Quality Comparison of Mineral, Organic and Biodynamic Cultivation of Potatoes: Contents, Strength Criteria, Sensory Investigations and Picture-Creating Methods

Summary

Nutritional quality of food can be characterized by the content of beneficial and harmful substances. For today’s consumers the most important criteria for buying potatoes are taste, quality and shelf-life.
Biodynamic preparations are used by about 20% of all organic farms in Germany. These preparations do not primarily serve to increase the yield but are said to support the production of high quality food, having balanced nutrient contents and improved shelf-life characteristics.
Since 1993 investigations have been carried out to evaluate the effect of mineral fertilization and organic manuring at varied intensities, combined with application of biodynamic preparations, on some of these parameters.
The potatoes of the variety ´Granola´ responded rather slightly to the factors of the trial, hence statistical differences could be confirmed only in few cases. Tubers deriving from the mineral fertilized plots showed the strongest response to elevated fertilization (decrease in dry matter, sucrose, chloride content and density, and an increase in glucose, fructose, fluoride and ash content). Only in three parameters tubers from the biodynamic plots responded in the same way as the organic ones to elevated fertilization (increase in the chloride and ash contents, stagnating fluoride contents). In four parameters, no or only a weak response of the biodynamic tubers has been found, whereas organic potatoes showed decreasing dry matter and sucrose contents, but no distinctive tendency in the parameters glucose and fructose. The parameter strength criteria has been assessed as the weakest in mineral fertilized potatoes. The sensory investigations did not allow to differentiate between the three cropping systems but there was a tendency of worsening sensoric quality at increased fertilization, particularly in the tubers of the mineral plots. The results of the determination of vital quality following picture-creating methods confirmed the applicability of this assay for additional quality determinations.
A final assessment of the quality according to the different cropping systems cannot be made at this point of time. Therefore, further parameters (nitrate, potassium, amino acids, ascorbic acid) will be analyzed which might allow a final assessment in combination with the present data. Furthermore, current trials might reveal if other varieties respond stronger to the relevant factors.