| Rock bean which has a history of consumption is the seeds of Millettia pielsiana Harms.It is not only rich in starch,but also is nutritional and healthy.However,little research on Rock bean starch has been reported.Starch is widely used in the food industry,and mixing different types of starch is considered a green,safe and non-polluting way to improve its properties.Therefore,in this paper,Rock bean was used as the object of study to determine the optimal extraction process of Rock bean starch and to characterize its structure;Adding common corn starch to Rock bean starch in certain proportions and investigating the pasting and aging properties of the starch blending system as well as the mechanism of interaction between them;Finally,the Rock bean starch/Corn starch blended system was applied to the production of Rock bean cold noodles.The main findings of the study are as follows:(1)The optimal extraction process for Rock bean starch is as follows:Material liquid ratio 1:50(g/m L),Soaking temperature 35℃,Soaking solution p H 9,Soaking time 1 hour.Under these conditions,the extraction rate of Rock bean starch is 73.6%.(2)The crystal type of Rock bean starch is type C with a crystallinity of 15.67%;FTIR analysis revealed that the experimentally prepared Rock bean starch conforms to the basic functional groups of starch;Rock bean starch has a number average molecular weight of2.14×10~4 g/mo L,a weight average molecular weight of 4.1×10~4 g/mo L,and a dispersion of 1.8;Most of the Rock bean starch granules were round or oval with different sizes,and the surface of starch granules was smooth with an average diameter of 21.14μm.(3)The research results on the gelatinization properties of Rock bean starch/Corn starch blend system indicate that:The Rock bean mixed starch with Corn starch has an increase in transparency,swelling power,and a decrease in solubility;The research on viscosity characteristics shows that the gelatinization temperature and retrogradation value of Rock bean mixed starch decrease,while the peak viscosity,minimum viscosity,final viscosity,and attenuation value all increase;The research on thermal properties shows that with the addition of Corn starch,the gelatinization starting temperature,peak temperature,and end temperature of the blend system all decrease to varying degrees.(4)The research results on the aging properties of Rock bean starch/Corn starch blend system indicate that:The Rock bean mixed starch with Corn starch has a weaker retrogradation and a delayed time to reach retrogradation equilibrium;Gel strength decreased;Enhanced freeze-thaw stability;The results showed that the hardness and adhesiveness of Rock bean mixed starch decreased,the elasticity did not change significantly,and the cohesion increased;The results of microstructure observation show that the gel of Rock bean mixed starch becomes more soft,and the order of microstructure is enhanced.(5)The research results on the interaction mechanism of Rock bean starch/Corn starch blend system indicate that:After adding Corn starch,the ability of starch molecules to bind water in the starch blend system increases;The analysis of force types shows that hydrogen bonding is one of the forces that maintain the Rock bean starch/Corn starch blend system,and the number and energy of hydrogen bonds in the system are related to the content of added Corn starch.(6)The best process for making rock bean noodles at a pasting temperature of 95℃is:material liquid ratio 1:8(g/m L),Rock bean starch/Corn starch ratio 7:3(g/g),and heating time 20 minutes. |
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