Internal Bruising Affects Chemical and Physical Composition of Tomato Fruit

Abstract

Tomato (Lycopersicon esculentum L.) fruits, cv. Solarset, were harvested at the mature-green stage and treated with 50 μL/L ethylene at 20C. Breaker fruits (<10% red coloration) were dropped from 40 cm onto a smooth, solid surface and held along with undropped fruits at 20°C and 85% relative humidity. At table-ripe stage, pericarp, placental, and locular tissue were individually excised and analyzed for total carotenoids, total soluble sugars, soluble solids content, titratable acidity, density (locule tissue), polygalacturonase activity, and electrolyte efflux (pericarp tissue). Internal bruising caused by impact forces significantly affected pericarp and locule tissues, but not placental tissue. For bruised locule tissue, total carotenoids content decreased by 37.1%, vitamin C content by 15.6%, and titratable acidity by 15.3% as compared to control. However, density was increased by 3.0%. For bruised pericarp tissue, vitamin C content decreased by 16.5%, while polygalacturonase activity and electrolyte efflux increased by 33.3% and 24.8%, respectively. The development of abnormal ripening following an impact was confined to locule and pericarp tissues and appears to be related to the disruption of cellular structure and stimulation of enzymic activity.