Hydrocolloids occurrence and functions in food system

2.  Hydrocolloids – hydrophilic,
long- chain, high molecular weight
molecules, with colloidal properties
 In water-based systems produce gels,
i.e, highly viscous suspensions or
solutions with low dry -substance content
 Colloid- A system in which finely divided particles
are dispersed within a continuous medium in such
a way that they are not filtered easily and do not
settle rapidly.

3.  Hydrocolloid (hydrophilic colloid) – the scientific
name for gums
 Not real colloids – because truly water soluble
 Some are water soluble and form colloidal
solutions others are only able to swell in water and
can be dispersed by means of shear forces
 Functions - thickening or gelation, emulsifying,
whipping, suspending, and encapsulating
 Hydrocolloids - not real emulsifiers because - do
not have the characteristic linkage of lipophilic
and hydrophilic groups in the molecular structure

4.  Hydrocolloids - linear or branched molecules
 Linear type (such as cellulose, amylose, alginates,
and pectin) - most abundant in nature and have
sugar units that repeat over the entire length of the
polymer
 Have side units (influence the properties) - single
or multiple sugar units, or simple as carboxyl
groups, sulfate groups, or a methyl ether group
 Hydrocolloids – naturally occuring and chemically
modified, such as carboxymethyl cellulose (CMC),
also known as cellulose gum, and propylene glycol
alginate

5. Based on their origin and way of manufacturing,
1) hydrocolloids purely isolated from plants (without
chemical modification)
2) hydrocolloids obtained by fermentation
3) plant-derived hydrocolloids that are chemically
modified
4) hydrocolloids from animals

6. According to their botanical origin and their function
in the plant organism,
1. exudates (protective colloids being deposited on
wounds)- acacia gum/gum Arabic, tragacanth,
karaya gum, ghatti gum
2. seed flours (reserve polysaccharides) - guar gum,
locust bean gum, tara gum, tamarind seed gum
3. extracts from land plants and marine algae
(scaffolding substances) - pectins, agar, alginate,
carrageenan, starches, cellulose, furcelleran, larch
gum

7. Additionally, there are
1. microbial or bacterial polysaccharides - xanthan,
dextran, curdlan, scleroglucan, gellan, pullulan
2. modified polysaccharides - propylene glycol
alginate, amidated pectin, modified starches,
cellulose derivatives
3. proteins of animal origin - gelatin, caseinates

9.  Viscosity enhancing or thickening properties
 Gelling properties
 Surface activity and emulsifying properties
 Hydrocolloids as edible films and coatings
 Hydrocolloids as fat replacers

10.  Thickener
 Stabilizer
 Emulsifier

11. Hydrocolloid: Pectin
Source: Fruits
Mode of gelation: Interactions between the pectin
molecules through hydrogen bonding

13.  Retards staling of bread
 Increases shelf life
 Dough conditioning
 Prevents lump formation
 Maintains the texture of final product

15.  Emerging technology used majorly in
fortification of food
 Encapsulation prevents loss of essential nutrient
(say DHA) during cooking process
 Gelatin, Alginate with calcium or polylysine forms
thin layer around the core

16.  Application of hydrocolloids – review by Zlatica et al.
 Hydrocolloids in food industry by Jafar et al.
 http://www.classofoods.com/page3_3.html
 http://www.food-info.com