Effect of l-ascorbic acid addition on quality, polyphenolic compounds and antioxidant capacity of cloudy apple juices

Abstract

Polyphenols are one of the most important dietary antioxidants, and the apples, being a major source of polyphenolic compounds. There is increasing evidence that the consumption of fruit and their preserves, which are rich sources of vitamins and phenolics, is negatively associated with lung cancer and coronary heart disease. The influence of ascorbic acid addition on the quality, polyphenolic profile and antioxidant capacity in 14 selected varieties of apple juices during the 3 years of study was examined. Evaluation of changes of ascorbic acid content allowed to demonstrate the differences in susceptibility of apples on the enzymatic oxidation. The study shows that the variations of the least susceptible to oxidation of ascorbic acid are ‘Shampion’ and ‘Topaz’, and to a lesser extent, ‘Szara Reneta’, ‘Arlet’ and ‘Jonafree’ apples. A total of 17 kinds of polyphenolic compounds including catechins, procyanidins, hydroxycinnamates, flavonols, anthocyanins and dihydrochalcones were identified in apple tissues by HPLC with DAD analysis and after phloroglucinolysis and LC–MS. During the 3 years of study, the addition of ascorbic acid positively affects on the polyphenol compounds and antioxidant capacity (DPPH, ABTS and FRAP), increasing their content in the analyzed samples by 65 and 433, 328 and 300 %, respectively. The correlation coefficient between DPPH, ABTS and FRAP antioxidant capacity and ascorbic acid was 0.71, 0.71 and 0.72, respectively.