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Structural, thermal, and rheological properties of Amaranthus hypochondriacus and Amaranthus caudatus starches

Singh, Narpinder, Kaur, Shubhpreet, Kaur, Amritpal, Isono, Naoto, Ichihashi, Yuya, Noda, Takahiro, Rana, Jai Chand
Die Stärke = 2014 v.66 no.5-6 pp. 457-467
Amaranthus caudatus, Amaranthus hypochondriacus, amylopectin, correlation, crystal structure, gelatinization, granules, heat treatment, pasting properties, principal component analysis, rheological properties, temperature
Structural, thermal, and rheological properties of starches from 13 Amaranthus hypochondriacus lines and 8 Amaranthus caudatus lines were evaluated and related using principal component analysis. Amylopectin chains with DP 6–12, DP 13–18, DP 19–24, and DP 25–30 ranged from 43.60 to 55.72%, 31.59 to 34.49%, 10.14 to 16.37%, and 2.56 to 5.53%, respectively, for A. hypochondriacus and 50.67 to 57.53%, 29.30 to 32.02%, 10.04 to 13.09%, and 2.75 to 4.2%, respectively for A. caudatus. A. hypochondriacus showed higher proportion of granules <1 µm (14.76–35.64%) than A. caudatus (0.16–6.92%). A. hypochondriacus and A. caudatus starches showed the granules of size 1–10 µm between 57.09 to 77.48% and 88.67 to 99.66%, respectively. The transition temperatures (Tₒ, Tₚ, and Tc) were negatively correlated with amylopectin short chains (DP 6–12). The pasting properties (PV, BV, FV, and SB) were positively correlated with DP 6–12 and negatively with DP 13–24. Starches with higher proportion of granules of 1–10 µm showed higher amount of DP 6–12, crystallinity, and paste viscosities. Starches with higher proportion of 11–30 µm had high DP 13–30 and gelatinization transition temperatures. The results reflected that the change in structure from liquid‐like to solid‐like was dependent upon chain length, starch with higher DP 6–10 showed higher Tcᵣₒₛₛₒᵥₑᵣ (temperature at which G′ became higher than G″ during heating) and those with higher DP 13–24 showed lower Tcᵣₒₛₛₒᵥₑᵣ.