Background and methodology
In 2002, neighboring plots of conventionally and organically managed ‘Dark Red Norland’ potatoes, separated by approximately 650 meters, were established as a part of two distinct studies in Wooster, Ohio (Wayne County). The organic variety included plots receiving no amendments and plots receiving compost, whereas the conventional variety trial was managed uniformly throughout. Therefore, samples later used in postharvest analysis were collected from plots of three field treatments: organically grown with compost, organically grown without compost and conventionally grown. Triangle tests were used to determine if panelists could distinguish (by tasting) cooked wedges of potatoes grown organically (either with or without compost), and conventionally. Mineral and glycoalkaloid analyses of tuber skin and flesh also were completed.
Findings
When the skin remained on the potatoes, panelists detected differences between conventional potatoes and organic potatoes, regardless of soil treatment. However, they did not distinguish between organic treatments (with or without compost) when samples contained skin, or between any treatments if wedges were peeled prior to preparation and presentation. Glycoalkaloid levels tended to be higher in organic potatoes. In tuber skin and flesh, potassium, magnesium, phosphorus, sulfur and copper concentrations also were significantly higher in the organic treatments, while iron and manganese concentrations were higher in the skin of conventionally grown potatoes.
Reference
Wszelaki, A. L., Delwiche, J. F. , Walker, S. D., Liggett, R. E., Scheerens, J. C., & Kleinhenz, M. D. (2005). Sensory Quality and Mineral and Glycoalkaloid Concentrations in Organically and Conventionally Grown Redskin Potatoes (Solanum tuberosum). Journal of the Science of Food and Agriculture 85(5), 720-726.