*2.2. Rapid Viscosity Analysis (RVA)*

The pasting properties of starches (RS, PoS and PeS) and starch–betanin mixtures were investigated by using an RVA (D8-ADVANCE, Perten, Sweden) according to a previous study [14]. Briefly, the starch sample (2 g) was mixed with betanin at a dosage of 0% or 5% (*w*/*w*) and added to 20 mL of distilled water. The "standard 2" thermal program offered by the supplier was used to determine pasting properties. The samples were held at 50 ◦C for 60 s, then heated to 95 ◦C within 225 s and maintained at 95 ◦C for 150 s, cooled to 50 ◦C at the same rate as heating, and held at 50 ◦C for 120 s to develop the final paste viscosity. The rotational speed was set at 960 rpm for the initial 10 s, then changed to 160 rpm. The pasting curves were obtained and parameters were recorded, including peak viscosity (PV), trough viscosity (TV), final viscosity (FV), breakdown (BD) and setback (SB). Some of the gelatinized samples were transferred for rheological and chromaticity value analysis, and others were reserved at 4 ◦C for 7 days to prepare the retrograded samples. In addition, the same mass ratio of starch to betanin (20:1) was used for DSC analysis of starch–betanin samples.
