A Study on Organic Tomatoes: Effect of a Biostimulator on Phytochemical and Antioxidant Activities

Abstract

The objective of the present study is to investigate nutritional and antioxidant activity of four types of organic tomato cultivars. The differences in tomato quality are also tested between groups with or without treatment using an organic biostimulator, Stimplex. Total phenolic compounds (TPC), lycopene,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>-carotene, DPPH free radical scavenging activity, reducing power, and color parameters were investigated in the current study. The results showed that there was no significant difference in TPC among cultivars regardless of Stimplex treatment. Higher lycopene and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>-carotene were obtained in Stimplex treated tomatoes. Lycopene and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>-carotene contents were significantly different among cultivars (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mi>P</mml:mi><mml:mo>&lt;</mml:mo><mml:mn fontstyle="italic">0.05</mml:mn></mml:math>). DPPH scavenging activity in controlled group was significantly higher than that in the Stimplex treated tomatoes (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mi>P</mml:mi><mml:mo>&lt;</mml:mo><mml:mn fontstyle="italic">0.05</mml:mn></mml:math>). No significant difference in reducing power was detected among cultivars treatment groups. The study showed that the darker the tomato color, the higher the lycopene and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>-carotene contents and the stronger the reducing power.