Abstract
Milk was homogenized at pressures ranging from 17.2 MPa to 100 MPa to determine the effect of homogenization pressure on the fat globule size distribution, viscosity, color, and temperature changes in milk. Milk containing 0, 1.5 and 3.0% milk fat was heated to 62.5 and 79.5'C and homogenized using a Rannie Model 12.51H double stage homogenizer. The difference in whiteness between unhomogenized milk and homogenized milk was significant. Homogenization appeared to have a slight effect on the viscosity of milk. Homogenization increased the temperature of milk an average of 3'C ︢1.5'C per 17.2 MPa. Increasing homogenizing pressure at 62.5'C reduced fat globule size which was reflected in the reduction of the volume surface average diameter and tenth percentile parameter and increased specific surface area. Homogenization was most effective between 0 and 58.6 MPa. This was confirmed by the rate of reduction of volume to surface average diameter and in the rapid increase in specific surface area. Double stage homogenization reduced particle size compared with single stage homogenization. Homogenizing at 79.50C produced clumping and coalescence of fat globules at pressures greater than 58.6 MPa. This effect was observed as increased volume surface average diameter, changes in the tenth and ninetieth percentile parameters and as a decrease in specific surface area. An increase in particle size due to double stage homogenization was observed when milk was homogenized at pressures greater than 72.4 MPa.
Gonzalez De Cossio, Carlos (1994). Effect of high pressure homogenization on the physical properties of milk. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -G643.