## 3 Results and Discussion
### Biodegradation Profile  
Biodegradation profiling typically begins with determining the theoretical oxygen demand (ThOD), calculated stoichiometrically based on the substrate's known chemical composition. However, for complex substrates--where the composition is either unknown or variable--the stoichiometric approach becomes impractical. In such cases, the chemical oxygen demand (COD) is determined experimentally, offering a realistic measure of the oxygen required to oxidize all oxidizable compounds in the sample.  
Table 2 presents the results of the analysis, and the COD values obtained. The COD of the tested suspensions is also interpreted as specific oxygen demand in grams of O\({}_{2}\) per gram of material.  
As expected, the results obtained show that the oxidation of the materials studied varies significantly among the different samples, which is probably due to their different composition.  
For a comprehensive biodegradability assessment, these data serve as a baseline for comparing with the biological oxygen consumption observed during simulated degradation processes (Figure 4).  
The degradation dynamics over the initial 28 days reveal distinct behaviors among the samples. All samples exhibited elevated oxygen consumption compared to the abiotic control, indicating active microbial decomposition of the bio-composite materials. Notably, the HERF:WS sample demonstrated the most rapid degradation rate under the test conditions, while the HERF-only samples showed the slowest rate, with oxygen consumption comparable to the control by day 22.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Sample**} & **COD of 500 mg/L Suspension** & **Theoretical Oxygen Demand per** \\  & **(mgO\({}_{2}\)/dm\({}^{3}\))** & **Gram Material** \\  & **(g/g)** \\ \hline HERF & 666 (\(\pm\)43) & 1.332 \\ \hline SDLS & 552(\(\pm\)26) & 1.104 \\ \hline WS & 584(\(\pm\)37) & 1.168 \\ \hline HERF:WS & 414 (\(\pm\)17) & 0.828 \\ \hline SDLS:WS & 440 (\(\pm\)11) & 0.88 \\ \hline WS: PS & 808 (\(\pm\)44) & 1.616 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Theoretical oxygen demand for the tested samples.  
Figure 4: Oxygen consumption dynamics during the biodegradation tests of the bio-composites and control samples.  
Over the extended 56-day period, the oxygen consumption data indicate that, following an initial phase of rapid degradation, the process continued with similar trends (Table 3). In terms of degradation extent, the HERF: WS sample achieved over 46 percent of the theoretical oxygen consumption necessary for complete mineralization, whereas the worst-performing samples (HERF-only and WS:PS samples) reached only about 15% of the ThOD.  
The observed behavior of the tested mycelium-based materials can be attributed to their specific composition, the nature of the raw materials employed, and the processing they undergo before being utilized as components of the bio-composites. For instance, the rapid oxygen consumption observed in the HERF:WS sample suggests that incorporating certain components (like WS) can enhance microbial activity and accelerate degradation. In contrast, the slower degradation seen in the HERF-only samples implies that these formulations may be more stable, due to the presence of specific chemical compounds, such as essential oils or polyphenols [11; 58], known to inhibit microbial activity [59].  
Ultimately, these insights are critical when designing bio-composites. They highlight the need to strike a balance between biodegradability and stability, ensuring that materials perform effectively during their intended use while still being capable of environmental breakdown once their service life is over.