Enhancing oilseeds cold pressing techniques based on HAZOP analysis for prickly pear seeds, Opuntia ficus-indica (L.) Mill.

Abstract

The main goal of the present study was to determine optimal conditions for the extraction of oil with high added value by cold pressing technique. Namely the feeding conditions of the Opuntia ficus-indica (L.) Mill. (OFI) seeds, as well as the definition of the manipulable variables of the Kern-Kraft 20 press were specified. These specifications combine HAZOP (Hazard and Operability) analysis and experience plan to find out correlation between yield and oil quality with the pressure, temperature, nozzle diameter, residence time, pressing speed while considering high hardness level of the seed under study. The seed oil extracted according to the proposed approach was highly unsaturated where linoleic acid is the main fatty acids (60.42 % of total fatty acids), followed by oleic acid (21.65 %), palmitic acid (12.24 %), and stearic acid (3.88 %), respectively. Furthermore, it is worth mentioning that beta-sitosterol and gamma-tocopherol were the principal components of sterols and tocopherols representing 67.56 % of total sterols and 330 mg.kg^-1 of total tocopherols. The proposed approach applied to prickly pear seeds had preserved the tocopherol fraction (796.70 mg.kg^-1 of total tocopherols) about two times more than other cold-pressed seed oils approaches. Based on trial-and-error conditions, no additional operating problem even has been reported with a seed of high level of hardness. Seed should be introduced with a humidity level of 10 % without grinding. Moreover, no heating should be supplied and an optimal pressing speed of 30 and a nozzle diameter of 15 mm.