Nixtamalization of Bitter Lupine Seeds; Prospective Functional Improvement
Hizia Berrou1, Mohammed Saleh2, Khalid Al-Ismail2
Department of Nutrition and Food Technology, The University of Jordan, Amman, Jordan,
Abstract:
Lupine; a potential functional crop is usually grown in variety of environments including marginal agricultural sites. Human consumption of lupine however, does not exceed 4% of the total production due to its content of alkaloids that restrict its direct use in food applications. Therefore, lupine pretreatment is usually essential before use as food ingredient. Nixtamalization is an example of such pretreatment technologies.
Nixtamalization is usually performed on grains to improve its final functional characteristics. During this work, white bitter lupine (Lupinus albus) seeds were nixtamalized using calcium hydroxide at various concentration of calcium hydroxide ranges (i.e., 0.16–3.33% ) at various temperatures (i.e., 50, 70, and 90°C) and steeped durations (i.e., 0, 8, 16, and 24 h). Moisture uptake hydration kinetics of lupine seeds, microscopic structure of seeds, alkaloids, and farinograph tests during Nixtamalization were studied.
White bitter lupine seeds used in this study were characterized of having 6.47% moisture content, 41.7% proteins, 14.2% lipids, 3.3% ash and a negligible amount of starch. Kinetics moisture uptake of lupine seeds increased with increasing nixtamalization temperature regardless of calcium hydroxide concentration used. Non-linear models (i.e., Page and Weibull models) were fit and were adequately described white bitter lupine hydration kinetics during Nixtamalization.
Lupine seeds surface microstructure cracks were visible during Nixtamalization with number and size increased proportional with the increase in Nixtamalization conditions (i.e., temperature, calcium hydroxide concentration, and steeping duration). The presented results may be useful in optimizing the industrial nixtamalization of lupine seeds and increasing the possibility of their use as a valuable food ingredient.
Alkaloid content of raw lupine was 1.08 g/100 g and was gradually decreased with Nixtamalization conditions. The addition of 10% of Nixtamalization lupine flour to wheat flour increases dough stability, water absorption, peak time, and degree of softening. Nixtamalization process enhanced lupine functional characteristics as well as protein digestibility that would ease the use of lupine in bakery products.