Thermodynamic analysis as a useful tool to study the physical properties of sweet‐potato starch films reinforced with alginate microparticles

Abstract

Thermodynamic analysis is a useful instrument for understanding the state of adsorbed water molecules and their influence on the physical and chemical stability of packaging materials during their functioning. This study assesses the effect of alginate microparticles as reinforcement on the water‐adsorption characteristics and physical properties of sweet‐potato starch biopolymer films. Glycerol was utilized as plasticizer. Then, physical stability was evaluated through minimum integral entropy criteria. The incorporation of alginate microparticles significantly decreased (p < 0.05) spin–lattice relaxation times, water‐vapor permeability, and the films' water solubility. Additionally, the adsorption capacity, as well as the physical stability of the films, were increased from 0.38 to 0.63 water activity at 25°C. An antiplasticization effect of water was noted in the water‐activity range, where the adsorption process was entropy‐controlled. Maximal resistance to breakage was enhanced in the minimum integral‐entropy zone. SEM micrographs revealed a rougher surface of reinforced films. Therefore, it is feasible to anticipate the most appropriate water activity where best film performance is achieved, employing minimum integral‐entropy criteria.

Effect of calcium hydroxide on pasting, thermal, and water‐adsorption behavior, and the flow properties of nixtamalized corn flour

“…As expected, C values decrease as the equilibrium temperature increases, whereas k values increase. This behavior is the result of the occupation of the monolayer sites by water molecules and the formation of water layers or capillary condensation (Acosta‐Domínguez et al, 2021). Different values of GAB constants have been reported by Samapundo et al (2007) and Oyelade et al (2008) for maize flour (lower monolayer moisture and higher C and k values).…”

Spray freezing drying microencapsulation of krill oil enhances digestion and storage stability

“…The differential enthalpy or isosteric heat of sorption indicates the strength of water molecules adsorbed by solid particles (Azhar et al, 2021), as it reflects the energies of the water molecules bound at a certain hydration point. Several authors have proved that the point where integral entropy finds its minimum (∆S min ) could be assumed as the best water activity (a w ) for preserving food, and that occurs because the water-food bond is the strongest one (Acosta-Domínguez et al, 2021;Cano-Higuita et al, 2015;Escalona-García et al, 2016;Osorio-Tellez et al, 2021;Velázquez-Gutiérrez et al, 2021).…”