Physicochemical Properties and Chemical Stability of β-Carotene Bilayer Emulsion Coated with Bovine Serum Albumin and Arabic Gum Compared to Monolayer Emulsions

Abstract

β-carotene is a lipophilic micronutrient that is considered beneficial to human health. However, there are some limitations in utilizing β-carotene in functional foods or dietary supplements currently because of its poor water dispersibility and chemical stability. A new type of β-carotene bilayer emulsion delivery system was prepared by a layer-by-layer electrostatic deposition technique, for which were chosen bovine serum albumin (BSA) as the inner emulsifier and Arabic gum (GA) as the outer emulsifier. The physicochemical properties of bilayer emulsions were mainly characterized by droplet size distribution, zeta potential, rheological behavior, Creaming Index (CI), and encapsulation ratio of β-carotene. Besides this, the effects of processing conditions (pH, thermal treatment, UV radiation, strong oxidant) and storage time on the chemical stability of bilayer emulsions were also evaluated. The bilayer emulsion had a small droplet size (221.27 ± 5.17 nm) and distribution (PDI = 0.23 ± 0.02), strong zeta potential (-30.37 ± 0.71 mV), good rheological behavior (with the highest viscosity that could reduce the possibility of flocculation) and physical stability (CI = 0), high β-carotene encapsulation ratio (94.35 ± 0.71%), and low interfacial tension (40.81 ± 0.86 mN/m). It also obtained better chemical stability under different environmental stresses when compared with monolayer emulsions studied, because it had a dense and thick bilayer structure.

Keywords: Arabic gum (GA); bilayer emulsion; bovine serum albumin (BSA); chemical stability; physicochemical property; β-carotene.

Figure 1

The variation of apparent viscosity (a) and shear stress (b) with the shear rate of the three emulsions studied.

Figure 2

The effects of pH on the β-carotene retention of the three emulsions studied. The pH of the three emulsions studied were adjusted to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 separately and they were stored at room temperature without light for 2 h. Then β-carotene retention was measured after storage. Each data point is an average of triplicate, and the standard deviations are given.

Figure 3

The effects of heating temperature on the β-carotene retention of the three emulsions studied. The temperature of the three emulsions studied were adjusted to 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C separately and they were stored without light for 2 h. β-carotene retention was then measured after storage. Each data point is an average of triplicate, and the standard deviations are given. Solid lines represent the fitting results from the linear equation using OriginPro.

Figure 4

The effects of UV irradiation on the β-carotene retention of the three emulsions studied. The β-carotene retention of the three emulsions studied were measured after the UV radiation for 0, 2, 4, 6, 8, 10 h. Each data point is an average of triplicate, and the standard deviations are given. Solid lines represent the fitting results from the linear equation using OriginPro.

Figure 5

The effects of NaClO on the β-carotene retention of the three emulsions studied. The β-carotene retention of the three emulsions studied were measured after the reaction for 0, 5, 10, 15, 20, 40, 60, 80, 100, 120 min. Each data point is an average of triplicate, and the standard deviations are given. Solid lines represent the fitting results from the linear (BSA-e and BSA/GA-e) and exponential (GA-e) equation using OriginPro.

Figure 6

The effects of storage time (25 °C) on the β-carotene retention of the three emulsions studied. The β-carotene retention of the three emulsions studied were measured after storage without light for 0, 1, 3, 5, 7, 14, 21, 28, 35 d. Each data point is an average of triplicate, and the standard deviations are given. Solid lines represent the fitting results from the linear equation using OriginPro.