Agriculture Reference
In-Depth Information
application. It is mainly used in meat applications where cold solubility and gel
clarity are not important.
The three carrageenan types (kappa, iota and lambda) differ in their
3,6-anhydrogalactose and ester sulphate content. Variations in these components
affect the gel strength, texture, solubility, melting and setting temperatures,
and the syneresis and synergy of the different carrageenans. All carrageenans
are soluble in hot water, but only the sodium salts of kappa and iota are soluble
in cold water. Lambda carrageenan is unaffected by the salts present in food
products. It develops viscosity in cold water but will become more viscous if
solutions are heated and cooled. These solutions are used for thickening,
particularly in dairy products, to give a full body with a non-gummy, creamy
texture.
Kappa and iota are affected by the presence of salts in foods. Kappa carrageenan
forms a fi rm, brittle gel with potassium ions, while iota carrageenan interacts with
calcium ions to give a soft, elastic gel. The kappa carrageenan gels have poor
freeze-thaw stability, but the iota gels have very good freeze-thaw stability. It is
common to use blends of iota and kappa carrageenan to give the desired texture,
stability and water binding for a particular application.
Care has to be taken with pH as carrageenan is degraded in systems with a pH
less than about 4.3, causing a loss in viscosity and gel strength. It is therefore
recommended that carrageenan is processed at neutral pH, and that the acid is
added to the food just before depositing and fi lling. In acidic foods, add the
carrageenan at the end of the process to avoid polymer breakdown. Further
breakdown does not occur after gelation of the carrageenan, so the shelf life of the
product is not adversely affected. Past animal studies have given health concerns
over the degraded products, and although carrageenan is considered safe to use in
many products, some retailers want to avoid use of carrageenan altogether. This,
together with the fact that alkali and alcohol are used in extraction, means that
carrageenans fall into the grey area of natural.
The texture of carrageenan gels can also be manipulated by using synergistic
mixtures of kappa carrageenan and locust bean gum. These form strong but elastic
gels, with low syneresis, similar to gelatin gels, and fi nd application as cake glaze
and fl an gels, and water dessert gels. Konjac fl our interacts even more strongly
with kappa carrageenan to form strong, elastic gels. This blend is not widely used
in Europe and the US because konjac has only been approved for use in these
countries for a relatively short time, but the superior synergy means that it is likely
that this blend will be used more in the future. Another synergistic interaction
unique to kappa carrageenan is that with milk protein. Kappa carrageenan interacts
with the kappa casein component of milk, and when used at very low levels, gives
a weak gel network that can prevent whey separation in a range of dairy products
(including ice cream, milk shake mixes, cream cheese and dairy desserts) during
manufacture and storage. In chocolate milks, this network is able to keep the
cocoa particles in suspension.
Blends of kappa and iota carrageenan are used in canned meats and petfoods,
and cooked, sliced meats and vegetarian 'meat' products. As previously mentioned,
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