Effect of Light on Carbohydrates and Hydrosoluble Vitamins of Lentils during Soaking

Lentils have been soaked with and without light to investigate the effect of the light on carbohydrates and soluble vitamins during the soaking process. Soaking significantly decreased the α-galactoside content of lentils (3.2% to 1.2% or 1.0%). Glucose (not present in raw seeds) and fructose increased with soaking with light. Raffinose was completely eliminated in presence of light but was still present after soaking in the dark (0.15%). The overall results confirm previous findings, but the soaking process cannot be explained simply as a result of sugars leaching into the soaking media. On the contrary, some metabolic processes must be inferred, and light plays a certain role in the process. The NDF, ADF, cellulose, hemicellulose, and lignin contents were not significantly modified by soaking with or without light. Total and digestible starch significantly increased after soaking (52% to 58% and 45% to 52%, respectively), but an influence of light was not detected. The ratio of digestible starch to total starch improved during soaking, an indication that digestibility could be enhanced after this process. No effect of light during the soaking process has been observed on the vitamin content of processed lentils. Thiamin and niacin decreased significantly with soaking as a result of leaching into the water, but riboflavin increased significantly. Again, this result may imply the onset of metabolic processes during soaking, although no light effect has been observed.