Kinetics and thermodynamics studies on thermal degradation of differently treated starch nanoparticles and estimation of the OH groups and H₂O content on particle surface

Abstract

The low thermodynamics and thermal decomposition kinetics properties of native starch (NS) make it unsuitable for use in food industries. Whether these properties are improved after converting the starch into nanoparticles (StNP) using ultrasonication treatment (UST), high-pressure homogenization (HPH), and StNP enrichment with carotenoids are investigated by differential scanning calorimetry and thermogravimetric analysis. The onset melting temperature and peak temperature of both peaks for HPH, UST and carotenoids enriched StNP are higher than the native one. First order model based on random nucleation with one nucleus on the individual particle is found to be best fitted to describe the thermal degradation kinetics and thermodynamic parameters of all StNPs. The activation energy value ranges from 143.857-162.481 KJ mol À1 and the values increase with treatment severity. Reactive hydroxyl groups present on the StNP surface increases after treatments (1037.488 to 1307.742 mg OH per 1 g of starch). Surface water amount also increases after the treatments except for carotenoids-enriched StNP. This study enables the estimation of the temperature conditions needed to obtain the desired properties. The results reveal the scope for developing thermally stable StNPs with desirable kinetics properties, which will be useful to overcome the disadvantages of NS in the food industries.