Substantial quantities of organic residue are generated during fruit and vegetable juice production. This presents opportunities for repurposing in biorefineries to support sustainable practices and to enhance resource efficiency in the food industry. These residues are rich in sugars and other nutrients that can support the growth of microorganisms. The high nutrient content of these residues provides a low-cost substrate for cultivation of microorganisms such as filamentous fungi to produce fungal biomass. Fungal biomass can be integrated with the cellulosic fraction of the waste for the development of mycelium-based biocomposites. Mycelium-based materials can be used as substitutes for synthetic materials or bio-based materials produced from first generation biomass which often have high environmental impacts. 

In this study, carrot pomace (CP), a byproduct of the carrot juicing process, was used as a source of nutrients for fungal cultivation and subsequent development of mycelium-based products. In an initial approach, nutrients were extracted from CP using enzymatic pretreatment. The nutrient-rich solution was separated from the insoluble fraction of CP and used for cultivation of Rhizopus delemar in shaking flasks and bench-scale bubble column bioreactors. The harvested fungal biomass and CP residues were combined at various ratios to produce mycelium-based papers (MBP) using the wet-laid method. MBP were evaluated as filter paper for dye removal, reaching approximately 83% of the methylene blue dye removal. 

In a second approach, whole CP suspension was used to cultivate two species of filamentous fungi (Rhizopus delemar and Aspergillus oryzae) in bench-scale bioreactors. Harvested solid from the bioreactor contained fungal biomass and CP residues, exhibiting elongated thin microfibrillar structures for A. oryzae, while R. delemar demonstrated shorter microfibers with larger diameters. MBP was prepared from the harvested solids using the wet-laid method. Ashby charts confirmed that the mechanical properties of MBP are comparable to those of conventional paper products. The same cultivation process for A. oryzae on whole CP was scaled up in a 26L bioreactor, and the harvested materials were processed to produce mycelium-based foam (MBF) for protective packaging applications. According to the Ashby chart, MBF were classified alongside commercial foam materials, corresponding particularly to light weight foams, which are appropriate for protective and cushioning applications. 

This thesis presents a fungal biorefinery model for transformation of carrot pomace into novel mycelium-based biocomposites in a scalable process. The obtained mycelium-based materials showed promising properties similar to conventional papers and light weight foams, indicating their potential to be used for diverse applications.