Amanda Buchko | ALES Graduate Seminar

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Amanda Buchko. This seminar is open to the general public to attend.

MSc with Dr. Lingyun Chen.

Thesis Topic: Impact of protein content, starch, and dietary fiber on faba and pea Texturized Vegetable Protein (TVP) functionality, protein matrix and microstructure

Abstract:

Low moisture extrusion is a complex scalable technology that uses heat, pressure and shear to texturize plant proteins into extrudates called texturized vegetable proteins (TVP) used in the development of meat analogue products. Increasing interest in meat analogues and the rise of new sources of plant proteins requires understanding of internal interactions by protein, starch and fiber to develop highly functional and healthy TVP. This thesis investigates the impact of moisture, protein, starch, and dietary fiber on faba bean and/or pea TVP to improve extrudate functionality and structure. Firstly, the impact of moisture (50%, 55%) and extrusion on the protein conformation and the melt rheological properties and microstructure was studied at increasing protein content (60%, 70%, 80%) as analyzed by Fourier transform infrared spectroscopy (FTIR), rheometer, confocal and scanning electron microscopy (SEM). Analysis performed correlated to TVP functionalities like expansion ratio, bulk density, water holding content (WHC), and oil holding content (OHC). Lower moisture content at 50% improved expansion of TVP with good WHC and OHC by forming a protein melt matrix with increased storage modulus (G’). As protein content increased from 60% to 70%, appropriate level of separation of the protein phase and the starch phase allowed the formation of a relatively homogeneous protein matrix, which facilitated TVP expansion. Whereas further increasing protein content to 80%, the oblong shaped air pocket microstructure shifted to a dense protein matrix with large sporadic air pockets resulting in decreased WHC. Secondly, the inclusion of pea starch, pea hull insoluble dietary fibers and oat β-glucan (soluble fiber) were assessed to determine improvement on TVP microstructure and functionality, while increasing the overall value-added health benefits. Inclusion of 7.5%-20% pea starch improved expansion and microstructure of pea protein and faba bean protein based TVP with iii larger pores and thicker cell walls, as well as WHC. Resistant starch (RS) and slowly digestible starch (SDS) in pea was mostly converted to readily digestible starches (RDS) after extrusion treatment. Insoluble fiber (5%, 10% at 100μm and 150μm sizes) had a negative effect on expansion and disrupted the TVP microstructure but did improve WHC. Whereas soluble fiber (5%, 10%, 20%) improved TVP expansion, WHC, and OHC at all inclusion levels. At 10% inclusion and above, the blending of soluble fiber into the protein phase might help TVP expansion, leading to a decrease in bulk density. Both faba and pea were shown to produce TVP from a protein concentrate, and the expansion and WHC were improved upon the addition of starch and soluble fiber. Faba bean TVP was more prone to aggregation, thus showed slightly lower expansion but had similar WHC and OHC as the pea TVP. The findings from this research can help to provide understanding of microstructure and TVP functionality by modulating moisture, protein content, starch and dietary fiber inclusion to improve TVP quality and to expand TVP source protein options like faba bean in the market.