PRE- AND POST-HARVEST MANAGEMENT OF FRUIT QUALITY, RIPENING AND SENESCENCE

Abstract

By the regulation of fruit ripening we ensure consumers have a year-round supply of fruit with acceptable eating quality and health promoting components. Fruit ripening is a highly regulated process with coordinated genetic and metabolic events, leading to essential changes in gene expression, physiology, biochemistry and anatomy. These complex regulatory events transform a physiologically mature but inedible fruit into an edible, tasty product. Molecular and genetic analysis of fruit development and especially of ripening, has resulted in confirmed gains in knowledge about ethylene biosynthesis and responses, cell wall metabolism and environmental factors. Innovations in CA technology like dynamic controlled atmospheres (DCA) and/or the use of the chemical ethylene inhibitor (1-MCP) are new tools for the enhancement and preservation of quality and health promoting components in climacteric fruit. DCA, with non destructive monitoring systems based either on ethanol concentrations or chlorophyll fluorescence allows the use of oxygen atmospheres during storage that are close to the lowest tolerance limits for fruit without inducing excessive anaerobic metabolism. In contrast to other available technologies, 1-MCP has the potential to control ethylene action by blocking the ethylene receptors and thereby maintaining fruit quality, and avoiding specific storage disorders not only in storage but also during marketing and shelf-life. Postharvest physiological disorders may result from oxidative stress influencing fruit physiology during fruit maturation and ripening when active oxygen species exceed the capacity of an organism to maintain redox homeostasis and exhaust the internal defence systems. Many postharvest researchers are involved in evaluating antioxidant activities as affected by cultivar, production practices and postharvest handling procedures. Sensory investigations and consumer expectation surveys have confirmed that the aroma, firmness, crispiness and juiciness are the most relevant sensory traits. Ripening regulation by modern storage technology shows great benefits in terms of texture, total soluble solids (TSS) and acidity but often hampers aroma formation mainly depending on the at-harvest ripening stage of the fruit. In the future, postharvest researchers will be challenged to meet consumer requirements with fruit that is well flavoured and nutritious.