Lemon Juice Enhances Antioxidant Nutritional Quality of Tomato (Solanum lycopersicon)

Abstract

The tomato plant is economically important and nutritionally beneficial to man. It is perishable in nature and preserved traditionally using lemon juice. The effects of this practice on antioxidant nutrients of this global vegetable food crop were investigated in this study. Tomatoes were preserved in four jars labelled 1 to 4. Jar 1 contained peeled, ground tomatoes (PG) and peeled non-ground tomatoes (PNG) without lemon juice. Jar 2 contained peeled, ground tomatoes and peeled non-ground with lemon juice (PG+LJ and PNG+LJ). Jar 3 contained unpeeled, ground tomatoes (UPG) and unpeeled non-ground (UPNG) samples while jar 4 contained unpeeled, ground and unpeeled non-ground samples with lemon juice (UPG+LJ and UPNG +LJ). The samples were analyzed for their antioxidant contents. Results revealed that concentration of ascorbic acid in tomato samples preserved with lemon juice varied from 14.70 – 20.30mg/100g FW. The values were significantly different (p<0.05) from the controls (PG, UPG, UPNG and PNG). The total phenolics content of lemon juice preserved tomatoes were also significantly different (p<0.05) from the control samples with UPNG+LJ having the highest phenolics content of 12.90mg/100g. The value of flavonoids ranged from 1.51 (PNG) to 2.95mg/100g (UPG+LJ) while ?-Carotene was from 1.78mg/100g (PNG+LJ) to 4.68mg/100g (PG+LJ). The unpeeled samples generally had higher antioxidant nutrients in comparison with the peeled samples. This study is relevant to the tomato canning industry and suggests that the use of lemon juice as tomato preservative agent should be encouraged.

Keywords: Preservation; lemon juice; antioxidant nutrients, peeling; tomato