Abstract
Antioxidant (AO) capacity of chocolates with 27, 44 and 75% cocoa was assessed after production and during twelve months of storage by direct current (DC) polarographic assay, based on the decrease of anodic current caused by the formation of hydroxo-perhydroxyl mercury(II) complex (HPMC) in alkaline solutions of hydrogen peroxide at potentials of mercury oxidation, and two spectrophotometric assays. Relative antioxidant capacity index (RACI) was calculated by taking the average value of the AO assay (the sample mass in all assays was identical). Oxidative stability of chocolate fat was determined by differential scanning calorimetry. Measured parameters and RACI were correlated mutually and with the content of total phenols (Folin-Ciocalteu assay), flavan-3-ols (vanillin and p-dimethylaminocinnamaldehyde assay) and proanthocyanidins (modified Bate-Smith assay). During storage, the studied functional and health-related characteristics remained unchanged. Amongst applied AO assays, the DC polarographic one, whose validity was confirmed by two-way ANOVA and F-test, correlated most significantly with oxidative stability (oxidation onset temperature and induction time). In addition, principal component analysis was applied to characterise chocolate types.
Highlights
Chocolate represents an important source of antioxidants (AOs)
Antioxidant (AO) capacity of chocolates with 27, 44 and 75 % cocoa was assessed after production and during twelve months of storage by direct current (DC) polarographic assay, based on the decrease of anodic current caused by the formation of hydroxo-perhydroxyl mercury(II) complex (HPMC) in alkaline solutions of hydrogen peroxide at potentials of mercury oxidation, and two spectrophotometric assays
The most potent effect on the anodic current originating from HPMC formation was ascribed to dark chocolate with the highest percentage of cocoa, as opposed to milk chocolate
Summary
Chocolate represents an important source of antioxidants (AOs). This is especially significant since it contains a superior amount of AOs compared to many other foods and beverages [1,2,3], as well as taking into account its wide consumption. In the US diet, chocolate provides an estimated 100– 107 mg per day of antioxidants, which represents more than 20 % of AOs originating from fruits and vegetables (total 488 mg per day) [4]. In the Dutch population chocolate contributes up to 20 % of the total flavonoid intake in adults, and in children the percentage is even higher [5,6]
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