Evaluation of whey protein as a natural hydrate kinetic inhibitor

The toxicity of hydrate inhibitors used in the field has attracted more attention. A natural material, i.e., whey protein, was assessed to act as kinetic hydrate inhibitors (KHIs) in a sapphire cell and an autoclave equipped with particle video microscope (PVM) and focused beam reflectance measurement (FBRM) probes. The pressure dropping method was utilized to estimate the hydrate induction time, and the results demonstrate that the hydrate inhibition performance of whey protein is superior to that of the commercial KHI, polyvinylpyrrolidone. The induction time for the pure water system was found to increase linearly with the increase in the dosage of whey protein until it reached approximately 2.5 wt%. As it is usually inevasible to apply KHIs under conditions of high water contents, the feasibility of whey protein as a KHI in the (oil + water) system with and without an emulsifier of Tween 20 was evaluated. A small amount of oil was found to have no obvious influence on the induction time for the system with whey protein under the circumstances without the addition of emulsifier. When Tween 20 was added, the induction time obviously increased under the same operating conditions, which could be attributed to the emulsifier–protein interactions in aqueous solutions. The oil drops decrease and are distributed more evenly with the increasing dosage of Tween 20 under the PVM and FBRM probes measurement. Additionally, the particles decrease during the hydrate formation process. This work presents a natural KHI and gives the inhibition discipline in a high-water-content system.