Studies On The Effect Of Antifreeze Protection On The Quality Of Pre-baked Frozen Bread

In this study,the process parameters of pre-baked frozen bread were optimized,and the anti-freeze protection of the pre-baked frozen bread was added to improve the quality by adding anti-freezing protective agent.Combining the detection results of the basic ingredients,flour properties and tensile properties of the four wheat flours,Jinshahe Fuqiang high-gluten flour(No.2 flour)was determined as the raw wheat flour for pre-baked frozen bread.Using the texture characteristics and sensory evaluation of the re-baked bread as the detection indicators,a single factor experiment was carried out,and on this basis,the response surface experiment was carried out to optimize the process parameters of the pre-baked frozen bread.The best process parameters are: proofing time 105 min,proofing temperature 35 ?,pre-baking time 10 min,pre-baking temperature 180 ?.The pre-baked frozen bread score is94 points,and the best process conditions are further confirmed according to the texture characteristics.In 0-5 freeze-thaw cycles,the texture characteristics of pre-baked frozen bread with AFPs and trehalose and their controls were studied.In the changes of the hardness,adhesiveness,elasticity,chewability,resilience and other indicators of pre-baked frozen bread,the added group is generally better than the control group,and the effect is obvious,in which each group is added with 0.6% antifreeze protein and 0.4% Of trehalose works best.The bread added with AFPs is superior to trehalose in recovery and elasticity.When the dough was frozen and thawed to 5 weeks,the quality of frozen dough in both groups dropped sharply.Thermogravimetric analysis shows that the thermogravimetric TG curve drawn in the range of 40-60°C shows that with the increase in the amount of antifreeze protection agent,the downward trend of dough weight is significantly slowed down,indicating that the rate of water loss is effectively controlled.When the amount of AFPs added is 0.8% and 1%,the weight loss mitigation effect is most obvious,and the weight loss percentage is reduced from13.65% to 3.43%;when the amount of trehalose added is 0.8% and 1%,the weight loss mitigation effect is particularly obvious.The percentage dropped from 13.65% to 2.86%.At the same time,through comparison,it was found that the weight loss rate of pre-baked frozen bread with trehalose was lower than that with AFPs.SEM observations showed that the freeze-thaw protection group was added 4 times a week,the gluten network structure of the anti-freeze protection group was increased continuously compared with the control group,and the starch granules had a regular shape and less exposure.The effect of AFPs and trehalose is obvious,and the effect of adding 0.6%antifreeze protein and 0.4% trehalose is good.Under this condition,the bread gluten network structure of the two antifreeze protective agents formed rapidly in the early stage of frozen storage,tightly wrapping the starch granules.As the freeze-thaw cycle increases,the protein structure is gradually destroyed,the more starch granules are exposed,and the starch granules are severely deformed.Observation of the cross section of the bread shows that the effect of adding 0.6% antifreeze protein and 0.4% trehalose group is obviously more dense pores,evenly arranged and moderate in size.