Agriculture Reference
In-Depth Information
Fig. 8.3
Thermoreversible gelling of gelatin.
Most types of gelatin require soaking to allow the granules to swell, before the
solution is heated to about 75°C to dissolve the gelatin. On cooling, the solution
forms a thermoreversible, fi rm but elastic gel. The gel has very good clarity and
resistance to syneresis. There are cold water soluble (instant) gelatin types
available, which have application in powdered dessert or cake mixes.
Gelatin gels are slower setting than other hydrocolloids, which is a benefi t for
pumping and fi lling operations, but means that particulates will tend to sediment
in gelatin only gels. The unique property of gelatin gels is the melting point - gels
melt at body temperature (37°C), so are the only gels to truly melt in the mouth.
This gives an intense fl avour and aroma release, and a very quick breakdown of
texture, leaving no gummy texture in the mouth. This is the property of gelatin
that is almost impossible to replace with gelatin alternatives, particularly in
products such as table jellies and confectionery jellies.
Since gelatin is a protein not a polysaccharide, it has extra functionality
compared with the other hydrocolloids, in particular its ability to form and
stabilise foams (in marshmallows and aerated desserts) and emulsions (in
caramels). It also acts as an adhesive (in tabletted confectionery and sugar pastes)
and a fi lm former (in coatings, glazes and capsules). The major application for
gelatin is in the confectionery industry, in many types of products, from fruit
gums, pastilles, mallows and caramels. It is also widely used in desserts to stabilise
and give the desired texture, including table jellies, low-fat yoghurts, mousses and
ice cream. The fi nal major application is in meat and fi sh products for emulsifi cation,
water and fat binding, to maintain texture and succulence.
8.4 Future trends
The introduction of totally new hydrocolloids for food use is restricted by the
huge fi nancial investment required to gain the necessary legislative approval. In
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