A green approach to the debittering of Lupinus Albus L.

Lupinus Albus L. has been widely used for human and animal consumption around the Mediterranean and Middle East, due to its interesting nutritional value, especially the high content of protein and carbohydrates. However, white lupin seeds cannot be consumed directly due to the high content of alkaloids, compounds that are toxic and confer a bitter taste. The traditional way to avoid this is successive rinsing and boiling with water, which uses a lot of water that becomes wastewater. The aim of this work is to propose an alternative method to extract the alkaloids from the seeds. Two methodologies were studied: extraction with water below its boiling temperature, and extraction with subcritical water, both under batch conditions. The main focus of this thesis was testing a set of extraction parameters: temperature, solventto-solid ratio, residence time, and successive extractions. White lupin seeds were first characterized, revealing a high content of protein (37%), carbohydrates (42%), and lipids (13%). The extraction study revealed a notable influence of temperature and solvent-to-solid ratio on the alkaloid yield. The best result achieved with waterbelow its normal point was at 80 °C, for 30 minutes and a 40:1 (water:lupin) ratio: 35.5% of the total amount of alkaloids present in the matrix were extracted. The best extraction result achieved with subcritical water was at 100 °C, for 60 minutes and a 40:1 (water:lupin) ratio: 77.4% of the total amount of alkaloids present in the matrix were extracted. At those conditions, other components were co-extracted, namely about 8 g/100 g lupin of carbohydrates, 7 g/100 g lupin of protein, and 4 g/100 g lupin of lipids. A second extraction assay, performed at the same experimental conditions as assay 1, using the lupin matrix obtained as solid residue in assay 1 but with fresh water, led to a negligible, further removal of alkaloids, both in experiments with water below its boiling temperature, and with subcritical wate