Effect Of Modified Starches On The Quality And Freezing Stability Of Frozen Raw Noodles

With the continuous development of cold-chain transportation and technology,the China’s frozen rice noodles industry develops rapidly.According to statistics,its annual output value has reached billions of yuan.Frozen raw noodles(FRNs),as an important part of the frozen rice noodles industry,have become the leader in the development of the "new track" in the noodles industry and quickly integrate into people’s lives.However,affected by the growth of ice crystals and water loss in the long-term frozen storage process,it will appear surface roughness,hardness decrease,easy to muddy soup and other problems,which restricts the development of frozen noodles industry.In this paper,modified starches(MS)were added to improve the quality of FWNs and FRNs.Meanwhile,the effects of MS on freezable water content and water migration of FRNs and the improvement of frozen storage stability were studied,which provided new insights and theoretical basis for improving the quality of FRNs and promoting the development of the industry.Firstly,the effects of 8 kinds of MS on the quality of FWNs were studied by moisture content,cooking characteristics,texture characteristics and color tests,and 3kinds of MS with the best effects were selected.The effect of 8 kinds of MS on moisture content of FWNs was different.Compared with the control group,the cooking loss rate of FWNs decreased by 6.3%,4.7%,3.0% and 3.0% when hydroxypropyl starch(HPS),hydroxypropyl distarch phosphate(HPDSP),oxidized starch(OS)and oxidized hydroxypropyl starch(OHS)were added to 5%,respectively,but excessive addition would produce the opposite effect(p < 0.05).In addition,with the increase of the addition of HPS,HPDSP,OS,pre-gelatinized starch(PGS),OHS and distarch phosphate(DSP),the hardness,springiness and chewiness of FWNs went up and then went down.The 8 kinds of MS can significantly increase the L* value of FWNs and improve its color(p < 0.05).Secondly,the gelatinization and expansion properties of HPS,HPDSP and OS,and the effects of selected MS on gelatinization properties of wheat flour and classical rheological properties of dough were studied.The results showed that compared with HPDSP and OS,the higher peak viscosity,minimum viscosity and final viscosity,and lower peak time,gelatinization temperature,solubility and expansion potential was shown in HPS.In addition,there was a same effect trend of HPS and HPDSP on the gelatinization properties,which was different in OS.Compared with control group,the stability time and energy of wheat flour gluten reached the maximum under 3%HPS addition,as well the resistance of wheat flour gluten reached maximum under6% HPS and 3% HPDSP addition,was 260 EU and 213 EU respectively(p < 0.05).Thirdly,the effects of selected MS with different addition on the quality of FRNs during long-term frozen storage were systematically studied.The results showed that the cooking loss of FRNs was continuously increased during frozen,which in hardness and chewiness results showed opposite results,thas was,continuous decreased,indicating that the quality of FRNs had degraded.Not only the L* value of FRNs was significantly improved(p < 0.05),the hardness and chewiness of FRNs were improved and the increase of cooking loss rate was delayed with the addition of HPS,HPDSP and OS under appropriate addition.Synthetically,the MS has the best effects on the quality improvement of FRNs under the addition of 6%.In addition,the addition of MS could also inhibit the migration of water of FRNs and limit the mobility of water.The results of FTIR and SEM showed that appropriate amount of MS was conducive to the stability of gluten network structure during frozen storage,and the aggregation between starch molecules and gluten proteins was closer.Finally,using 6% HPS,HPDSP and OS,the mechanism of 3 kinds of MS to improve the frozen storage stability of FRNs was preliminatively explored,which the addition of HPS,HPDSP and OS was 6%.The results showed that the viscosity decline of FRNs was delayed with the addition of HPS,HPDSP and OS.Meanwhile,the absorption and expansion of starch granules in the system was promoted and the viscosity of the system was increased.The granules expansion capacity of FRNs in the experimental group was higher than that in the control group under the same frozen storage time,indicating that the addition of MS had a certain effect on the maintenance of the starch-protein network structure of FRNs.After freeze-thaw and centrifugal treatment,the water of FRNs was lost,and the dehydration rate increased especially in the late frozen storage(p < 0.05),accompanied by the occurrence of drying loss during long-term freezing.In addition,the water inside FRNs was limited as far as possible,which was attributed to more hydrogen bonds formation by the hydrophilic groups of MS as well as the molecular "steric hindrance" effect.And it can diminish the loss of water and drying loss rate of FRNs during frozen storage.X-ray diffraction(XRD)results showed that the addition of MS had no effect to the crystal type of FRNs,but the possibility of V-shaped crystal formation was increased,which took a positive effect on the anti-digestion of FRNs.The decrease of disulfide bonds in gluten was improved with the substitution of HPS,HPDSP and OS,as well the fracture and transformation of disulfide bonds were inhibited to a certain extent.In conclusion,the addition of modified starch could effectively improve the quality and frozen storage stability of FRNs.Not only provided theoretical basis and new insights for the application of modified starch in FRNs,but also provided potential support for promoting the the rapid development of frozen noodles industry.