Tropentag, October 7 - 9, 2008 in Hohenheim "Competition for Resources in a Changing World: New Drive for Rural Development"

Variation in Chemical Composition of the Hypocotyle of Maca (Lepidium meyenii Walp.) cultivated in Czech Republic and in Peru

¹Czech University of Life Sciences Prague, Department of Crop Sciences and Agroforestry in Tropics and Subtropics, Czech Republic
²Czech University of Life Sciences Prague, Department of Microbiology, Nutrition and Dietetics, Czech Republic

Abstract

Maca (Lepidium meyenii Walp., Brassicaceae) is a Peruvian crop cultivated high in the Andes mountains. Maca is cultivated for consumption of its hypocotyl and is used extensively for medicinal purposes. According to folk beliefs, Maca is an aphrodisiac which enhances sexual drive and female fertility in humans and domestic animals. The beliefs have been sustained by a various experiments in rats and in men. Maca has been reported to be rich in amino acids, glucosinolates and alkaloids macamides, which are probably responsible for the aphrodisiac effects and therefore they are the main quality markers in Maca.
The nutritional value (relative contain of macamides, fatty acid composition and energetical value) of three samples of Maca of Peruvian origin was compared to one sample of Maca cultivated in Czech Republic. The plant material was obtained from comercial sources except the sample, wich was grown on experimental field of Czech University of Life Sciences Prague. Although the period of growth of Maca in Czech Republic was approximately the same as in Peru, the yield of bulbs was much lower than in samples of Peruvian origin. All the samples were prepared by extraction and repeated percolation in petrolether and analysed by RP-HPLC with DAD detection. The macamides and fatty acids were tentatively identified by retention time comparison on Agilent Eclipse XDB–C18 column and UV spectra matching. Bound fatty acids were determined as methylesters after alkaline hydrolysis using gas chromatography. Gross energy was determined using calorimetry.
There was a significantly lower concentration of macamides in the sample grown in Czech Republic compared to Peruvian samples (4–9 times lower) as well as of free fatty acids, linoleic and linolenic. The gross energy of Maca averaged 1740 KJ / 100 g and was similar in all samples tested as well as the composition of bound fatty acids. The analysis showed that Maca cultivated in weather condition of Czech Republic is similarly rich on energy as Maca cultivated in Peru, but contains significantly lower concentration of bioactive macamides and free fatty acids.

Keywords: Fatty acids , maca, Lepidium meyenii Walp., macamides, nutritional value

Contact Address: Ingrid Melnikovova, Czech University of Life Sciences Prague, Department of Crop Sciences and Agroforestry in Tropics and Subtropics, Kamycka 129, 165 21 Prague 6, Suchdol, Czech Republic, e-mail: melnikovovaits.czu.cz