Metabolic and sensory evaluation of ultrasound-assisted osmo-dehydrated kiwifruit

The aim of this work was to investigate the effect of ultrasound (US) pre-treatment on endogenous metabolic activity of kiwifruits slices subjected to osmotic dehydration (OD), measured by metabolic heat production in isothermal calorimeter, respiration rate, structure changes and cell viability. Moreover, the overall changes on minimally processed kiwifruit were also studied by means of electronic tongue system. Kiwifruit slices (10 mm thick) were treated with US in the bath at a frequency of 35 kHz for 10, 20 and 30 min. The OD process was conducted in a 61.5% sucrose solution at 25 °C for pre-established contact period of 0, 10, 20, 30, 60 and 120 min. The results showed that the application of US pre-treatment and OD process promoted the reduction of metabolic heat as a consequence of a partial loss of vitality. Moreover, US and US + OD treatment specifically impacted the structure and the chemical picture of kiwifruit samples. Industrial relevance: Ultrasound treatment coupled with osmotic dehydration could be applied at industrial level in order to save time and energy for a further dehydration process. Moreover, fruit tissue treated with ultrasound treatment promoted structural modifications and chemical changes in the kiwifruit tissue, as resulted from the present study, which could be useful for the industries to design novel products with intermediate moisture content.