Insight into the promoted recrystallization and water distribution of bread by removing starch granule - surface and - associated proteins during storage.

The influence of starch granule surface proteins (SGSPs) and starch granule-associated proteins (SGAPs) on bread retrogradation was investigated in a reconstituted dough system. The removal of both SGSPs and SGAPs resulted in poor bread qualities, decreasing specific volume and crumb porosity, leading to more baking loss and compact crumb structure. Particularly, removing SGSPs was effective in promoting the bread retrogradation. After 7 days of storage, the hardness of bread without SGSPs showed an increase of 353.34 g than the bread without SGAPs. Proton population and relaxation times exhibited that the absence of SGSPs significantly decreased the content of bound water from 11.51 % to 7.03 %, indicating lower water-holding capacity due to the loosen gelling structure. Compared to the control group, bread without SGSPs accelerated the starch recrystallinity by a reduction in soluble starch content, thereby increasing the retrogradation enthalpy and relative crystallinity through promoting the molecular reassociation in starch.

Retrogradation behaviors of damaged wheat starch with different water contents.

The retrogradation behaviors of five damaged wheat starches (DS) after milling 0, 30, 60, 90, and 120 min with different water contents (33, 50, 60 %) were evaluated. Milling treatment increased DS content and developed an agglomeration of small particles. After 7 days of storage, the recrystallinity and long-range ordered structure of starch pastes were increased with the contents of DS and water. This process led to a lower setback viscosity and poor leaching of amylose. LF-NMR indicated a conversion from tightly bound water and free water to weakly bound water. During storage, DS12 with 60 % water content had the highest retrogradation tendency where the retrogradation enthalpy increased by 1.5 J/g and 2.2 J/g compared with DS0 with 60 % and DS12 with 33 % water content. DS with higher water content promoted the water mobility and made the starch molecular chains migrated conveniently. These changes facilitated the recrystallinity process during retrogradation period.