Starch Gelatinization and Retrogradation

In texture analysis, softness and firmness express fhe same concept inversely, although they are not simple reciprocals. Softness is defined as the deformation occurring at constant load and is normally what is measured qualitatively by a consumer to gauge freshness of bread. Firmness is the force required to provide a constant deformation it is the measurement usually made to assess the progress of crumb firming of bread using an insfrument such as the Baker compressimeter or the 

B = rate of change of firmness with change in position 

Both amylose and amylopectin take part in the retrogradation process and network structure formation and up to four different steps of ordering have been postulated [30]. The first one, which takes place in a few hours, has been ascribed to gelation of the solubilized amylose in the intergranular space forming double helices structures. The second and the third one, for which days are needed, have been ascribed to chain reordering and crystallization of amylopectin. 

The fourth step involves phase separation of water (syneresis) due to excessive retrogradation of starch chains [30-33], 

These two peaks are pointed as Gr and Mir and are correlated with the G and Mi peak in the gelatinization phenomenon. Gr and Mir are mainly due to amylopectin, which, after the gelatinization process, can rebuild its structure under appropriate time-temperature conditions giving rise to new thermal transitions close to the original ones [34], Gr and Mir are detectable both in normal starches and in waxy (high amylopectin content) starches (in this case Gr and Mir are more pronounced) [34,35]. 

One practical effect of starch retrogradation is on bakery products recrystallization of amylopectin has a great role in staling of baked products during storage. As amylopectin 

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