INTEGRAL EXPLOITATION FROM OLIVE CAKE FOR ENERGY PRODUCTION IN A BIOREFINERY SCHEME

Abstract This research aims to optimize the hydrothermal pretreatment based on previous studies, with the objective of extracting and determining value-added products from olive cake, and improve the energy solid properties. For this purpose, a hydrothermal pretreatment following of an autohydrolysis of the resulting solid were carried out in a biorefinery scheme. To the best of our knowledge this process has not been previously tested with olive cake by other authors. The conditions of the hydrothermal pretreatment were 30 °C and 1 h to prepare a suitable solid with mild conditions because polyphenols, water soluble extracts and tars precursors were eliminated. Sucrose was the value-added product with the best extraction 2.48% at this conditions. Therefore, resulting solids were subjected to an autohydrolysis to improve the value-added products extractions. The autohydrolysis was based on a design of experiments with temperatures of 120, 140, 160 and 180 °C and time of 30, 60 and 90 min to study the influence between the independent variables and the dependent variables (yield % and calorific value from each resulting solid and saccharides extractions from liquid extracted). The saccharides extracted were glucose, xylose, fructose, sucrose and glucose and xylose oligomers. Glucose and xylose oligomers contents were highest with 4 g and 19.24 g per 100 g of solid respectively. The solid energy properties were improved because a solid with a calorific value of 5970 kcal/kg was obtained. All experimental results were fitted to neural-fuzzy and polynomial model.