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GRANULE SIZE DISTRIBUTION AND RHEOLOGICAL BEHAVIOR OF HEATED MODIFIED WAXY AND UNMODIFIED MAIZE STARCH DISPERSIONS
Author(s) -
VA PEDRO M.S. da SIL,
OLIVEIRA JORGE C.,
RAO M.A.
Publication year - 1997
Publication title -
journal of texture studies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.593
H-Index - 54
eISSN - 1745-4603
pISSN - 0022-4901
DOI - 10.1111/j.1745-4603.1997.tb00107.x
Subject(s) - rheology , granule (geology) , materials science , starch , corn starch , particle size distribution , maize starch , particle size , food science , composite material , chemical engineering , chemistry , engineering
The effect of granule size distribution, supported by microscopic analysis, on the steady shear and dynamic shear rheological behavior of 5% gelatinized modified waxy maize starch (MWMS) dispersions heated at 80C for time periods from 0.5 to 30 min was examined and data obtained with 5% unmodified maize starch (UMS) dispersions was used to provide additional insight. The MWMS dispersions showed a faster and more extensive swelling than the UMS dispersions at 80C. They also exhibited rheopectic (anti‐thixotropic) time‐dependent and shear thinning with yield stress behavior. UMS dispersions showed shear thickening characteristics after short heating times that gradually turned to shear thinning as the heating time was increased. Dynamic tests on MWMS dispersions showed G’ was about ten times higher than G″. G′ showed a small dependence on frequency over 0.6–63 rad/s while G”, after an increase at low frequencies, became less sensitive. The gelatinized MWMS dispersions can therefore be classified as ‘weak gels.’ The flow behavior index of UMS dispersions was strongly