Hardening

Hardening is the process of making or becoming solid, firm and rigid, and it can be either a defect or a deliberate objective in food processing. It is problematic when common beans harden during storage, causing cooking difficulties, while the hardening stage is essential in manufacturing good-quality ice cream, where controlled freezing firms the structure. Hardening is also a stage in fats and oils processing, for example in margarine manufacture, where it is usually called hydrogenation and involves catalytic addition of hydrogen to unsaturated oils. Whether hardening helps or harms depends entirely on controlling its rate, extent and timing.