Quantitative assessment of the main antioxidant compounds, antioxidant activities and FTIR spectra from commonly consumed fruits, compared to standard kiwi fruit

- Quantitative assessment of main antioxidant compounds in fruits.
- Best predictors for antioxidant capacity in fruits were polyphenols and vitamin C.
- IR spectra provide information of potential polyphenols.
- Methanol/water/acid is a better extraction solvent of total soluble phenolics from fruits than without acid.

Bioactive compounds (polyphenols and ascorbic acid) and dietary fibers, and related antioxidant activities of commonly consumed apples, bananas, peaches, pears, blond and red grapefruits, pomelos, oranges, lemons, red plums, white grapes, mango, persimmon and strawberries grown in the same geographical and climatic conditions were compared with standard kiwi fruit. The presence of polyphenols was studied by Fourier transform infrared (FT-IR) spectroscopy. The contribution of dietary fibers to antioxidant activity of the fruits was minimal (R2 from 0.3078 to 0.3626), of the ascorbic acid - moderate (R2 from 0.6402 to 0.6734) and of total polyphenols - decisive (R2 from 0.9792 to 0.9827). It was found that strawberries and kiwi fruits have the highest phenolic contents and their antioxidant activities following by red plum > mango > white grapes ≥ persimmon > apples > pears ≥ red grapefruit > lemons = oranges = blond grapefruits ≥ pomelos > bananas > peaches (P < 0.05). FTIR spectroscopy and radical scavenging assays are suitable for bioactivity determination of these fruits. In order to receive best results for human consumption, a combination of these fruits has to be included in the everyday diet. The methods used are applicable for bioactivity determination in food analysis in general.