An attempt to improve the traditional olive (Olea europaea) oil eco-extraction as applied in the Bouzeguène municipality (Northern Algeria)

Abstract

This work is an attempt to improve the traditional olive (Olea europaea L.) oil (OO) eco-extraction (TOOEE) as applied in the Bouzeguène municipality (extreme south-east of Tizi-Ouzou, chief town of the region of the same name located 100 km east of Algiers). The improvement concerns the possible replacement of the direct solar drying (DSD), habitually applied before OO extraction, by indirect solar drying (ISD). For comparison purpose, oven drying (OD) was also considered. The drying kinetics of fresh olives (FOs), OO yield (OOY, % w/w in relation to the FO weight), rate of released olive vegetation water (OVW, % w/w in relation to the FO weight), and OO physicochemical quality parameters (free acidity (FA, % w/w oleic acid), specific extinction coefficient at 230 (K230) and 270 nm (K270), etc.) were investigated. For the three drying procedures tested, the quadratic equation was found to correctly describe the whole drying curves, with R2 and mean absolute percentage error (MAPE) varying from 0.995 (case of ISD) to 0.999 (case of DSD) and from 5 (case of DSD) to 21.33 % (case of ISD), respectively. The DSD-dried olives and ISD-dried olives gave the OOY of 11 % on average with a release of only 0.20 % OVW. For physicochemical parameters, the results were contradictory. For example, the mean FA value for OO from DSD-dried olives (DSD-OO) was ∼ 2.86 % (against ∼ 4.57 % for OO from ISD-dried olives (ISD-OO)) while the mean radical scavenging activity (RSA) for ISD-OO was ∼ 34 % (against ∼ 18 % for DSD-OO). This study confirms the ecological character of the TOOEE and the possibilities of its improvement, which could make it inspiring for all the actors of the field.