| Quick-frozen raw-dough sticks are the product of recent research on the frozen dough,which have greatly satisfied the demand of the consumer community.However,quick-frozen raw-dough sticks on sensitive to temperature fluctuations during frozen storage,leading to deterioration in the quality of deep-fried dough sticks,such as specific volume,texture,etc.Recent studies have found that the addition of polysaccharide hydrocolloids could improve the quality of frozen dough.To enhance the quality of quick-frozen raw-dough sticks,seven common polysaccharide hydrocolloids were selected,including kappa-carrageenan(KC),konjac gum(KGM),sodium alginate(SA),gum arabic(GA),hydroxypropyl methylcellulose(HPMC),xanthan gum(XG),and guar gum(GG),and added to the dough,which investigate of the changes in dough properties during dough mixing and resting,the effects on the quality of fried dough stick products,and the influence on the properties,moisture content,oil content,water migration,and secondary structure of proteins in the dough during the freezing and thawing processes.The main findings were as follows:(1)The influence of polysaccharide hydrocolloids on the dough properties during dough mixing and resting processes.Correlation analysis revealed that the addition of polysaccharide hydrocolloids to the dough during mixing had a significant and strong correlation with its hardness and cohesiveness(P<0.05),as well as with the hardness and cohesiveness of the dough during resting(P<0.05).According to the cluster analysis biplot,the distance between the dough during mixing and resting is relatively large,indicating a weak correlation.Polysaccharide hydrocolloids show a strong correlation with the hardness of the mixed dough and the cohesiveness of the resting dough,while a weak correlation with the elasticity and adhesiveness of the resting dough.Among all indices,the cohesiveness of the resting dough has a significant and strong correlation with its elasticity and adhesiveness(P<0.05).KGM significantly affects the hardness of the mixed dough,while XG,GG,and GA significantly affect the cohesiveness of the resting dough.XG significantly affects the elasticity of the resting dough.SA,GG,XG,and KGM significantly affect the hardness of the resting dough.The addition of 0.2% GG and GA,0.6% HPMC and SA,and 1.0% GA can significantly improve the elasticity of the resting dough,with GA having the greatest impact on the elasticity of the resting dough(P<0.05).Therefore,different polysaccharide hydrocolloids have varying effects on the dough’s properties,and they primarily enhance the dough’s cohesiveness during the resting process,leading to increased elasticity and adhesiveness of the dough,ultimately improving the quality of the finished fried dough stick products.(2)Research on the properties,physicochemical,sensory,and specific volume characteristics of the finished deep-fried dough sticks products fried into from quick-frozen raw dough.Correlation analysis indicates that polysaccharide hydrocolloids significantly affect the crispiness(r=-0.43,P=0.044<0.05),cohesiveness(r=0.51,P=0.015<0.05),and mouthfeel(r=0.46,P=0.032<0.05)of the fried dough stick,and there is a significant correlation among the various indices of the fried dough(P<0.05),with the specific volume being significantly correlated with the internal structure(r=0.51,P=0.016<0.05).Cluster analysis divides the frozen dough with added polysaccharide hydrocolloids into four groups.The largest specific volume in each group is achieved with the addition of 1.0% KGM,1.0%KC,1.0% GA,and 1.0% HPMC,respectively.The change in the specific volume of the fried dough stick made from the dough with added polysaccharide hydrocolloids before and after freezing exhibits inconsistency,and after freezing,the impact of KGM on the specific volume of the fried dough stick significantly increases(P<0.05).(3)By the effects of polysaccharide hydrocolloids on the frozen storage period of quickfrozen raw-dough sticks,it was found that with the extension of the storage period,the specific volume,elasticity,water content,strongly bound water(A21),β-turns,and α-helix content of the quick-frozen raw-dough sticks,gradually decreased(P<0.05),while the hardness,chewiness,cohesiveness,adhesiveness,oil content,weakly bound water(A22),free water(A23),β-sheets,and random coil content gradually increased(P<0.05).The impact on adhesiveness was not significant(P>0.05).Among them,the content of weakly bound water was the highest,with a trend of strongly bound water transforming into weakly bound water and free water.The secondary structure of proteins changed from ordered to disordered,and the surface pore size increased to varying degrees after 30 days of storage and decreased to different extents after 90 days.Quick-frozen raw-dough sticks with added polysaccharide hydrocolloids exhibited larger specific volumes,higher water content,higher oil content after90 days,a decrease in proton density in the atomic nucleus,and reduced internal water content(P<0.05).The trend of a smaller scanning electron microscopy image of the quick-frozen rawdough with added gum arabic appeared after 90 days and was the latest to manifest.Therefore,the addition of polysaccharide hydrocolloids can retain more moisture,reduce water loss caused by freezing,slow down the rate of moisture migration,stabilize the gluten protein network structure,and thus reduce the impact of the storage period on the quality of the finished fried dough stick(such as specific volume).(4)The influence of gum arabic on the quick-frozen raw-dough during freeze-thaw cycles.As the number of freeze-thaw cycles increases,the specific volume,elasticity,cohesiveness,strongly bound water(A21),and proton density in the atomic nucleus of raw-dough sticks during the frozen storage period of decreases,while the internal water content decreases(P<0.05).The hardness,chewiness,adhesiveness,weakly bound water(A22),and free water(A23)gradually increase(P<0.05).The water and oil content shows a trend of decreasing first and then increasing(P<0.05).Moreover,the finished products of quality deep-fried dough stick after frying with added gum arabic has a larger specific volume,higher water content,higher oil content,stronger nuclear magnetic resonance signal,higher content of ordered structures in the protein secondary structure,and a higher content of strongly bound water after the third freeze-thaw cycle.As the number of freeze-thaw cycles increases,the percentage of freezable water content in the quick-frozen raw-dough sticks initially decreases and then increases(P>0.05).The percentage of freezable water content in the quick-frozen raw-dough sticks with added gum arabic is lower,reaching its lowest level after three freeze-thaw cycles.If the number of freeze-thaw cycles continues to increase,the percentage of freezable water content significantly increases(P>0.05).The surface pore size of the dough initially increases and then decreases,and after the third freeze-thaw cycle,the surface pore size of the quickfrozen raw-dough sticks with added gum arabic decreases,proving that the addition of gum arabic delays the rate of water migration during the freeze-thaw process,maintains the stability of gluten proteins,reduces the deterioration of gluten proteins caused by temperature fluctuations,and it is speculated that the number of freeze-thaw cycles for frozen dough with added gum arabic should not exceed three.In summary,the addition of polysaccharide hydrocolloids to quick-frozen raw-dough s can reduce the damage to the dough’s tissue structure,specific volume,and texture during freezethaw and freezing processes.It slows down the loss and migration of water,the decrease of α-helix content,and the increase of β-turn content during this period.This enhances the crosslinking effect with small protein molecules,improves the dough’s elasticity and resilience,and strengthens the stability of the gluten protein network.As a result,the quality of quick-frozen raw-dough is improved,its shelf life is extended,and its resistance to temperature fluctuations is enhanced,laying the foundation for the quality improvement of quick-frozen raw-dough. |
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