Comparison of apples from organic and integrated farming

Due to food safety reasons, there is an increasing interest towards products of organic farming, At the same time there are relatively few studies collating the effect of different farming technologies.DoAmarante et al., (2008) compared the yield and fruit quality of apple (‘Royal Gala’and ‘Fuji’) from conventional and organic production systems. The organic apples contained less K,Mg andN in fruits, and leaves, and fruits were smaller for both cultivars. Organic fruits of Royal Gala variety had lower acidity, but higher soluble solids. Gonda et al. (2000) compared some fruit quality parameters of apple cultivars in organic production to apples grown in integrated production. Carbonaro & Mattera (2001) found significantly higher polyphenol level and polyphenol oxidase activity in organic peaches and pears as compared to those from conventional production.As reported by Dani et al. (2007), organic grape juices showed statistically higher values for the total polyphenol and resveratrol content as compared to conventional ones. Róth et al., (2007) investigated the postharvest quality of integrated and organically produced apple fruit and found that storage conditions had amuch stronger influence than the production system. Stracke et al., (2009)made a three-year comparison of the polyphenol contents and antioxidant capacities in organically and conventionally produced ‘Golden Delicious’ apple. Their main conclusion was that production method had a smaller impact on the variation in the polyphenol content and antioxidant capacity of apples than the yearly climate. Some scientists are sceptic on the advantages of bio fruits and vegetables (Magkos et al. 2003, Trewavas 2004). In their research work Bourn & Prescott (2002) compared the nutritional value, sensory qualities and safety of organic and conventional foods and came to the conclusion that except with nitrate, there is no strong evidence on compositional differences.

unpeeled using a Waring blender.The blended fruit sample was used in the different tests and analyses.
Soluble solids were measured from pressed apple juice with an Abbe refractometer (Carl Zeiss, Jena) according to Hungarian Standard MSZ EN 12143 at 20°C.
Titratable acidity was determined according to MSZ EN 12147 from 10 grams of fruit pulp by an automatic titrator (Mettler DL 70).Results obtained at pH 8.1 are expressed as citric acid equivalent.
Polyphenols were measured after 80% methanol extraction of fruits.Twenty ml of methanol was added to 5 g fruit pulp and incubated overnight at 4°C.After sonication, the sample was filtered and subjected to colour reaction with Folin-Ciocalteu reagent, which was performed according to MSZ 9474:1980 and given as gallic acid equivalent (GAE).
The free radical scavenging activity (antioxidant capacity) was determined by DPPH method.The DPPH free radical scavenging assay was performed according to the method reported by Brand-Williams et al. (1995) with some modification.Fifty L of methanolic extract of sample or methanol (control) were added to two ml of methanol solution of a 100 µM DPPH.Liquid in the cuvette was mixed and left to stand in a thermostated spectrophotometer in the dark at 36°C for 30 min and absorbance was then read at 517 nm using a Unicam spectrophotometer.Antiradical activity was expressed in mmol/kg using a Trolox calibration curve.
Copper and zinc were determined with atomic absorption spectrometry with flame ionisation mode (AAS) according to AOAC 975-03 (1990).Five g of the blended fruit were digested with a mixture of HNO 3 -HClO 4 -H 2 SO 4 (30:1:5) acids.Measurement was carried out using Solaar M5 AA spectrometer (Thermo Elemental).Measurement conditions are summarized in Table 1.
The values are given as means and standard deviation of triplicate samples.Principal component analysis was performed using Minitab software version 13,0.

Results and Discussion
The results from literature indicated that the probable difference between apples from organic and integrated farming is smaller than between organic and conventional ones.
Basing on the fact that apple is not nitrate accumulating fruit in this work nitrate (expected to be under 5 mg/kg) was disregarded among different measurements, although.Bourn & Prescott (2002) accentuated nitrate as the main difference in foods from diverse farming systems including organic and conventional.
The fruit size and weight are summarized in Table 2, while results obtained by chemical analyses for the different parameters with standard deviations are shown in Table 3.All values were calculated in proportion to the fresh weight.
Tóth-Markus, M., Adányi, N., Boross, F., Daood, H.G., Bánáti, D., Szabó, T. & Nyéki, J.The highest level of total titratable acidity was found in bio apples, 13 cases from the 15 bio-integrated sample pairs.In contrast to our results, do Amarante et al., (2008) found lower acidity with organic apple cultivar 'Royal Gala', while Róth et al., (2007) measured uniform acidity in organic and integrated 'Jonagold' apples at harvest and during storage.Difference in acid content may be due to different ripening stages at harvest.
The total polyphenol content did not differ significantly in organic and integrated sample pairs.The polyphenol level is also expected to strongly be influenced by ripeness.
The heavy metal content of integrated samples was mostly higher.From the 15 bio-integrated pairs, 12 and 10 apple cultivars contained higher level of copper and zinc respectively.
A 4-month storage caused a loss of 12% (in Topáz, organic) and 49% (in Remo, integrated) in titratable acidity, with integrated fruits losing higher amounts of malic acid.
Because of the small number of sample pairs, so far, available for analysis, this needs further investigation for more clarification.Not agreeing with our results, Róth et al., (2007) did not find any difference between organic and integrated apples in the acid loss of at the end of shelf-life (six months) neither in air storage nor in controlled atmosphere.The acid loss measured by them was much higher (above 40%) in air storage than under controlled atmosphere.
Water soluble solids (Brix degree) decreased by 0.7-1.8degree as a function of storage.This finding is also not agreeing with what Róth et al. ( 2007) observed.There are opposite processes influencing water soluble solids: While weight loss causes a concentration, dissimilation consumes sugars.
Polyphenols and free radical scavenging activity have also fallen during storage, but not significantly.The differences were in the range of measurement uncertainty.The dataset for bio and integrated cultivar pairs were compared by principal component analysis based on correlation matrix.Fruit size and fruit weight were not included in PCA.According to the loading plot, (Figure 1) the first component is connected with the titratable acidity and concentration of copper and zinc, while the second factor is composed by antioxidant capacity, polyphenolics and soluble solids.First two principal components explain 63% of the variability in the data.

Comparison of apples from organic and integrated farming
The samples from Pallag and Ujfehértó region are separated on principal analysis score plot, (Figure 2) and a separation is observable between the fresh and stored apples because of the lower acidity of stored fruits.
These results are considered as preliminary, as the experiment is continued in 2009-2010 season.

Figure 2 .
Figure 1.Principal component analysis, loading plot of apple data

Table 1 .
Measurement conditions

Table 2 .
Size and weight of apples at harvest and after storage

Table 3 .
Composition of apples at harvest and after storage