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Advisor(s)
Abstract(s)
A new starch was isolated from fruits of two acorn species, Quercus rotundifolia and Quercus suber by
alkaline (A3S) and enzymatic (ENZ) methods and physical and functional properties were studied. The
isolation method induced changes in most of those properties in the isolated starches, mainly in resistant
starch content, syneresis, pasting, thermal and rheological properties. Isolated acorn starches presented
high amylose content (53e59%) and resistant starch content (30.8e41.4%). Acorn starches showed
limited and similar solubility values and swelling power values, showing a gradual increase from 60 C to
90 C. The pasting temperatures ranged from 67.5 to 72.0 C and pastes did not present breakdown,
which is suggestive of a high paste stability of acorn starches during heating. At ambient temperature the
turbidity and syneresis values were low, but when held at freezing temperatures the syneresis significantly
increased. Thermal analysis revealed that the acorn starches easily undergo transition phenomena
as shown by the low To and enthalpy values (4.1e4.3 J/g), these effects were more evident in starches
isolated by ENZ method. Pastes are more elastic than viscous and form strong gels after cooling. Q. suber
starch was shown to be more sensitive to the effect of isolation method. Generally, starch isolated by
enzymatic method presented less interesting functional properties, since this isolation procedure greater
affected the raw structure of starches
Description
Keywords
acorns isolation method starch functional properties thermal properties rheological properties
Pedagogical Context
Citation
"Food Hydrocoloids". ISSN 0268-005x. 30 (2013) 448-455
Publisher
Elsevier