Alkaloid analysis and reduction in lupins (Deliverable 6.4)

Lupins contain alkaloids, plant defence substances that can be toxic to humans and animals above a certain dose. Determining alkaloids content in grain lots and, when needed, debittering lupins are two crucial steps to grant their use in food production and increase their economic value. The alkaloid content should be determined after the first rough pre-cleaning of the harvest, taking a representative sample taken from all “layers” of the lupin batch. A wide-ranging alkaloid content may result from harvests from different fields (batches), which should be stored separately (e.g. in big bags) until the analysis results are available. In this way, contamination of good batches with bitter batches can be avoided. Approximately 200 grams of lupins are taken from this homogenised bulk sample and sent in as a laboratory sample. If the alkaloid content exceeds the guideline value of 200 ppm (or mg/kg, or 0,02%) of dry matter, the lupins can either be used as animal feed (guideline value of 500 ppm) or debittered. A reference debittering method includes the following steps: 1. Add six parts cold water to one part lupin grains and soak for 24 hour, drain and rinse; 2. Add six parts water again to one part lupins and cook for about 10 minutes, drain and rinse; 3. Soak again for several days until the lupins no longer taste bitter; change the water two to three times a day Depending on the initial alkaloid content, the soaking time and the number of water changes can be adjusted.