Effects of isolated soy protein (ISP), frozen, textured isolated soy protein (FTISP), soybean oil (SO), and hydrogenated soybean oil (HSO) addition on chemical, color, sensory, and microbial stability of lean (>90%) ground beef patties (LGBP) were evaluated. Soy oil was incorporated as an emulsion (SE). Nine treatments, including two all beef controls (20 and 10% fat), were formulated to contain combinations of SE, HSO and FTISP. Sensory panelists found LGBP with 25% FTISP (10% fat from beef) to have as intense beef flavor (P>0.05) as all beef controls. Lipid oxidation and pigment discoloration rates were slowed by fat adjustment to 10% with SO and/or HSO. Soy had no effect (P>0.05) on microbial stability.

Properties associated with fast twitch muscles are light color and biochemical factors associated with anaerobic metabolism, whereas slow twitch muscles are red and designed to metabolize aerobically. Twitch speed is regulated at the molecular level by isoforms of proteins involved in contraction. Isoforms are grouped into general classes of fast and slow; however, there are also different isoforms within each general group.Myojibrillar proteins are of primary importance to textural and water holding properties of meat products. Research on gelation of myojibrillar protein isofonns has shown that fast twitch myosin forms more rigid gels than slow twitch myosin. This trend is not universal in studies which used more complex proteins (e.g., myojibrils) and/or methods which determine mechanical properties other than rigidity. Possible mechanisms which explain these variations are discussed, 'Paper No.