Abstract
There is growing interest in finding more sustainable alternatives to animal-derived foods, like meat, fish, egg, and dairy products. This study focusses on the formation and properties of hybrid protein-rich foods consisting of potato protein and mushroom, specifically Oyster (Pleurotus ostreatus) and Shiitake (Lentinula edodes) mushrooms. Hybrid products with the same total solids content (20% w/w) were formed by combining potato protein (10% or 15% w/w) with powdered mushroom (10% or 5% w/w) in aqueous solutions (100 mM NaCl). Measurements of the z-potential versus pH profile showed that the electrical charge of both the proteins and mushrooms went from positive at pH 3 to negative at pH 8, but the point of zero charge was around pH 5.0, 4.0, and 3.5 for potato protein, Oyster mushroom, and Shitake mushroom, respectively. Consequently, there were intermediate pH conditions where there should be an electrostatic attraction between the proteins and mushrooms. Differential scanning calorimetry showed that the potato proteins were originally in their native state but underwent irreversible thermal denaturation around 66 oC, whereas the mushroom dispersions exhibited no thermal transitions. Thermal denaturation of the potato proteins was still observed in the presence of mushrooms. The potato protein was soluble at low and high pH values, but insoluble around its isoelectric point (pI 5). In contrast, the mushroom dispersions contained insoluble particles across the entire pH range. The protein-mushroom hybrids were heated at 90°C for 30 minutes to promote thermal denaturation and gelation of the proteins. Texture profile analysis showed that the hybrids were harder and chewier than protein alone, especially when shiitake mushrooms were added, making them more meat-like. Dynamic shear rheology showed that strong irreversible heat-set gels were formed when the proteins were thermally denatured. Tristimulus color analysis showed that the L*, a*, and b* values changed upon adding the mushrooms, leading to a browner appearance. Microscopy analysis showed that the hybrids had a heterogeneous microstructure, which was attributed to the dispersion of insoluble mushroom particles in a potato protein matrix. These results suggest that potato protein and mushroom hybrids could be healthy, eco-friendly, and tasty substitutes for meat, but further research is required on their nutritional and sensory attributes.