Summary_csm

= **GUMS & STABILIZERS** =

What is Hydrocolloid?

 * Food hydrocolloids is a range of polysaccharides and proteins, also known as 'water soluble gum', 'gum', 'stabilisers'.
 * Primary functions: Thickening agents, Gelling or texturizing agents.
 * Secondary functions: Stabilisation of emulsions, suspension of particulates, control of crystallisation, encapsulation, formation of film.



Factors affect gum properties

 * molecular weight
 * monosaccharide composition
 * type of chains
 * number of side chains
 * distribution of side chains

Main classes of hydrocolloids

 * derivatives from exudation or sap of trees (e.g. cellulose, gum arabic, gum karaya, gum ghatti, gum tragacanth)
 * extract from seed (e.g. guar gum, LBG, tara gum, tamarind gum)
 * extract from seaweeds (e.g. agar, carrageenan)
 * microbial gums (e.g. xanthan, dextrun,curdlan)
 * extract from tubers (e.g. konjac)
 * extract from plant parts (e.g. starch, pectin, cellulose)



__ Main Hydrocolloids - Thickeners __

 * 1) xanthan gum
 * 2) carboxymethylcellulose
 * 3) methylcellulose and hydroxypropyl cellulose
 * 4) galactomannas (guar and LBG)

- Thermoreversible gelling agents

 * 1) gelatin
 * 2) agar
 * 3) kappa carrageenan
 * 4) iota carrageena
 * 5) low methoxy (LM) pectin
 * 6) gellan gum
 * 7) methyl cellulose and hydroxypropyl cellulose
 * 8) xanthan gum and locust bean gum or konjac mannan

- Thermally irreversible gelling agents

 * 1) alginate
 * 2) high methoxyl (HM) pectin
 * 3) konjac mannan
 * 4) locust bean gum

Pectin

 * ===derived from peel of citrus fruits, apple pomace, sugar beet, sunflower heads.===
 * ===types of pectin---High methoxyl pectin (HMP), DE> 50% and Low methoxyl pectin (LMP), DE< 50%===

__High methoxyl pectin (HMP)__

 * DE---58% to 75%
 * to form gel, soluble solid content 55-85%, pH 2.8-3.8. (e.g. jam and jellies)
 * ultrarapid/rapid set (DE as high as 77)---used in jam with whole fruits, to ensure uniform distribution of fruits particles.
 * slow set (DE~58) ---used in very acid fruits such as blackcurrant to avoid premature gelation.



__ Low methoxyl pectin (LMP) __

 * two sub-groups---Conventional low methoxyl pectin (LMP) and Amidated low methoxyl pectin (ALMP).
 * form gels in presence of calcium ions, low soluble solid content, wide pH range (1-7). Soluble solid can up to 85%.
 * LMP - less calcium ion reactive than ALMP---used as thickening agent in yogurt fruits.
 * ALMP - very calcium ion reactive---used in low sugar fruits preparatuin (e.g. low-sugar jam and jellies).



Guar Gum

 * 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



Xanthan Gum

 * completely soluble in cold water, produce high viscosity at low concentration
 * excellent stability to heat and pH
 * viscosity remain unchanged across temperature range (0-100 degree celcius), pH 1-13
 * used as a thickening, suspending and stabilizing agents.



Cellulose Derivatives

 * alkaline treatment converts cellulose into ether
 * examples---carboxymethylcellulose (CMC), hydroxypropyl methylcellulose (HPMC)
 * very clear solution, stable over pH 4-10
 * used as thickener, suspending and stabilizing agents. Modify flow characteristics.
 * use in fried foods---create a barrier to oil absorption, retard loss in moisture, improve adhesion of batter.



Carrageenan

 * three types of carrageenan: kappa, lamda and iota
 * in a concentration as low as 0.5%, kappa and iota carrageenan can form thermoreversible gel upon cooling of hot aqueous solution containing various cations.
 * some examples of food application for carrageenan: water dessert gels, chocolate milk, canned and processed meat, ice-cream, cold prepared custard. [[image:foodingredients/c.milk.jpg width="162" height="179"]][[image:foodingredients/y.jpg width="150" height="179"]]

Alginate

 * made up of blocks of D-mannuronic acid (M-blocks) and L-glucuronic acid (G-blocks)
 * can form gel in presence of calcium ion in cold water; the gels is thermo-irreversible
 * provide excellent stabilizing effects in frozen products. (e.g. ice-cream)
 * act as thickeners and stabilizers in beverages (e.g. dry mix fruit drinks)
 * propylene glycol alginate with emulsification property, used as stabilizer in emulsion (e.g. mayonnaise)



Gum Arabic

 * dissolve easily in hot/cold water
 * least viscous and most soluble of all hydrocollods-up to 55%solid concentration can be used
 * encapsulate volatile flavour
 * promote stabilisation in beer foam
 * give viscosity and emulsifying properties. Used as emulsifier and stabilizer in soft drinks



Locust Bean Gum (LBG)

 * insoluble in cold water, must be heated to dissolve-max viscosity develop when heated to~95 degree celcius, then cooled
 * does not form gel by itself but form gel when combined with xanthan gum
 * non-ionic, stable over pH 3.5-11.0
 * primary functions: hickening, stabilization of emulsions, inhibition of syneresis
 * used in canned foods, sauces, desserts, ice-cream, processed meat



Relative Ranking of Gum Properties

 * 1) solution claity
 * 2) solubility at various temperature
 * 3) gelling vs thickening
 * 4) suspension ability
 * 5) natural vs not natural
 * 6) ability to tabilize protein at low pH
 * 7) acid stability
 * 8) relative cost per unit weight

What is Gelatin?

 * edible natural foodstuff
 * raw material used---skin (pigskin and hide split) and bone taken from slaughtered animals
 * collagen contained in raw materials is starting material for manufacture of gelatin
 * type A---derived from acid processed materials (porkskin)
 * type B---derived from alkaline or lime processed materials (calf hides,ossein)
 * forms thermally eversible gel wit water
 * melting temperature <35 degree celcius---give the melt-in-mouth properties, rapid release of aroma
 * used in gelled jelly, yogurt, fruit iuices, top quality ice-cream and frozen produts, gummy bears, etc.

__ Typical functional properties __

 * gel formation
 * water binding
 * texturizing
 * thickening
 * emulsion formation anfd stabilisation
 * foam formation and stabilisation
 * film formation
 * adhesion/cohesion
 * protective colloidal function