Development and Use of Pork Skin Fat Emulsion Gels in Low-Fat, High-Added-Water Bologna

1999 University of Nebraska-Lincoln Extension Swine Report. Reduced-lean pork trimmings (~70 percent fat and 30 percent lean) have low economic value due to inherent high fat content. Mechanically modified pork skin was used to extend reduced- lean pork trimmings by making a fat emulsion gel, lowering fat content by dilution in an attempt to increase the value of reduced lean trimmings. The first objective was to extend reduced-lean pork trimmings by creating a pork skin fat emulsion gel (FG) and to characterize and optimize the functionality of FG from combinations of pork skin, reduced-lean trimmings and added water (AW). The next objective was to incorporate the best FG into low-fat bologna. Fat emulsion gels were characterized and optimized using combinations of pork skin (3 to 10 percent), AW (25 to 50 percent) and reduced-lean pork trimmings (20 to 40 percent final fat content). To make FG, flaked pork skin and water were chopped and heated to 160oF to solubilize collagen. The cooled (<85oF) skin/water mixture, combined with reduced-lean trimmings and salt (4 percent), were then chopped to 105oF. Regression analysis predicted optimal emulsion stability (lowest ml fluid released/100g of FG during simulated cooking) in FG occurred with 5 to 6 percent pork skin. Incorporation of selected FG, with known characteristics, into low-fat comminuted pork products could improve water binding properties and help achieve desired sensory properties when used at appropriate levels. It was determined FG should be formulated with 6 percent skin for optimal functionality and at least 30 percent fat to utilize more reduced-lean trimmings. Pork skin fat emulsion gels with the best emulsion stability [30 percent fat, 25 percent added water (AW)], the best hydration/ softest texture (30 percent fat, 50 percent AW) and the most economical FG (40 percent fat, 50 percent AW) were selected to evaluate how FG with known characteristics would impact low-fat/high-added-water bologna. There was a low-fat/high-added-water control (10 percent fat/30 percent AW) and a 30 percent fat/10 percent AW control. Common problems associated with low-fat/high-added-water bologna include dark color and soft texture. The texture of bologna containing FG was improved, it required more force to fracture and was harder (P<0.05) than control low-fat/highadded- water bologna but similar (P>0.05) to the full-fat control. The sensory panel found bologna containing FG was more like the full-fat control bologna and had a lighter (P<0.05) color and a more (P<0.05) springy and firm texture than the low-fat/highadded- water control. The value of reduced- lean trimmings could be increased by production and incorporation of fat emulsion gels into comminuted meat products.