Effects of micro- and nano-sized emulsions on physicochemical properties of emulsion-gelatin composite gels

In this study, we aimed to investigate the effects of emulsion droplet size on the physicochemical and rheological properties of emulsion-gelatin composite gels. Gelatin or lecithin solutions (1-4%) as emulsifiers were ho-mogenized with canola oil using a high-speed and/or high-pressure homogenizer to obtain micro-and nano-sized emulsions. Gelatin (8%) was mixed with an equal amount of the prepared emulsion and subsequently cooled at 4 degrees C for cold-set gelation. Gel strength of the emulsion-gelatin composite gels was higher when the concentration of gelation was increased, regardless of the droplet size of the emulsion. In terms of droplet size, gel strength, G ', and water-holding capacity of emulsion-gelatin composite gels with nano-sized emulsions were significantly higher than those of gels with micro-sized emulsions, except for lecithin. Fourier-transform infrared and dif-ferential scanning calorimetry analyses of emulsion-gelatin composite gels revealed that the emulsion size had a significant effect on the physicochemical properties of the gels, except for lecithin. Conformationally, droplet size influenced the gel strength of the emulsion-gelatin composite gels owing to the high specific surface area of the nano-sized droplets, which formed a relatively high number of junctions of gelatin random coils during cold-set gelation.