Agriculture Reference
In-Depth Information
Tomato Fruit Quality from Organic and Conventional Production
http://dx.doi.org/10.5772/58239
3. Materials and methods
Three tomato varieties (Robin F 1 , Amati F 1 and Elpida F 1 ) have been tested in greenhouse
production (plastic tunnels 3.5m high, covered with termolux 180 μm) during 2008-2010,
located in the Sapes, Northeastern Greece, using two different growing systems: organic and
conventional. Greenhouse technology and horticultural practices differ little. The main
variations concerned pest control, fertilization and fertility of soil, which was of much better
quality in the organic production. In conventional cultivation mineral fertilizers and chemical
plant protection were applied. The differences between production systems were the fertilizers
used (organic: goat manure 3 tonnes/ha; conventional: mineral fertilizer NPK (12:12:17),
nitrophos blue special+2MgO+8S+Trace elements - 400 kg/ha), the number of phytosanitary
(solarization) treatments (larger in organic system), the pesticide types applied (preventive in
the organic systems and preventive or healing with variable period of effectiveness in the
conventional one). It was an early-medium production; planting was done between 15 April
and 20 April at a density of 2.64 plants/m 2 .
At the pink stage of ripening determined by visual inspection, samples were collected for
quality analyses (colour, firmness, total soluble solids, total sugar, total acidity content of
vitamin C, content of carotenoids and lycopene). For sensory evaluation fruits were evaluated
by trained descriptive panelists on the day of harvest (red stage). Tomato samples (20 fruits)
were collected each year from June till August and were taken from the third to sixth floral
branches.
Determination of total soluble solids (TSS) was carried out by a refractometer. The results were
reported as o Brix at 20 o C. The titrable acidity (TA) was measured with 5 ml aliquots of juice
that were titrated at pH 8.1 with 0.1 N NaOH (required to neutralize the acids of tomatoes in
phenolphthalein presence) and the results were expressed as citric acid percentages.
Pigment extraction from tomato fruits, preparation of extracts for analysis and calibration plots
of standard components were determined according to a described method [26].
Approximately 0.5 g of freeze-dried sample was weighed into porcelain crucibles that had
previously been heated for 3 hr at 550 o C and was converted to white ash at this same tem‐
perature over 12-18 hr. Each ashed sample was dissolved in 20 mL of 3 M HCl, and K, Ca, Na,
Mg, Fe, Zn, Mn and Cu levels were determined by atomic absorption spectrophotometry.
Besides, a taste index and the maturity were calculated using the equation proposed by X et
al. [27] and Y and co-workers [28] starting from the Brix degree and acidity values which were
determined in a previous paper [29].
Brix degree Brix degree
Taste index = ---------- + Acidity Maturity = -----------
20 × Acidity Acidity
Search WWH ::




Custom Search