Modified Starch -RevisitedModified Starch -Revisited

Substituted (Derivitized)

Cross Linked

Substituted and Cross Linked

Modified Starches - Modified Starches - SubstitutedSubstituted

Starch esters– Acetate Starch– Starch phosphate– Succinylated

Starch ethers– carboxy methyl starch– hydroxyl propyl starch

Substituted StarchesSubstituted Starches

Made from starch in granule form Low level subsitution interupts linearity and –

– retards retrogradation, – increase water binding capacity, – lowers gelation temperature, – introduction of hydrophobic groups impart

emulsification properties– Alters clarity

Acetate starchAcetate 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.

Phosphate starchPhosphate 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.

 

Succinylated starchSuccinylated starch

This is a substituted starch ester Retards retrogradationIncreases hydrophobicity and can assist

in emulsification

Substituted starch etherSubstituted 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).

Substituted starch ether (cont)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.

Hydroxypropyl starchHydroxypropyl starch..

The hydroxyl-propyl groups act as pegs to prevent retrogradation.

Similar to the starch acetates above but the substituted group is larger,

Cross linked StarchesCross linked Starches

Vary in degree of cross linkingMay be double modified – substituted

starchesReduce elasticity found in native starchesMore tolerant to high shear in processingLess effected by acid, sugarMore resistant to heat

Cross Linked StarchCross Linked Starch

Degree of cross linking Application

Lightly cross linked Neutral and slightly acidic foods

Medium cross linked High acid foods;delay gelation for some canned foods; foods stored at low temperature;

Highly cross linked High shear, high temperature

Substituted or Cross Linked?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.