Effects Of Three Functional Sugars On The Quality Characteristics And Anti-staling Of Bread

In recent years,with the progress of science and technology and the change of people’s life concept,consumers have put forward higher requirements for the functionality of bread.Under the basic conditions of satisfying delicious food,the bread industry continues to develop in the direction of health and nutrition.Functional sugar has the effects of low calorie,rich nutrition,enhancing immune regulation and anti-staling.Its application in food has attracted more attention.In this paper,lactosucrose,isomarto-oligosaccharides and isomaltulose were selected to explore the effects of three functional sugars with different levels on the rheological properties,quality characteristics and anti-staling properties of wheat flour.Firstly,the effects of three functional sugars with different amounts（1%,2%,3%,4%,5%）on the properties of wheat flour and dough.The powder test showed that the addition of three functional sugars significantly reduced the water absorption of the dough.lactosucrose prolonged the stability time and breaking time of dough.When the amount of Isomalto-oligosaccharide was 3%-5%,the dough formation time,stability time and breaking time remained at a high level.The addition of isomaltulose reduces the stability time of dough,which may be due to the melting effect of isomaltulose,which reduces the stirring resistance of dough.The tensile test showed that the addition of three functional sugars increased the area of dough tensile curve,and lactosucrose increased the tensile resistance,elongation and maximum tensile resistance of dough.When the amount of isomaltone added to the dough is 4%-5%,the overall elongation of the dough is better.In the gelatinization test,lactosucrose（2%-5%）,Isomalto-oligosaccharide and isomaltulose reduced the peak viscosity,attenuation value,final viscosity and retrogradation value of wheat flour,and had no significant trend effect on the gelatinization temperature of wheat flour.The results showed that the addition of three functional sugars inhibited the short-term regeneration of wheat products.The dough fermentation test showed that when the content of lactosucrose was 1%-4%,it had a certain effect on the increase of dough fermentation height,and Isomalto-oligosaccharide and isomaltulose had a negative effect on the increase of dough height.The addition of three functional sugars shortened the time for the gas release curve to reach the maximum height and raised the gas content of the dough.The dynamic rheological test results showed that the storage modulus G’and loss modulus G’of dough increased after adding three functional sugars compared with the blank group.When the addition of lactosucrose reached 5%,the loss angle tanδGreater than 1 enhances the viscosity of the dough.The loss angles of Isomalto-oligosaccharide and isomaltulose were less than 1.Secondly,the effects of three functional sugars on bread quality were explored.The texture results showed that the addition of three functional sugars reduced the hardness and chewability of bread and enhanced the elasticity of bread.When the addition amount of lactosucrose was 1%-5%,Isomalto-oligosaccharide was 4%-5%and isomaltulose was2%-5%,the cohesion of bread was increased.lactosucrose and isomaltulose enhanced the recovery of bread,while Isomalto-oligosaccharide showed the opposite trend.Specific volume and sensory results showed that the addition of three functional sugars increased the volume and sensory score of bread.When the addition of three functional sugars reached 5%,it would reduce the specific volume of bread.The results of slice tissue showed that the number of pores in bread increased significantly and the ratio of thick to fine pores decreased after adding three functional sugars.In the range of 1-4%,the stomatal area of the three functional sugars was smaller than that of the control group.When the amount of lactulose oligosaccharide was 1-3%,Isomalto-oligosaccharide was2-5%and isomaltulose was 4-5%,the pore wall thickness was lower than that of the control group.The thinner the pore wall,the softer the bread.The results of bread core chromaticity showed that the addition of lactosucrose and Isomalto-oligosaccharide increased the brightness L*of bread crust,and the addition of three functional sugars increased the yellowness b*.When the addition amount of Isomalto-oligosaccharide is1%-2%and isomaltulose is 1%-3%,the redness a*is reduced.The addition of isomaltulose showed concentration improvement for L*,a*and b*.The results of protein secondary structure showed that the presence of lactosucrose and isomaltulose promotedβ-sheet directionβ-turn transformation,increaseα-helix ratio.Effects of Isomalto-oligosaccharide onβ-sheet andβ-turn showed the opposite transformation trend.Isomalto-oligosaccharide and isomaltulose can reduce the proportion of random coil.Based on the analysis of the effects of three functional sugars on dough properties and bread quality,2%lactosucrose,4%isomalto-oligosaccharide and 5%isommalulose were used to study the anti-staling mechanism during bread storage.The storage time is 0,1,3,5 and 7 days,and the temperature is 4℃.The results of hardness during storage showed that compared with the control group,the hardness of bread decreased significantly after adding three functional sugars.On the 7th day,the hardness decreased by 22.5%,6.6%and32.5%respectively compared with the control group.The addition of three functional sugars reduced the slope n in the Avrami equation of bread samples,and the crystal nucleation mode of each sample was instantaneous nucleation.After adding three functional sugars,the staling rate constant k of bread decreased,indicating that the staling effect of bread during storage was delayed.In the water content determination test,the water content of the samples in the test group was low at the initial stage of storage.The addition of three functional sugars reduced the water loss rate and showed good water retention performance.The NMR data showed that during the storage of bread,the relaxation time of the sample decreased with the extension of the storage period.After adding three functional sugars,the T₂₁of the sample did not change significantly,and the A₂₁and A₂₂of bread increased,indicating that the water holding capacity was enhanced,which corresponded to the water content.On the 7th day of storage,the addition of three functional sugars reduced T₂₂and T₂₃of the sample.The results of thermodynamic characteristics and crystal structure test showed that after adding three functional sugars,the△H and crystallinity of bread samples decreased during the whole storage process.It shows that the addition of three functional sugars can inhibit starch recrystallization and delay starch retrogradation.In conclusion,the addition of 2%lactosucrose,4%Isomalto-oligosaccharide and 5%isomaltulose to wheat flour can improve the rheological properties of dough,improve the baking quality of bread and delay the staling of bread.It provides a theoretical basis for the application of functional sugar in baking products and is conducive to the long-term development of functional sugar industry.