Ultrasound-Assisted Infrared Drying of Pear Slices: Textural Issues

The aim of this research was to investigate the impact of high-intensity ultrasound as pretreatment on the duration of drying and texture characteristics of infrared-dried pear slices using different amplitudes. Ultrasound device with a power capacity of 400W, working at a frequency of 24kHz and amplitudes of 25, 50, 75 and 100%, was used for pretreatment. Drying was performed in an infrared dryer at 70C. The results obtained showed how application of ultrasound with various amplitudes influenced the shortening of the drying time and allows the elimination of more water from the pear slices. The results showed that hardness of samples gradually decreased (from untreated sample [104.72N], 50% of amplitude [93.461N] to 100% amplitude [62.206N]) with an increase in ultrasound intensity and that all process parameters had significant influence on the textural properties of pear slices (hardness, elasticity and work required for chewing). Practical Applications Drying in food technology is usually based on the use of conventional methods such as heat exchange by conduction or convection, which may have negative effects on textural issues of final products. In order to achieve final products of high quality, new and sophisticated techniques for food treatment are required. One of such methods is the power ultrasound-aided drying. This method is proven efficient for preserving main characteristics and quality of products, and additionally leads to shortened drying time.