Coconut milk allergenicity: Insight into reducing the affinity of coconut globulin to immunoglobulin E by atmospheric cold plasma

Abstract

Atmospheric cold plasma (ACP) presents a promising method for the sterilization of coconut milk and exhibits a modifying effect on coconut globulin (CG), the primary allergen in coconut milk. This study investigated the potential role of ACP treatment in mitigating the allergenic properties of coconut milk by examining changes in protein structure. ACP treatment induced structural alterations in CG, disrupting binding sites with immunoglobulin E (IgE). Consequently, this led to a reduction in the affinity between CG and IgE, evidenced by a decrease in K_a from 2.17 × 10⁴/M to 0.64 × 10⁴/M, thereby diminishing IgE-mediated allergic reactions. The findings from allergenic and cellular models further corroborated that ACP treatment decreased the allergenicity of CG by 55.18%, while inhibiting degranulation and the release of allergic mediators. This study presents an innovative methodology for producing hypoallergenic coconut milk, thereby expanding the applicability of ACP technology within the food industry.

Keywords: Affinity; Allergenicity reduction; Binding capacity; Hydrophobic group; Spatial structure.

Graphical abstract

Fig. 1

Protein structure of CG treated by ACP at 0, 50, 60, and 70 kV: (a) carbonyl content; (b) free -SH and S—S bond content; (c) CD spectra; (d) secondary structure content; (e) FTIR spectra; (f) fluorescence spectra. Different lowercase letters indicate significant differences (p < 0.05).

Fig. 2

Particle size distribution (a) and microstructure (b) of CG treated by ACP at 0, 50, 60, and 70 kV.

Fig. 3

Thermogram (left) and binding isotherm (right) of CG treated by ACP at 0, 50, 60, and 70 kV. (a) and (b): 0; (c) and (d): 50 kV; (e) and (f): 60 kV; (g) and (h): 70 kV.

Fig. 4

SPR sensor grams of interaction between IgE and CG (1–16 nM) after ACP treatment at 0 (a), 50 (b), 60 (c), and 70 kV (d); The frequency shift and dissipation shift of IgE binding to CG after treated with ACP at 0 (e), 50 (f), 60 (g), and 70 kV (h).

Fig. 5

a: Relative allergenicity of CG after ACP treatment at 0, 50, 60, and 70 kV; release content of β-hexosaminidase (b), histamine (c), TNF-α (d), IL-4 (e), and IL-6 (f) of KU812 cell after sensitized by CG after ACP treatment at 0, 50, 60, and 70 kV. Different lowercase letters indicate significant differences (p < 0.05).