Intensified Protein Structuring for more sustainable foods: Development of the up-scaled Couette Cell for the production of meat replacers

Intensified Protein Structuring for more sustainable foods: Development of the up-scaled Couette Cell for the production of meat replacers

Krintiras, G.

Stankiewicz, A.I. (promotor)
Stefanidis, G.D. (promotor)

Mechanical, Maritime and Materials Engineering

Process and Energy

2016-03-03

To meet the increasing need for protein-rich food of an ever growing population, plant-based proteins are being utilized in meat products as replacements for animal-based proteins. Legumes such as soy can serve as an alternative protein source, by featuring both high protein content (36%) and protein functionality (gelation). Nowadays various meat replacement products are commercially available and thus more and more customers are willing to switch their diet to a vegetable-based one. Currently, the most efficient technology for the production of meat replacers is extrusion cooking and new methods of protein structuring (Shear Cell and Couette Cell) have only recently been introduced. These two new technologies were developed based on the principle of applying simple shear flow and heat in the protein mixture. Initially, a device called the Shear Cell was developed featuring a cone-cone design that could structure soy-based mixtures in meat-like products. However, since the Shear Cell design is limited to lab use only, a new technology was developed and presented in this thesis. The Couette Cell concept, which is based on the concentric cylinder principle, has been studied, since it allows for further upscaling at industrially relevant production volumes. The research starts with a proof of concept study by using the lab scaled Couette Cell, which features a volume of 0.14 L and a shearing zone gap size of 5 mm, between the two cylinders (Chapter 2). Applying simple shear and heat at varying process conditions (temperature, time and rotation rate) to a soy-based mixture, has yielded anisotropic structures that resembled meat. In particular, fibrous structures were favoured at temperatures between 90 and 100 °C. The fibrous products with the highest anisotropy indices were further examined and characterized with a set of complementary techniques (Chapter 3). With light microscopy we could observe structure formation over the visible surfaces of the specimens and by using a stain we could distinguish between the different ingredients. According to the texture analysis results, the anisotropy indices of the obtained meat replacer and raw meat (beef) are comparable. We introduced the use of neutron refraction method by utilizing spin-echo small angle neutron scattering (SESANS) to provide a look inside the bulk of the anisotropic meat replacer. It was therefore possible to quantify the number of fibre layers and the orientation distribution of the fibres present inside the specimens. The calculated fibre thickness was in line with the observations obtained with scanning electron microscopy (SEM). Since the Couette Cell concept proved successful and enabled scalable operation, we developed a new up-scaled Couette Cell, which can treat 7 L per batch, 50 times more than the lab-scaled Couette Cell. The detailed design of the up-scaled Couette Cell is discussed in Chapter 4. The up-scaled device allows for production of fibrous meat replacers at industrially relevant scales and opens the possibility of commercial production in an emerging market. The device is comprised of two concentric cylinders with the inner cylinder rotating while both are being heated by means of steam. The unique characteristic feature of the up-scaled Couette Cell is its 30 mm gap size, which is 6 times more than the lab-scaled counterpart. Finally, a parametric study was used to find the optimum process conditions between the process time and rotation rate while maintaining a constant temperature (Chapter 5). This study yielded highly fibrous structures with a characteristic 30 mm thickness, which emulates meat accurately. The Couette Cell concept and the flexibility in its design allow production of meat replacers at proportions currently not available. Additionally, no barriers were found for further upscaling this concept by preferably designing a continuous process.

protein
sustainable
food
couette
cell
production
meat
replacers
soy
gluten
structuring

https://doi.org/10.4233/uuid:03d60954-4f2a-4989-8368-c9ccaf73ca4c

978-94-6299-299-3

Institutional Repository

doctoral thesis

(c) 2016 Krintiras, G.