Effects of varieties and cultivation conditions on the composition of strawberries

Mineral elements, vitamin C and pesticides of frozen strawberries (Fragaria x ananassa Duch.) grown in Finland were studied. ‘Senga Sengana’, ‘Jonsok’, ‘Korona’, ‘Polka’, ‘Honeoye’ and ‘Bounty’ were cultivated applying normal farming practices and harvested analogously in 1997 and 1998. Organically cultivated ‘Polka’, ‘Jonsok’ and ‘Honeoye’ were also analysed. The variation of components in the ‘Senga Sengana’ fruit of two domestic and two imported origins was investigated. Ca, Mg, K, Fe, Zn, Cu, and Mn were determined using an atomic absorption spectrometer applying the flame technique, Cd and Pb applying the graphite furnace technique. Vitamin C was measured by using high-pressure liquid chromatography. The average concentration of vitamin C ranged from 32.4 mg/100 g to 84.7 mg/100 g. Strawberries were found to be a good source of potassium (1.55–2.53 g/kg), magnesium (0.11–0.23 g/kg) and calcium (0.16–0.29 g/kg). The lead content was in general below its detection limit (0.004 mg/kg). The cadmium level in the Finnish berries was lower than 0.016 mg/kg. In all samples levels of pesticides were below their maximum residue limits. In general, genotype and origin proved to have a greater effect than the cultivation techniques on parameter levels.