but cryoprotectant (10 g/100 g) was required to inhibit the gravitational
separation and the extensive aggregation during frozen
storage. Interestingly, calcium-fortified soy beverages showed a
better behavior than the control because the mean De Brouckere
particle diameter, which is especially sensitive to the presence of
large particles or aggregates, was almost maintained even after 30
days of storage at subzero temperatures. In the presence of sucrose
at the highest concentration (10.0 g/100 g), the apparent viscosity
of all soy beverages decreased as a function of frozen storage time,
presumably due to progressive dehydration and close packing in
the unfrozen aqueous phase.
Undoubtedly, due to the high ionic strength of calcium-fortified
soy beverages, a cryoprotectant is required at relatively high concentration.
Moreover, as a consequence of different free Ca2þ activity
and solubility associated to calcium salts, further studies will
be necessary if other calcium salts (e.g. gluconate) are employed for
fortification. In the same way, further investigation will be required
if other sugars or non sweet cryoprotectans are used. The results of
this study could facilitate the development of a calcium-fortified
soy beverage with good stability to freeze-thawing.
Acknowledgments
Authors wish to acknowledge the financial support of Consejo
Nacional de Investigaciones Científicas y Tecnicas (PIP 2012e2014
N 11220110100398) and Universidad Nacional de Quilmes (53/
1007 I þ D grant).