海藻酸丙二醇酯对全麦冷冻面团冻藏稳定性和烘焙特性的影响

本文研究了海藻酸丙二醇酯（Propylene glycol alginate，PGA）对全麦冷冻面团冻藏期间稳定性的影响，并探究了冷冻面团烘焙面包品质的变化。将0.3%的PGA加入全麦面团，通过测定冷冻面团冻藏1、2、3、4和5周后发酵特性、流变特性、蛋白质二级结构、微观结构以及面包的比容、质构特性、内部纹理结构和老化程度等，研究冷冻面团冻藏期间的稳定性。结果表明，随着冻藏时间的延长，添加PGA的冷冻面团在冻藏5周后具有较好的保水性，其发酵特性及流变特性相对于对照组均有所改善。冻藏5周后，对照组与PGA组其面包比容分别下降了19.872%和14.153%；面包硬度分别升高了64.186%和36.386%；气孔表面积分率分别下降了3.497%和2.300%；老化焓值分别上升了65.142%和42.416%。添加PGA能延缓冷冻面团冻藏期间β-折叠含量的上升和β-转角相对含量的下降。电镜扫描图（SEM）显示，随着冻藏时间的延长，PGA组的冷冻面团孔洞数目相比对照组明显减少且大小均匀，面筋网络结构完整性和连续性提高。研究结果表明PGA可以有效地延缓冷冻面团在冻藏期间的品质劣变，维持冷冻面团的稳定性并提高面包的烘焙特性。

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.