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 International European system Other 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 prices Not influenced on taste Giving better rheological properties of the products Hydrocolloids 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 ago Use mainly of their colloidal properties 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.

Applications of Agar Food application (Gelidium, Gracillaria, Pterocladia, Gelidiella) Insect culture media formulation Vegetable culture media formulation MO 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 goods Batters and breading Beverage emulsions and flavour encapsulation Confectionery Dairy products Fruit preparations Gravies, soup, sauces Mayonnaise and salad dressings Meat products Savoury 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, kappa Uses for food, dairy application.