Besan cake crumbles after freezing because the freezing process causes ice crystals to form, disrupting the cake's structure and leading to dryness and a crumbly texture upon thawing.
Freezing any cake, including besan cake, involves a significant drop in temperature. This causes the water content within the cake to freeze and form ice crystals. These ice crystals expand, pushing apart the gluten and starch molecules that provide the cake's structure. When the cake thaws, the ice crystals melt, leaving behind larger air pockets and a weakened structure. In the case of besan cake, which is already denser and potentially drier than cakes made with wheat flour, this structural damage is more pronounced. The cake loses moisture during the freezing and thawing process, further contributing to its crumbly and dry texture. The binding agents in the cake are compromised, resulting in the cake falling apart easily.
To minimize crumbling, wrap the besan cake tightly in multiple layers of plastic wrap before freezing to reduce moisture loss and ice crystal formation. Thaw it slowly in the refrigerator rather than at room temperature to help retain some of its original texture.