Effects of infrared radiation intensity and ultrasound pretreatment on the appearance quality of raisins in the secondary drying stage in the packaging plants

Authors

1 Department of Biosystems Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran

2 Department of Mechanical Engineering, Faculty of Engineering, University of Bonab, Bonab, Iran

Abstract

Raisin is one of the most important agricultural products in Iran. Turkey, USA and Iran are the biggest exporters in raisins industry. One of the stages of raisin processing is rewashing to remove chemical materials used in primary drying, dust and waste materials, as well as to improve the quality of the product. Therefore, secondary drying of raisins is necessary. Based on the field studies, one of the problems of packing raisins is non-uniformity in moisture content and quality of raisins after secondary drying. Today, in most processing plants, hot air systems are used for secondary crown drying. This system has some disadvantages such as long drying time, energy consumption and high cost. Therefore, the optimization or replacement of the mentioned system is very important. For this purpose, single infrared drying at three intensity levels of 0.5, 0.7 and 0.9 W/cm2 were studied. The qualitative properties of raisins (color index, acidity, rehydration, shrinkage and browning index) were studied with and without ultrasound pretreatment. The applied drying methods had no significant effect on the rehydration and shrinkage. Ultrasound pretreatment improved the quality of raisins in terms of color changes and browning index. Also, the lowest amount of acidity was obtained in the infrared intensity of 0.7 W/cm2 without ultrasound pretreatment.

Keywords

Main Subjects

Agricultural Mechanization
Volume 8, Issue 4
January 2024
Pages 41-51

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History

  • Receive Date: 02 January 2024
  • Revise Date: 15 May 2024
  • Accept Date: 15 May 2024

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