## 4 Conclusions  
This study provides a detailed analysis of the composition of DSG obtained from nine distilleries, emphasizing its variability and potential as a valuable resource for biorefinery applications. The findings reveal significant differences in the proximate and structural composition of DSG, including moisture, protein, cellulose, hemicellulose, lignin, and extractive content, which can be attributed to variations in processing techniques and raw material inputs across distilleries. Despite these differences, this study highlights the consistent presence of key components like protein, cellulose, and lignin, underscoring DSG's suitability as a feedstock for the synthesis of high-value bioproducts. The high moisture content of fresh DSG poses storage and stability challenges, necessitating pretreatment processes such as drying and mechanical water removal. While drying improves nutrient density and stability, it is energy-intensive, highlighting the importance of optimizing cost-effective preservation methods. This study also underscores the potential of DSG as a rich source of phenolic compounds and plant-based proteins, which can be harnessed for diverse applications in food, biomedicine, biopolymers, and energy sectors. PCA further demonstrated that protein, lignin, cellulose, and hemicellulose are the primary contributors to the compositional variance among samples, with no discernible clustering of distilleries based on their DSG composition. This variability reinforces the importance of characterizing DSG from multiple sources to develop standardized and tailored approaches for its utilization in biorefinery operations. This study highlights the potential of DSG as a cost-effective and sustainable resource for the development of bioproducts, contributing to the circular bioconomy. By addressing challenges related to variability and storage, this study lays a foundation for the broader industrial application of DSG, aligning with global efforts to promote sustainability, reduce waste, and create value from industrial byproducts. Future research could focus on optimizing processing techniques to enhance the recovery of valuable components and exploring innovative applications to maximize the economic and environmental benefits of DSG.  
Figure 3: Biplot derived from PCA.  
**Author Contributions:** R.S.A.: Conceptualization, data curation, investigation, methodology, writing--original draft, writing--review and editing; D.P.: Validation, writing--original draft, writing--review and editing; S.J.: Conceptualization, supervision, validation, writing--review and editing; A.K.J.: Conceptualization, supervision, validation, funding acquisition, writing--review and editing. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Technological University Dublin under the Researcher Award 2021.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request.  
**Conflicts of Interest:** The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.