Klara Nilsson

Soy (Glycine max) is used in a wide range of products and plays a major role in replacing animal-based products. Since the cultivation of soy is limited by cold climates, this review assessed the nutritional, sensory, and functional properties of three alternative cold-tolerant crops (faba bean (Vicia faba), yellow pea (Pisum sativum), and oat (Avena sativa)). Lower protein quality compared with soy and the presence of anti-nutrients are nutritional problems with all three crops, but different methods to adjust for these problems are available. Off-flavors in all pulses, including soy, and in cereals impair the sensory properties of the resulting food products, and few mitigation methods are successful. The functional properties of faba bean, pea, and oat are comparable to those of soy, which makes them usable for 3D printing, gelation, emulsification, and extrusion. Enzymatic treatment, fermentation, and fibrillation can be applied to improve the nutritional value, sensory attributes, and functional properties of all the three crops assessed, making them suitable for replacing soy in a broad range of products, although more research is needed on all attributes.

Faba bean (Vicia faba minor) is a cool-climate crop that could serve as a locally sourced sustainable ingredient in transition towards a more plant-based diet in temperate regions. Poor texture is one of the main aversion factors of plant-based foods, so this thesis characterised the functionality of faba bean components and their effect on structure and texture in different food matrices. The main aim in this thesis was to increase the knowledge on structure-texture relationship in increasingly complex faba bean food prodcuts. Isolated faba bean fractions (starch, protein and fibre) were studied. Faba bean starch was physiochemically characterised and microscopic and macroscopic properties were correlated. Different ratios of starch and protein were then combined to create mixed gels. Faba bean starch formed a relatively viscous paste due to long branch-chains, high amylose content and larger granule size. Addition of protein perturbed starch network formation, delaying and reducing associated pasting and gel viscosities in mixed systems. For food model systems, two prototypes were designed: i) a combination of faba bean starch, protein and fibre to produce edible ink for 3D-printed foods and ii) faba bean protein films reinforced with cellulose nanocrystals (CNC) for use as bio-degradable edible packaging. For the 3D samples, fibre appeared to have a stabilising effect on structure, improving ink printability while also ensuring that 3D-printed objects retained their shape. Carbohydrate-rich 3D-printed objects had a more porous structure that required less force to compress than structurally more compact protein-rich objects. Addition of CNC resulted in stronger, stiffer and more opaque films with improved barrier properties. Thus faba bean fractions in different combinations and processing approaches yield different textures. Using the basic knowledge of component functionalities in simple systems obtained in this thesis, intra- and intermolecular factors influencing product texture in more complex systems can be assessed.

The structure and physicochemical properties of starch isolated from the cotyledon and hull of faba beans and from wheat (as reference) were examined using 16 different methods. The amylose content in faba bean cotyledon and hull starch was 32% and 36%, respectively, and that in wheat starch was 21%. The faba bean cotyledon and hull starch were structurally alike both displaying C-polymorphic pattern, a similar degree of branching and similar branch chain length distributions. Wheat starch had a significantly greater prevalence of short amylopectin chains (DP < 12) and a higher degree of branching. Granules in both faba bean starches exhibited surface cracks and were more homogenous in size than the smoother wheat starch granules. Gelatinisation temperature was higher for the faba bean starches, likely as an effect of high amylose content and longer starch chains delaying granular swelling. Cotyledon starch produced pastes with the highest viscosities in all rheological measurements, probably owing to larger granules. Higher prevalence of lipids and resistant starch reduced the viscosity values for hull starch. For all starches, viscosity increased at faster heating rates. During the rheological analyses, the samples were exposed to different instruments, heating rates and temperatures ranges, differing from standard rheological procedures, which could help predict how different processing techniques effect the final starch textures. Graphical abstract

Food 3D printing allows for the production of personalised foods in terms of shape and nutrition. In this study, we examined whether protein-, starch- and fibre-rich fractions extracted from faba beans can be combined to produce fibre- and protein-rich printable food inks for extrusion-based 3D printing. Small amplitude oscillatory shear measurements were used to characterise the inks while compression tests and scanning electron microscopy were used to characterise the freeze-dried samples. We found that rheological parameters such as storage modulus, loss tangent and yield stress were related to ink printability and shape stability. Investigations on the effect of ink composition, infill pattern (honeycomb/grid) and direction of compression on textural and microstructural properties of freeze-dried 3D-printed objects revealed no clear effect of infill pattern, but a strong effect of direction of compression. Microstructure heterogeneity seemed to be correlated with the textural properties of the printed objects.