Evaluating effects of climate variability on postharvest quality of strawberries

The strawberry is one of the most popular fruits worldwide cultivated in many regions of the globe contributing to human health and nutrition of consumers, as well as generating income for growers and retailers. The UK is one of the main importers of strawberries worldwide and one of the major strawberry exporters is Spain. The aim of this work was to evaluate the effects of environmental variability on several characteristics of strawberry postharvest quality. Acids, sugars, colour, firmness, anthocyanins, visual evaluation for detection of bruises and mould development were assessed. Work at the initial stages revealed a positive relationship between increased preharvest temperature and softening of fruits. Subsequent experiments took place in order to verify this finding and examine the physiological and biochemical mechanisms that contribute to this phenomenon. Contribution of pectate lyase (PEL) action to softening was assessed. No evidence was found to indicate that PEL activity was the key factor for lowering strawberry firmness. Furthermore, plants were cultivated under controlled conditions in growth cabinets in order to evaluate the effects of temperature and light on quality of strawberries. It was noticed that the effect of higher preharvest temperature over longer periods of time (weeks) was more important for reducing firmness when compared to the effect of higher temperature over shorter periods (hours). In addition the impact of force on development of bruise and the positive relationship that this has with reduced firmness of fruits was investigated. It was shown that firmer fruits grown at lower preharvest temperature had reduced levels of dry bruise development when exposed to artificial transport stress. Finally, the changes in quality profile of fruits through the harvest season and the way that these changes affect consumer acceptability were also evaluated. Consumers were able to relate sweeter strawberries to increased TSS and sugar levels and they also showed preference for them when compared to fruits with lower levels of sugars and TSS