The Science of Stubborn Pulses
The main reason older pulses take longer to cook comes down to moisture loss and changes in their cellular structure. Dried pulses contain around 14-16% moisture when fresh. As they age, especially in warm, humid conditions, this moisture evaporates.
This causes the pectin in the bean's cell walls, which acts like a natural glue, to harden. The older and drier the pulse, the more robust this pectin becomes, making it much harder for water to penetrate and soften the seed during cooking. Eventually, very old beans may become almost impossible to soften completely.
Smart Storage Is Your First Defence
How you store your pulses can make a huge difference in their shelf life and cookability. To slow down the aging process, keep them in a well-sealed, airtight container. This prevents moisture loss and protects them from humidity. Store the container in a cool, dark, and dry place like a pantry, away from direct sunlight or heat from the stove. Storing pulses at high temperatures and high humidity significantly speeds up the hardening process and can even lead to changes in colour and nutritional value. An environmentally controlled warehouse is ideal, but a cool pantry is the next best thing for home storage.
The Power of a Thorough Soak
Soaking is the most crucial step for rehydrating pulses before cooking, and it's especially important for older, drier ones. Soaking allows the seeds to absorb water, which begins the softening process and significantly shortens cooking time. For a standard soak, cover the pulses with at least four times their volume in water and leave them for 6-8 hours or overnight. If you're short on time, a quick-soak method works well: bring the pulses to a boil for 2-3 minutes, then remove them from the heat and let them stand in the hot water for about an hour.
Consider Your Water Quality
If your pulses still won't soften, your water might be part of the problem. Hard water, which is high in minerals like calcium and magnesium, can interfere with the cooking process. These minerals can reinforce the pectin in the cell walls, preventing the pulses from softening properly and increasing the cooking time. If you live in an area with very hard water, using filtered or bottled water for soaking and cooking your beans can make a noticeable difference. It might seem like an extra step, but it can save you a lot of time and frustration.
A Pinch of Baking Soda to the Rescue
For particularly stubborn or old pulses, a little baking soda can work wonders. Baking soda is alkaline, and adding it to your soaking or cooking water raises the pH. This alkaline environment helps to break down the hardened pectin much more effectively, allowing water to get into the bean and soften it faster. It's a trick often used for making dishes like mushy peas. Be careful not to use too much—about half a teaspoon for a pound (around 450g) of dried beans is enough. Using too much can result in a soapy taste, so it's best to rinse the beans thoroughly after soaking if you use this method.
When in Doubt, Use a Pressure Cooker
The pressure cooker is your best friend when dealing with older pulses. The combination of high pressure and high temperature inside the cooker creates an environment where even the toughest beans are forced to soften. It dramatically speeds up the process by raising the boiling point of water and forcing it into the pulse. This is also why pressure cookers are essential at high altitudes, where lower atmospheric pressure means water boils at a lower temperature, extending cooking times. For very old chana or rajma, the pressure cooker is often the only tool that can get the job done efficiently.
