Effects of pre-treatment and drying on the quality attributes of fruit

Fruits are a great source of fibre and phytochemicals with health beneficial properties. In particular, citrus, blueberries, bananas, pomegranate and cherry tomatoes are rich in bioactive compounds and are regarded as super foods. Fresh minimally processed fruits have a limited shelf life and are prone to deteriorating over time due to respiration and enzymatic activities. To reduce postharvest losses and preserve the bioactive content of fruit, a shelf stable product can be developed by using appropriate drying techniques. During the process of drying, the water activity is reduced which lowers the rate of spoilage. Drying also enhances the storage stability, minimises packaging and reduces weight for easier transportation. Several measures are to be considered before drying these small fruits for nutraceutical or functional food industries. They offer health benefits beyond basic nutritional demands which need special pre-treatments to minimise the opposition of their skin to moisture movement. Pre-treatments have shown to maintain the colour of fruit and also inactivate enzymes that may cause undesirable changes during drying. This review discusses several types of pre-treatments (sulphur, blanching, ascorbic acids, etc.) and drying methods (hot air drying, freeze drying, etc.) that are available for the modification and suitability of each product.