KAOLIN EFFECT ON FRESH AND CANNED CLINGSTONE PEACH FRUIT QUALITY AND INORGANIC ELEMENT COMPOSITION

Abstract

Recently, kaolin sprayable materials are studied and used with many crops to control insects and diseases, alleviate heat stress and reduce sunburn damage. Furthermore, kaolin has been found to positively affect fruit external and internal quality with various fruit species. We investigated the effect of kaolin particle film application on fresh and canned clingstone peach fruit quality and inorganic element composition. Kaolin was applied periodically from early July to early August 2010 on ‘Andross’ peach trees. Fresh peach fruit treated with kaolin and harvested at commercial maturity (middle of August) had increased flesh firmness (FF), soluble solids content (SSC) and acidity and lower water content (WC) compared to control fruit. Kaolin presence on fresh peach fruit skin did not affect L*, but decreased a* compared to control fruit even after kaolin removal with water. In addition, kaolin-treated fresh peach fruit had similar P, K, Ca, Mg, Fe, Mn, Zn, Cu, Na, Cd, and Ni and slightly lower Pb contents compared to control peach fruit, while Co and Cr were not detected. Canned peach fruit had modified quality compared to fresh fruit, but most of the differences in quality attributes between kaolin-treated and control fruit remained after canning. Peach fruit color was similar in the two treatments after peeling and canning. Finally, the processed peach fruit treated with kaolin had decreased P, K, Mg, Fe, Mn, Zn, Cu, Ni and similar Ca, Na, Cd, Pb contents compared to processed control fruit, while Co and Cr were not detected. It seemed that certain nutrients leaked from the kaolin-treated processed peach fruit to the syrup resulting in decreased SSC and inorganic element content in the processed peach halves compared to the fresh kaolin-treated fruit.