Drying effects on food coloring

A great range of chemical changes can take places during food dehydration along with the physical changes and these contribute to the final quality of both the dried items and their reconstituted counterparts in terms of food color, flavor texture, viscosity, reconstitution rate, nutritional value and storage stability.

High temperatures greatly affect food color, as in classical manufacturing process, such as the common thermal treatments of sterilization and pasteurization.

Food pigment may he destroyed completely 0r converted into other product having undesirable color during drying. The color of tomatoes is mainly determined by the carotenoids lycopene, which is natural pigment that gives tomato and tomato products their characteristics deep-red color.

Tomato fruit

High temperatures lead to degradation of lycopene, which depends on many factors including processing conditions (such as temperature). The degradation of lycopene in tomato dehydration affects both color and their nutritive value of final products.

In addition, such common food components as sugars may undergo caramelization, producing an-off colored product. Maillard-type browning, like other chemical reactions, is favored by high temperature and by high concentrations of reactive groups in the presence of some water.

Browning reactions may be caused by enzymatic oxidations of polyphenols and other susceptible if the oxidizing enzymes are not activated. Drying temperatures, because of the water evaporation cooling effects, often are not sufficient to inactivate these enzymes, so it is common to pasteurize or blanch foods with heat or chemicals prior to drying.
Drying effects on food coloring