Variation of quantitative composition of phenolic compounds in apples during ripening.

The aim of the research – to investigate variation of quantitative composition of phenolic compounds in Lithuania grown apples cultivars 'Connel Red' and 'Ligol' in apples during ripening and to evaluate the antioxidant activity of these extracts. The objectives of the research: 1. To determine variation of total content of phenolic compounds in apple cultivars 'Connel Red' and 'Ligol' apples during ripening. 2. To determine variation of quantitative composition of ascorbic acid in apple cultivars 'Connel Red' and 'Ligol' apples during ripening. 3. To investigate antioxidant activity of ethanolic apple extracts by performing DPPH, FRAP and TFPH methods of Lithuania grown apples cultivars 'Connel Red' and 'Ligol'. 4. To evaluate correlation between 'Connel Red' and 'Ligol' cultivars of apple extracts containing quantitative composition of phenolic compounds, flavonoids, proanthocyanidins and antioxidant activity. Object and methods: Apple fruits samples of cultivars 'Connel Red' and 'Ligol' were collected in 2013 on different phonological stages from June to November. The total content of phenolic compounds, flavonoids and proanthocyanidins in apples samples was performed using UV-VIS spectrophotometric method, ascorbic acid - titration with 2,6-dichlorphenolindophenol sodium salt solution. Antioxidant activity was assessed by DPPH, FRAP and TFPH spectrophotometric methods. Results: Total content of phenolic compounds in apples samples ethanolic extracts during ripening period varied from 7,20 mg GAE/g to 77,23 mg GAE/g in 'Connel Red' cultivar and from 8,12 mg GAE/g to 80,26 mg GAE/g in 'Ligol' cultivar. Total content of flavonoids varied from 0,81 mg RE/g to 3,27 mg RE/g in 'Connel Red' cultivar and from 0,63 mg RE/g to 3,61 mg RE/g in 'Ligol' cultivar. Total content of proanthocyanidins varied from 3,10 mg/g to 18,00 mg/g in 'Connel Red' cultivar and from 2,67 mg/g to 18,13 mg/g in 'Ligol' cultivar. Content of ascorbic acid varied from 0,029 percent to 0,058 percent in 'Connel Red' cultivar and from 0,031 percent to 0,058 percent in 'Ligol' cultivar. The highest TE values ('Connel Red' – 735,27 ± 25,38 μmol TE/g, 'Ligol' – 715,63 ± 24,19 μmol TE/g) in apple samples ethanol extract was assessed FRAP method. The strongest correlation (0,963 – 0,997) between phenolic compounds, flavonoids and proanthocyanidins content and antioxidant activity was estimated using FRAP method. Conclusion: During development and ripening stages of apples major phenolic compounds, flavonoids, proanthocyanidins and ascorbic acid were determined at the beginning of their stage of development (17 June). Therefore at this stage we recommend to carry out the set-ups of apple extracts production or extraction of individual compounds