Effect of pretreatment and air temperature on the drying rate, rehydration capacity and color of artichoke

Parin, Harika
In this study, cleaned artichoke hearts belonging to three different ages were dried under constant external conditions at 50, 60 and 70°C using an air inlet velocity of 8.1 m/s. The sample to be dried was pretreated either by keeping it in distilled water or 1% (w/v) ascorbic acid or sodium bisulfite solutions for 30 minutes at the corresponding drying temperatures. Further, for comparison, the use of citric acid solution, increasing the concentrations of the solutions, reducing the pretreatment time, effect of degree of trimming and halving the samples were investigated. The experimental drying rate data were treated to estimate the effective diffusivities and the effect of temperature together with the activation energy according to an Arrhenius type relation. For the product quality, rehydration capacity of the dried samples in water at 20°C as well as their color were determined. As expected, the rate results indicated an increase in the drying rate hence the effective diffusivity with temperature for the distilled water and ascorbic acid pretreated samples. However, a reduction in the rate at the high drying temperature when sodium bisulfite solution used was attributed to the clogging of the pores by the precipitated solid due to rapid evaporation at the surface. Similarly, rehydration capacity and color of the water treated samples were enhanced with temperature where with the solution treated ones a reverse effect was observed. It is also found that the rehydration data could be well represented by Peleg equation. Further, when citric acid solution was used for pretreatment, the results were quite identical to those of ascorbic acid. Also, increasing the ascorbic acid concentration to 2% (w/v) improved color whereas decreasing the dipping time increased discoloration. Finally, as an important parameter, the degree of trimming of the hearts proved to be highly


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Citation Formats
H. Parin, “Effect of pretreatment and air temperature on the drying rate, rehydration capacity and color of artichoke,” M.S. - Master of Science, Middle East Technical University, 2004.