TITLE:
Comparison of Functional Properties between Native and Chemically Modified Starches from Acha (Digitaria Stapf) Grains
AUTHORS:
B. I. Olu-Owolabi, O. O. Olayinka, A. A. Adegbemile, K. O. Adebowale
KEYWORDS:
(Digitariaexilis Stafp); Functional Properties; Chemical Modification; Rheological Properties; Starches
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.5 No.2,
January
20,
2014
ABSTRACT: Acha grain (Digitariaexilis)
starch was isolated and subjected to chemical modifications by acetylation,
benzylation, succinylation, carboxymethylation and acid-thining. Functional
properties (swelling, solubility, gelation, oil and water absorption capacities,
alkaline water retention) and rheological properties of the native and modified
starches were determined. Swelling power and solubility of the starch samples
increased with increase in temperature. Swelling power and solubility were pH
dependent, with maximum values obtained at pH 12 in both native and modified
starches. Increasing degree of alkalinity increased both solubility and
swelling capacity. Water absorption capacities of chemically modified starches
decreased, but acetylated starch, ATAS showed higher value compared to the
native and also chemically modified starches improved oil absorption capacity
of the native starch. The modified starches showed increase in alkaline water
retention. Gelation studies revealed that ACAS had higher LGC than the native
while some chemically modified starches did not alter the gelation capacity of the
native starch except for BAS and ACAS with LGC of 10% and 16% v/w. There were
significant differences in functional properties between native and chemically
modified starches from acha, so chemical modification improved functional
properties. Chemical modifications increased pasting temperature except for
ATAS and BAS. Set-back values were reduced after modifications, indicating that
modification would minimize starch retrogradation.