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

TY - JOUR

T1 - Quality optimisation of combined osmotic dehydration and microwave assisted air drying of pineapple using constant power emission

AU - Botha, G. E.

AU - Oliveira, J. C.

AU - Ahrné, L.

PY - 2012

Y1 - 2012

N2 - 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.

AB - 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.

KW - Combined technologies

KW - Drying rate

KW - Microwave drying

KW - Osmotic dehydration

KW - Overheating

U2 - 10.1016/j.fbp.2011.02.006

DO - 10.1016/j.fbp.2011.02.006

M3 - Journal article

AN - SCOPUS:84859007714

SN - 0960-3085

VL - 90

SP - 171

EP - 179

JO - Food and Bioproducts Processing

JF - Food and Bioproducts Processing

IS - 2

ER -