It is evident that the growing interest in organically grown produce has correspondingly necessitated
the debate on the nutritional supremacy between organically and conventionally grown produce. A
study was carried out to determine and compare vitamin C, calcium and potassium in organically and
conventionally grown cabbage, carrots, Cos lettuce and Valencia oranges. Samples were purchased
from local supermarkets within Central Coast, New South Wales in Australia from late March to early
April 2007. Vitamin C content was determined by 2,6-dichloroindophenol titrimetric method while
calcium and potassium were determined by atomic absorption spectroscopy. Results from the study
showed inconsistent pattern with respect to vitamin C, calcium and potassium contents in the
conventionally and organically grown samples. No significant differences were observed in vitamin C
content in conventionally and organically grown cabbage, carrots and Cos lettuce while significant
differences were observed in Valencia oranges which showed higher vitamin C content in organic
Valencia oranges as compared to conventional ones (51.8 to 43.4 mg/100 g fresh weight). Results on
calcium and potassium contents showed significant differences in all the samples with the trend of
higher values for organically grown cabbage, carrots and Cos lettuce as opposed to their
conventionally grown counterparts. However, for Valencia oranges, results showed that the calcium
and potassium contents were significantly higher in conventional Valencia oranges compared to the
organic Valencia orange (54.5 and192.0 mg to 51.8 and 189.5 mg/100 g, respectively).