Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2004
Publication Date: 4/1/2005
Citation: Garcia, R.A., Flores, R.A., Phillips, J.G. 2005. Use of an aspirator to separate meat & bone meal into high ash and high protein streams. Transactions of the ASAE. 48(2):703-708.
Interpretive Summary: Meat & bone meal (MBM), a byproduct of the rendering industry, is primarily used as an ingredient in farm animal feed. Since the outbreak of mad cow disease in Europe and elsewhere, new legislation has progressively restricted the feed use of MBM. A looming glut of MBM has spurred research to find new applications for it. Many of these applications will only be possible if the meat portion of MBM can be separated from the bone portion. Our objective was to evaluate whether an aspirator, a device that was designed to clean undesirable material from grain, can be used to separate the bone and meat portions of MBM. Our studies revealed some problems with this approach. MBM is slightly sticky, causing it to clump up and stick to the surfaces of the aspirator. We partially solved this problem by designing a new part for the aspirator. We investigated the effect of the different aspirator settings on how well it separated the MBM. With the ideal settings, the aspirator was fairly effective in separating MBM. This work provides an economical method to process MBM so that it is more useful for value-added applications.
Technical Abstract: Meat & bone meal (MBM) is a byproduct of the rendering industry. It is a heterogeneous mixture consisting of particles derived from bone and from soft tissues. Novel applications for the protein and minerals in MBM are being developed. MBM would have improved characteristics for these applications if the bone and soft tissue-derived particles could be efficiently separated. An aspirator is a device that separates mixtures of particles based on the terminal velocity of each particle. Our objective was to evaluate whether an aspirator can be used to separate MBM into high ash and high protein fractions. We found that the cohesive MBM particles tended to clog the hopper and aspirator column and foul the other interior surfaces of the aspirator, making continuous operation of the aspirator problematic, unless a modification was made. Our results show that with this modification, and appropriate settings for feed rate and operating pressure, the aspirator produces two fractions, one of which is considerably higher in ash, and one which is moderately higher in protein. Specifically, with a MBM feed rate of 8.0 g/s and an operating pressure of -116 Pa, the high ash fraction was 52.0% ash (dry basis), compared to 34.5% ash in the unprocessed material. With a feed rate of 13.7 g/s and a pressure of -28Pa, the high protein fraction was 60.9% crude protein (dry basis), compared to 55.8% crude protein in the unprocessed material. We found that the aspirator tested achieved acceptable separation at a low cost.