Abstract
The aim of this work was to compare the surface adsorption and lubrication properties of plant and dairy proteins. Whey protein isolate (WPI) and pea protein isolate (PPI) were chosen as model animal and plant proteins, respectively, and various protein concentrations (0.1–100 mg/mL) were studied with/without heat treatment (90 °C/60 min). Quartz crystal microbalance with dissipation monitoring (QCM-D) experiments were performed on hydrophilic (gold) and hydrophobic polydimethylsiloxane (PDMS) sensors, with or without a mucin coating, latter was used to mimic the oral surface. Soft tribology using PDMS tribopairs in addition to wettability measurements, physicochemical characterization (size, charge, solubility) and gel electrophoresis were performed. Soluble fractions of PPI adsorbed to significantly larger extent on PDMS surfaces, forming more viscous films as compared to WPI regardless of heat treatment. Introducing a mucin coating on a PDMS surface led to a decrease in binding of the subsequent dietary protein layers, with PPI still adsorbing to a larger extent than WPI. Such large hydrated mass of PPI resulted in superior lubrication performance at lower protein concentration (≤10 mg/mL) as compared to WPI. However, at 100 mg/mL, WPI was a better lubricant than PPI, with the former showing the onset of elastohydrodynamic lubrication. Enhanced lubricity upon heat treatment was attributed to the increase in apparent viscosity. Fundamental insights from this study reveal that pea protein at higher concentrations demonstrates inferior lubricity than whey protein and could result in unpleasant mouthfeel, and thus may inform future replacement strategies when designing sustainable food products.
Highlights
The increasing number of overweight and obese people in the pop ulation has put a growing demand on the consumption of low fat foods
The final concentration and solubility of Whey protein isolate (WPI) and pea protein isolate (PPI) with or without heat treatment are shown in Table 1
PPI revealed a frequency shift (Fig. 2ai and 2aii) of − 30 and − 35 Hz for non-heated and heated systems, respectively, while the dissipation shift (Fig. 2bi and 2bii) was approximately 1.7 ppm and 2 ppm. For both non-heated and heated systems, the frequency shift and dissipation shift for WPI was approximately − 20 Hz and 1 ppm, respectively. These results reveal a higher adsorption of PPI on the PDMS surface as compared to WPI, irrespective of heat treatment
Summary
The increasing number of overweight and obese people in the pop ulation has put a growing demand on the consumption of low fat foods. Plant proteins (e.g., pea, soy) as alternatives to conventional animal proteins (e.g. casein, whey protein, gelatine) have gained significant research attention in recent years owing to the lower environmental footprints as compared to those associated with the production and consumption of the animal proteins (Jędrejek, Levic, Wallace, & Oleszek, 2016; Koneswaran & Nierenberg, 2008; Rodahl, Hook, Krozer, Brzezinski, & Kasemo, 1995; Zhang, Holmes, Ettelaie, & Sarkar, 2020). Soy protein has often been considered as an alternative to the dairy counterparts (Shevkani, Singh, Kaur, & Rana, 2015), pea protein has been the preferred choice recently owing to a number of health benefits (Dahl, Foster, & Tyler, 2012), low cost, high abundance, as well as benefits from having a hypoallergenic and gluten-free status (Lan, Chen, & Rao, 2018). A recent study has investigated the use of pea protein as a replacement of milk proteins in food products and revealed that sensorial acceptability gradually decreased with increased levels of replacement by pea protein
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
