Papers by Georgios Krintiras
We have demonstrated that application of simple shear flow and heat in a Couette Cell is a scalab... more We have demonstrated that application of simple shear flow and heat in a Couette Cell is a scalable process concept that can induce fibrous structural patterns to a granular mixture of plant proteins at mild process conditions. In particular, a Couette Cell device with 7-L capacity was employed for the production of structured soy-based meat replacers. A reduced factorial experimental design was used to find the optimum process conditions between two relevant process parameters (process time and rotation rate), while the process temperature remained constant at 120 C. Fibre-structured products with high anisotropy indices were produced. Fibrousness is favoured at 30 ± 5 min and 25 ± 5 RPM. The up-scaled Couette Cell can be operated in higher industrial values and yield 30 mm thick meat replacers, which emulate meat. Besides, the study did not reveal any barriers for further upscaling of this concept. The flexibility in design allows production of meat alternative products with sizes that are currently not available, but could have advantages when aiming at replacement of complete muscular parts of animals, for instance, chicken breast or beef meat.
In this paper, a set of complementary techniques was used to characterize surface and bulk struct... more In this paper, a set of complementary techniques was used to characterize surface and bulk structures of an anisotropic Soy Protein Isolate (SPI)–vital wheat gluten blend after it was subjected to heat and simple shear flow in a Couette Cell. The structured biopolymer blend can form a basis for a meat replacer. Light microscopy and scanning electron microscopy provided a detailed view of structure formation over the visible surfaces of the SPI–gluten blend. Protein orientation in the direction of the flow was evident and fibrous formation appeared to exist on the macro- and micro-scale. Furthermore, according to texture analysis, the structured biopolymer obtained from the Couette Cell after processing at 95 °C and 30 RPM for 15 min has high tensile stress and strain anisotropy indices (∼2 and ∼1.8, respectively), comparable to those of raw meat (beef). The novel element in this work is the use of the neutron refraction method, utilizing spin-echo small angle neutron scattering (SESANS), to provide a look inside the anisotropic biopolymer blend complementing the characterization provided by the standard techniques above. With SESANS, it is possible to quantify the number of fibre layers and the orientation distribution of fibres. For a specimen thickness of 5 mm, the obtained number of fibre layers was 36 ± 4 and the standard deviation of the orientation distribution was 0.66 ± 0.04 radians. The calculated thickness of one layer of fibres was 138 μm, in line with SEM inspection.
A Couette Cell device was employed to provide proof of concept for the production of structured m... more A Couette Cell device was employed to provide proof of concept for the production of structured meat analogues by application of simple shear flow and heat to a 31 wt% Soy Protein Isolate (SPI)–Wheat Gluten (WG) dispersion. Three relevant process parameters (temperature, time and rotation rate) were varied over a range of realistic values (90–110 C, 5–25 min and 5–50 RPM, respectively). Layer- or fibre-structured products with high stress and strain anisotropy indices have been demonstrated. Fibrousness is favoured at temperatures over 90 C and under 100 C, whereas the role of process time and rotation rate is not critical. Simultaneous application of simple shear and heat is the key to obtaining structured plant protein-based products. The Couette Cell concept is scalable and can enable continuous operation. On this ground, it appears as a realistic option for production of meat analogues at commercial scale.
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Papers by Georgios Krintiras