Albert-Ludwigs Universität Freiburg, Germany
This talk presents a novel numerical approach to better understand, asses and optimize high-moisture extrusion cooking for vegetarian meat substitutes.
The production processes of vegetarian meat-like products represent a big challenge in the food industry. High-moisture extrusion cooking is a state-of-the-art manufacturing technique by which a meat-like fibrous product is obtained from a homogeneous mixture of pea proteins and water. Interestingly, the desired fibrous texture is only achieved in a very narrow range of extrusion parameters, namely flow speed and temperature. Extensive experimental work has been published [Osen et al, 2018] in order to find the optimal parameters that lead to extrudate products which best emulate structure and visual characteristics of cooked meat. Nevertheless, a concise explanation to the texture formation was not found. Denaturation of the proteins during the extrusion was a first understanding that could explain the structure formation as the protein molecules align in the direction of the flow [Chen et al. 2011]. However, this theory is contradicted by the fact that the proteins are already denatured before the extrusion cooking takes place.
A physically based mechanism that involves phase separation during the extrusion cooking into protein-rich and water-rich domains was first published in [Sandoval et al, 2019]. This model successfully predicts structure formation due to spinodal phase separation in the cooling channel of the extruder. While these simulation results already agree qualitatively with experimental observations, a more quantitative analysis is still needed to correlate the structure formation or the extrudate’s texture with the extrusion parameters.
In this talk, I will present the mechanism that models structure formation due to phase separation. Additionally, a quantitative correlation between texture and extrusion parameters, which explains the narrow window of extrusion process parameters that lead to the formation of fibrous structures.