Abstract:
The objective of this study was to investigate antioxidant activity by DPPH assay, vitamin C and phenolic compounds content in three types of lettuce such as green cos, red cos and butterhead produced in hydroponic system and soil-based cultivation system from vegetable farmers near Ubon Ratchathani University. The results showed that antioxidant activity of green cos and butterhead had no significant difference between the cultivation systems while red cos had a significant higher value in soil-based systems. Comparison the antioxidant activity values between lettuce types at the same cultivation systems, green cos and red cos obtained similar value (67.45±6.71-89.83±4.30%) which was higher than that of butterhead (40.60±6.64-53.88±13.04%). For vitamin C and phenolic compound contents, the results revealed that there was no significant difference either hydroponic or soil-based system. However, there was significant difference between lettuce types at the same cultivation systems. For vitamin C contents, the results showed that green cos and red cos obtained similar values in the range of 195.20±10.75-213.22±18.59 mg/100 g of sample that was higher value than that of butterhead (79.36±0.51-95.33±9.89 mg/100 g of sample). For phenolic compounds content, the higher value was exhibited by green cos in the range of 15.80±0.85-18.98±0.76 mg GAE/100 g of sample while red cos and butterhead obtained similar value in the range of 10.95±0.47-12.90±0.27 mg GAE/100 g of sample.