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W/O/W double emulsion systems offer the ability to co-deliver water-soluble and oil-soluble bioactives, making them a promising choice for multifunctional delivery applications. This study focused on the development of a whey protein isolate-based W/O/W emulsion encapsulating fish oil and anthocyanins, with the addition of sodium alginate (SA) into the external aqueous phase. The physicochemical properties, emulsion stability, anthocyanins encapsulation efficiency (EE), and anthocyanins release during simulated gastrointestinal digestion were studied. The results indicated that the physical stability of W/O/W emulsions improved with increasing SA, attributed to the higher viscosity and the protective coating of SA on the WPI-stabilized interface. However, the EE of anthocyanins in SA-reinforced W/O/W emulsions was found to be lower. Excessive SA concentration, such as 1.0 %, was observed to be unfavorable to maintaining the internal W1/O interface integrity. Overall, the double emulsion structure effectively regulated the release of anthocyanins throughout the digestion process. The study concluded that W/O/W emulsions containing 0.75 % SA achieved optimal stability and controlled-release characteristics. These findings offer valuable insights into fabricating double emulsions for multifunctional delivery purposes, showcasing their potential applications in the food and pharmaceutical industries.

Using prolamins to prepare delivery systems is promising for pharmaceutical and food industries. It is very necessary to find a reliable strategy to probe the assembly-release mechanisms of prolamin-based delivery systems, which could accelerate the screening of fabrication conditions. In this study, interactions of zein and gliadin with curcumin at different temperatures and ethanol concentrations was investigated by fluorescence quenching and other spectroscopic methods. It was found that the binding affinity between curcumin and gliadin gradually decreased with increasing ethanol concentration, but that of curcumin-zein gradually increased with increasing ethanol concentration. Zein and gliadin showed highest binding constant values (Ka) of 2.29 × 105 L mol−1 at 80% ethanol and 293K, 2.0 × 105 L mol−1 at 60% ethanol and 293 K, respectively. The temperature-dependent thermodynamic parameters were calculated. And the main driven forces were determined to be electrostatic interactions for gliadin-curcumin complexation, while van der Waals forces and hydrogen bonding were also involved in the binding of zein with curcumin in low ethanol conditions (60–70%). The curcumin-encapsulated zein/gliadin nanoparticles were prepared at various conditions, and their physicochemical properties were compared. The highest EE and LC values of zein nanoparticles were observed at 80% ethanol (95.8% and 19.2 μg/mg), while those of gliadin were observed at 60% ethanol (95.7% and 19.1 μg/mg). The change of encapsulation efficiency and loading capacity of nanoparticles was basically consistent with the binding affinity tendency between curcumin and zein/gliadin, confirming that the fluorescence quenching method is applicable to guide the screening of encapsulants and fabrication conditions.

Anthocyanins are natural colorants receiving increasing interests from food industry due to their variety of colors and health benefits. However, the instability of anthocyanins against environmental stress may limit their applications, which could be improved by the encapsulation systems built by various biopolymers including proteins, polysaccharides, and the composite formulations. In this review, the main biopolymers utilized as encapsulant materials for anthocyanins’ protection and delivery have been introduced; the geometry of these encapsulation systems, their properties and the technologies involved in the fabrications have also been discussed. The information present in this review is useful to guide the encapsulation of anthocyanins for food applications.