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Effect of Specific Mechanical Energy on Properties of Extruded Protein‐Starch Mixtures
Author(s) -
Gropper Maoz,
Moraru Carmen I.,
Kokini Jozef L.
Publication year - 2002
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem.2002.79.3.429
Subject(s) - extrusion , chemistry , starch , food science , chemical engineering , carbohydrate , glass transition , starch gelatinization , polymer , biochemistry , organic chemistry , composite material , materials science , engineering
The effect of the specific mechanical energy (SME) during extrusion of a protein‐starch mixture was studied by analyzing the glass transition temperature ( T g ) and starch gelatinization. We found that the SME values of 344 to 2108 kJ/kg did not significantly change the T g of the product. To explain the insensitivity of T g to SME in spite of reported fragmentation taking place during extrusion, we studied the effect of the molecular weight (MW) on T g in a model system consisting of dextrans of varying molecular weights. We found that the effect of the molecular weight on the T g reached a plateau at 6.7 × 10 4 . Because the reported size of the fragments created during the extrusion process is larger than this, we were able to explain the apparent insensitivity of T g to SME in the protein‐carbohydrate matrix studied. However, we found that starch gelatinization varied with SME, the degree of gelatinization being higher for systems exposed to higher SME.