Laboratory-Scale Optimization of Roasting Conditions Followed by Aqueous Extraction of Oil from Wild Almond

The effects of roasting and aqueous extraction conditions for oil recovery from wild almond were optimized using response surface methodology (RSM). Optimum conditions for oil extraction were obtained at 142 °C roasting temperature, 16.5 min roasting time, 5.67 extraction pH and 4.6 h extraction time. Under these conditions, the extraction yield of 34.5% (w/w, based on the original weight of the sample) was obtained, which is equivalent to 80.0% of the total oil in the kernel. This was lower than that obtained by hexane Soxhlet (HS) extraction (43.1%, w/w, considered as 100% of total oil) but higher than that of cold pressing (CP) (18.5%, w/w; i.e., 42.9% of total oil). The refractive indices and saponification values of the oils were not affected by the extraction method. However, fatty acid and tocopherol compositions and DPPH radical scavenging capacities as well as unsaponifiable matter, iodine, peroxide and acid values of the obtained oils were impacted by the extraction method. The results showed that the quality attributes (omega-6 fatty acid content, peroxide and acid values, total tocopherol contents and antioxidant activity) of the oil obtained by AEP were somewhat similar to those of the oil extracted by CP and much superior to those of the oil obtained by HS.