Effect of synergism between sodium alginate and xanthan gum on characteristics of composite film and gloss of areca nut coating

In this study, two polysaccharides of sodium alginate (SA) and xanthan gum (XG) were compounded in proportions of 100:0, 75:25, 50:50, 25:75, 0:100 with 1% total mass concentration and then coated on areca nuts. The effects of their synergistic interactions on the optical appearance of the edible coating were investigated for the first time. Areca nuts coated by 50:50 SA-XG presented the highest gloss (2.69 GU) and maximum spreading coefficient (−33.95 mN/m), indicating the improved wettability of the coating solution on the fruit's surface. The polarized light microscopy exhibited the unique birefringence phenomenon caused by the liquid crystal state, resulting in the better optical properties of the coating. UV–vis transmittance, Fourier transform infrared, and scanning electron microscopy indicated the good compatibility of SA and XG. The SA-XG film was more compactly arranged and had a denser microstructure due to hydrogen bonding. Additionally, the SA-XG combination improved the mechanical properties and water resistance compared to a single polysaccharide films and enhanced the water retention properties for the areca nut coating. Therefore, the SA-XG combination is promising to prepare edible films with improved optical properties for areca nuts.

Formation mechanism and stability of low environment-sensitive ternary nanoparticles based on zein-pea protein-pectin for astaxanthin delivery

This study was devoted for preparing zein-pea protein-pectin ternary nanoparticles through an alcohol-free pH-shifting method for the delivery of astaxanthin(Ax).The complexation of zein and pea protein(PP)in the weight ratio range of 1:2.5 to 1.2:1 maintained the dispersity at pH 7.0 with the average particle size of 90.47-132.38 nm and the polydispersity index of 0.204-0.245.The circular dichroism,fluorescence,Fourier transform infrared spectroscopy and other analyses indicated that the zein interacted with PP to form a composite structure through the folding action of protein structure in the process of pH reduction driven by hydrophobic and electrostatic forces.The incorporation of pectin(pec)further enhanced the physicochemical stability of the nanoparticles.The optimal weight ratio of zein/PP/pec was 2:4:3,and the encapsulation efficiency of astaxanthin reached 94.22%.The X-ray diffraction results showed that the astaxanthin was amorphous after embedding.Compared with Ax/zein-PP,the Ax/zein-PP-pec showed better colloidal stability under the conditions of wide pH range(4.0-8.0),high temperature(90℃),long time ultraviolet light treatment,and 15-day storage.These results indicated that the construction of the zein-PP-pec nanoparticles could be used as a low environment-sensitive nanocarrier for the loading,protection,and delivery of hydrophobic functional substances such as astaxanthin.