GUM AND STABILISER

Factors affects gum properties

Molecular weight

Monosaccharide composition

Type of side chain

Number of side chain

Distribution of side chains

Main topic

HYDROCOLLOID

DS=Degree of substitution=side chain per unit

Higher DS~faster to hydrate

Lower DS~slower to hydrate

High MW polymers consisting long chain sugar unit

A range of polysaccharides and proteins-also known as 'WATER SOLUBLE GUMS' ,'GUMS','STABILISERS'

DP=Degree of polymerization-chain length

Higher DP~Higher viscosity~slower to hydrate

Lower DP~Lower viscosity~faster to hydrate

FUNCTION

PRIMARY

Thickening agent

Gelling or texturizing agents

SECONDARY

Stabilisation of emulsions

Suspension of particulates

Control of crystallisation

Encapsulation

Formation of film

Main classes of Hydrocolloids

Exydation or sap of tree

extract from seed

extract from seaweeds

microbial gums

extract from tubers

extract from plants parts

Gelation of Hydrocolloids

THERMOREVERSIBLE

gelatin

agar

kappa carrageenan

iota-carrageenan

low methoxyl pectin (LMP)

Gellan gum

methyl cellulose

hydropropylmethylcellulose (HPMC)

THERMO-IRREVERSIBLE GELLING AGENT

Alginates

starch

konjac

High methyl pectin (HMP)

COMMON TYPES OF HYDROCOLLOIDS

Pectin

HIGH METHOXY PECTIN (HMP)

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Commercial high methoxy pectin:DE 58% TO 75%-Rapid set pectin used in jams with whole fruit.-very acid fruits (eg:blackcurrant) requires slow set pectins to avoid premature gelation.-HMP-have a firm &short structure ,clear &transparent ,excellent flavour release -not heat reversible

LOW METHOXY PECTIN (LMP)

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DE <50%-two subs group-Conventional low methoxyl pectin (LMP)-Amidated low methoxyl pectin (ALMP)-Form gels in the presence of Ca2+,with slow content & wide pH rangeLMP-less Ca2+ reactive than ALMP=Used in thickening agent in yogurt fruitALMP-very reactive Ca2+=assist gelation in low-sugar fruit preparation

Carrageenan

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-highly refined extract of seaweed from rhodopyhta family-structure composed of linear galactan polysaccharides that have a sulfate content of 15-40%-Commercial carrageenans are not pure kappa ,iota or lambda but contain amount of othe types ,the exact amount depending on the weed source and the extraction process

Kappa (k-carrageenan)

Lambda carrageenan

Iota carrageenan

Alginates

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-derived brown seaweed-made up of block of D-mannuronic acid (G-block)high G alginates -strong ,brittle gel with heat stability-can form gel in cold water in presence of Ca ion;gel is thermo-irreversible-provides stabilizing effect in frozen productsin beverages -acts as thickeners &stabiliser

Gum arabic

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-dissolve easily in hot water-least viscous & the most soluble of all the hydrocolloids-complex structure-polysaccharides containing galactose ,rhamnose ,arabinopyranose, arabinofrusanose glucuronic acidUSES-Encapsulation agent-to encapsulate volatile flavour compounds -promote stabilization of foam in beer-act as emulsifier &stabilizer in soft drink emulsion

Known as gum Acacia

Locust bean gum (LBG)

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-come from the seed of leguminose Ceratonia siliqua -galactomannan gums-made up of mannose &galactose in a ratio of 4:1-insoluble in cold water &must be heated to dissolve-does not form gel by itself-but it can form gel when combined with xanthan gum.USES-LBG is non ionic-stable over the pH range of 3.5-11.0-functions:thickening stabilization of emulsions, inhibition of syneresis

Xanthan gum

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more highly substituted than LBG -more soluble &hydrates fully in cold water giving high viscosity-Non gelling -used as viscosity builder,stabilizer &water binder-very stable from pH 4-10

linear chain of mannose with single galactose unit attached as side chains

Cellulose

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USES:-for thickening,suspending ,stabilizing & modified flow characteristics

chemically modified cellulose

alkaline treatment converts cellulose into an ether

ex: carboxytmethylcellulose (CMC) , hydropropylmethylcellulose (HPMC)