OSMOTIC PRETREATMENT OF STRAWBERRIES AND SHRINKAGE EFFECTS

The shrinkage and increase in density resulting from an osmotic pretre atment were studied for two varieties of strawberries, Honeoye and Dan ia. Aqueous sucrose solutions (20-85% w/w) and granulated sucrose Mere used as the osmotic media. A simplified model is presented where the shrinkage factor was con-elated to changes in weight. Solids uptake wa s found to be of great importance for determining the final volume of the strawberries. The two varieties of strawberry correlated well to t he proposed model with a correlation coefficient of r(2) = 0.8995 for the Honeoye and of r(2) = 0.9465 for the Dania. Pretreatment in a 60% (w/w) sucrose solution gave the best result and resulted in an increas ed density combined with a small decrease in volume. The use of granul ated sucrose resulted in the greatest shrinkage. Subsequent thermal pr ocessing did not notably change the volume of the pretreated strawberr ies. (C) 1998 Elsevier Science Limited. All rights reserved.