Bioprospecting for seed oils from wild plants in the Mediterranean Basin for biodiesel production

Abstract

In the Mediterranean Basin, petroleum energy resources are scarce. For an environmentally sustainable solution, the seeds collected from wild plants indigenous to this area could be used as biodiesel producers to meet the energy demand. For this, the fatty acid profiles of seed oils from 127 species belonging to 30 plant families, all native of the Mediterranean Basin, were surveyed in a search for fossil-fuel substitutes. The saponification number (SN, mg KOH/g), iodine value (IV, g I2/100 g), cetane number (Ф), higher heating value (δ, MJ/kg), cold filter-plugging point (CFPP, °C), density (ρ, g/cm3), induction period (IP, h) and kinematic viscosity (η, mm2/s) were empirically determined and then used to establish the suitability of the different seed oils for biodiesel production. The aptness to serve as biodiesel was determined by applying the specification for biodiesel standard made by several organizations. In addition to three already well-characterized species, the fatty acid methyl esters from the seeds of Conium maculatum (Ф = 53.7; δ = 40.1), Eryngium maritimum (Ф = 53.2; δ = 40.2), Nigella damascena (Ф = 58.1; δ = 40.1), Portulaca oleracea (Ф = 62.9; δ = 40.5), Prangos uechtritzii (Ф = 52.8; δ = 40.1), and Tribulus terrestris (Ф = 59.4; δ = 40.1), meet the major quality standards set by several organizations, and thus are suitable for biodiesel production. Data from empirical models used for estimating biodiesel properties was compared with experimental data from biodiesel prepared with available seeds, and good correlations between the two methodologies were found.The sowing of selected species in natural habitats, in addition to providing a valuable resource, i.e. biodiesel, both the Mediterranean Basin ecoregions and unproductive agricultural lands could be improved as appropriate habitats for wildlife, and in parallel this action would create employment in rural areas using natural resources.