Drying of ultrasound pretreated apple and its selected physical properties

• Published in: Journal of food engineering Vol. 113; no. 3; pp. 427 - 433
• Main Authors: Nowacka, Małgorzata, Wiktor, Artur, Śledź, Magdalena, Jurek, Natalia, Witrowa-Rajchert, Dorota
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2012; Elsevier
• Subjects: Apples; Biological and medical sciences; Drying; Food engineering; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General aspects; Malus; Microstructure; Physical properties; Rehydration; Ultrasound; Apples; Rehydration; Microstructure; Ultrasound; Physical properties; Drying; Apple; Fruit; Pretreatment
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2012.06.013

► The effect of ultrasonic treatment before drying of apples were investigated. ► The influence of ultrasound treatment on rehydration properties of dried material was studied. ► The changes in apples microstructure were examined. ► Ultrasound application caused alteration of rehydration properties. ► Ultrasound treatment and subsequently drying induced changes of apple microstructure. The aim of this work was to investigate the utilization of ultrasound as a mass transfer enhancing method prior to drying of apples tissue. Ultrasound power was provided at a frequency of 35kHz for 10, 20 and 30min in the ultrasound bath. Apple cubes were dried using convection method in 70°C and at air velocity of 1.5m/s. The effects of ultrasound pre-treatment upon drying were investigated. The ultrasound treatment caused reduction of the drying time by 31% in comparison to untreated tissue. The ultrasound treated apples exhibited between 9% and 11% higher shrinkage, 6–20% lower density, and porosity of 9–14% higher than untreated samples. Considerable differences in the density and porosity of the dried apple with and without ultrasonic application were confirmed by scanning electron microscopy image analysis of the investigated tissue. Moreover, ultrasound application caused alteration of rehydration properties in comparison to untreated sample.