Upscaling of Apple By-Product by Utilising Apple Seed Protein as a Novel Wall Material for Encapsulation of Chlorogenic Acid as Model Bioactive Compound

Abstract

Encapsulation is a versatile technique used to protect sensitive bioactive compounds under gastrointestinal conditions. In this study, nanoencapsulation of chlorogenic acid into the apple seed protein matrix was performed using the green technique ultrasonication to protect it from harsh gastric conditions and increase its biological activity and bioavailability upon digestion. Both nano (Nano-Chl) and native capsules (NT-Chl) were characterised by particle size, charge, structure, and morphology. The encapsulation efficiency, release behaviour, antioxidant and antidiabetic properties were also evaluated. The experimental results show that the particle size of the NT-Chl and Nano-Chl was found in the range of 1.4 µm to 708 nm. The encapsulation efficiency was found to be 69% and 80% for NT-Chl and Nano-Chl, respectively. Furthermore, an in vitro digestion study revealed that Nano-Chl showed controlled-release behaviour under simulated intestinal conditions in comparison to NT-Chl. Moreover, Nano-Chl showed enhanced antioxidant and antidiabetic activity in comparison to NT-Chl after simulated digestion. It was concluded that the protein from apple seeds could be utilised as a functional ingredient itself or as a wall material for the encapsulation of sensitive bioactive compounds. Furthermore, these encapsulated particles can be fortified into different food formulations for the development of functional food.

Keywords: antidiabetic; antioxidant; chlorogenic acid; nanoencapsulation; protein; release behaviour.

Figure 1

Encapsulation efficiency and swelling index at pH 3 and pH 7 of NT-Chl and Nano-Chl. Bars represent standard deviation (n = 3). Different letters on the bars representing different encapsulation method indicate significant differences (p < 0.05). Key: For caption, see Table 1.

Figure 2

SEM images of NT-Chl and Nano-Chl. Key: For caption, see Table 1.

Figure 3

FTIR spectrum of Native apple seed protein (N-Protein), Ultrasonicated apple seed protein (Us-Protein), Chlorogenic acid (Chl), chlorogenic acid loaded in native apple seed protein (NT-Chl) and chlorogenic acid loaded in nano apple seed protein (Nano-Chl).

Figure 4

Release pattern of Free-Chl, NT-Chl, and Nano-Chl under simulated gastrointestinal conditions, where SGC (simulated gastric condition) is at 30 and 60 min of incubation and SIJ (simulated intestinal condition) is at 30, 60, and 120 min of incubation. Key: For caption, see Figure 3.

Figure 5

Antidiabetic activity of the NT-Chl and Nano-Chl. Bars represent standard deviation (n = 3). Different letters on the bars representing same enzyme treatments and encapsulation methods indicate significant differences (p < 0.05). Key: For caption, see Figure 3.

Figure 6

Antioxidant activity of the NT-Chl and Nano-Chl. Bars represent standard deviation (n = 3). Different letters on the bars representing same antioxidant assay and encapsulation methods indicate significant differences (p < 0.05). For caption, see Figure 3.