Emulsifying properties of protein fractions prepared from heated milk

Development of antioxidant chitosan film with banana peels extract and its application as coating in maintaining the storage quality of apple

In the present study, the antioxidant chitosan (CS)-banana peels extract (BPE) composite film was developed. The different content of BPE (4%, 8% and 12%) was added to the CS film not only as the antioxidant but also as the cross-linking. The CS, CS-4% BPE, CS-8% BPE and CS-12% BPE films were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD) and thermogravimetric analysis (TGA). The physical and mechanical properties possessed by the CS and CS-BPE films were compared as well, and the CS-4 %BPE composite film exhibited the most excellent properties. The decline in moisture contents, water solubility and water vapor permeability of CS-BPE composite film indicated the reduced hydrophilicity. Moreover, the CS-BPE composite film exhibited excellent antioxidant activity in different food simulants. Finally, the optimal concentration of CS-BPE coating treatment was identified and applied to apple fruit, and the results showed that CS-BPE coating was more capable of improving the postharvest quality of apple fruit than CS coating. This study evidences the promising nature of CS-BPE composite film and coating as a desirable alternative for active packaging and it is believed as conducive to valorization of banana peel by-products for allied applications.

Low-resolution 1H spin-spin relaxation of n-decane/water emulsions stabilized by beta-casein

A low-resolution 1H NMR relaxometry study on the dynamics of an n-decane/water emulsion stabilized by beta-casein is presented. Spin-spin (transverse) relaxation time constants (T2) were used to assess relative mobilities of emulsion components, by a selective deuteration procedure. Data analysis allowed the emulsion investigated to be described by a heterogeneous collection of dynamically distinct populations. A major population of n-decane molecules presented an average mobility that very nearly approached that of pure solvent, which is compatible with its occurrence in the emulsion continuous microphase. beta-Casein molecules displayed a prevalent population with significantly decreased mobility as compared to the free protein in solution, which is in accordance with the protein location at the oil/water interface. Also, a major H2O population with significantly lower average T2 as compared to the pure liquid was detected and has been assigned to interfacial water.

Destabilization of Oil-in-Water Emulsions Formed Using Highly Hydrolyzed Whey Proteins

Oil-in-water emulsions (4 wt % soy oil) were prepared with 0.5-5 wt % whey protein hydrolysate (WPH) (27% degree of hydrolysis), in a two-stage homogenizer using various first-stage pressures of 10.3, 20.6, and 34.3 MPa and a constant second-stage pressure of 3.4 MPa. Destabilization studies on the emulsions were carried out for up to 24 h, using both laser light scattering and confocal laser microscopy. It was found that emulsions formed with <2% WPH showed oiling off and coalescence at all homogenization pressures. Emulsions formed with 2, 3, and 4% WPH showed coalescence and creaming only, while slight flocculation but no creaming occurred in emulsions formed with 5% WPH. Furthermore, the apparent rate of coalescence increased with homogenization pressure but decreased with WPH concentration. In contrast, the surface concentration of WPH increased with the WPH concentration in the emulsions but decreased with homogenization pressure. Analysis of WPH by high-performance liquid chromatography showed an increase in the concentration of high molecular weight peptides at the droplet surface compared to the WPH solution. This was considered very important for the stability of these oil-in-water emulsions.