Effect Of Two Cellulose Ether Hydrocolloids On The Quality Of Frozen Dough And Steamed Bread

In this paper,sodium carboxymethyl cellulose(CMC)and sodium hydroxypropyl methyl cellulose(HPMC)were respectively applied to frozen dough to study their effects on frozen dough and steamed bread during the freezing process.The addition ratio of CMC and HPMC was optimized.The effects of different compounding ratios of CMC and HPMC on the quality of frozen dough and steamed bread,as well as on the properties of gluten were investigated.The effects of CMC and HPMC on frozen dough and steamed bread were studied respectively.The results show that the addition of CMC and HPMC could significantly increase the water absorption,formation time,stabilization time and powder quality index of the dough,and reduce the weakening of the dough.CMC and HPMC could increase the elastic modulus(G')and viscous modulus(G")of frozen dough.Frozen water content(C_FW)in frozen dough increased due to the formation and growth of ice crystals after 28 days of storage.C_FW of frozen dough without CMC or HPMC increased by 9.9%,while that of frozen dough with 0.7%CMC and 0.5%HPMC increased by 6.72%and 5.02%.The specific volume and elasticity of the frozen raw embryos without CMC or HPMC decreased by 0.38cm³/g and 0.06,respectively,and the hardness increased by 1086.18 g after frozen stored for28 days.The specific volume and elasticity of steamed buns supplemented with 0.7%CMC and 0.5%HPMC decreased by 0.18 cm³/g,0.04 and 0.20 cm³/g,0.04,respectively,and the hardness of steamed buns increased by 904.16 g and 830.36 g,respectively.The microstructure of the frozen dough shows that the frozen storage after 28 days,the network structure of the frozen dough with 0.7%CMC and 0.5%HPMC added respectively remained intact and continuous.The effects of different ratios of CMC and HPMC on frozen dough and steamed bread were studied.The results showed that the addition of CMC and HPMC increased the water absorption rate,the formation time and stabilization time of the dough,and decreased the degree of weakening.Adding different ratios of CMC and HPMC could increase the G'and G"of the frozen dough.When the compounding ratio is 0.7:0.3,the G'of the frozen dough and G"were greater than the G'and G"of frozen dough with CMC and HPMC added separately.CMC and HPMC in different compound ratios could reduce the C_FW of frozen dough and the rate of increase of C_FW during the freezing process.At 0 days of frozen storage,adding different proportions of CMC and HPMC increased the specific volume and elasticity of steamed bread to 2.40 cm³/g and 0.87,respectively,and reduced the hardness of the steamed bread to 3076.02 g(frozen storage for 28 days).After 28 days of freezing storage,the microstructure of frozen dough with adding sodium carboxymethyl cellulose and hydroxypropyl methyl in a ratio of 0.7:0.3 did not change significantly compared with 0days of frozen storage.The effect of different ratios of CMC and HPMC on gluten were studied.The results show that different compound ratios of CMC and HPMC could increase the G'and G"of GLUTEN,and increase the?-fold and?-helix,reduce the irregular curls and?-turn angles of GLUTEN,and make the secondary structure of gluten relatively stable during the freezing process.Different ratios of CMC and HPMC increased the denaturation temperature(Td)of the gluten to 56.77?(frozen storage for 28 days),indicating that the different proportions of s CMC and HPMC could increase the thermal stability of gluten.During the freezing process,the formation and growth of ice crystals destroyed the disulfide bonds in the gluten molecules and increase the free sulfhydryl content of the gluten.However,the addition of CMC and HPMC with different compound ratios could delay the increase in free sulfhydryl content.Because ice crystals destroyed the gluten molecules during the freezing process,the surface hydrophobicity of the gluten was increased.Different compound ratios of CMC and HPMC not only reduced the surface hydrophobicity of gluten,but also delayed the increase of the surface hydrophobicity of gluten during the freezing process.From the microstructure of the gluten,it could be seen that the network structure of the gluten control was broken and large holes appeared when the gluten was frozen for 28 days.When CMC and HPMC were added in a mixture ratio of 0.7:0.3,the gluten in the dough maintained a uniform size network structure.Though frozen storage reduces the quality of frozen dough and steamed bread,CMC and HPMC were added separately or mixed in different proportions could improve the quality of frozen dough and steamed bread.Moreover,the improvement effect of adding CMC and HPMC with a mixture ratio of 0.7:0.3 was greater than that of adding CMC and HPMC.Adding mixture of CMC and HPMC in different proportions could reduce the damage of gluten during the freezing process.