Cross‐linking reactions in food proteins and proteomic approaches for their detection

Abstract

Various protein cross‐linking reactions leading to molecular polymerization and covalent aggregates have been described in processed foods. They are an undesired side effect of processes designed to reduce bacterial load, extend shelf life, and modify technological properties, as well as being an expected result of treatments designed to modify raw material texture and function. Although the formation of these products is known to affect the sensory and technological properties of foods, the corresponding cross‐linking reactions and resulting protein polymers have not yet undergone detailed molecular characterization. This is essential for describing how their generation can be related to food processing conditions and quality parameters. Due to the complex structure of cross‐linked species, bottom‐up proteomic procedures developed to characterize various amino acid modifications associated with food processing conditions currently offer a limited molecular description of bridged peptide structures. Recent progress in cross‐linking mass spectrometry for the topological characterization of protein complexes has facilitated the development of various proteomic methods and bioinformatic tools for unveiling bridged species, which can now also be used for the detailed molecular characterization of polymeric cross‐linked products in processed foods. We here examine their benefits and limitations in terms of evaluating cross‐linked food proteins and propose future scenarios for application in foodomics. They offer potential for understanding the protein cross‐linking formation mechanisms in processed foods, and how the inherent beneficial properties of treated foodstuffs can be preserved or enhanced.

Proteomics as a promising biomarker in food authentication, quality and safety: A review

“…Proteins, therefore, act as markers of food composition, origin, and processes done on food (Ortea et al, 2016). Thus, the knowledge of proteomics can help in enhancing the quality of food by optimizing the food production process, studying the effect of different processes on proteins in food, and identifying such proteins modified by processing conditions (Pedreschi et al, 2010;Renzone et al, 2021).…”

Proteomic Characterization of Native and Rearranged Disulfide Bonds in Proteins from Thermally Treated and Commercial Milk Samples

“…Likewise, they are associated with dedicated treatments conceived to intentionally modify the structure and texture of raw materials. Although protein cross-linking reactions are known to influence the sensory and technological characteristics of foods, the corresponding products have been poorly characterized so far . This is due to evident limits of proteomic procedures initially designed to assign modifications in linear peptides, which proved ineffective for the characterization of cross-linked species.…”

Focus on the Protein Fraction of Sports Nutrition Supplements

“…Small amounts of α-La and bovine serum albumin were found in the aggregates only at higher temperatures. These interactions are irreversible and actually initiate the formation of stable heat-induced aggregates in milk [ 11 , 14 ]. Provided that heating conditions and pH of the liquid whey are sufficiently mild, large amounts of native whey proteins can be present in WPC even after spray-drying [ 15 ].…”

“…Protein modifications induced by heat treatments increase the protein tendency to further crosslink during the subsequent storage period of the powdered products, thus leading to formation of large insoluble aggregates. The Maillard reaction is responsible for protein glycosylation in products containing lactose or other sugars, whereas, in sugar-free products, crosslinks such as the dehydroalanine-derivatives lysinoalanine and lanthionine, isopeptides, or oxidation products, prevail depending on processing conditions [ 12 , 14 ]. Colantuono et al [ 16 ] have recently demonstrated that large aggregates involving casein micelles can persist in long-stored SMP after rehydration and are unaffected by microbial proteases activity.…”