BAKING
Wet dough pieces of desired weight and shape are then passed on to oven band through swivel panner web .Ovens are of different types classified into following categories .
a. type of heating
b. type of fuel
c. type of design
d. width of oven band
e. Number of zones .
Heat is transferred to biscuit on band through all the three ways of heat transfer ie conduction , convection , radiation .
Following are the chemical and physical changes which occurs in oven ,When dough piece is passed on to oven .
Physical changes .
1. Formation of crust
2. Melting of fat
3.gas expansion in dough piece due to co2 expansion at higher temperatures .
4. Water converted into steam .
Escape of gases and steam would result in collapse of biscuit structure , Hence these are passed on to different zones with gradual increase or decrease of temperature .zones are classified as
1. Heating zone
2. Baking zones
3.Coloring zones
Chemical changes
1. Gas formation
2. starch gelatization
3. Protein changes
4. caramelisaion of sugar
5. Dexterisation
COOLING
Cooling process is as important than any other process , When biscuit comes out with oven the temperatures of biscuit are around 70-95deg c, These biscuit can be cooled by letting it travel for distance of 1.5 times of baking time . so if you have a oven of 200 ft then cooling conveyor length would be approx 300 - 350 . In some places forced cooling is also done due to space constrain or for special features .Cooling brings temperatures to room temperature for handling of biscuit for packing.
