Structural and physical properties of dried Anaheim chilli peppers modified by low-temperature blanching

The effect of low-temperature blanching and drying processes on the ultrastructural and physical properties of Anaheim chilli pepper was studied and optimum conditions to provide a final product with maximum firmness were determined. Lots of Anaheim pepper were blanched in water for 4min at 48, 55, 65, 75 and 82 ◦ C and maintained for hold times of 35, 45, 60, 75 and 85min, blanched again for 4min at 96 ◦ C and dehydrated at 53, 60, 70, 80 and 87 ◦ C. After treatment the samples were rehydrated in water at 30 ◦ C. Rehydration ratio, texture and structural changes were evaluated. Optimisation used a second-order rotatable central composite design. Texture and rehydration ratio were affected by blanching temperature and the interaction of blanching temperature with hold time (p ≤ 0.05); drying temperature did not show a significant effect. The best results, ie those which gave greatest firmness, were obtained by blanching at 64 ◦ C for 4min, holding for 55min after blanching, followed by a second blanching at 96 ◦ C for 4min and then drying at 70 ◦ C. Evaluation of the rehydrated dried pepper by microscopy showed that low-temperature blanching close to the optimum conditions provided a protective effect in maintaining cell wall integrity. The results of processing increased firmness in the rehydrated product by a factor of 1.97.  2003 Society of Chemical Industry