Chemistry Reference
In-Depth Information
12.4.4 Synthetic chelators and sequesterants
EDTA
Calcium disodium ethylenediaminetetraacetic acid is a food grade, FDA-
approved metal sequestering agent (Ash and Ash, 2004). EDTA is widely used
in the USA to slow down color loss, as well as rancidity and off-flavor
development in lipid containing foods. In spite of its relatively wide-spread
acceptance in the USA, it is more restricted in Europe (limited applications) and
Japan (low dose). EDTA is not particularly useful in bulk oils due to its
insolubility, but it is very effective in beverages and in water-phase containing
emulsions, where it forms stable metal complexes and hence prevent transition
metal ions from initiating the Fenton reaction that generates hydroxyl radicals in
the initiation stage of the lipid peroxidation cycle.
EDTA is particularly useful in mayonnaise, salad dressings, sandwich
spreads and margarines. However, EDTA is also useful in a variety of fruit and
vegetable products, vitamin stabilization, dairy products, beverages and meat
products (Madhavi and Kulkarni, 1996).
12.4.5 Synthetic secondary antioxidants
Thiodipropionic acid and thiodipropionates
Dilauryl thiodipropioate (DLTDP) has been approved for use in food since the
1950s. Thiodipropionic acid (TDPA) and its dilauryl and distearyl diesters can
function as chelators and synergists. They act to decompose peroxy acids and
hydroperoxides into relatively harmless compounds such as carboxylic acids and
alcohols (see Fig. 12.5), and provide superior performance when used in
conjunction with primary radical scavengers. Thiodipropionic acid derivatives
are allowed in foods in the United States, but their use is rather limited in
practice. This may in part be due to the potential formation of sulfur-derived
aromas that would be unacceptable in certain food applications. Their limited
use might also be due to some dispute as to their effectiveness.
Karahadian and Lindsay (1988) found that extremely high concentrations of
dilauryl thiodipropionate (50 000 ppm), far above the regulatory limits, were
required to see a significant reduction of hydroperoxide concentration in heat-
Fig. 12.5 Structures of thiodipropionic acid and its dilauryl and distearyl esters.
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