Agriculture Reference
In-Depth Information
currently increasing - believed to be due to its high demand for use in oil drilling
applications (Food Navigator 2011). Combining with other gums also overcomes
the problem that at higher concentrations, guar gum solutions have an unpalatable
'long' and sticky texture.
Guar gum solutions show good stability to most food processing operations
and recipes, having good thermal stability, but are less stable at low pH. Guar gum
is widely used as a thickening, stabilising and suspending agent in drinks, sauces,
soups, ketchups and mayonnaises. Its cold solubility and excellent freeze-thaw
stability makes it popular in cold-prepared frozen foods. Like LBG, it is often
used in ice cream to provide smooth meltdown and reduce thermal shock. It is
also used in meat products, helping to prevent fat migration and 'weep' in
sausages. Guar gum is used to control viscosity during processing (e.g. at the
fi lling head for canning, preventing clumping while retorting) and is also widely
used as a fl our additive in the bakery industry.
While many of the hydrocolloids discussed in this chapter are classed as a
soluble fi bre and believed to have some other health benefi ts, guar gum has been
scientifi cally established to maintain normal blood cholesterol concentrations. In
Europe, the European Food Safety Authority (EFSA) has given a positive opinion
on this health claim. The technical challenge to make use of this health claim in
food products is that foods should provide at least 10 g of guar gum in one or more
servings. Since the key property of guar gum is its high viscosity at low
concentrations, including high concentrations of guar gum in a food product will
inevitably have a signifi cant effect on the texture, and will limit the types of food
products that can incorporate the guar gum. However, there are low viscosity
versions of guar gum available, which will be ideal for these applications.
8.3.3 Pectin
Pectin is a natural hydrocolloid found as a component of cell walls in fruits, as
well as some roots (sugar beet). As such, it is a natural part of the human diet.
Pectin has traditionally been used in the home for gelling jam, and is therefore
probably the hydrocolloid that the consumer knows best (in the Western world at
least) and considers natural. It is therefore very popular with retailers in the current
drive to re-formulate food products as being 'clean label'. Pectin is still classed as
a food additive and has an E number in the EU, but as consumers recognise the
name pectin, it is rarely referred to by its E number on ingredient lists. However,
pectin does use some simple chemicals during its extraction, namely acid and
alcohol.
Commercially, pectin is manufactured predominantly from the waste products
of the citrus or apple juice manufacturing industry. The citrus peel is treated with
dilute acid to extract the pectin into the aqueous phase. The liquid extract is then
clarifi ed using fi ltration or centrifugation to remove the particulates, before
evaporation and then precipitation of the pectin with alcohol. The pectin is dried
and milled to the desired particle size. The pectin produced by this process is high
methoxyl pectin (HM pectin). A low methoxyl pectin (LM pectin) is produced by
Search WWH ::
Custom Search