What are the different compositions of wheat?
- Pure endosperm
- Bran and endosperm stuck together
- Pure bran
What are characteristics of hard wheat?
- High yield of white flour from milling
- Large smooth flour particles
- Flows and sieves easily
- Takes more energy to mill because the adhesive strength between the starch and protein is greater than in soft wheat and is greater than the strength of the endosperm cell walls.
- Fracture during milling occurs at endosperm cell walls
What are characteristics of soft wheat?
- White powdery endosperm
- Low water absorption
- Takes less energy to mill as the adhesive strength between starch and protein is smaller
- Fracture during milling occurs at starch granule surfaces.
What do amorphous and semi-crystalline mean in the context of starch?
• Amorphous means without shape. Molecules are arranged randomly with no ordered structure
Semi- crystalline means most molecules have a regular three- dimensial structure. In starch molecules are lined up next to eachother as single helix’s or around neighbours as double helix’s
What is starch compromised of?
- Amylose which is a linier polymer
* Amylopectin which is a branched polymer
How is starch damage caused and what effect does it have on starch?
It is caused by mechanical shock as grain passes through the nip of a roller mill. It introduces microscopic cracks in the semi-crystalline parts of starch granules. Water can be absorbed into the cracks.
