Effect Of Cyclodextrins On The Quality And Anti-staling Of Prebaked Bread

Prebaked frozen bread belongs to the frozen dough series,which has completed the fermentation and partial baking process before the freezing,not only avoiding the problem of yeast damage,but also satisfying the needs of consumers to eat freshly baked bread.At the same time,the special processing technology of prebaked frozen bread also puts higher requirements on the selection of raw flour and delaying aging in industrial production.At present,the production of prebaked bread in China is still in its infancy.The screening of prebaked bread special powder and the selection of effective anti-aging additives are the key to improve the quality of prebaked bread products.This study compared the quality of wheat and flour from different sources,and screened wheat flour suitable for making prebaked frozen bread.Based on the relevant instructions for the use of ?-CD,?-CD and ?-CD in baked goods in GB 2760-2014,the effect of three kinds of cyclodextrins on wheat flour,dough properties and pre-baked bread were explored.This experiment firstly compared the wheat properties,flour quality and quality of pre-baked bread of foreign Canadian wheat 2#,Kazakhstan wheat and domestic wheat Shiluan 02-1,Xinong 979 and Xinmai 26.In general,compared with the other four types of wheat,Xinmai 26 has a high powder yield,full grain,high crude protein content,long dough stability and strong toughness.The pre-baked bread made in Xinmai 26 has a larger specific volume,the bread core has less hardness,higher elasticity,and better sensory score,which indicates that Xinmai 26 can be better applied to prebaked frozen dough products,and also shows that the quality of high-quality wheat in China is continuous improving.Based on the selection of flour suitable for making prebaked bread,the effects of different concentrations of ?-CD,?-CD and ?-CD on the quality of flour was investigated.The Mixolab test showed that the addition of ?/?/?-CD significantly increased the water absorption of the flour and significantly reduced the dough formation time.Adding a/y-CD could shorten the dough stability time to a small extent,but did not affect the dough stability,the addition of ?-CD can significantly shorten dough settling time.The addition of ?/?-CD significantly reduced the heat resistance abilitiy of gluten,and P-CD had no obvious effect on the heat resistance abilitiy of gluten.The addition of y-CD had no significant effect on ?-amylase activity,and the addition of 2.0 wt%a-CD and 1.5 wt%?-CD slightly increased a-amylase activity.The tensile test showed that the dough tensile resistance decreased with the addition of three kinds of cyclodextrin,and the addition of 2.0?3.0 wt%?-CD significantly reduced the tensile resistance of the dough;the rapid viscosity analyzer(RVA)showed the addition of ?-CD significantly reduced peak viscosity and final viscosity.Conversely,the addition of a-CD and y-CD significantly increased the peak viscosity and final viscosity of the flour.The addition of three cyclodextrins had no significant effect on the gelatinization temperature,gelatinization time and retrogradation value of wheat flour.Scanning electron microscopy(SEM)results showed that adding proper amount of cyclodextrin could improve the three-dimensional network structure of gluten,which showed that the roughness of the dough surface was reduced and the integrity of the gluten network was increased.The Fourier transform infrared spectrum showed that the addition of cyclodextrin changed the a-helix and ?-sheet in the dough protein.Fermentation test showed that adding proper amount of cyclodextrin to the wheat flour significantly increased the fermentation height of the dough.The addition of 2.0 wt%a-CD,1.5 wt%?-CD,and 3.0 wt%?-CD maximally increased the gas production and gas holding capacity of the dough fermentation.This study further explored the effects of three cyclodextrins on the quality of prebaked bread.The texture results indicated that the addition of 0.5?2.5 wt%?-CD,0.5?3.0 wt%?-CD and ?-CD reduced the hardness of the prebaked bread.Adding 0.5?3.0 wt%cyclodextrin increased the elasticity of the bread to varying degrees,which indicated that the addition of appropriate amount of three cyclodextrins could improve the texture of prebaked bread;the addition of 0.5?2.5 wt%a-CD,0.5?1.5 wt%?-CD and 2.0?3.0 wt%y-CD could increased the specific volume,it indicated that the addition of high concentration of a-CD and ?-CD was not conducive to the increase of specific volume of prebaked bread;the addition of 0.5?2.5 wt%a-CD,0.5?2.0 wt%P-CD,0.5?3.0 wt%?-CD increased the number of pores in the prebaked bread,reduced the number of holes and the average pore wall thickness.Based on the optimum amount of cyclodextrin,the effect on the staling of prebaked bread was further explored.The texture properties of pre-baked breads after different freezing cycles were investigated.The results of the texture analyzer showed that the hardness of the pre-baked bread increased with the extension of the freezing cycle,and the elasticity and recovery were deteriorated,indicating that the frozen storage had a negative impact on the quality of the pre-baked bread.After adding three kinds of cyclodextrin,The quality of the pre-baked bread was improved.The enthalpy of the pre-baked bread core samples of different frozen period was measured by DSC.From the results of 3 weeks of frozen storage,the enthalpy value of the sample added with cyclodextrins decreased from 238.8 J/g to 215.6 J/g,208.1 J/g,199.7 J/g.To further investigate the effects of three cyclodextrins on the aging of prebaked bread,the change in hardness of prebaked bread at different days was observed.The Avremi equation was used to calculate the aging rate of prebaked bread at different times.The results showed that n<1,indicating that the crystal nucleation of starch in bread was instantaneous nucleation,that was,the formation of crystallization mainly occurred in the early stage of refrigeration.The addition of three cyclodextrins reduced the staling rate of the prebaked bread,which delayed the staling of the bread.To illustrate the anti-staling mechanism of the three cyclodextrins in the prebaked bread,In this study,X-rd was used to investigate the effects of 2.0 wt%a-CD,1.5 wt%?-CD and 3.0 wt%y-CD on the crystal form and crystal strength of gelatinized starch during aging.The results showed that the crystalline form of retrograded starch was mainly B-type starch.After adding cyclodextrin,V-type starch appeared and the crystal strength was decreased,indicating that it may delay the staling of bread by inhibiting starch rejuvenation.