Compositional changes in kiwifruit infected withBotrytis cinerea1. In vivo studies

Abstract

Natural infections of Botrytis cinerea on kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson) cv. Hayward in commercial storage started from the stem end and progressed along the friut. To study ilie chemical changes occurring during disease development, three fruit sections from individual infected fruit were analysed—non-infected part, invasion zone, and infected part. The chemical changes which were detected in juice extracted from the invasion zone and which became more intense in the infected part included: a decrease in total soluble solids and reducing sugars which was mainly because of disappearance of glucose (ilie amount of fructose remained unchanged); a decrease in pH accompanied by an increase in titratable acidity, mainly because of increases in citric (3×), quinic (2×), oxalic (10×), and fumaric (20×) acids; a decrease in chlorophyll content; and an increase in total phenols. Proteolytic activity was variable in healthy tissue, highest in ilie invasion zone, but almost non-existent in ilie noninfected part.