Optimization and quality evaluation of infrared-dried kiwifruit slices.

Ebrahim Sadeghi,Kamyar Movagharnejad,Ali Haghighi Asl

doi:10.1002/fsn3.1253

Ebrahim Sadeghi, Kamyar Movagharnejad + Show 1 more

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https://doi.org/10.1002/fsn3.1253

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Abstract

Infrared drying characteristics of kiwifruits under natural and forced drying air convection with different conditions were investigated. An experimental study along with statistical analysis aimed to evaluate quality characteristics of infrared‐dried kiwifruit slices, in terms of drying time, rehydration ratio and shrinkage as a function of infrared power levels, slice thicknesses, slice distance from the infrared lamps, and air velocity. Response surface methodology was used for optimization of drying parameters with employing desirability function. Minimum drying time, shrinkage, and maximum rehydration ratio assumed as criteria for optimizing drying conditions of kiwifruit slices were strongly dependent on the drying conditions. All operating variables had a significant effect on total responses, but slice thickness almost was the most prominent factor. The slices dried at the highest power level, the lowest distance from the Infrared lamp, the least thickness, and air velocity showed a higher rehydration capacity than slices dried at the other conditions.

Highlights

The aim of our study was to investigate the IR drying of kiwifruit slices under natural and forced drying air convection modes with respect to drying kinetics, shrinkage, and rehydration and to relate operating variables in a mathematical equation and to optimize the drying conditions of kiwifruit slices regarding to the quality parameters to determine acceptable product quality in IR drier
This is most likely due to the fact that each of the mentioned items might increase the amount of radiation absorbed by the kiwifruit surfaces, describing the higher drying rate during IR drying
Similar to findings reported by Panyawong and Devahastin (2007), the results suggest that drying rate notably changes with velocity

Summary

Introduction

The growing reduction of the use of chemical for food preservation and high rate of the popularity of high‐quality fast‐dried products with good rehydration attributes have led to renewed interest in drying (Maskan, 2001).Owing to the low thermal conductivity of the high sugar‐containing food such as kiwifruit, heat transfer inside the inner sections of it in the falling rate period is restricted during conventional heating, which causes prolonged drying time, reduction in its physicochemical properties, and low energy efficiency (Kocabiyik, Yilmaz, Tuncel, Sumer, & Buyukcan, 2015).During drying, a pressure unbalance produced between the inner of the material and the external pressure by eliminating moisture from the material generates contracting stresses that cause to material shrinkage (Mayor & Sereno, 2004). The growing reduction of the use of chemical for food preservation and high rate of the popularity of high‐quality fast‐dried products with good rehydration attributes have led to renewed interest in drying (Maskan, 2001). Owing to the low thermal conductivity of the high sugar‐containing food such as kiwifruit, heat transfer inside the inner sections of it in the falling rate period is restricted during conventional heating, which causes prolonged drying time, reduction in its physicochemical properties, and low energy efficiency (Kocabiyik, Yilmaz, Tuncel, Sumer, & Buyukcan, 2015). A pressure unbalance produced between the inner of the material and the external pressure by eliminating moisture from the material generates contracting stresses that cause to material shrinkage (Mayor & Sereno, 2004). Prolonged exposure to high drying temperature may lead to considerable degradation of quality characteristics (Zhang, Tang, Mujumdar, & Wang, 2006)

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