Abstract: The nutritional quality of food raised by organic farming in comparison to conventional farming is a current topic that focuses interest and generate discussion. The data on nutritional quality of organic produce in comparison to conventional produce are often inconclusive. The study presents comparison of some nutritional values of juices made from organic and conventionally grown fruits (apple, pear, black currant). For the experiment 33 orchards located in the south and east of Poland were chosen. All organic farms were certified according to UE Council Regulation no. 2092/91 and obtained valid certificates. Unclarified juices were obtained with cold press juicer. After microwave mineralization in HNO3 the following nutrient elements were measured: P, K, Mg, Ca, S, Fe, Zn, Mn, Cu, B as well as Na, Cd, Pb, and Ni. Moreover, ammonium N and nitrates content were evaluated using FIA method. Black currant juices contained the highest amounts of Ca, K, Mg, P, S, Fe, Mn and Na. In the case of Ca, Fe and Mn the measured levels were ten times higher than for other juices. The highest content of Cu was proved for pear, whereas apple juices revealed the highest B amount. The husbandry method also influenced the mineral content of the juices, however in different manner for each species. Organic apple juices were having lower content of S, Na, Cu, B i Ni than their conventional contra partners. Organic farming method favored higher accumulation of Ca, Mg, P, Na, Zn, Cu, B, Cd and Ni in organic currant juices. The only difference in pear juices was found analyzing Mg content. 'Bio' juices revealed lower amount of this element.
Reference: Gastol, Maciej; Domagala-Swiatkiewicz, Iwona. (2012). Comparative study on mineral content of organic and conventional apple, pear and black current juices. Acta Scientiarum Polonorum-Hortorum Cultus 11(3): 3-14.