A recent study conducted in the United States has highlighted the potential of upcycling nutrient-rich wastewater from poultry slaughterhouses for the cultivation of nutritional yeast, specifically Yarrowia lipolytica. The research, published in the Journal of Environmental Chemical Engineering, suggests that this innovative approach could not only lead to more sustainable waste management practices in the poultry industry but also yield valuable single-cell proteins.
Poultry processing operations typically generate significant volumes of wastewater, much of which is typically discharged into municipal treatment facilities. One common byproduct is the liquid fraction extracted during the process of separating fatty materials in dissolved air flotation (DAF) units, commonly referred to as ‘blood water.’ Despite its high nutrient content – containing approximately 3.5 g/L of free amino acids and 0.9 g/L of proteins – blood water is often discarded, representing a missed opportunity for resource recovery, according to the researchers from Auburn University in Alabama.
By exploring the potential of using blood water as a fermentation medium for Y. lipolytica, known for its ability to thrive on lipid- and protein-rich organic waste, the authors believe that upcycling this resource through yeast cultivation could offer both economic and environmental benefits. The yeast has the potential to serve as a functional animal feed additive and is classified as Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (FDA).
One of the challenges associated with utilizing blood water is its instability and tendency to produce malodorous compounds over time. To address this issue, the researchers conducted experiments to assess the impact of different storage temperatures (-20℃, 4℃, and 22℃) on the quality of the medium and the growth performance of the yeast over a six-week period. The results showed that storage at -20℃ and 4℃ maintained the yeast growth potential for up to one week with minimal performance loss, whereas storage at 22℃ resulted in significant degradation, leading to a decline in yeast growth by more than 0.8 log.
Frozen storage at -20℃ was found to prevent amino acid loss and reduce the formation of sulfur-containing volatile compounds, effectively controlling malodors. Storage at 4℃ also helped maintain amino acid stability, although to a lesser extent.
Given that the US poultry industry produces over 253 billion liters of wastewater annually, with 21.3 million metric tons of chicken meat produced in 2023 alone, the study underscores the potential benefits of establishing yeast production facilities in close proximity to poultry processing plants. This co-location strategy could help reduce the costs associated with cooling and transporting blood water while maximizing nutrient recovery.
In conclusion, the research highlights the promising opportunities for upcycling nutrient-rich wastewater from poultry slaughterhouses for the cultivation of nutritional yeast, offering a sustainable solution for waste management in the industry. By leveraging the unique capabilities of Yarrowia lipolytica and optimizing storage conditions for blood water, this innovative approach has the potential to not only enhance resource recovery but also contribute to the production of valuable single-cell proteins. Source: Journal of Environmental Chemical Engineering.