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Cross-linked pectin to lead to better emulsions for food?
25-Apr-2008 - Using enzymes to
cross-link pectin may produce new emulsions with enhanced functional
properties, and opportunities for food formulators, American
researchers report.
The enzyme laccase was used to cross-link specific groups present in
beet pectin, which could then be electrostatically deposited onto
the surfaces of protein-coated droplets, and offer food formulators
new opportunities, according to the research published in the
journal Food Hydrocolloids.
"We believe that mimicking biochemical processes prevalent in nature
(such as enzymatic cross-linking of pectin) allows one to rationally
design novel functional performance into commercial emulsified
products," wrote Francois Littoz, D. Julian McClements from the
Department of Food Science at the University of Massachusetts.
"We should note that as well as improving the stability of
emulsified lipids in food products during their production,
transport, storage, and consumption, this approach may also prove
useful for controlling the digestibility of lipids in vivo since the
ability of digestive enzymes at accessing encapsulated lipids may be
altered by the presence of a cross-linked interfacial layer," they
added.
Emulsions are applied to a range of food products, including salad
dressings, beverages, dips, sauces, desserts, and yoghurts.
Promising findings
Littoz and McClements prepared emulsions containing 0.1 weight per
cent corn oil, 0.05 weight per cent beta-lactoglobulin (Davisco
Foods), and 0.02 weight per cent beet pectin (Herbstreith and Fox
KG) at pH 7.
The pH was then lowered to 4.5 to promote the electrostatic
deposition of the pectin, and laccase was then added to promote
cross-linking of the adsorbed beet pectin molecules.
The technique was shown to work, with stable emulsions formed.
"Our results suggest that the beet pectin layer remains attached to
the droplet surfaces when the pH is raised from 4.5 to 7.0, even
though it would normally be expected to become detached because of
the electrostatic repulsion between the anionic pectin and anionic
protein-coated droplets at pH 7," they stated.
The Amherst, Massachusetts-based researchers also report a higher
stability to salt for the emulsions containing lipid droplets coated
by beta-lactoglobulin and cross-linked beet pectin than for
emulsions containing lipid droplets coated only by beta-lactoglobulin.
This attributes to the adsorbed pectin's ability to reduce
agglomeration by increasing the repulsive and decreasing the
attractive interactions between the droplets.
"These results suggest that emulsions with improved functional
performance can be prepared using a bio-mimetic approach that
utilizes enzymes to cross-link adsorbed biopolymers," they
concluded. |