New US focused research has unveiled the potential of upcycling nutrient-rich wastewater from poultry slaughterhouses for the cultivation of nutritional yeast, Yarrowia lipolytica.
Writing in the Journal of Environmental Chemical Engineering, the authors said their findings could pave the way for more sustainable waste management in the poultry industry while producing valuable single-cell proteins.
Addressing wastewater challenges
Poultry processing generates vast amounts of wastewater, much of which is discharged to municipal treatment facilities. One significant byproduct is the liquid fraction separated from fatty materials in dissolved air flotation (DAF) units, colloquially termed ‘blood water.’
DAF systems, widely used in abattoirs, play a crucial role in reducing fats, oils, and grease (FOG) in wastewater.
Blood water, despite its nutrient density – containing approximately 3.5 g/L of free amino acids and 0.9 g/L of proteins – is often discarded, representing a missed opportunity for resource recovery, according to the researchers, all based at Auburn University in Alabama.
Upcycling this resource through yeast cultivation could provide economic and environmental benefits, they argue.
The authors explored the feasibility of using blood water as a fermentation medium for Y. lipolytica, which is known for its ability to thrive on lipid- and protein-rich organic waste.
The yeast holds promise as a functional animal feed additive and is classified as Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (FDA), said the team.
Investigating optimal storage conditions
A major obstacle to utilizing blood water is its instability and tendency to produce malodorous compounds over time. To address this, the researchers said they examined the effects of different storage temperatures (-20℃, 4℃, and 22℃) on the medium’s quality and yeast growth performance over six weeks.
Key findings revealed that blood water stored at -20℃ and 4℃ maintained yeast growth potential for up to one week, with minimal performance loss. By contrast, storage at 22℃ led to significant degradation, with yeast growth declining by more than 0.8 log.
Frozen storage (-20℃) prevented amino acid loss and mitigated sulfur-containing volatile formation, effectively curbing malodors. Storage at 4 ℃ similarly extended amino acid stability but to a lesser extent.
Implications
The US poultry industry, responsible for producing 21.3 million metric tons of chicken meat in 2023, generates over 253 billion liters of wastewater annually.
The study emphasized the potential advantages of situating yeast production facilities adjacent to poultry processing plants. Such co-location would reduce costs associated with cooling and transporting blood water while maximizing nutrient recovery.
Source: Journal of Environmental Chemical Engineering
