Optimisation of the hot air drying of mango slices

Abstract

Mango (Mangifera Indica, L.) slices were dried using hot air in a laboratory tray dryer by varying drying air temperature (40, 50, 60°C), airflow (0.15 to 0.25 m/s) and slice thickness (4, 5, 6 mm). Average drying rate, rehydration ratio, rehydration rate, sensory quality and hardness of the dried product were response variables in a fractional factorial design (3 level-3 parameter) with 15 runs. Response surface methodology was performed to analyse and predict optimum conditions. Drying air temperature significantly affected average drying rate while airflow affected hardness and sensory quality. Second order polynomial models for hardness and sensory quality were significant models at the 95% level, while average drying rate was significant only at the 90% level. Optimum drying conditions were determined with the following response limiting values: average drying rate of at least 6%/h, hardness of not more than 2 kg and sensory quality of 60% or more. Through superimposition of contour plots of the responses, a drying air temperature of 50°C and an airflow of 0.205 ms-1 were generated as optimum drying conditions for 4 to 6 mm slices. Validation test results were fairly acceptable with coefficients of variation less than 10% except for sensory quality (15.8%). The optimum drying experimental data for mangoes fitted well to the Page thin layer drying model.

Source or Periodical Title

Food Australia

ISSN

10325298

Page

237-243

Document Type

Article

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