1a. Objectives (from AD-416):
1) Produce functional protein isolates from animal by-products. 1a. Develop a pilot scale process for producing poultry blood-based flocculant. 1b. Increase the yield and molecular weight of soluble peptides extracted from rendered animal protein. 2) Utilize animal-protein isolates in biobased applications. 2a. Broaden the application range for animal protein-based polyacrylamide (PAM) substitutes. 2b. Develop practical processes for the production of fermentation feedstocks derived from animal by-product proteins. Evaluate these feedstocks in fermentation systems.
1b. Approach (from AD-416):
Meat animal processing inevitably yields by-products, which include tissues and organs that are unsuitable for human food, such as feathers and bones, or for which there is low food market demand, such as blood. The current outlets for animal by-products, either through profitable use or disposal in the environment, are limited and shrinking. The proposed project is designed to create new utilization opportunities for these substances and reduce the environmental impact of meat processing. Two groups of promising applications are targeted here, use as fermentation feedstocks and use as renewable alternatives for synthetic polymeric flocculants such as polyacrylamide (PAM). Rendered protein will be processed into forms well-adapted for use in non-pharmaceutical industrial fermentations. Poultry blood and substances derived from rendered proteins will be tested in applications including algae culture flocculation, ethanol whole stillage clarification, mine tailings flocculation, cellulosic fiber flocculation, and municipal sewage sludge settling. At all stages, emphasis will be placed on employing processing techniques that are appropriate to the relatively low value of the products to be produced. Successful completion of this project will yield technologies that can be commercialized in a relatively short time period and produce new revenue streams for renderers and meat processors, while benefiting the environment.
3. Progress Report:
Flocculants are substances which help in clarifying liquids by causing suspended particles to settle more quickly; they are employed in a wide variety of industrial, agricultural, environmental and construction applications. Development of both bio-based and synthetic polymeric flocculants is a very active area of research. In previous reporting periods we have shown that hemoglobin from poultry blood is promising as a biobased flocculant; the source material (blood) is a by-product that is burdensome to the poultry industry, and its technical performance as a flocculant is very strong. In FY13, our flocculant work advanced along a couple of fronts. Commercial production of flocculant from poultry blood is likely to involve collection of blood from multiple slaughterhouses and transport to a central processing facility; such an arrangement will require blood to held for 2-4 days prior to processing. Blood is highly unstable, and once outside the animal it quickly begins to degrade in a variety of ways. It coagulates within minutes, making recovery of the hemoglobin impractical. On a longer time scale, the red cells begin to break open, releasing their contents and greatly increasing the cost to recover the hemoglobin. Finally, the action of microbial contaminants in the blood produces hazardous hydrogen sulfide which is a major workplace safety concern. In our research we have measured the extent and timescale of each mode of blood degradation under industrially relevant conditions, beginning with collection of blood directly from slaughtered birds. We have identified inexpensive chemical treatments to inhibit the breakdown and studied the effect of these treatments on flocculant performance. Completion and refinement of this work will greatly facilitate the commercial adoption of the blood flocculant technology by allowing the blood collection and processing to be further separated in time and place. In all prior flocculant work in this project, the substance to be flocculated has been clay. About one-third of biomass is composed of lignin. During biomass processing this lignin is often extracted into an alkaline solution. Lignin is normally recovered by treating the solution with sulfuric acid, which causes it to precipitate. Over the past year, we have worked with an industrial collaborator who requires a method for recovering the lignin without the acid. We have determined appropriate dosing and conditions for using hemoglobin coagulation in place of sulfuric acid precipitation. This work expands the range of applications for hemoglobin flocculant.