Agriculture Reference
In-Depth Information
4. Phytochemicals
The levels of some phenolic compounds are known to be higher in organic fruit. Plants create
phenolic compounds for many reasons, but a major reason is to make plant tissues less
attractive to herbivores, insects and other predators. Accordingly, it is important to sort out if
higher levels of phenolic compounds affect the taste of organic fruits and vegetables when
compared to conventionally grown produce [30].
The organic growing system affects tomato quality parameters such as nutritional value and
phenolic compound content. The effect of variety, season, harvest time, maturity, as well as
environmental factors such as light, water and nutrient supply on the antioxidant content of
tomatoes are reviewed by Dumas et al. [31].
Vitamin C of tomato fruits accounts for up to 40% of the recommended dietary allowance for
human beings. Farm management skills combined with site-specific effects contribute to high
vitamin C levels, and the choice of variety significantly influences the content of ascorbic acid
[32]. The variation in vitamin C content in tomatoes depends mainly on environmental
conditions. Exposure to light is a favorable factor for ascorbic acid accumulation [31; 33].
Therefore, it is important to compare organic and conventional foods that are planted and
harvested during the same season of the year and that originate from regions with similar
incidence of solar radiation.
Ascorbic acid content in organically fertilized tomatoes ranges between 29% and 31% [23, 34],
which is higher than the results obtained from tomatoes that were fertilized with mineral
solutions. Similarly, ascorbic acid content in tomatoes cultivated with an organic substrate was
higher than hydroponically cultivated tomatoes [35]. Many citations from literature confirm
that tomatoes coming from organic cultivation procedures present higher vitamin C content
than fruits from conventional cultivation [36; 37]. It was also found that fertilizer that was rich
in soluble nitrogen (N) could cause a decrease in the ascorbic acid content, probably for indirect
reasons, since the nitrogen supply increased the plants' leaf density, which promoted shading
over the fruits.
Amati
Robin
Elpida
Organic
Conventional
Organic
Conventional
Organic
Conventional
11.73
13.8
12.6
13.87
14.33
13.7
LSD 5% 5.69 3.15 6.13
LSD 1% 13.12 7.26 14.15
Table 1.
Vitamin C content (mg 100g
-1
) in tomato at the organic and conventional production system
The results demonstrate consistent differences in vitamin C content between tomato cultivars
and method of cultivation. Thus, Elpida' tomato fruit in organic production system contained
the highest level of vitamin C. Irrespective of the cultivation method used, 'Elpida' on average
