Advancement in fruit drying through the analysis of moisture sorption isotherms: Processing effects on Australian native fruits in comparison to apple

Australian native fruits are well-adapted to local climate and have growing interest in their nutritional and sensory qualities. Among the most highly produced are finger limes and muntries. However, published literature on their characterisation and especially their processing is limited. How processing affects the water binding in foods is poorly understood but influences microbial activity and drying behaviour. This work utilised dynamic vapour sorption to study the water binding of apples compared with the native fruits muntries and finger limes, as well as how drying affected this water binding. Unlike in apple, water binding in native fruits was observed to increase after drying. By analysing associated changes to composition, cellular structure and carbohydrate structure, this was correlated to increased breakdown of complex carbohydrates into simple sugars in native fruits. It is suggested this may be a feature of their drought adaptation. Together with a newly proposed equation for the drying heat required, allowing for calculation of the drying heat, these findings can guide more sustainable processing of Australian native fruits as well as other foods.