Óleo e biodiesel de uricuri (Scheelea phalerata Mart. Ex Spreng)

Abstract

Scheelea phalerata Mart. ex Spreng (Arecaceae), popularly known as uricuri, is a native amazonian palm tree, which has seeds with significant amounts of oil that can be used in the production of biodiesel. This study aimed to chemically characterize the oilseed of uricuri in order to add value to this important non-timber forest product. Two lots of oilseeds were obtained from Comunidade do Roque, located in the Extractive Reserve of Juruá. The two lots of oilseed were submitted to standard physico-chemical methods used to analyze vegetable oil described by AOAC and Moretto and Fett: acid value, iodine value, peroxide value, saponification number, unsaponifiable matter and specific gravity. Lot 1 presented low acid value, whereas lot 2 a higher value. For both lots the unsaponified value was considered low. The fatty acid composition was obtained by GC-FID by two different methods and it could be observed that most of them were saturated with short carbon chain. In all experiments, biodiesel analysis was performed by HPLC with a UV detector (215 nm). In normal phase, it was not possible to separate all components of biodiesel mixtures. Moreover some of them have very different response to the detector; therefore it was not possible to analyze biodiesel by normal phase HPLC. In the reversed phase, the separation of all components could be accomplished with good separation and time analysis. The ester value was determined by the quantification of FAME by RP-HPLC using the external standard method. Lot 1, with low acid value, was converted into biodiesel by transesterification with methanol (molar proportion of 1:6) employing three different basic catalysts. The best result, considering the yield, the quality determined by the specific gravity and the conversion determined by ester value, was obtained using 1 % NaOH at 50 ºC for 2 h. The acid catalysis in the transesterification process was studied with lot 2 due to its higher acid value. Three variables were evaluated: type of alcohol (methanol vs. ethanol), temperature and time. The best condition was achieved with ethanol at 75 ºC, using as catalyst 1M of HCl. Some of the components of unsaponifiable matter were isolated by chromatography and their characterization was done by MS and NMR experiments (1H and 13C, COSY, HSQC, HMBC). In fraction Fr4 a mixture of hydrocarbons was identified by GC-MS. In fraction Fr7, a mixture of methyl esters was identified by GC-FID. In fraction Fr14, a cis/trans mixture of 9-10-epoxy-stearic acid was identified.