Influence of acid hydrolysis on thermal and rheological properties of amaranth starches varying in amylose content.
BACKGROUND
The granules of amaranth starch are very small compared with starches from other sources. In the current work, amaranth starches with different amylose contents were treated with hydrochloric acid as a function of time in order to study the effect of acid treatments on starches. Differential scanning calorimetry and dynamic oscillation in shear were employed to analyse the thermal and rheological properties of acid-modified amaranth starch.


RESULTS
Results showed that gelatinisation temperatures and enthalpy change of gelatinisation (ΔH) decreased steeply initially, and had a slight increase with further treatment up to 12 h then decreased, an outcome that reflected distinct resistance to acid with various amylose contents. Rheological parameters of storage and loss moduli during heating, cooling and frequency sweep of modified starches reflected the differential scanning calorimetry results by decreasing in value as the time of acid hydrolysis increased.


CONCLUSIONS
With amylose content increase, the effects of acid hydrolysis on gelatinisation temperatures became less pronounced. Nevertheless, prolonged acid hydrolysis decreased the storage and loss moduli, with the starch pastes becoming more liquid-like.
Institute of Nuclear Agricultural Sciences, Huajiachi Campus, Zhejiang University, Hangzhou, China.
Xiangli
X
Kong
Stefan
S
Kasapis
Jinsong
J
Bao
Harold
H
Corke
D027721:Amaranthus / Q000737:chemistry*; D000688:Amylose / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D006851:Hydrochloric Acid; D006868:Hydrolysis; D012212:Rheology; D012639:Seeds / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
D005782:Gels; D000688:Amylose; D006851:Hydrochloric Acid