The objective of this study was to analyze the effect of sour cherries drying technique and process parameters on textural properties of dried fruits assessed using acoustic and mechanical methods. The stoned and frozen sour cherries were dried using different techniques: convection, microwave, vacuum, and sublimation. Determined were the moisture and water activity as well as the porosity of the fruits dried. Compression tests were performed on each single dried cherry fruit and, at the same time, the acoustic emission (AE) was registered by a contact method. The technique and parameters of the process of sour cherries drying impacted their textural properties, which were assessed based on the analysis of acoustic emission descriptors and mechanical parameters. The occurrence of three groups of dried sour cherries was found; those groups differed in their textural properties. The increase in the temperature of the freeze drying process from 30 to 50 °C caused the number of EA events and the compression work to increase. During the convective drying process, the increase in the temperature from 50 to 70 °C caused the amplitude of the sound to significantly increase, the number of EA events to decrease, and the compression force and work to increase. During the compression test on dried cherries, the raise in the microwave power from 100 to 300 W caused the generation of acoustic emission that had decreasing amplitude, increasing number of EA events, and a significantly lower compression work and force. The EA descriptors and mechanical properties of the sour cherries dried using various drying techniques were negatively correlated with the humidity of dried cherry fruits.
sour cherries, drying, texture, acoustic emission, mechanical properties