Extracts from paprika, annatto and marigold, rich in antioxidant carotenoids, could significantly reduce the spoilage due to oxygen of model oil-in-water emulsions, says new research from Greece.
The research taps into the current trend for natural additives at the expense of synthetic alternatives, and adds that the extracts could also inhibit the formation of compounds associated with off-flavours.
On the other hand, according to the findings published in Food Chemistry, other carotenoids such as alpha- and beta- carotene, and lycopene did not benefit the emulsions.
“Given the present preference of food technology for the use of natural additives as preservatives against the oxidative destabilisation, these results could offer the basis for more systematic research in this field,” wrote Sotirios Kiokias from the Laboratory of Food Chemistry and Technology at the National Technical University of Athens.
“In particular, the optimisation of conditions that would favour the inhibitory effect of natural carotenoid extracts on the ‘off flavour’ quality deterioration of related products during storage is a topic of great interest that certainly requires further investigation.”
Using a model sunflower oil-in-water emulsion, Kiokias and his co-workers investigated if certain natural mixtures, such as marigold (lutein-rich), tomato (lycopene-rich), paprika and annatto extracts could offer an antioxidant activity in dispersed systems.
“The understanding and optimisation of the carotenoid activity in novel emulsion systems could offer the basis for their more systematic use by food industry as functional ingredients, which could protect the related food products from their sensory and nutritional oxidative deterioration,” they explained.
At a concentration of 2 grams per litre of emulsion and 30 degrees Celsius, none of the carotenoids had an effect on the production of hydroperoxides, used as a measure of oxidation and spoilage. However, the researchers did note a significant retardation the formation of volatile aldehydes, known ‘off-flavours’.
A second experiment at a higher temperature (60 C) to simulate accelerated oxidation, showed that carotenoid extracts of paprika, annatto and marigold showed significant anti-hydroperoxide activity at a concentration of only one gram per litre. The other carotenoids did not show any effect.
In explaining these observations, Kiokias and his co-workers note that the carotenoids in paprika, annatto and marigold are mainly polar, while carotene in alpha- and beta-carotenes and lycopene are mostly hydrophobic.
“Therefore, the carotenoid structure modulated their antioxidant effect, while concentration and emulsion structure may also affect carotenoid activity in protein dispersed systems,” they concluded.
Source: Food ChemistryVolume 114, Issue 4, Pages 1278-1284“Activity of natural carotenoid preparations against the autoxidative deterioration of sunflower oil-in-water emulsions”Authors: S. Kiokias, C. Dimakou, V. Oreopoulou