Differential effect of organic cultivation on the levels of phenolics, peroxidase and capsidiol in sweet peppers

BACKGROUND: Coincident with the changes in agricultural practices from conventional to organic, changes in the nutrient composition of fresh fruits and vegetables have been identified. The levels of peroxidase, total phenolics content, and capsidiol activity in organic as compared with conventional sweet pepper fruit were examined in this study. In order to avoid interferences of environmental factors on the studied parameters, the sweet peppers were grown (organically and conventionally) in a greenhouse under the same soil and climate conditions. RESULTS: Peroxidase was partially purified using the Triton X-114 method and both organic and conventional peppers had the same isoenzymatic form. However, peroxidase activity in organic sweet peppers was higher than in conventional ones, in both maturity stages studied. The level of total phenolics compunds was also higher in organic than in conventional sweet peppers. With respect to the capsidiol activity, expressed as inhibition of fungus growth, it was not affected by the cultivation method at the green mature stage. However, at the red mature stage, organic sweet peppers showed higher capsidiol activity than those grown under the conventional system. CONCLUSION: Sweet peppers grown under organic culture have a maturity-related response, with high levels of phenolic compounds, and peroxidase and capsidiol activity that contribute to disease resistance in organic farming. (C) 2007 Society of Chemical Industry.