and oxidative stability

In order to optimize the screw-press extraction conditions of oil from goldenberry (Physalis peruviana L.) seeds obtained from nectar processing waste, a face centered design was applied. The oil was extracted at different temperatures (60, 80, and 100 degrees C) and seed moisture contents (8, 10, and 12%). Oil recovery (OR) increased and residual oil in the cake decreased significantly as moisture content and temperature were reduced; oil moisture and volatile matter as well as acid value, K-232, K-268, and p-anisidine, respectively, decreased proportionally with the moisture extraction. Thus, the highest OR (86.4%) and the best quality were obtained at 8% moisture content and 60 degrees C pressing temperature. Under these conditions, the extracted oil presented high linoleic acid (76.0%), iodine value (140.0 mg I-2 /g), and refractive index (1.4769). The oil stability index, measured by Rancimat, varied from 3.65 h (120 degrees C) to 14.87 h (100 degrees C); the predicted shelf life at 25 degrees C was 120.4 days and the activation energy was 85.6 kJ/mol. The results highlighted that screw-pressing of goldenberry seeds provides quality oil without employing polluting and hazardous solvents.