Modified Starches - Substituted. Starch estersAcetate StarchStarch phosphateSuccinylatedStarch etherscarboxy methyl starchhydroxyl propyl starch. Substituted Starches. Made from starch in granule formLow level subsitution interupts linearity and
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1. Modified Starch -Revisited Substituted (Derivitized)
Substituted and Cross Linked
2. Modified Starches - Substituted Starch esters
carboxy methyl starch
hydroxyl propyl starch
3. Substituted Starches Made from starch in granule form
Low level subsitution interupts linearity and –
increase water binding capacity,
lowers gelation temperature,
introduction of hydrophobic groups impart emulsification properties
4. Acetate starch Class: Substituted starch
Acetylated starch. Granular starch ester with a CH3CO-group introduced
Improves paste stability and clarity.
The acetate groups act as pegs on the amylopectin chains to reduce or prevent retrogradation. Acetate starches are used in chilled or frozen preparations such as icecream cheesecakes etc.
The level of acetelation can be altered to tailor the properties.
5. Phosphate starch There are two classes of phosphate starches.
Substituted starch phosphate esters. eg. monostarch phosphate.
Similar in function to starch acetate. The phosphates act as pegs to prevent retrogradation.
Improves paste stability and clarity
Crosslinked starch esters. Crosslinks starch chains to stabilize viscosity and reduce shear thinning.
6. This is a substituted starch ester
Increases hydrophobicity and can assist in emulsification
7. Substituted starch ether General term for three classes of starch ether substitution are:
Anionic (Carboxy methyl starches),
cationic (Quaternery ammonium) and
Non-Ionic (Hydroxy alkyl starches).
8. Substituted starch ether (cont) Substituted starch ethers have improved clarity, better resistance to retrogradaion and improved viscosity
The substituted starch ethers (carboxy methyl starch and hydroxyl propyl starch) are generally preferred as they offer improved functionality compared with the substituted starch esters (starch acetate and monostarch phosphates). Crosslinked hydroxyl-propyl starches are among the most functional of the food grade modified starches.
9. Hydroxypropyl starch. The hydroxyl-propyl groups act as pegs to prevent retrogradation.
Similar to the starch acetates above but the substituted group is larger,
10. Cross linked Starches Vary in degree of cross linking
May be double modified – substituted starches
Reduce elasticity found in native starches
More tolerant to high shear in processing
Less effected by acid, sugar
More resistant to heat
11. Cross Linked Starch
12. Substituted or Cross Linked? Crosslinking protects against high shear, acid processing and prolonged heating. It depends on the food or other use, processing conditions and the cost of the modified starch.
Most modified starches are BOTH crosslinked and substituted, It is the level of each of these processes that is used to adjust functionality. The levels of both crosslinking and substitution are adjusted depending on end use.