Effect of the production method on the properties of RS3/RS4 type resistant starch. Part 1: Properties of retrograded starch (RS3) produced under various conditions and its susceptibility to acetylation

The objective of this study was to establish the effect of the concentration of a starch paste subjected to freezing on the properties of the produced retrograded starch, and to determine its susceptibility to acetylation with acetic acid anhydride. A starch paste (1, 4, 10, 18 or 30 g/100 g) was produced from native potato starch that was frozen, defrosted and dried. Al preparations of retrograded starch had the same chemical structure determined with the technique of nuclear magnetic resonance (NMR) and diversified physical form visible on photos taken with an electron microscope (SEM). An increase in the concentration of paste, used to produce the preparations, resulted in decreased: amylose content (from 25.0 to 20.4/100 g), solubility in water (from 41.1 to 20.1/100 g), swelling power (from 45.0 to 19.3/g), and susceptibility of the preparations to the action of amyloglucosidase (from 95.4 to 83.6/100 g). The heat of phase transition of solubilisation determined with differential scanning calorimetry (DSC) ranged from 3.8 to 7.1 J/g, and the initial temperature of transition was increasing from 43.4 to 49.7 °C along with an increasing concentration of the paste subjected to retrogradation. The 1–10/100 g concentration of the paste used to produce preparations was observed to increase, whereas that between 10 and 30/100 g to decrease the susceptibility to acetylation and viscosity of the prepared pastes, determined both with a Brabender viscograph and a Haake oscillating-rotational viscosimeter.