Effect of aqueous ozonation on the pasting, flow and gelatinization properties of wheat starch

- Ozonation resulted in decreased retrogradation, increased thermal stability and increased gelatinization in wheat starch.
- Ozonation decreased the pasting temperature of wheat starch.
- Ozonation can be used as an alternative to chemical and thermal treatments to modify wheat starch.

Wheat starch-water suspensions were exposed to ozone gas for 15, 30, and 60 min at 5 °C at a concentration of 0.00042 g dissolved ozone/100 g. Pasting properties were determined by using a Rapid Visco Analyzer (RVA) while a Bohlin rheometer was used to obtain flow behaviour (n) and consistency (K) indices. An enzymatic method using glucoamylase was applied to calculate percent starch gelatinization. Pasting temperature (PT) of ozonated starch samples decreased significantly (P < 0.05) as compared to that of native starch. Cooking stability starch samples increased upon ozonation indicated by lower breakdown viscosity (BV) values. The retrogradation tendency of wheat starch samples was reduced after ozonation which was indicated by lower setback viscosities (SV). Native and ozonated starch samples exhibited a shear-thinning behaviour with values of flow behaviour indices (n) between 0.57 and 0.76. The greater n values obtained for ozonated starch samples as compared to native starch showed that ozonation increased the shear-thinning behaviour of wheat starch. Percent gelatinization for all ozonated starch samples were significantly higher than the control starch samples (P < 0.05), probably due to, weakened hydrogen bonding between the starch molecules and partial depolymerization of starch molecules by ozonation.