Effect of Processing on the Diffusion of Alkaloids and Quality of Lupinus mutabilis Sweet

Abstract

Cold water processing by soaking, cooking and washing has been used for hundreds of years to produce debittered lupine in the Andean region. The process of debittering lupine (Lupinus mutabilis Sweet) was investigated at semi-industrial village-scale and laboratory scale in Ecuador. The process took 5.7 ± 1.0 days, removed 94.9% of the total alkaloids, used water at almost 62 times the weight of the raw dry and bitter lupine, and caused a 22% loss of total solids, principally fat, minerals and carbohydrates. During the debittering process the microbiological quality deteriorated. Mathematical modeling based on Fickian diffusion suggested that the diffusion coefficient of alkaloids would be expected to be between 10−10 and 10−11 m2/s because the lupine endosperm is a polymer matrix whose properties change during processing. Of the process operations, cooking was the most efficient at removing alkaloids both in terms of time and water used, followed by soaking and washing. Practical Applications The current debittering process of bitter toxic lupine in San Pedro, Ecuador, is effective but consumes much water and time. During the process, not only alkaloids are removed but also 22% of total solids, principally fats, minerals and carbohydrates. The microbiological quality of the product deteriorates during this long processing time. Improving the efficiency of the debittering process would reduce water consumption, save time and improve the nutritional and microbiological quality of the final product. Future work will focus on strategies to optimize the debittering process.