Quality optimisation of combined osmotic dehydration and microwave assisted air drying of pineapple using constant power emission

G. E. Botha*, J. C. Oliveira, L. Ahrné

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

39 Citations (Scopus)

Abstract

Combination of osmotic dehydration with microwave assisted air drying offers increased flexibility for process control and product quality. Osmotic dehydration (55°Brix solution at 40 °C for 90 min) combined with microwave assisted air drying (MWAD) was tested on smooth cayenne pineapples. The influence of the four most relevant processing parameters (osmotic treatment time, microwave power, air temperature and air velocity) was studied using a 2 4 circumscribed central composite experimental design. The product quality was evaluated in terms of charred appearance at the surface, moisture content, soluble solids content, water activity, firmness, colour and volume. Microwave power and air temperature were the two most important processing parameters that influenced the quality of the dehydrated pineapple, with the parameters most affected by the operating conditions being water content and percentage of charred pieces. Only in the latter was a significant quadratic effect found, all others were approximately linear. There was also a significant interactive effect between microwave power and air temperature affecting the percentage of charred pieces. Model predictions using a quadratic surface for water content and % charred pieces were validated with an additional experiment. Quadratic models were used to indicate optimum drying conditions for various targets.

Original languageEnglish
JournalFood and Bioproducts Processing
Volume90
Issue number2
Pages (from-to)171-179
Number of pages9
ISSN0960-3085
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Combined technologies
  • Drying rate
  • Microwave drying
  • Osmotic dehydration
  • Overheating

Cite this