Bioaccessibility and Stability Studies on Encapsulated Phenolics and Carotenoids from Olive and Tomato Pomace: Development of a Functional Fruit Beverage

Abstract

This study pertains the encapsulation of bioactive compounds, specifically phenolic compounds and lycopene, extracted from olive and tomato by-products via oil-in-water (O/W) nanoemulsions and their potential application in functional beverages. The effect of various edible oils (olive pomace oil (OPO), sunflower oil (SFO), corn oil (CO), fish oil (FO), and canola oil (CLA)) in the lipid phase and antioxidants (ascorbic acid and phenolic extracts) in the aqueous phase on the physicochemical properties of oil-in-water (O/W) nanoemulsions enriched with lycopene was evaluated, along with the bioaccessibility of the encapsulated bioactive compounds using the static INFOGEST in vitro simulation protocol for gastrointestinal food digestion. All examined edible oils led to nanoemulsions with uniform droplet sizes (droplet size < 300 nm, droplet distribution < 0.3) and high stability during storage at 4 °C, with FO being the smallest, at 259.3 ± 9.1 nm, and OPO the largest, at 286.6 ± 10.0 nm. Ascorbic acid increased the droplet size by 5–8%, improved droplet distribution, and led to a lower deterioration rate (−0.014 d−1) when compared to the “control” counterparts (−0.037 d−1). Lycopene bioaccessibility was significantly affected by the lipid phase, with OPO exhibiting the highest percentage (53.8 ± 2.6%) and FO the lowest (40.1 ± 2.1%). The OPO nanoemulsion was selected for the development of a functional beverage, showing excellent long-term stability. The phenolic compound concentration remained consistent during storage, and the lycopene degradation rate was minimal, at −0.0088 d−1, resulting in an estimated shelf life of 165 days at 4 °C, based on a 50% reduction in lycopene content. Similarly, phenolic compounds demonstrated high bioaccessibility, without a significant dependence on the lipid phase, and stability during shelf life, enhancing the beverage’s overall antioxidant profile. These results indicate that O/W nanoemulsions are effective delivery systems for functional beverages, offering improved stability and bioaccessibility of lycopene.

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