Food Additive Tue,6 Maret 2012

hydrocolloid

Refers to a range of polysaccharides and proteins that are nowadays widely used in a variety of industrial sectors to perform a number of functions including thickening and gelling aqueous solutions, stabilising foams, emulsions and dispersions, inhibiting ice and sugar crystal formation and the controlled release of flavours, etc

hydrocolloids and sources of material

Tree (selulosa), tree exudates (gum arabic, gum karaya,gum ghatti, gum tracanth), plants (starch, pectin, selulosa) seeds (guar gum, locust bean gum, tara gum, tamarind gum), tuber (konjac mannan)

Red seaweed (agar, karagenan), brown seaweed (alginate)

Mikrobial (xanthan gum, curdlan, dextran, gellan gum, selulosa)

Animals (gelatin, caseinate, whey protein, chitosan)

Fungsi hydrocolloid

Thickener (CMC, hydroxypropyl cellulose, methyl cellulose, microcrystalline cellulose, guar gum, karaya gum, locust bean gum, starch, tragacanth, xanthan gum)

Gelling agent (agar, alginate, carrageenan, PES, methyl cellulose, gelatin, pectin)

Emuslifier (methyl cellulose, arabic gum, hydroxypropyl cellulose)

Regulatory aspects

InternationalEuropean systemOther trade blocks (FCC, Japanese system)International numbering system for food

additives (INS)

Main hydrocolloid thickeners

Xanthan gum Very high low-shear viscosity (yield stress), highly shear thinning, maintains viscosity in the presence of electrolyte, over a broad pH range and at high temperatures.

Carboxymethyl celluloseHigh viscosity but reduced by the addition of electrolyte and at low pH.

Methyl cellulose and hydroxypropyl methyl celluloseViscosity increases with temperature (gelation may occur) not influenced by the addition of electrolytes or pH.

Galactomannans (guar and locust bean gum)Very high low-shear viscosity and strongly shear thinning. Not influenced by the presence of electrolyte but can degrade and lose viscosity at high and low pH and when subjected to high temperatures.

Thermoreversible gelling agents

Gelatin: gel formed on cooling. Molecules undergo a coil-helix transition followed by aggregation of helices.

Agar: gel formed on cooling. Molecules undergo a coil-helix transition followed by aggregation of helices.

Kappa Carrageenan: gel formed on cooling in the presence of salts notably potassium salts. Molecules undergo a coil- helix transition followed by aggregation of helices.

Iota Carrageenan: gel formed on cooling in the presence of salts. Molecules undergo a coil-helix transition followed by aggregation of helices.

Pectin: gels formed in the presence of divalent cations, notably calcium at low pH (3–4.5). Molecules crosslinked by the cations. The low pH reduces intermolecular electrostatic repulsions.

Gellan gum: gels formed on cooling in the presence of salts. Molecules undergo a coil-helix transition followed by aggregation of helices.

Methyl cellulose and hydroxypropyl methyl cellulose: gels formed on heating. Molecules associate on heating due to hydrophobic interaction of methyl groups.

Xanthan gum and locust bean gum or konjac mannan: gels formed on cooling mixtures. Xanthan and polymannan chains associate following the xanthan coil-helix transition.

Thermally irreversible gelling agents

Alginate: gels formed on the addition of polyvalent cations notably calcium or at low pH 4. Molecules crosslinked by the polyvalent ions.

High methoxyl (HM) pectin: gels formed at high soluble solids (e.g. 50% sugar) content at low pH 3.5. The high sugar content and low pH reduce electrostatic repulsions between chains. Chain association also encouraged by reduced water activity.

Konjac mannan: gels formed on addition of alkali. Alkali removes acetyl groups along the polymer chain and chain association occurs.

Locust bean gum: gels formed after freezing. Galactose deficient regions associate.

Advantages of hydrocolloids

Cheap pricesNot influenced on tasteGiving better rheological properties of the

productsHydrocolloids fibers has many purposes

Agar

Agar is defined as a strongly gelling hydrocolloid from marine algae.

Agar is a polysaccharide that accumulates in the cell walls of agarophyte algae. It is embedded in a structure of fibres of crystallised cellulose, constituting its polysaccharide reserve.

Its main structure is chemically characterised by repetitive units of D-galactose and 3–6,anhydro- L-galactose, with few variations, and a low content of sulfate esters.

Employed more than 300 years agoUse mainly of their colloidal propertiesAgar is a polysaccharide that accumulates in the cell

walls of agarophyte algae. It is embedded in a structure of fibres of crystallised cellulose, constituting its polysaccharide reserve.

Applications of Agar

Food application (Gelidium, Gracillaria, Pterocladia, Gelidiella)

Insect culture media formulationVegetable culture media formulationMO culture media formulation Health Industry

Starch

starch, an anhydroglucose polymer, member of the ‘polysaccharide’ group of polymers. It is laid down as insoluble, compact and microscopic semi-crystalline granules of size 1– 100μm.

Apps

Baked goodsBatters and breadingBeverage emulsions and flavour encapsulationConfectioneryDairy productsFruit preparationsGravies, soup, saucesMayonnaise and salad dressingsMeat productsSavoury snacks

Gelatin

Collagen, the basic raw material for gelatin production, is the major constituent of all white fibrous connective tissue occurring in animal bodies such as cartilage, sinews, the transparent sheaths surrounding muscles and muscle fibres, skin and ossein (the protein matrix of bone)

Uses for food, medical, and photography

Carrageenan

Extracted from Rhodophyceae (E. cottoni, E. spinosum, Chondrus crispus, Gigartina, Fucellaria)

Consists of iota, lambda, kappaUses for food, dairy application.