On characterization of anisotropic plant protein structures

Abstract

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.

Shear-induced structuring as a tool to make anisotropic materials using soy protein concentrate

“…Those requirements are derived from studies in which shear-induced structure formation was studied using model systems (Manski et al, 2007a;Sprakel et al, 2008;Van Loon et al, 2014;Vermant, 2001). We have applied this principle to dense biopolymer blends, for example a blend that contained soy protein isolate (SPI) and vital wheat gluten (WG) (Grabowska et al, 2014;Krintiras et al, 2014Krintiras et al, , 2015. Here, the phase-separation was induced by blending two incompatible biopolymers.…”

Dry fractionation for sustainable production of functional legume protein concentrates

“…Soy concentrate and wheat gluten have been reported to form fibrous structures under shear flow (Grabowska, Tekidou, Boom, & van der Goot, 2014;Krintiras, Gobel, Bouwman, van der Goot, & Stefanidis, 2014). The presence of two separate biopolymeric phases is generally thought to be needed for structure formation.…”

Immobilization of gluten in spherical matrices of food‐grade hydrogels

“…In other work (Krintiras et al, ) the Couette Cell was used with free gluten powder. The sheared mixtures had a composition like that in Table , but without the hydrogel component and with more salt.…”

“…The κ‐carrageenan particles did release the gluten and fibrilization occurred to a much larger extent during the shearing process. However, while comparing the structure sheared from the particles with the structures obtained after shearing the original mixture without particles (Krintiras et al, ), it was observed that although fibrilization occurs, it is much less than with the original mixture. The macrostructure of the meat analog is not yet well developed.…”

“…A novel process was developed for the production of highly fibrous meat analogs, using the lab‐scaled Couette Cell device (Krintiras, Göbel, Van Der Goot, & Stefanidis, ). This process achieves meat‐like structure formation by applying simple shear flow and heat to plant protein suspensions, resulting in the formation of fibers, which enhance the structure and mouthfeel of the product (Krintiras, Gobel, Bouwman, Jan Van Der Goot, & Stefanidis, ). During the mixing step of the ingredients prior to loading of the Couette Cell, soy protein isolate (SPI) is premixed with water and left to rest.…”