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The effects of different heat-treated temperatures (75, 85 and 95 °C) and times (15, 30 and 45 min) on physical, structural, thermal and morphological characteristics of zein in ethanol-water solution were investigated. The result of particle size distribution suggested that the volume percentage of small zein colloidal nanoparticles (d < 200 nm) was increased from 87.9% to 98.2% after heat treatment at 75 °C for 15 min. Both of the fluorescence intensity and ultraviolet absorption of zein approached to the maximum value when zein solution was heated at 95 °C for 30 min. Differential scanning calorimetry thermograms implied that heat treatment enhanced the thermal stability of zein with the rise of denaturation temperature. The secondary structure changes of zein induced by heat treatment might be explained by a potential mechanism of three-step process, including partial protein folding, a larger extent unfolding and the formation of partial protein aggregates. In addition, heat treatment significantly modified the morphology of zein from the typical sphericity to distinct oval at 75 and 85 °C, as well as obvious dumbbell-like shape at 95 °C for 30 min. [ABSTRACT FROM AUTHOR]

Curcumin is a natural food coloring agent with many pharmacological effects such as anti-oxidation and anti-cancer. In this study, curcumin was dissolved in different oil phases (medium chain triglyceride, canola oil and linseed oil) by different treatments (heat, ultrasonic and microwave). Curcumin nanoemulsions stabilized by different emulsifiers (Tween-80, lecithin, whey protein isolation and acacia) with different concentrations were prepared using high pressure homogenization to evaluate physicochemical properties including curcumin content, particle size, potential, physical stability and storage stability (variation of curcumin content and particle size under different temperatures in 60 days). The increase in oil phase concentration caused increase in curcumin content, particle size and viscosity of the emulsions but decrease in stability. Meanwhile, temperature significantly affected the stability of nanoemulsion stabilized by lecithin instead of Tween-80. Curcumin nanoemulsion could achieve the maximum curcumin content when choosing medium chain triglyceride as its oil phase. These results may broaden the application of curcumin in food industry for improving its solubility and bioavailability. [ABSTRACT FROM AUTHOR]