Formulation and characterization of water-in-oil nanoemulsions loaded with açaí berry anthocyanins: Insights of degradation kinetics and stability evaluation of anthocyanins and nanoemulsions

Açaí berry is the fruit of an Amazonian palm tree and rich in anthocyanins (ACNs). Scientific studies have proven the health benefits of açaí berry and declared this fruit as “super fruit”. ACNs have high antioxidant activities, but they are unstable and can easily deteriorate during food processing. In order to protect ACNs and increase their applicability, food-grade water-in-oil (W/O) emulsions were successfully formulated with different concentrations of açaí berry extracts (AEs). The formulated W/O nanoemulsions were relatively stable, with no phase separation after 30 days of storage. The average droplet size varied between 146.8 and 814.8 nm, with higher values corresponding to samples without AEs. All W/O nanoemulsion samples exhibited antioxidant activity and high retention rates of polyphenols after 30 days of storage. ACN retention followed first-order kinetics, with high protection of ACNs observed in emulsified samples. 2% AE encapsulated in a 30 wt% W/O nanoemulsion had an estimated half-life of 385 days. The results indicate that stable nanoemulsion systems with high ACN protection can be produced with possible applications in the food and pharmaceutical industries. [Display omitted] •Successful formulation of anthocyanin loaded water in oil nanoemulsions.•Probable surfactant properties of açaí extracts•Smaller droplet size distribution for samples emulsified with açaí extracts.•Water-in-oil nanoemulsions have good antioxidant activity after 30 days of storage.•Degradation rate of anthocyanins decreased significant after encapsulation.