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Research Project: Commercial Flocculants from Low-Value Animal Protein

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Title: Practical Limitations of the Dilute Acid Hydrolysis Method for Solubilizing Meat and Bone Meal Protein

item ESSANDOH, MATTHEW - Orise Fellow
item Garcia, Rafael
item NIEMAN, CHRISTINE - Drexel University
item Bumanlag, Lorelie
item Piazza, George
item ZHANG, CONGMU - Orise Fellow

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2017
Publication Date: 10/26/2017
Citation: Essandoh, M., Garcia, R.A., Nieman, C.M., Bumanlag, L.P., Piazza, G.J., Zhang, C. 2017. Practical Limitations of the Dilute Acid Hydrolysis Method for Solubilizing Meat and Bone Meal Protein. ACS Sustainable Chemistry & Engineering. 5(12):11652-11659.

Interpretive Summary: Meat and bone meal (MBM) is a protein of commercial importance. However, the utilization of MBM for any application is very difficult because its highly insoluble and heterogeneous. Previously, we showed how MBM can be hydrolyzed using dilute acid. However, the conditions used may not be practical. In order to overcome these challenges, we tested whether fat, particle and substrate concentration have any effect on protein solubilization. To our surprise, both particle size and fat showed no negative effect on the conversion rate. This is interesting in the sense that an industrial process utilizing MBM will not necessary require grinding or the removal of fat in the MBM in order to achieve high protein conversion rate. However, substrate concentration was found to have an effect on protein solubilization. Thus, when the MBM concentration increases, the protein conversion rate decreases. In an industrial scale, higher concentration (>200 g/L) can be used as long as care is taken to ensure rapid mixing of the sample mixture. Further, we found both hydrolysate and extract can be used to clarify a suspension of kaolin clay particles.

Technical Abstract: Previous studies reported hydrolysis conditions that would cause the hydrolysis of meat and bone meal (MBM) protein in a very specific manner, transforming insoluble MBM protein into large, soluble protein fragments with good flocculant functionality. It is not clear, however, that these results provide a practical approach for large scale conversion of MBM into a more useful soluble protein hydrolysate. The present study examines whether the desirable characteristics of the reaction are retained when hydrolysis is conducted using high MBM concentration, MBM with relatively large solid particles, and also in the presence of bone mineral and fat. The results showed that bone mineral did interfere with the reaction progressively as the substrate concentration increased, probably due to the solubilization of bone phosphate. If the reaction acid concentration was increased to compensate for the bone mineral interference, then good conversion rates were achieved for up to 200 g substrate per liter. Particle size and fat showed no consistent effect on the conversion rate. The reaction was shown to retain its specificity to particular hydrolysis sites under all conditions tested. Higher substrate concentration and longer reaction times both favored the production of relatively large peptides (MW > 5 kDa). Finally, the MBM protein hydrolysate was shown to retain flocculant properties comparable to those of MBM water extracted protein. These results indicate that the reaction under consideration could be used to convert MBM protein into a more valuable functional product.