Osmotic pretreatment to assure retention of phenolics and anthocyanins in berry jams

A Rotational Central Compound Design was used to optimize time and sucrose concentration for osmotic pretreatment of blueberries and strawberries to preserve anthocyanin and phenolic compound content and color during subsequent jam preparation. No significant differences were found for color, but statistically significant differences in the phenolic compounds and anthocyanins content in the resulting jam were observed. Superposition of the resulting response surfaces allowed for prediction of optimized osmotic pre-treatment time and sucrose concentration. The predicted values were confirmed in triplicate. The results indicate that pretreatment times of 242 and 219 min and sucrose concentrations of 1.65 and 1.46 M recovered the greatest amount of the target compounds in blueberry and strawberry jams, respectively.