Evaluation of in vitro Antioxidant Activities of Lemon Juice for Safety Assessment

Safety assessments of branded lemon juice are currently evaluated with parameters such as the formalin index, acidity, Brix, pH and dry content. In this study, other parameters such as vitamin C, antioxidant and phenolic compounds were evaluated to introduce some new and reliable indexes for safety assessments of lemon juice. Two groups of lemon juice were evaluated in the study. The two groups consisted of branded and natural products and were tested for total phenolic compounds (Folin-Ciocalteu), antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl) and ascorbic acid content (2-4-dinitrophenylhydrazine). Results demonstrated that total phenolic contents in both groups showed non-significant difference but the group of natural lemon juice samples had the better antioxidant capacity (795.61 mg VEE L-1) and higher ascorbic acid content (187.52 mg L-1). Levels of antioxidant capacity ranged from 476.60 to 1378.12 and from 235.47 to 888.59 (mg VEE L-1) in branded and natural sample groups, respectively. Amounts of ascorbic acid in branded lemon juice samples ranged from 23.53 to 492.91 and in the natural lemon juice samples amounts ranged from 99.32 to 196.49 mg L-1. Analysis of interrelations between these three measured parameters indicated that phenolic compound and ascorbic acid content both had significant correlations with antioxidant capacity. In summary, ascorbic acid content and antioxidant capacity are parameters suitable for safety assessments of lemon juice, but further investigation such as flavonoid profile may also be helpful.