Effects of nitrogenous substances on heat transfer fouling using model thin stillage fluids

Authors: YOU, J - University Of Illinois; Johnston, David; Dien, Bruce; SINGH, V - University Of Illinois; ENGESETH, N - University Of Illinois; TUMBLESON, M - University Of Illinois; RAUSCH, K - University Of Illinois

Submitted to: Food and Bioproducts Processing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2019
Publication Date: 1/1/2020
Citation: You, J., Johnston, D., Dien, B.S., Singh, V., Engeseth, N.J., Tumbleson, M., Rausch, K.D. 2020. Effects of nitrogenous substances on heat transfer fouling using model thin stillage fluids. Food and Bioproducts Processing. 119:125-132. https://doi.org/10.1016/j.fbp.2019.10.010.
DOI: https://doi.org/10.1016/j.fbp.2019.10.010

Interpretive Summary: In the production of fuel ethanol, the deposition of unwanted material on the surface of processing equipment is called fouling. These deposits result in the need for additional capital investment and lower processing efficiency. Protein is known to contribute to fouling in other industries when it interacts with phosphate. To better understand how these deposits form in ethanol processing and potentially develop ways to reduce or eliminate the formation, the fouling properties of nitrogenous substances (urea and yeast) using model fluids were investigated. Additionally, the impact of protease addition on the fouling properties of model and commercial thin stillage fluids were examined. The results showed that urea addition did not increase fouling while glucose-yeast model fluids did increase fouling tendencies. The addition of protease from pineapple stems (bromelain) increased fouling in both model and commercial fluids indicating peptides and amino acids are involved in deposit formation. These results will be beneficial to ethanol producers and researches investigating ways of improving processing efficiency and lowering capital and operating costs.

Technical Abstract: Fouling is unwanted deposition of materials on surfaces of processing equipment, which leads to additional capital investment and lower processing efficiency. During fuel ethanol production, fouling occurs when thin stillage is concentrated into condensed distillers solubles. Investigations of protein impact on fouling are limited despite high protein concentration in thin stillage (17 to 33% db). Protein contributions to fouling have been verified in the dairy industry. Whey proteins and calcium phosphate interact with each other or other proteins and form aggregates on heated surfaces. Due to complex components in thin stillage, it is difficult to study a single effect on fouling without interference from other factors. The objective was to investigate fouling properties of nitrogenous substances (urea and yeast) using model fluids; effects of protease addition on fouling properties of model and commercial thin stillage fluids. Urea addition did not lead to fouling while glucose-yeast model fluids displayed fouling tendencies. Protease from pineapple stem (bromelain) incubation increased fouling in model and commercial fluids, which were indicative that hydrolyzed molecules such as peptides, amino acids or protease can be involved in deposit formation.