Chemistry Reference
In-Depth Information
of stiff macromolecules are highly viscous, which is generally true
for alginates. The thickening effect and rheology of alginate solutions,
however, can be controlled through the choice of grade and formulation
as well as concentration of alginate (Onsøyen, 2001).
Alginates are commonly used as thickening agents in ice creams,
desserts and savoury sauces, including mayonnaise as well as in jams,
marmalades and fruit sauces (Brownlee
et al.
, 2009).
Use of alginates on their own or in conjunction with other thickening
agents has been shown to improve the acceptability of a number of
low-fat processed foods (Rehm, 2009).
6.6.3
Film-forming agent
A film or coating can be achieved by applying a thin layer of alginate
gel or alginate solution and, consequently, drying it (Onsøyen, 2001).
Edible films and coatings for foodstuffs are developing technologies that
have a high potential, owing to the current call for reduction or replace-
ment of non-biodegradable or non-recyclable food packaging (Brownlee
et al.
, 2009).
Sodium alginate food films show good tensile strength, flexibility and
resistance to tearing, and are impermeable to oils. Antimicrobial agents
can be incorporated in the alginate gel to provide an effective barrier to
microbial surface spoilage of vegetables, meat and fish products. The
low temperature formation of the alginate gel coating minimises damage
to the antimicrobial agents as well as to the foodstuff itself. This prop-
erty makes the alginate coating suitable for fresh fruit and vegetable
products, such as lettuce and freshly cut apple and melon sections,
where the coating increases the shelf life, reduces browning, main-
tains crispness and texture and reduces vitamin C loss (Brownlee
et al.
,
2009).
Alginates films also can be used to protect frozen fish from oxidation
and loss of water by stabilising the ice layer and making it more imper-
meable to oxygen and moisture. Meat carcasses and meat pieces can be
protected by a calcium alginate film, which both reduces water loss and
improves the food safety (Onsøyen, 2001).
6.6.4
Encapsulation and immobilisation
Encapsulation in food processing is a specialised form of edible packag-
ing. If encapsulation is utilised in a food process, usually the approach
is to apply the encapsulation only to those ingredients which are unsta-
ble, volatile or particularly reactive. Therefore, encapsulation renders a
cover around these ingredients, which provides stability and protection
for the whole product (Nussinovitch, 2003).
