Structural, functional and mechanistic insights uncover the role of starch in foxtail millet cultivars with different congee-making quality

Abstract

Ten foxtail millet cultivars with different congee-making quality were investigated for relationships between starch structures, functional properties and congee-making qualities. Swelling power, pasting peak viscosity (PV) and setback (SB), gel hardness and resilience, and gelatinization onset (To), peak (Tp) and range (R) temperature were correlated with congee-making performance significantly. Good eating-quality cultivars with these parameters were in the range of 15.41–18.58 %, 3095–3279 cp, 1540–1745 cp, 430–491 g, 0.47–0.57, 64.43–65.28 °C, 69.97–70.32 °C and 23.38–24.52 °C, respectively. Correlation analysis showed that amylose, amylopectin B2 chains and A21 were essential parameters controlling the functional properties. Amylose molecules with linear molecular morphology would cause crystal defects and a wide range of molecular weight distribution. Additionally, they were more prone to re-association, which influenced the PV, SB, To, Tp and gel hardness. B2 chains impacted the gelatinization temperature range (R), gel resilience and swelling behavior by affecting the alignment of double helices and the size of starch particles and pores. Starch with more binding sites of bound water (A21) tended to leach from the swelling granules easily and contributed to higher values of PV. The content of amylose, B2 chains and A21 of good eating-quality cultivars were 16.19–18.46 %, 11.60–11.69 % and 96.50–97.02 %, respectively.