Internal quality of coated eggs with soy protein isolate and montmorillonite: Effects of storage conditions

Abstract

The development of the bio-nanocomposite coating materials for eggshells has received more attention because of the decline in interior egg quality. This work evaluated the effects of weight loss, Haugh unit, yolk index, air space and albumen pH, eggshell strength, number of microorganisms on eggshells, contact angle and water vapor permeability of uncoated eggs and eggs coated with soy protein isolate/montmorillonite emulsions (5/0, 5/ 0.20, 5/0.50, 5/0.80; w/w) during 6 weeks at 25°C. A scanning electron microscope was used to visualize morphologies of soy protein isolate and the soy protein isolate/montmorillonite composite coatings, and the scanning probe microscope was determined. Compared with uncoated and soy protein isolate-coated eggs, the interior egg quality was improved by the increase of Haugh unit, yolk index, air space or eggshell strength, and decrease in weight loss, albumen pH, or the number of microorganisms on eggshells. The higher contact angle indicated the hydrophobicity of coatings. The values of water vapor permeability with 0.2% montmorillonite, 0.5% montmorillonite, and 0.8% montmorillonite were reduced by 21.14, 57.78, and 69.13%, respectively, as compared to those of soy protein isolate coatings. The images by a scanning electron microscope indicated that coatings could cover the cracks of eggshells to preserve the interior egg quality. The experimental values of the scanning probe microscope showed that montmorillonite would not penetrate through the eggshell pores, and it was safe to coat with montmorillonite. This study highlights the use of soy protein isolate/montmorillonite coating to maintain the internal quality and enhance the shelf life of eggs stored at 25°C.

Properties of soy protein isolate/nano‐silica films and their applications in the preservation of Flammulina velutipes

“…Figure d shows a smoother surface and cross‐section morphology for the film with 6% nano‐SiO 2 compared to the other films, consistent with the properties of the SPI/nano‐SiO 2 composite films. Similar observations were seen in studies by Xu, Zhang, Lv, et al () and Lee and Kim (), supporting our results.…”

“…Figure 5 shows the SEM images of the SPI and SPI/nano-SiO 2 films on the surface and in the cross-section. Figure 5a shows the morphology of the SPI films, showing an obviously uneven surface, and seen in studies by Xu, Zhang, Lv, et al (2016) and Lee and Kim (2010), supporting our results. Figure 6 shows the sensory quality of F. velutipes.…”

“…The maximum value was observed by the addition of 6% nano‐SiO 2 (129.6°). This may be attributed to the interaction between SPI and nano‐SiO 2 , which leaves fewer available interaction sites for the retention of water (Xu, Zhang, Lv, et al, ). Similar results have been reported by Liu et al who investigated the effect of the modified nano‐TiO 2 content on the CA of the SPI films with modified nano‐TiO 2 .…”

“…Currently, the soy protein isolate (SPI) film has been widely studied as a packaging material due to its biodegradability. The incorporation of nanoparticles, such as montmorillonite (Xu, Zhang, Lv, et al, ), nano‐TiO 2 (Zhang, Lin, Lin, & Wang, ), and nanocelluloses (Chen & Liu, ), into the SPI film has been reported to improve the properties of films. Nano‐silica (nano‐SiO 2 ), which has a small particle size, large specific surface area, high surface energy, and large proportion of surface atoms, can improve the properties of the material.…”

Mechanical property stability of soy protein isolate films plasticized by a biological glycerol‐based polyester and application in the preservation of fresh‐cut apples

“…Before the SEM measurement, the cross sections of the films were sprayed with a thin layer of gold (Xu et al, 2016). The dried films were frozen with liquid nitrogen.…”