Emerging Chemical, Biochemical, and Non-Thermal Physical Treatments in the Production of Hypoallergenic Plant Protein Ingredients

Abstract

Allergies towards gluten and legumes (such as, soybean, peanut, and faba bean) are a global issue and, occasionally, can be fatal. At the same time, an increasing number of households are shifting to plant protein ingredients from these sources, which application and consumption are limited by said food allergies. Children, the elderly, and people with immune diseases are particularly at risk when consuming these plant proteins. Finding ways to reduce or eliminate the allergenicity of gluten, soybean, peanut, and faba bean is becoming crucial. While thermal and pH treatments are often not sufficient, chemical processes such as glycation, polyphenol conjugation, and polysaccharide complexation, as well as controlled biochemical approaches, such as fermentation and enzyme catalysis, are more successful. Non-thermal treatments such as microwave, high pressure, and ultrasonication can be used prior to further chemical and/or biochemical processing. This paper presents an up-to-date review of promising chemical, biochemical, and non-thermal physical treatments that can be used in the food industry to reduce or eliminate food allergenicity.

Keywords: enzymatic catalysis; fermentation; food allergen; glycation; polyphenol complexation; protein–polysaccharide complexation.

Figure 1

Protein structures and their conformations can suggest food allergen stability. The content of β-sheet is positively correlated with the stability of the secondary structure of a protein. Gluten structures from wheat (Triticum aestivum): (A) low-molecular-weight glutenin subunit 1D1 (accession: P10386); (B) α/β-gliadin MM1 from amino acid positions 246–260 (accession: P18573); (C) γ-gliadin (accession: P21292); and (D) β-Conglycinin beta subunit 2 (Gly m 5) from soybean (Glycine max) showing the “jellyroll” (double-stranded β-helix) structure that contributes to its thermal stability (accession: F7J077; taken from UniProt).

Figure 2

Structures of proteins from the prolamin superfamilies showing similarities and potential cross-reactivities: (A) 2S seed storage albumin protein from soybeans (Glycine max) (accession: P19594); (B) Ara h 9 allergen from peanuts (Arachis hypogaea) (accession: B6CEX8); (C) Pru p 3 allergen from peaches (Prunus persica) (accession: P81402); (D) Pru ar 3 allergen from apricots (Prunus armeniaca) (accession: P81651); and (E) Mal d 3 allergen from apples (Malus domestica) (accession: Q9M5X7) (all taken from UniProt).

Figure 3

Possible mechanism for allergenicity reduction by polyphenol complexation. The polyphenols shield the allergenic epitope and/or the IgE epitope, resulting in less protein allergen immunoreactivity.

Figure 4

Scheme for a reduction in the protein allergen content (for example, in soymilk) by colloidal complexation with polysaccharides.