Physicochemical and rheological properties of flour and starch from Thai pigmented rice cultivars

• Published in: International journal of biological macromolecules 2019-09, Vol.137, p.666-675
• Main Authors: Tangsrianugul, Nuttinee, Wongsagonsup, Rungtiwa, Suphantharika, Manop
• Format: Article
• Language: English
• Subjects: Amylose - analysis; Amylose content; Chemical Phenomena; Color; Flour - analysis; Oryza - chemistry; Particle Size; Physicochemical properties; Pigmented rice; Rheology; Solubility; Starch - chemistry; Thailand; Viscosity
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2019.06.196

Flour and starch from four Thai pigmented rice cultivars, i.e., Riceberry (RB), Hom Nil (HN), Niaw Dang (ND), and Kum Pleuak Khao (KP) were compared for their physicochemical and rheological properties. Amylose content of all rice starches decreased in the following order: RB (12.09%) > HN (8.14%) > KP (2.87%) ~ ND (2.77%). The HN starch had the lowest proportion of amylopectin short A chains, while the KP starch showed the highest. Pasting temperature, setback, and final viscosity increased, while breakdown and swelling power decreased with increasing amylose content for both flour and starch samples. The flours and starches from the RB and HN showed greater onset and peak temperatures and enthalpy change (ΔH) of gelatinization than those from the ND and KP. Moreover, the gelatinization temperatures of all starches were significantly lower, but ΔH was higher than their flour counterparts. Dynamic viscoelastic tests revealed weak-gel like behavior of all flour and starch gels as evidenced by their G′ > G″ and tan δ values were smaller than unity. •Different rice cultivars exhibited different physicochemical and rheological properties.•Difference was due to variation in amylose content and amylopectin branch chain lengths.•Difference between flour and starch properties was due their different compositions.•Flour color was influenced by rice grain color, whereas all starches were almost white.