No abstract

No 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.

This version is available at https://strathprints.strath.ac.uk/59904/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge. The aim of this paper is to produce spherical encapsulates of wheat gluten in a food-15 grade biopolymer for preparing sheared meat analogs, in order to prevent instant 16 fibrilization of the gluten during a pre-mixing step. The hydrogel should release the 17 gluten inside the Couette Cell, as a result of the higher temperature and shear in the 18 process. Both sodium alginate and -carrageenan were used as encapsulants. 19Spherical particles of hydrogel-gluten mixtures were produced by means of a 20 dripping method using an encapsulator. While the particle properties of -21 carrageenan surpassed those of alginate in terms of controlled release of the core, the 22 particle production using the encapsulator was more complicated. carrageenan, a layer of oil on top of the cross-linking bath fluid, as well as through 24 the outer orifice of a concentric nozzle were required to obtain a good sphericity of 25 2 the particles. For the alginate particles the use of oil was not necessary. Gluten 26 loadings of 7 % w/w were achieved with 1.5 % w/w alginate and with 2 % w/w 27 -carrageenan. The water content of the particles can be easily controlled by a 28 subsequent partial drying step. A mixture of Soy Protein Isolate (SPI) and particles 29 was sheared in the Couette Cell. Controlled release of the gluten from the alginate 30 particles was not achieved properly by temperature or shear. The controlled release 31 of the gluten was achieved at the processing conditions only with -carrageenan. 32Some fibrilization was observed in the sheared product, but the macrostructure was 33 not yet well developed. However, an optimization of the shearing process for the use 34 of the particles may lead to an improved structure for the meat analogs. 35 36 Practical applications 37This paper investigated the effect of encapsulation in hydrogels on the fibrilization 38 behavior of wheat gluten upon contact with water. A cheap and easily scalable 39 dripping technique was used to create spherical particles in which the gluten did not 40 fibrilize, although the coating material consists of ≥95% of water. Upon reaching the 41 process conditions in the shearing device, the gluten are released and able to form 42 fibers. The results show that hydrogels can mechanically protect the c...