(441a) The Chickpea or Egg Problem in Engineering Plant-Based Mayo Emulsions

We are inspired by the complex fluid beauty and the challenges underlying the design and use of plant-based foods. The need to provide food to the exploding world population promises to exacerbate climate change due to the high carbon cost per calorie. Plant-based foods offer promising alternatives; however, their suitability as sustainable substitutes will require emulating properties, processing, and functionalities of animal-based products. Replacing eggs within a recipe by plant-based alternatives requires simultaneous assessment and engineering of interfacial properties and rheological response, and often polysaccharide additives are needed as rheology and texture modifiers. Here we show that even though rate dependent variation in shear viscosity for real and vegan mayo appears comparable, the dispensing behavior, stringiness, and sensory perception are distinct and not captured by rate-dependent viscosity or measurement of elastic and viscous moduli in oscillatory shear rheology. Flow behavior, stringiness and performance of formulations are often assessed qualitatively by dripping from a nozzle or a ladle or by stretching a liquid bridge between two surfaces (thumb and forefinger or between parallel plates). The handy tests examining the pinching time of a columnar neck undergoing spontaneous capillarity-driven pinching and extensional flows correlate better with stringiness, dispensing behavior, and sensory attributes than shear rheology characterized using torsional rheometers. However, well-documented challenges arise for the quantitative characterization of extensional rheology response and dispensing behavior. Here we show that the dripping-onto-substrate (DoS) rheometry protocols we developed provide suitable capabilities for contrasting the response of polysaccharide thickeners and polysaccharide-protein complexes. However, we find that DoS rheometry protocols are inadequate for characterizing materials with yield stress like real and vegan mayo emulsions and show how to conduct supplementary analysis by dripping and filament stretching protocols. We translate the search for sustainable alternatives into bitesize problems regarding how polysaccharides, plant-based proteins and their complexes influence adsorption kinetics and interfacial viscoelasticity, drop interactions and coalescence, and shear and extensional rheology of food emulsions.