Development and application of novel ɞ-lactoglobulin nanofibrils coacervated with alginate for encapsulation of carotenoids enriched palm olein

β-Lactoglobulin (β-lg) has the ability to form fibrils, and palm carotenoids have important biological activities affecting human health. However, carotenoids are unstable, and their insolubility in water makes them difficult to incorporate into many food matrixes. Therefore, this study addressed the development and application of β-lg nanofibril to produce palm carotenoid emulsions to improve the stability and bioavailability of these carotenoids. First, the impact of different stirring speeds on the characteristics of β-lg fibrils was investigated. The results showed that stirring significantly (p<0.05) enhanced the formation and stability of β-lg fibril. Second, a β-lg nanofibril solution was produced by a homogenization process. The results showed that increasing the homogenization pressure and cycles led to significantly decrease the fibril concentration, particle size, viscosity and turbidity. The emulsifying properties of the β-lgs were generally improved by the homogenization process. Third, different concentrations of sodium alginate (0.2-1.0% w/w) were added to a fixed concentration of β-lg nanofibrils (1.0% w/w) to form a complex. The results showed that the zeta potential decreased from a positive charge to a more negative charge (+13.7 ± 1.4 to -41.7 ± 1.2 mV). The addition of alginate resulted in an increase in the emulsifying properties of the β-lg nanofibrils. Fourth, the complex was used to produce a palm olein oil-in-water (o/w) emulsion. The results showed that increasing the oil concentration caused an increase in viscosity and particle size and reduced emulsion stability. The homogenization process was shown to produce an emulsion that with smaller particle size (29.92 ± 5.8 to 0.82 ± 0.05 μm), more negative of zeta potential (- 59.5 ± 2.0 to -67.5. ± 1.2 mV), less viscous (26.0 ± 0.7 to 11.8 ± 0.1 mPa-s) and more stable of emulsions (75.0 ± 3.5 to 91.3 ± 1.9%). Finally, the palm carotenoids were incorporated into the palm olein oil to produce β-lg nanofibrilalginate complex-stabilized palm carotenoids. The results showed minimal changes in the carotenoid content of the emulsion upon exposure to environmental stresses and storage, indicating the high stability of the emulsion. In addition, the cellular uptake of the emulsion (931.30 ± 125.50 fmol/ cell) was double compared to bulk oil (509.30 ± 37.30 fmol/ cell). The findings of this study suggest the suitability of the β-lg nanofibril-alginate complex to produce a palm carotenoid emulsion that exhibits high stability and better bioavailability.

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