BACKGROUND The development of bioactive compound delivery systems using protein‐based nanoparticles as carriers is a rapidly growing field of study. α‐Lactalbumin (α‐La) nanoparticles are adequate for this task because they are nonantigenic, biodegradable, and easily modifiable via the surface physical adsorption of other molecules. Here, the effect of poly‐L‐lysine (PLL) coating of α‐La nanoparticles on the stability against enzymatic degradation in the gastrointestinal tract was investigated. RESULTS α‐La nanoparticles were prepared by desolvation with acetone. It was observed that the pH of the initial protein suspension did not have a significant effect on the size, polydispersity index (PDI), or ζ‐potential of the nanoparticles, so the subsequent experiments were performed at pH 9, where 151.2 nm nanoparticles with a PDI of 0.072 and a ζ‐potential of −29.7 mV were obtained. The nanoparticles coating was performed with two MW‐range PLL at three concentrations. Coating efficiency increased as the polymer concentration increased and this was independent of the PLL MW. The best coating efficiency (90–95%) was obtained in the case of the 1 mg mL−1 PLL coating. Most PLL‐coated nanoparticles showed a good stability to the conditions of in vitro simulated gastrointestinal digestion compared with the uncoated nanoparticles. CONCLUSION It can be concluded that the acetone desolvation method at pH 9 is adequate to obtain α‐La nanoparticles with good characteristics. The process of PLL coating of nanoparticles showed an increase in efficiency with the increase in concentration of the polymer. The resulting coated nanoparticles had enhanced resistance to simulated gastrointestinal conditions. © 2021 Society of Chemical Industry (SCI).

Whey protein is a byproduct of cheese, casein, and Greek yogurt produced in Europe, North America, and Australasia. It is a substantial source of functional proteins and peptides for the worldwide food industry. α-Lactalbumin (α-La) is a globular protein that can be isolated from WPI (whey protein isolates) using techniques such as chromatography/gel filtration, membrane separation, etc. α-La is used in the elaboration of functional foods and is a very good source of peptides with anticancer, antimicrobial, antiviral, antihypertensive, immunomodulating, opioid, mineral-binding, and antioxidant bioactivities. Nanotubes and nanoparticles generated from this protein are utilized as vehicles for the transport of active compounds, and thus, can be used in foods and pharmaceutical industries. The contaminant effects of whey, characteristics of α-La, production technologies, and its applications in nanotechnology are reviewed here.

The stabilization of Pickering emulsions by nanoparticles has drawn great interest in the field of food science and technology. In this study, α-Lactalbumin nanoparticles prepared by the desolvation and cross-linking method from protein solutions with initial pH values of 9 and 11 were used to stabilize squalene-rich amaranth oil Pickering o/w emulsions. The effect of different concentrations of nanoparticles on the size, size distribution, ζ potential, and emulsion stability was evaluated using dynamic light scattering, electron microscopy, and light backscattering. Dependence of the emulsions’ droplet size on the nanoparticle concentration was observed, and the critical coverage ratio was reached when 5–10% nanoparticles concentration was used. Our findings suggest that α-LA nanoparticles at a 10% concentration can be used as novel stabilizers for Pickering emulsions to provide protection for beneficial lipophilic bioactive compounds. This is the first time that native α-LA nanoparticles have been used as stabilizers of Pickering emulsions.