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 effective on the rate and the other studied
parameters as well as the post harvest and storage time.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12605458/index.pdf |
| Date | 01 October 2004 |
| Creators | Parin, Harika |
| Contributors | Esin, Ali |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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