Skim, sweet buttermilk, and butter derived aqueous phase components were used to re-emulsify low-melt and medium-melt fraction butteroils to yield 20% milkfat creams. The implications of separation temperature in obtaining components, melting point characteristics, and formulation on the chemical and physical properties of reformulated and natural creams were analyzed. Transmission electron microscopy indicated that both reformulated and natural creams were oil-in-water emulsions, demonstrating lipid globules surrounded by surface material. Chemical analysis of components proved that sweet buttermilk and butter-derived aqueous phase components had significantly higher (p less than or equal to 0.01) amounts of cholesterol and phospholipid than skim milk, resulting in creams formulated with sweet buttermilk and butter-derived aqueous phase creams having significantly higher (p less than or equal to 0.01) amounts of cholesterol and phospholipid than creams formulated with skim milk. Butter-derived aqueous phase had higher (p less than or equal to 0.01) amounts of lipid, cholesterol, and phospholipid than sweet buttermilk. However, skim component had higher (p less than or equal to 0.01) amounts of protein than butter-derived aqueous phase. When compared to natural creams, creams consisting of sweet buttermilk and butter-derived aqueous phase components had similar amounts of total phospholipid and amount of phospholipid adsorbed to lipid globules than creams consisting of skim component. Creams consisting of skim component had higher (p less than or equal to 0.01) amounts of protein than natural cream. Reformulated creams having low-melt fraction butteroil had higher (p less than or equal to 0.01) amounts of cholesterol. For reformulated creams, creams processed from components obtained by 49oC separation had significantly higher (p less than or equal to 0.01) amounts of cholesterol than like creams manufactured from 55oC separation components. Creaming stability, viscosity, feathering, and sensory quality of reformulated and natural creams were analyzed over a 13 day storage period at 3.3oC. Formulation, separation temperature, or melting point characteristics did not significantly (p greater than 0.01) affect creaming stability of reformulated and control creams homogenized at 13.6/3.4 MPa. The day within storage period, however, was a significant factor (p less than or equal to 0.01) in determining creaming stability of reformulated and natural creams. All creams displayed typical non-Newtonian behavior at 7oC, displayed by hysteresis curves in which viscosity decreased as shear rate increased. Formulation and separation temperature used to obtain components did not have a significant (p greater than 0.01) effect on viscosity; however, all creams formulated with medium-melt fraction butteroil had significantly (p less than or equal to 0.01) higher apparent viscosity values than creams with low-melt fraction butteroil at shear rate 692.48 s-1 and at 1384.96 s-1 and 2769.92 s-1 for creams formulated with skim component. Regardless of formulation, separation temperature, and melting point characteristics, all creams feathered in a pH range of 4.70-5.09. Reformulated and natural creams met sensory quality specifications as determined by the In/Out Method of Specification, except for creams formulated with skim milk and low-melt fraction butteroil which were characterized as having oxidized flavors. Creams formulated with buttermilk and butter derived aqueous phase had more comparable physical properties to natural creams than skim milk creams. / Master of Science

A reduced cholesterol butteroil was emulsified into skim milk, buttermilk, or buttermilk/butter-derived aqueous phase using different homogenization pressures and heat treatments to produce a 20% milk fat cream with a reduced cholesterol content. Transmission electron microscopic examination of reformulated cream emulsions showed an oil-in-water emulsion typical of milk lipid globules found in natural homogenized cream. Heat treatment (pasteurized and unpasteurized) and homogenization pressure (1500/500 PSI and 2000/500 PSI) had no effect on cream composition except for the significant effect of homogenization pressure on cholesterol content and the amount of phospholipid associated with the lipid globules. The formulations using buttermilk or buttermilk and butter-derived aqueous phase were the most similar in the amount of protein and phospholipid associated with the lipid globules when compared to a natural homogenized cream. The viscosity. interfacial area of lipid globules. creaming stability, and feathering stability of the three formulations and a control at the two homogenization pressures were measured over a two week storage period at 7°C. The apparent viscosity and interfacial area of the different creams varied significantly with formulation but not with homogenization pressure or length of storage time (p ≤ 0.05). Creaming stability was significantly affected by formulation, homogenization pressure, and length of storage tinle (p S ≤.05). Feathering appeared to be unaffected by any of the treatment factors. The reformulated cream using buttermilk and butter-derived aqueous phase was the closest in comparison to a natural homogenized cream in chelllical composition and physical properties. The ability to emulsify the reduced cholesterol butteroil into a stable cream emulsion may allow for the use of reduced cholesterol butteroil in fluid dairy products, ice cream, and cheese. Development of any full-fat product with a reduced cholesterol content will require a reformulation step until a method for cholesterol removal directly from fluid milk or cream is developed. / Master of Science