Influence of nixtamalization on nutritional and functional properties of white lupin (Lupinus albus)

Abstract

White lupin ( Lupinus albus ) is a protein-rich legume; its use for human consumption is limited due to the presence of certain anti-nutritional factors, primarily the presence of alkaloids (such as quinolizidine alkaloids). Nixtamalization, a thermal alkaline treatment, was used in this study as a processing method to reduce the alkaloid content to acceptable levels without compromising the nutritional or functional properties of this legume flour. The raw and roasted lupin was nixtamalized by different alkaline solutions, specifically by calcium hydroxide, potassium hydroxide, and sodium hydroxide solutions for better removal of alkaloid and recovery of crude protein after the treatment. Nixtamalization with calcium hydroxide solution resulted in higher protein recovery and greater alkaloid removal compared to other alkaline treatments, and was therefore selected for further optimization experiments. Calcium hydroxide concentration (3% – 4%), cooking temperature (70 – 80 °C), and steeping time (14 – 18h) were the chosen main processing parameters during the optimization process. Under the optimal conditions of 3.5% calcium hydroxide, 75°C cooking temperature, and 16 h steeping, a low alkaloid content (0.019%) and a high crude protein content (35.2%) were achieved. Moreover, the biochemical compositions and functional properties of optimized nixtamalized lupin flour were improved compared to the raw counterpart. In a nutshell, this study demonstrates that nixtamalization is one of the simplest and effective food processing methods to improve the values of white lupine seeds.