Starches starch-sucrose hydrocolloids

Physicochemical Changes in Frozen Products Glass Transition and Rheological Behavior in Frozen Starch-Sucrose Hydrocolloid Systems... 

In the present chapter the effect of sucrose and hydrocolloids (xanthan gum, guar gum, and sodium alginate) on (i) Tg of the freezeconcentrated matrix (7 ), (ii) amylose and amylopectin retrogradation, and (iii) rheological behavior of the system, are analyzed in gelatinized water-starch formulations frozen at different rates and stored at — 18°C. Besides, the importance of Tg as a parameter related to texture quality of starch-sucrose-hydrocolloids-based foods during frozen storage is discussed. 

Onset (T g), Medium (T and Conclusion (T p Glass Transition Temperatures (°C) of Concentrated Aqueous Starch-Sucrose-Hydrocolloid Systems Submitted to Slow Freezing and Annealing... 

Results obtained with different starch-sucrose-hydrocolloid samples are shown in Figure 18.3. A peak of additional ice formation before ice melting was not observed because the freezing process led to maximum ice formation. 

Ferrero, C. and Zaritzky, N.E. Effect of freezing rate and frozen storage on starch-sucrose-hydrocolloid systems, /. Sci. Food Agric., 80, 2149, 2000. 

DSC thermograms obtained during thawing of starch pastes (sucrose not included) (a) without hydrocolloid, (b) with xanthan gum, (c) with guar gum, and (d) with sodium alginate. Upper curves not-annealed samples numbers indicate Tg onset. Lower curves samples annealed at - 4.5°C numbers indicate onset. Curves were not normalized and correspond to different mass samples. 

From the results of the present work, it can be concluded that the storage at the usual commercial temperatures (T = — 18°C slightly above T g) affects the quality of aqueous starch sucrose pastes without gums caused by amylose and amylopectin retrogradation. However, when hydrocolloids are included in the formulations, the usual storage conditions allows main-tainence of acceptable textural attributes. 

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