Rheological characteristics of different tropical root starches

• The rheological properties of starch extracted from ten different species of tropical tuber crops were examined using a Bohlin rheometer. Suspensions with starch concentrations of 3, 4 and 5% were gelatinised at 757C and fed into the rheometer cup. A C 25 measuring system was used and the heating rate was 1.57C/min, heating schedule 75-957C, holding at 957C for 600 s, cooling to 357C at 1.57C/min, holding for 3600 s. For strain sweep tests, the range of strain used was 0-0.2% and the temperature of test was 357C. The data on viscosity, storage modulus (G0) and phase angle were obtained from the rheograms. The results indicated variability in the various properties of the different starches. However the results did not follow a definite trend. The viscosity of Colocasia starch was low while Canna edulis and yam starches had high viscosities. The storage modulus was also highest for Canna starch (70-93 Pa) for 5% and gel strength was comparatively high for Canna edulis, Dioscorea esculenta and D. rotundata starches. The phase angle values followed the pattern of G0 and all the starch pastes were found to be elastic in nature at higher concentration. The wide variability in rheological properties can be useful in different applications of tuber starches.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Annan teknik -- Livsmedelsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Other Engineering and Technologies -- Food Engineering (hsv//eng)

Nyckelord

Tuber starches

Rheology

Storage modulus

Loss modulus

Phase angle

Viscosity

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