Please enable JavaScript.
Coggle requires JavaScript to display documents.
Week 13: Starch -Primary carbohydrate source for plant growth &…
Week 13: Starch -Primary carbohydrate source for plant growth & Development
Widely used as food ingredient for many purposes. (eg thickener, binders)
A very wide selection of starches
Native Starches: most common native starches:
Corn (maize), rice, wheat, potato, tapioca (cassava) and waxy maize.
Waxy maize and other waxy native starches contain <2% amylose.
contain from 15-27% amylose.
with high amylose content ie. >30%
have quite different properties:
Difficult to gelatinise >100°C
Ability to form films and fibres
need higher energy to gelatinise to breakdown the layers of high-amylose starch granule which allows water to penetrate and interact.
starches with higher amylose content show greater retrogradation.
Starch gelation and pasting characteristics are altered by other ingredients and processing conditions.
Starch Forms: polymers of glucopyranose molecules
Amylopectin
Amylose
glucopyranose: a form of glucose where carbon atoms 1 and 5 are bridged by an Oxygen atom.
When starch is heated up,….
Retrogradation:
starch chains start to re-associate into an ordered structure. In initial phase, two or more starch chains may form a simple junction point, which then may develop into more extensively ordered regions. Ultimately, under favourable conditions, a crystalline order appears.”
Factors relating to retrogradation
The botanical source:
Sources with different amylose content.
Different sources with very similar amylose content.
Higher No. branching → Lower retrogradation
High amylopectin starches e.g. waxy maize shows no retrogradation when it is frozen.
Hydrogen bonding between OH groups in amylose in gelatinised starches during cooling
