Solubilization of meat & bone meal protein by dilute acid hydrolysis for the production of bio-based flocculant

Authors: ZHANG, CONGMU - Orise Fellow; Garcia, Rafael; Piazza, George

Submitted to: Journal of Food and Bioproducts Processing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2017
Publication Date: 2/21/2017
Citation: Zhang, C., Garcia, R.A., Piazza, G.J. 2017. Solubilization of meat & bone meal protein by dilute acid hydrolysis for the production of bio-based flocculant. Journal of Food and Bioproducts Processing. 102:362-366.

Interpretive Summary: Flocculants are substances which facilitate the removal of small particles from water. They are used in water treatment, erosion control, manufacturing, and other application areas. Meat and bone meal (MBM) is an inexpensive and under-utilized by-product of meat processing. MBM is very high in protein, and this protein has flocculant properties. Poor solubility is the primary impediment to the use of MBM protein as a flocculant. Previous attempts to increase the solubility of MBM protein without compromising the flocculant properties have had unsatisfactory results. The present project adapted a chemical reaction that had decades ago become obsolete for its original purpose. It was shown that this reaction can be successfully utilized to solubilize almost all MBM protein, while retaining the flocculant properties. These results show that a simple, inexpensive treatment can greatly increase the utility of MBM protein.

Technical Abstract: Flocculants are substances that cause suspended particles to aggregate, therefore accelerating sedimentation to produce a clarified solution. They find use in a huge variety of applications including wastewater treatment, erosion control, and paper manufacture. Meat and bone meal (MBM) is a high protein by-product of meat processing. Protein extracted from MBM has been shown to have good flocculation activity, but this protein has poor solubility. Previous attempts to improve solubility through alkaline or enzymatic hydrolysis have produced small protein fragments with low flocculation activity. The objective of this project was to produce large, soluble MBM protein fragments by applying reaction conditions that are known to hydrolyze peptide bonds only at aspartic acid and asparagine residues. In this project, milled MBM was suspended in 0.03N hydrogen chloride solution, under vacuum, and incubated at 108 degrees C. Samples were removed after 1, 2, and 4 hours, and the soluble and insoluble material was separated. The molar mass distribution of soluble material was examined by size exclusion chromatography (SEC), progressive solubilization of protein was measured by using a test for organic nitrogen, and flocculation activity was tested by measuring kaolin clarification effectiveness (KCE). Results showed that at all hydrolysis times, concentration of solubilized material was increased approximately 3-fold compared to the acid-free controls. Results also showed that as reaction duration increased, more MBM protein was solubilized, but average molecular weight (MW) of solute was reduced, and flocculation activity was dependent on reaction duration. The dilute acid hydrolysis (DAH) employed in this project could be a simple and inexpensive treatment that has potential to add value to MBM and provide a new source for bio-based flocculants.