Phosphorus flow and characterization in dry-grind corn ethanol plants.

Area of Science:

• Agricultural Science
• Environmental Science
• Biochemistry

Background:

• High phosphorus (P) content and bioavailability in corn-ethanol coproducts (e.g., distillers grains with solubles, DDGS) can increase manure and soil P levels.
• These elevated P levels pose environmental risks, including eutrophication.

Purpose of the Study:

• To model total phosphorus mass flow to DDGS.
• To quantify the distribution of P into inorganic and phytase-hydrolyzable forms in coproducts.
• To inform strategies for phytase enzyme supplementation in corn-ethanol processing.

Main Methods:

• Detailed modeling of total phosphorus mass flow.
• Quantification of P distribution (inorganic vs. phytase-hydrolyzable) in thin stillage, DDGS, and modified DDGS (mDDGS).
• Evaluation of phytase enzyme efficacy in hydrolyzing nonorthophosphate P components.

Main Results:

• Corn accounts for 80.2% of P in coproducts, while yeast contributes 19.4%.
• Condensed solubles, despite lower mass, yield 70.9% of the P in DDGS.
• The phytase enzyme effectively hydrolyzed nonorthophosphate P in thin stillage, DDGS, and mDDGS.

Conclusions:

• Tracking P movement during corn-ethanol processing is essential for environmental management.
• Yeast and condensed solubles are significant P contributors in DDGS.
• Phytase supplementation is a viable strategy to reduce P bioavailability in corn-ethanol coproducts.