Hydration Kinetics of Nixtamalized White Bitter Lupin (Lupinus albus L.) Seeds

Abstract

Nixtamalization is usually performed on grains by cooking in an alkaline solution to improve the final product characteristics. White bitter lupin ( Lupinus albus ) seeds were nixtamalized at various concentrations of calcium hydroxide in the range of 0.16–3.33% at 50, 70, and 90°C for 35 min and steeped for 0, 8, 16, and 24 h, and the moisture uptake was determined to model seed hydration kinetics. Moisture uptake increased with in - creasing nixtamalization temperature regardless of calcium hydroxide concentration. The Page and Weibull models adequately described white bitter lupin hydration kinetics during nixtamalization. Model parameters K p (Page model) and α (Weibull model) ranged from 80.2 to 410.03 and from 88.21 and 93.96, respectively, for nixtamalization at different calcium hydroxide concentrations, and from 58.55 to 662.88 and from 68.74 and 132.99, respectively, for nixtamalization at different temperatures. The alkaloid content of raw lupin flour was 1.08 g/100 g and it gradually decreased as a result of nixtamalization in increasingly concentrated calcium hydroxide solutions and higher temperatures. The cracks were visible in the microstructure of nixtamalized seed coats. Their number and size increased with the increase of processing temperature, calcium hydroxide concentration, and steep - ing duration. Overall, the presented results may be useful in optimizing the industrial nixtamalization of lupin seeds and increasing the possibility of their use as a valuable food ingredient.