The Effect of Ultrasound and Pulsed Electric Field on the Osmotic Dehydration Process of Strawberries

Abstract

Currently, the demands of consumers are growing, and they expect safe and natural products of higher quality compared to products processed using thermal methods. Thermal treatment influences the sensory as well as quality and nutritional value of processed plant material. This results in the development of innovative, non-thermal methods of food preservation and processing. Hence, the study was conducted to examine how ultrasound (US) and pulsed electric field (PEF) affect the osmotic dehydration process of strawberries. An US treatment with a power of 400 W and a frequency of 24 kHz for 30 and 90 s and a PEF treatment were used, adopting the appropriate energy consumption of 1 and 2.5 kJ/kg. Then, strawberries after both processes were osmotically dehydrated in 0.5; 1, and 2 h at 30 °C. Dehydration was carried out in a 50% sucrose solution. Research findings have indicated that the pretreatment positively enhanced the efficiency of osmotic dehydration. An improvement in the dry weight gain rate was noted. Strawberries dehydrated with the use of pretreatment had similar or lower color values and the content of bioactive components compared to strawberries subjected to dehydration only. The material treated with the PEF turned out to be the softest. Significant differences in sugar content were noted in fruits after pretreatment. Sucrose levels increased, glucose levels decreased, and fructose remained at a comparable level.

Keywords

• osmotic dehydration
• ultrasounds
• pulsed electrics field
• strawberries
• microbiology
• color