A study on physicochemical properties of protein gels and patties made from faba bean protein isolate and New Zealand Perna canaliculus concentrate : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Auckland, New Zealand
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2024
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Massey University
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This study examines the physicochemical, textural, and microstructural characteristics of protein gels and patties made from faba bean protein isolate (FBPI) and New Zealand Perna canaliculus in the form of defatted mussel powder (DMP). The initial investigation explored the influence of different proportions of FBPI and DMP proteins (100:0, 75:25, 50:50, 25:75, and 0:100 by weight) at a total protein concentration of 12.5% on the gelation process, water-holding capacity (WHC), texture, color, and microstructure of protein gels. Various methods such as rheology, confocal laser scanning microscopy (CLSM), particle size distribution analysis, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were employed. The gelation temperature ranged from 20 °C to 90 °C, with the strength of the gel significantly affected by the FBPI to DMP ratio. The 50:50 protein mixture of FBPI and DMP proteins exhibited an increase in gel strength compared to gels made from either protein individually. The water-holding capacity (WHC) of the gels decreased as the amount of DMP increased, with the 50:50 protein ratio showing a slight improvement in WHC, suggesting better water retention. Textural analysis showed that the hardness of the gels decreased with higher DMP content, indicating a reduction in structural rigidity. Particle size distribution analysis indicated that smaller particles were associated with a denser gel network and higher storage modulus (G') values. Color analysis showed that the lightness of the gels decreased after heating, and the addition of DMP increased redness and yellowness. CLSM images revealed that FBPI formed a more continuous and denser gel structure than DMP, with the latter forming a weaker gel network. SDS-PAGE analysis offered insights into the protein composition and the effects of heat treatment on protein solubility and aggregation, showing that the solubility of proteins in the mixtures was influenced by intermolecular interactions, with different levels of solubility observed across various extraction solvents and protein ratios. When not mixed together, FBPI and DMP exhibited distinct differences in their gelation properties. FBPI gels (100:0) demonstrated a higher gel strength and better water-holding capacity compared to DMP gels (0:100). FBPI gels also showed a denser and more continuous network structure, as observed through CLSM, while DMP gels formed a weaker and less cohesive network. Additionally, FBPI gels had higher hardness values, indicating greater structural rigidity, whereas DMP gels were softer and more pliable. The second study examined the development of plant and seafood blended patties by investigating the effects of varying FBPI and DMP protein ratios (100:0, 75:25, 50:50, and 0:100 w/w%) on texture, color, and physicochemical properties. The previous study found that a 50:50 protein blend of FBPI and DMP proteins was the best for maximizing gel strength and water-holding capacity. To further improve the processing attributes of the patties, the total protein content was increased to 15% by weight, and polysaccharides were added. The study focused on blended protein mixtures (75:25 and 50:50 w/w%) combined with polysaccharides to enhance the textural attributes and stability of the analogue patties. The research aims to assess how varying protein proportions and the inclusion of polysaccharides affect the texture, color, and physicochemical attributes of the patties. Adding polysaccharides, such as methylcellulose (MC) at concentration 2 ,3, 4 w/w% and konjac glucomannan (KGM) 3, 4, 5 w/w%, significantly influenced the texture, color, and physicochemical characteristics of the analogue patties. The study utilized various analytical methods, including texture profile analysis, color measurement, cooking loss analysis, and microstructure analysis, to assess the effects of different protein ratios and polysaccharide additions. The findings indicated that the inclusion of polysaccharides can improve the patties texture, reduced cooking loss, and enhanced shape retention and structural integrity after cooking. Additionally, the color analysis revealed changes in color attributes before and after cooking, with higher DMP content leading to increased redness and yellowness. The microstructure analysis demonstrated that polysaccharides can create a denser and more uniform matrix within the patties, enhancing their overall quality. The research offered significant findings for the food sector, guiding the development of sustainable and nutritionally rich protein substitutes that align with consumer preferences for nutritional content, texture, and appearance. It highlighted the promise of integrating FBPI and DMP, along with polysaccharides, to produce blended patties with favorable characteristics. Notably, the 50:50 protein blend performed exceptionally well in the patties, demonstrating improved gel strength, water-holding capacity, and overall textural quality, making it a promising candidate for further development and commercialization.
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Figures 1 and 2 are reproduced with permission.