| Potato starch is widely used in food and nonfood fields for its excellent properties,such as lower gelatinization temperature and high transparency.Maize starch that various with amylose content could change the properties of potato starch system.The objective of this study was to investigate the effects of maize starches with different amylose contents on the properties of potato starch.The study selected five kinds of maize starch,including waxy,normal and high amylose maize starch as additives and added into potato starch.The properties of blend starches vermicelli were also determined.The results exhibited as followed:1.Added with the different kinds of maize starches,light transmittance of potato starch paste system decreased,and the higher amylose content of maize starch,the more obvious decrease in the transparency.The addition of maize starch inhibited the swelling degree of the starch granules and the solubility,which was related to starch category.The addition of waxy and high amylose maize starch had lowered the solubility,while normal maize starch solubility increased slightly.Combined with RVA,DSC and light microscopy,maize starch pasting delayed the pasting of the potato starch and elevated gelatinization temperature for inhibition starch swelling.2.The addition of different maize starches accelerated the retrogradation of potato starch paste,and increased with the amylose content.Both of waxy and high amylose maize starches reduced the gel strength of potato starch gels,while for normal one,the gel strength increased first and then decreased with the increase of the addition amount.Waxy maize starch significantly reduced the hardness of the blend system.Normal and high amylose maize starches had a promoting effect on the hardness of the system gel.The trends of gumminess were the same as hardness.Maize starches increased the yellowing value of the potato mixed starch gel.Waxy maize starch could improve the freeze-thaw stability of potato starch gel.The higher amount of amylopectin formed more soft gel.With the increase of amylose content in the mixed system,the network of the gel became dense,and the expanded starch granules physically supported the structure.3.The storage modulus of the mixed system increased first and then decreased with the addition of maize starches.At the same time,it was found that the temperature which was the G' began to increase gradually moved to higher temperature,indicating that the gelatinization of the mixed system was delayed.The mixed system of waxy maize and potato starches was relatively stable in the cooling process,while the aging trend of the higher amylose maize starch addition group was more obviously.All the blends were non-Newtonian fluids and exhibited pseudoplastic.The addition of normal maize starch could significantly improve the shear stability of the mixed system.4.Micro-rheometer can record the viscoelasticity of starch paste under zero shears.Adding waxy maize starch,the elasticity index of mixed starches system decreased,while with the increase in amylose content in the mixed system,the EI of the mixed system increased gradually and then decreased gradually compared with the control.The addition of maize starches inhibited the swelling of starch granules,which affected the amount of leached amylose and in turn decreased the solid characteristics of the mixed system.The amylopectin improved the macroscopic viscosity index of the system.Otherwise,the amylose reduced the MVI of the system.5.From the CLSM,it can be seen that the starch gelatinization began from the umbilical point of the granules,and appeared the cavity.After adding the maize starches,the rhodamine fluorescence mark was more obviously and the cavity area decreased compared with control,which indicated that the gelatinization of starches had been suppressed.The interaction between potato starch and maize starch was mainly through the hydrogen bonds,and the number of hydrogen bonds depended on the type of maize starches.Compared with the original potato starch,there was not new absorption peaks appeared in the mixed starch system from FTIR.6.The addition of normal maize starch could improve the cooking properties of potato starch vermicelli.Vermicelli with high amylose starch reduced the breaking rate to a certain extent,and the addition of high amylopectin starch was not conducive to the cooking properties of mixed starch vermicelli. |
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