This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.

The effects of single and dual heat-moisture treatment (HMT) of rice, cassava and pinhão starches at 100 °C and 120 °C were investigated. The starches were adjusted to 22% w.b. moisture content and subjected to single HMT (autoclaved for 2 h) or dual HMT (after being autoclaved for 1 h, the material was allowed to stand for 24 h and was autoclaved again for more 1 h). Starch crystallinity, solubility, swelling power, thermal properties, pasting properties, and gel hardness were evaluated. The temperature variation affected more the starch properties than the single or dual HMT. The starch subjected to single HMT at 120 °C was the most applicable to food applications, where low swelling power, low viscosity and high thermal stability are necessary.

No abstract

Ozone is a more powerful oxidant than common oxidising agents, such as sodium hypochlorite and hydrogen peroxide. It is considered as a safer starch modification method for both consumers and the environment. However, few studies have investigated the changes in starch properties associated with ozone treatment, particularly when applied in aqueous solution. This work aimed to evaluate the carbonyl and carboxyl contents, the X-ray diffraction patterns, the spectrum profiles of Fourier transform infrared spectroscopy, the pasting properties and the surface morphology of ozone-oxidised cassava starch during 60 min under different pH (3.5, 6.5 and 9.5) at 25°C. The pH 6.5 and 9.5 seemed to favour the cross-linking between the depolymerised starch molecules during ozonation. The pH 3.5 was more effective in reducing the peak viscosity, breakdown, setback and final viscosity of cassava starch during ozonation in aqueous solution. No differences in the granule surface morphology were observed in the ozone-treated cassava starches compared to native starch.

The effect of heat‐moisture treatment (HMT) on the properties of pinhão starches under different moisture and heat conditions was investigated. The starches were adjusted to 15, 20 and 25% moisture levels and heated to 100, 110 and 120°C for 1 h. The X‐ray diffractograms, swelling power, solubility, gel hardness, pasting properties and thermal properties of the native and HMT pinhão starches were evaluated. Compared to native starch, there was an increase in the X‐ray intensity and gel hardness of HMT starches, with the exception of the 25% moisture‐treated and 120°C heat‐treated starch. HMT reduced the swelling power and solubility of the pinhão starches when compared to native starch. There was an increase in the pasting temperature, final viscosity and setback and a decrease in the peak viscosity and breakdown of HMT pinhão starches compared to native starch. HMT increases the gelatinisation temperature of native pinhão starch and reduces gelatinisation enthalpy.

No abstract

The aim of this study was to produce and characterize inclusion complexes (IC) between β-cyclodextrin (β-CD) and orange essential oil (OEO) or eucalyptus essential oil (EEO), and to compare these with their pure compounds and physical mixtures. The samples were evaluated by chemical composition, morphology, thermal stability, and volatile compounds by static headspace-gas chromatography (SH-GC). Comparing the free essential oil and physical mixture with the inclusion complex, of both essential oils (OEO and EEO), it was observed differences occurred in the chemical composition, thermal stability, and morphology. These differences show that there was the formation of the inclusion complex and demonstrate the necessity of the precipitation method used to guarantee the interaction between β-CD and essential oils. The slow loss of the volatile compounds from both essential oils, when complexed with β-CD, showed a higher stability when compared with their physical mixtures and free essential oils. Therefore, the results showed that the chemical composition, molecular size, and structure of the essential oils influence the characteristics of the inclusion complexes. The application of the β-CD in the formation of inclusion complexes with essential oils can expand the potential applications in foods.

No abstract