In the study of Koh et al. [32], 27 spinach varieties
grown in certified organic and conventional cropping systems were undertaken in order to compare the levels of vitamin C. The mean levels of ascorbic acid were significantly higher in the organically grown spinach compared to the
conventionally grown spinach. These results suggest that
organic cropping systems result in spinach with higher levels of ascorbic acid.
In the 2 years of the experiment by Hallmann [33], there
was a significant effect of cultivation method on the vitamin C content. Organic tomatoes had significantly higher
content of vitamin C compared with conventional tomatoes. On the other hand, Pieper and Barrett [34] obtained a
lower content of vitamin C in organic tomatoes compared
to conventional ones. Similar results were presented by
Juroszek et al. [35], who indicated that organic tomatoes
showed a tendency to higher content of vitamin C, although
the differences between organic and conventional tomatoes
were not statistically significant.
In the study of Bizjak Bat et al. [36] the average ascorbic acid content of 32.2 mg/100g in the organically grown
fruits was higher than the average content of 23.0 mg/100g
in the conventional ones. Higher ascorbic acid content was
also found in organically grown fruits [37].
Similar results were obtained by Hallmann and
Rembiałkowska [38], who reported that organic bell pepper
fruits were distinguished by a significantly higher content
of vitamin C compared with conventional fruits