Effect of thermal and microwave processing on secondary structure of bovine β‐lactoglobulin: A molecular modeling study

Abstract

Milk allergy is known to cause severe allergic reactions in hypersensitive patients, especially in infants and children. β‐Lactoglobulin is one of the major allergens in bovine milk. The influence of thermal and microwave processing on the structural deviations of β‐lactoglobulin protein have been studied using molecular modeling techniques. The structural deviations are studied using root mean square deviations, radius of gyration, dipole moment, and solvent accessible surface area. STRIDE analysis showed significant changes in the β‐lactoglobulin, especially when oscillating electric fields were applied along with heat. Root mean square fluctuations (RMSF) has been assessed for known epitopes in the β‐lactoglobulin molecule. This showed that when the protein is exposed to certain thermal stress, it compacts by burying hydrophobic residues in the core. However, few allergic epitope residues also exhibit increased RMSF leading to higher reactive sites on the surface of the protein molecule. Practical applications This study showed that molecular modeling can be used to gain valuable insights regarding the structural changes during processing. In the future, with more computational capacity, it can be used to make comparison between results obtained from simulations and real‐time experiments. The current techniques used in food industries such as Nuclear Magnetic Resonance Imaging, Fourier Transformation Infrared Spectroscopy, X‐ray diffraction can analyze pre‐ and post‐processing effects. Hence, it become necessary to understand the changes that takes place during the processing techniques. Molecular dynamic simulation could be a useful technique in analyzing the changes occurring during the processing.

An Overview of Molecular Dynamics Simulation for Food Products and Processes

“…. ] and solvent accessible surface area" and analyzed using the STRIDE algorithm [16,34]. The calculation of the root mean square deviation (RMSD) assigns a quantitative value to the structural deviations that occur through the simulation, as it compares the final coordinates of the atoms in the studied molecule to the atoms' initial coordinates before the imposition of external stress [17].…”

“…Elsewhere, Saxena et al [16] applied thermal and oscillating electric fields to the common allergen β-lactoglobulin protein present in cow's milk. In this study, the AMBER99SB-ILDN force field was utilized, and, considering the net negative charge (−14e) of the βlactoglobulin protein, it was neutralized with fourteen positively charged sodium ions [16]. This particular modeling study identified the important effect the treatments had on epitopes that lead to IgE-mediated allergic reactions by the immune system.…”

“…This particular modeling study identified the important effect the treatments had on epitopes that lead to IgE-mediated allergic reactions by the immune system. Epitopes on β-lactoglobulin are specific regions on the protein that readily interact with immunoglobulin E antibodies present in the body, thus causing allergic reactions by the immune system [16]. At lower thermal treatment temperatures, Saxena et al [16] observed that the allergenic epitopes began gradually losing their rigidity and opened up new sites for the binding of immunoglobulin E antibodies, which may further increase the risk of an allergic reaction.…”

“…Protein structure, which dictates the protein's function, may influence viscosity, texture, emulsification, gelation, and water absorption and retention. It has equally been suggested that changes in proteins' conformational state, notably their surface area, limits access to allergenic epitopes, which, when in contact with a T cell or immunoglobulin E antibody, cause allergic reactions by the immune system [16].…”

“…Studies targeting food proteins that have already utilized atomistic MD simulations include Ara h 6 in peanuts [17], trypsin inhibitor in soybean [18], bovine β-lactoglobulin in cow's milk [16], profilin in hazelnuts [12], Act d 2 in kiwifruit [19], avidin in egg whites [20], and myofibrillar proteins in pale, soft, exudative chicken breast meat [21]. MD simulations have equally been employed to simulate the effects of diverse food processes, including the application of thermal and electric fields, both static and oscillating [17].…”