Updated project metadata. Protein aggregation in biotherapeutics can reduce their activity and effectiveness. It may also promote immune reactions responsible for severe adverse effects. The impact of plastic materials on protein destabilization is not totally understood. Here, we propose to deconvolve the effects of material surface, air/liquid interface, and agitation to decipher their respective role in protein destabilization and aggregation. We analyzed the effect of polypropylene, Teflon, glass and LoBindTM surfaces on the stability of purified proteins (BSA, hemoglobin and α-synuclein) and on a cell extract composed of 6,000 soluble proteins during agitation (P = 0.1-1.2 W/kg). Proteomic analysis revealed that chaperonins, intrinsically disordered proteins and ribosomes were more sensitive to the combined effect of material surfaces and agitation while small metabolic oligomers could be protected in the same conditions. Protein loss observations coupled to Raman microscopy, dynamic light scattering and proteomics allowed us to propose a mechanistic model of protein destabilization by plastics. Our results suggests that protein loss is not primarily due to the nucleation of small aggregates in solution, but to the destabilization of proteins exposed to material surfaces and their subsequent aggregation at the sheared air/liquid interface, an effect that cannot be prevented by using LoBind tubes. A guidance can be established on how to minimize these adverse effects. Remove one of the components of this combined stress – material, air (even partially), or agitation – and proteins will be preserved.