Adding lemon juice too early in dal can prevent the lentils from softening properly, resulting in a dish that takes longer to cook and may have a slightly tougher texture.
The acidity in lemon juice interferes with the breakdown of pectin in the lentils. Pectin is a structural component of plant cell walls, and its breakdown is essential for lentils to soften and become creamy during cooking. When acid is introduced early, it strengthens the pectin, making it more resistant to heat and hindering the lentils' ability to absorb water and cook evenly. This can lead to a longer cooking time and a less desirable texture in your dal. It's best to add lemon juice towards the end of the cooking process, after the lentils have already softened. This allows the lentils to cook properly and still retain the bright, tangy flavor of the lemon.
If you accidentally add lemon juice too early, try adding a pinch of baking soda. Baking soda is alkaline and can help neutralize the acid, potentially allowing the lentils to soften a bit more. However, be cautious not to add too much, as it can affect the flavor of the dal.