Scientific Findings About Organic Agriculture

Quality of Organically vs. Conventionally Grown Potatoes

Background and methodology

The quality of potatoes from organic and conventional farming was investigated in this study. Tubers of eight potato varieties, organically and conventionally produced at one or two geographical sites in controlled field trials, were collected in four consecutive harvests from 1996-1999. The parameters analyzed included nitrate, trace elements (arsenic, cadmium, cobalt, copper, iron, mercury, manganese, nickel, lead, selenium and zinc), vitamin C, potato glycoalkaloids, as well as chlorogenic acid, polyphenol oxidase and rate of tuber enzymic browning.

Findings

The results indicated lower nitrate content and higher vitamin C and chlorogenic acid content to be the parameters most consistently differentiating organically from conventionally produced potatoes. Elevated concentrations of glycoalkaloids also were observed throughout the experiments in some potato varieties grown in organic farming systems. Principal component analysis (PCA) of the analytical and other data confirmed a good separation between the organically and conventionally produced potatoes when studied in single crop years. However, score-plots (objects) and loading-plots (variables) of pooled results from the consecutive harvests showed that between the years’ changes and also variety as well as geographical variations are equally or more important factors in determining the quality of potatoes than the farming system. Further studies of various marker compounds of potato quality related to the organic or conventional farming systems should be performed before unbiased information can be given to the consumers.

Reference

Hajšlová , J. Schulzová, V., Slanina, P., Janné, K. Hellenäs, K. E, & Andersson, C. H. (2005) Quality of organically and conventionally grown potatoes: Four-year study of micronutrients, metals, secondary metabolites, enzymic browning and organoleptic properties. Journal of Food Additives and Contaminants: Part A, 22(6), 514 – 534.