Background and methodology
Despite increasing interest in organic products, knowledge about how different levels of fertilization affect nutritionally relevant components is still limited. This study examined the concentration of polyphenols and the activity of polyphenol oxidase (or PPO, an enzyme found in many fruit that causes browning), together with ascorbic acid, citric acid and α- and γ-tocopherol levels measured in peaches and pears grown under conventional and organic systems. Investigations occurred over a period of three years (1998-2000). Peaches and pears of the same age, either conventionally grown on tilled soil or organically grown according to European Union regulation, were obtained from the experimental orchard of the Istituto Sperimentale per la Frutticoltura in Ciampino, Rome.
Researchers found a parallel increase in polyphenol content and PPO activity of organic peaches and pears as compared with the corresponding conventional samples. Ascorbic and citric acids were higher in organic peaches than conventional, whereas α-tocopherol increased in organic pears. The concentration of oxidation products in organic samples of both fruits was comparable to that of the corresponding conventional ones. The data strongly suggest that metabolic changes, resulting in an improvement in the antioxidant defense system of the plant, occurred as a consequence of the organic cultivation practice. Indeed, organic and conventional fruits presented a similar level of oxidation products. This is likely to exert protection against damage of fruit when grown in the absence of pesticides.
Carbonaro, M., Mattera, M., Nicoli, S., Bergamo, P., & Cappelloni, M. (2002). Modulation of antioxidant compounds in organic vs conventional fruit (Peach, Prunus persica L, and Pear, Pyrus communis L). Journal of Agricultural and Food Chemistry, 50(19), 5458-5462. Available on-line at: http://dx.doi.org/10.1021/jf0202584