Effect Of Inulin On The Quality Of Frozen Cooked Noodles

In recent years,the development and utilization of inulin has become a hot research topic in food field.Inulin can be used not only as a sweet substitute,but also as a dietary fiber supplement.At present,studies on inulin in China and abroad mainly focus on the influence of inulin on the processing technology of steamed bread,biscuits,bread and other flour products,while there are no reports on the influence of inulin with different degree of polymerization on the quality of noodles and frozen cooked noodles.This paper discussed the influence of inulin with different degree of polymerization on the quality of dough and fresh surface,and the changes of macro quality and microstructure of frozen cooked surface with inulin with different degree of polymerization during frozen storage,providing a certain theoretical basis for the application of inulin in frozen cooked noodles.The main research results are as follows:Firstly,we measured the gluten content,tensile properties,gelatinization properties and dynamic rheological properties of doughs with different polymerization degrees of inulin.The study found that compared with the control group,the addition of 5% long chain inulin increased the gluten index,prolonged the stability time and made the dough more resistant to kneading.The tensile energy increased,the dough strength improved,and the elasticity and viscosity decreased compared with the control group.It improves the stability of starch granule in gelatinization process and has a good effect on inhibiting starch aging.However,the addition of 5% short chain inulin significantly reduced the flour index of dough,shortened the stability time,increased the degree of weakening,resulting in gluten resistance to mixing,the dough was not easy to shape,decreased elasticity and increased viscosity,and the inhibition effect of starch regeneration is not as significant as long chain inulin.Secondly,we explored the effects of inulin with different degree of polymerization on texture characteristics,cooking quality,sensory quality,freezable water content and water distribution of fresh surface.The results showed that both inulin and inulin reduced the hardness,chewiness and viscosity of fresh surface,and increased brightness.Adding 5% shortchain inulin reduced the breaking force and water absorption of fresh surface,and the cooking loss rate was 5.31%,which was significantly higher than the control group’s 4.77%,and palatability decreased.The proportion of tightly bound water decreased,the content of freezable water increased,and the water mobility of the system increased.The addition of 5%long chain inulin increased the stretching distance and water absorption of fresh noodles,and increased the viscosity and toughness,and the noodles were refreshing and chewy;The combination of gluten protein to water in fresh noodles was closer,and the freezable water content decreased,which inhibited the migration of non-freezable water.Then,we analyzed the changes of texture,cooking and sensory quality of frozen cooked noodles with different degree of polymerization inulin during freezing storage period of 0,30,60,90 and 120 days.The results showed that adding 5% long chain inulin greatly delayed the decrease in the hardness,chewiness,breaking force and stretching distance of the frozen cooked noodles during the frozen storage process,the re-cooking loss rate did not increase significantly,the re-cooking water absorption rate decreased slightly,the taste was better after reheating.However,the frozen cooked noodles with 5% short chain inulin added in the early stage of frozen storage,although the quality has decreased,but the change was not significant;After 60 days of frozen storage,texture properties and tensile properties decreased significantly,recooking loss was more,water absorption was also significantly reduced,the sensory sense of sticking teeth,insufficient elasticity,palatability decreased significantly.The research results show that: after 120 days of freezing,the frozen cooked noodles with5% long chain inulin the freezer water content measured by differential scanning calorimeter has increased from 47.6% at 0 days to 75.24%;low-field nuclear magnetic resonance It shows that the proportion of tightly bound water decreased from 15.61% to 12.6% under ice crystal destruction,and gradually migrated into weakly bound water;X-ray diffractometer showed that the crystallinity of starch increased from 10.25% to 22.39%,indicating that starch has been aging during the frozen storage period;scanning electron microscopy found that the gluten network has holes,but it is relatively continuous and intact,and the starch granules are less deformed.However,the frozen cooked noodles with 5% short chain inulin can freeze up to 94.36% after being stored for 120 days.A large number of starch granules were dissolved.Finally,we used differential scanning calorimeter,low-field NMR,X-ray diffrotometer,Fourier transform infrared spectrometer and scanning electron microscope to determine the changes of internal composition and microstructure of frozen cooked surface with inulin of different degree of polymerization during freezing storage.The results showed that: After 120 days of frozen storage,the proportion of tightly bound water in frozen noodles with 5% short and long inulin decreased to 10.98% and 12.60%,the crystallinity of starch increased to 26.14%and 22.39%,and the α helix content that maintained the stability of protein secondary structure decreased by 47.23% and 37.97%,respectively.As a result,the freezable water content reached 94.36%,the gluten network structure was torn in a large area,and starch particles were dissolved out in large quantities.However,the freezable water content increased to75.24%,the gluten network was relatively continuous and intact,and the deformation degree of starch grains was small.The results showed that long chain inulin could delay the deterioration of quality of frozen ripe noodles and improve the quality of frozen ripe noodles.