Optimum physical properties of fruit puree for freeze-drying: Effect of pulp content on freeze-concentrated glass transition temperature and yield stress of mango puree

摘要

The freeze-concentrated glass transition temperature (T-g') and yield stress (sigma(yield)) of mango puree-mango syrup mixtures with varying pulp (water insoluble materials) contents and the relationship of these parameters on the collapse of freeze-dried solids were investigated. The T-g' values were almost equivalent among the samples. Freeze-dried samples with low pulp content (0-6.91 g/100 g-DM) collapsed while samples with higher pulp content (8.07-11.52 g/100 g-DM) maintained the apparent volume of the freeze-dried solid and had much higher sigma(yield) than the collapsed ones. The solid weight fraction of samples in the freeze-concentrated state was estimated from the state diagram, and sigma(yield) of the pseudo freeze-concentrated samples was evaluated. From these results, it was suggested that freeze-dried samples did not collapse even if the sample was freeze-dried at a much higher temperature than the T-g' when sigma(yield) was higher than the stress due to its own weight.