Biaxial testing and sensory texture evaluation of plant-based and animal deli meat

Animal agriculture is one of the largest contributors to global carbon emissions. Plant-based meats offer a sustainable alternative to animal meat; yet, people are reluctant to switch their diets and spending habits, in large part due to the taste and texture of plant-based meats. Deli meat is a convenient form of protein commonly used in sandwiches, yet little is known about its material or sensory properties. Here we performed biaxial testing with multiple different stretch ratios of four plant-based and four animal deli meats, fit the neo Hooke and Mooney Rivlin models to the resulting stress-stretch data, and discovered the best constitutive models for all eight products. Strikingly, the plant-based products, turkey, ham, deli, and prosciutto, with stiffnesses of 378 ± 15 kPa, 343 ± 62 kPa, 213 ± 25 kPa, and 113 ± 56 kPa, were more than twice as stiff as their animal counterparts, turkey, chicken, ham, and prosciutto, with 134 ± 46 kPa, 117 ± 17 kPa, 117 ± 21 kPa, and 49 ± 21 kPa. In a complementary sensory texture survey, n = 18 participants were able to correlate the physical stiffness with the sensory brittleness, with Spearman's correlation coefficient of $\rho =0.857$ and $p=0.011$ , but not with the sensory softness or hardness. Notably, the participants perceived all four plant-based products as less fibrous, less moist, and less meaty than the four animal products. Our study confirms the common belief that plant-based products struggle to meet the physical and sensory signature of animal deli meats. We anticipate that integrating rigorous mechanical testing, physics-based modeling, and sensory texture surveys could shape the path towards designing delicious, nutritious, and environmentally friendly meats that mimic the texture and mouthfeel of animal products and are healthy for people and for the planet. Data and code are freely available at https://github.com/LivingMatterLab/CANN.