Potato, corn and wheat starch containing 20% moisture were treated with a flow tester under heated and heated‐sheared conditions. Then heated and heated‐sheared starch specimens were prepared from three kinds of intact starches. Small amount of glucose was detected in water‐soluble fractions of heated and heated‐sheared specimens in spite of almost no detection in intact starches. By viscometry, the viscometric molecular weight of intact potato, intact corn and intact wheat starch with 20% moisture were 104kDa, 527kDa and 605kDa, respectively. While for heated specimens their molecular weights were depolymerized into 986kDa, 34kDa and 511kDa, respectively, and for heated‐sheared specimens, they were significantly depolymerized into 539kDa, 169kDa and 279kDa, respectively. Those facts were also supported from gel filtration profiles. As the results from glucose formation, viscometric molecular‐weight depolymerization and gelfiltration profiles, the considerable depolymerization in melt starchmolecules is yielded by the physical shearing‐force on starch melt despite starch varieties.
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