Ultrases Ön İşleminin Elma Dilimlerinin Kurutma ve Rehidrasyon Karakteristikleri ile Mikroyapısına Etkisinin Araştırılması

Senem Tüfekçi̇,Sami Gökhan Özkal

doi:10.29133/yyutbd.698826

Senem Tüfekçi̇, Sami Gökhan Özkal

Open Access

https://doi.org/10.29133/yyutbd.698826

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Abstract

In this study, the effects of ultrasound pretreatment on hot air drying and rehydration characteristics and microstructure changes of apple slices were examined. Slices of apple cv. Granny Smith having 5 mm thickness were used as the material. Pretreatments with ultrasound application were done by an ultrasonic generator with 20 kHz frequency. Effect of pretreatment time (10, 20, 30 min) and amplitude (55 and 100 %) were evaluated. Drying experiments were performed in a cabinet drier at 60°C with 0.3 m.s-1 constant air velocity. Application of ultrasound pretreatment decreased the drying time of apple slices in some conditions. Amongst the five thin layer drying models tested, the Page and Modified Page models found to be the best fitting models for the expression of the drying of apple slices. Microstructural changes caused by ultrasound pretreatment enhanced the rehydration ability of dried apples. As the pretreatment time and ultrasound amplitude increased, the rehydration ratio had an increasing trend. Peleg model represented the rehydration kinetics of the samples successfully. Changes in the microstructure of the apple samples caused by the ultrasound pretreatment were clearly observed with scanning electron microscopy images. Structural changes, caused by ultrasound pretreatment in apple tissues, resulted in low shrinkage values.

Highlights

Apple is used as a raw material in many food formulations and cultivated in almost every part of the World because of its flavor and rich nutrients (Andres et al, 2004; Aras and Eşitken, 2019)
The objective of this study was to determine the influence of ultrasonic pretreatment on hot air drying and rehydration characteristics, shrinkage, rehydration ratio, water holding capacity and microstructural changes of Granny Smith apple slices
Rise in temperature of surrounding water during ultrasound pretreatment (Table 2) is due to the fact that the magnitude of acoustic energy transferred into the medium increases with increasing pretreatment time and ultrasound amplitude

Summary

Introduction

Apple is used as a raw material in many food formulations and cultivated in almost every part of the World because of its flavor and rich nutrients (Andres et al, 2004; Aras and Eşitken, 2019). In recent years demand for the dried snack fruit products increasing due to their ease of use and healthy effects (Turgut and Topuz, 2020). Developing new apple preservation techniques is important. Hot air drying is widely used for preservation of food and agricultural products. This method has several disadvantages like undesirable flavor and color, nutrient loss due to long drying time (Contreras et al, 2008). The use of ultrasound as a new technology may defeat some of the disadvantages of hot air drying (Garcia-Perez et al, 2007). Utilization of ultrasound technology has attracted large interest due to its promising effects in food processing (Knorr et al, 2004). Ultrasound has increased the diffusion of water by reducing the internal resistance caused by the inner boundary layer (Rastogi, 2011)

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