Explain Vegetable dehydration
It reduces the natural water content below the level critical for the growth of microorganisms (12-15%), without being detrimental to important nutrients. Also, it is aimed at preserving flavour, aroma and appearance, and the ability to regain the original shape or appearance on reconstitution with water.
However, the dehydration process is also accompanied by significant alterations. These include:
First, there is a concentration of major ingredients such as proteins, carbohydrates and minerals. This occurs along with some chemical changes. Fats undergo oxidative gradation and, although present in low amounts in vegetables, this oxidation often diminishes odor and flavour. Amino compounds and carbohydrates interact in a Maillard reaction (you would recall reading about the Maillard reaction in Unit 2), resulting in a darker colour and development of new aroma substances. Vitamin levels may also decrease sharply. The original volatile aroma and flavour compounds are lost to a great extent during processing depending upon the severity of the processing conditions.