Title page for ETD etd-07092008-145646


Document Type Master's Dissertation
Author Lwadya, Mujanay
Email mujanaylwadya@yahoo.co.uk
URN etd-07092008-145646
Document Title The drying characteristics of mango fruit strips
Degree MInstAgrar (Rural Engineering Technology)
Department Civil and Biosystems Engineering
Supervisor
Advisor Name Title
Prof H L M du Plessis Supervisor
Keywords
  • drying characteristics
  • mango
Date 2006-05-24
Availability restricted
Abstract
A diffusion model is proposed to simulate the drying of mango fruit strips. The mass transfer in terms of Ficks law have been applied to the drying fruit and an effective diffusivity coefficient was identified for mango strips at air drying temperatures of 50C, 75C, and 83 C.

Most of the moisture diffusivity data available originated from the method of applying drying curves. A drying curve represents the change in moisture content of mango strips with time, and also the change in the drying rate with moisture content. Depending on the material and drying conditions, the drying curve may adopt different shapes. Sometimes two or even three drying periods may in general be identified.

To evaluate the optimum conditions for drying, relevant mathematical models were considered. The base of the proposed model is minimum drying time, low specific energy consumption and acceptable quality for the dried mango strips.

The best fit for the thin-layer drying data was obtained using the average trend line of product over time due to moisture reduction. The Original moisture content did not significantly affect the thin-layer drying mango fruit for the range of conditions used in this study.

All data used to develop the thin-layer mango fruit moisture were within the temperature range of 50C to 83C and relative humidity range of 20% to 83%.

Although the conclusion was made that original moisture content did not significantly influence the parameters, the use of the curve of drying presented here should be limited to the original moisture content range of approximated for fresh prepared mango slices having moisture of typically 81% ie 614% db; the final moisture contents were 23% and 1.7% respectively w.w.b. The effect of a wider range of original moisture content rates needs further study.

University of Pretoria 2005

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