Effect of Propylene Glycol Alginate on Storage Stability and Baking Properties of Frozen Whole Wheat Flour Dough

The effects of propylene glycol alginate (PGA) on the storage stability of frozen whole wheat flour dough were investigated, as well as the changes in baking quality of the frozen dough. The stability of frozen dough was evaluated by measuring the fermentation characteristics, rheological properties, secondary structure of protein, microstructure, specific volume, texture properties, internal texture structure, and aging degree of frozen dough after 1, 2, 3, 4 and 5 weeks after adding 0.3% PGA to whole wheat flour dough. The results showed that after 5 weeks of frozen storage, the frozen dough with PGA had a higher water holding capacity, as well as improved fermentation and rheological properties, as compared to the control group. After 5 weeks of freezing, compared with bread made from unfrozen dough, the specific volume of bread in control group and PGA group decreased by 19.872% and 14.153%, bread hardness increased by 64.186% and 36.386%, and area fraction (AF) decreased by 3.497% and 2.300% respectively for bread made from dough with and without PGA after 5 weeks frozen storage. Accordingly, the retrogradation enthalpy value increased by 65.142% and 42.416%. The addition of PGA to frozen dough could slow down the increase of relative content of β-sheet and the decrease of relative content of β-turn structures caused by frozen storage. SEM photos of the frozen dough supplemented with PGA revealed fewer and even-sized holes, and the integrity and continuity of gluten network structure increased. These findings suggest that PGA can help slow down the deterioration of dough during frozen storage, improving frozen dough stability and baking properties.