Processing-Induced Markers in Proteins of Commercial Plant-Based Drinks in Relation to Compositional Aspects

Abstract

The consumption of plant-based drinks is increasing, but they represent a product category normally with lower protein content as compared with bovine milk. Furthermore, the products are highly processed and, therefore, the proteins in this product category may carry a significant processing history. In the present study, a series of 17 freshly produced, commercially available plant-based drinks were benchmarked according to protein-quality parameters. The plant-based drinks represented different plant sources, as well as some mixed products, and were investigated relative to composition, aggregate sizes, presence of non-reducible proteins complexes, and level of processing-induced markers in the proteins. Processing-induced changes in the proteins were determined by a newly developed cocktail method, determining markers related to Maillard and dehydroalanine pathways, as well as intact lysine by triple quadrupole-multiple reaction monitoring-mass spectrometry. It was found that all drinks contained non-reducible protein complexes, but specifically, oat-based drinks represented the largest span contents of processing-induced markers within the proteins, which may relate to their inherent processing histories. Furthermore, it was shown that in products containing added sugar, Maillard reaction-related processing markers were increased over the dehydroalanine pathway.

Keywords: Maillard reaction; furosine; lanthionine; multiple reaction monitoring; plant-based drinks; processing.

Figure 1

General flowchart of industrial-scale manufacturing process of PBDs [7,8,9].

Figure 2

Protein content in PBD’s measured by Dumas or Bradford and compared with the declared value from manufacturers. Gray: declared, dark blue: Dumas, light blue: Bradford.

Figure 3

Tris-HCl (4–20%) gel electrophoresis of PBDs. 20 µg protein was added to each lane under reducing conditions and visualized with Coomassie Brilliant Blue. The protein ladder on the left indicates protein size, and on the right are identified proteins based on previous findings [19,20].

Figure 4

Tris-HCl (4–20%) gel electrophoresis of PBD made from almond (A), pea and in combination with oat (B) and soy (C). A total of 20 µg protein were added to each lane under reducing conditions and visualized with Coomassie brilliant blue. The protein ladder on the left indicates protein size, and on the right are identified proteins based on previous findings [21,22,23].