Emulsifying capacity and stability of freeze-dried beef muscle and meat by-products

The relationship of emulsifying capacity and emulsion stability with bovine tissue parameters (total protein, salt-soluble protein, total lipid, neutral lipid, polar lipid and ash) was studied. Beef muscle (Psoas major) and meat by-products (liver, kidney and heart) were chopped, freeze-dried, ground and screened through No. 10 and No. 20 mesh size sieves, respectively. The samples were analyzed for emulsion capacity and stability, and the tissue parameters were determined. Based on the results of this study, the following conclusions were made: Of the four tissues, liver had the highest emulsion capacity, although there were no significant differences among the means of muscle, liver and kidney (P<0.05). Heart tissue had significantly lower emul-sion capacity than the other tissue powders. Liver possessed the highest emulsion stability, followed by kidney and muscle. Emulsions of heart tissue were the least stable. A negative nonlinear relation was established graphically between total protein and emulsion capacity and stability (r = -.63 and r = -.78, respectively). As the concentration of protein increased, emulsion capacity and stability decreased. In liver, salt-soluble protein constituted the greatest proportion of total protein, followed by heart and kidney. Regardless of the amount of salt-soluble protein, a relatively weak relation was observed with emulsifying capacity (r = 0.56). However, a stronger relation was found between emulsion stability and salt-soluble protein (r = 0.75). Total lipid content appeared to be one of the factors with most influence on emulsion capacity and stability. Strong linear correlations were observed (r = 0.99 and r = 0.97, respectively). By its biological nature, liver tissue contained the highest amount of total lipids, which was assumed to be directly responsible for its higher emulsion capacity and stability. Neutral lipid content did not seem to exert any effect on either emulsion capacity or stability and exhibited weak relations with them (r = 0.55 and r = 0.32, respectively). Along with total lipid content, polar lipid content also seemed to be an important factor in emulsion capacity and stability. Polar lipid content exhibited a moderate correlation with emulsion capacity (r = 0.77), but was highly correlated with emulsion stability (r = Q.91). Ash content of muscle and tissue powders did not exhibit any strong correlation with either emulsion capacity or stability (r = 0.39 and r = 0.59, respectively.