Free Oil and Rheology of Cheddar Cheese Containing Fat Globules Stabilized with Different Proteins

Cheddar cheese was manufactured from recombined milk containing fat globules coated with alpha(s1)-CN (casein), alpha(s2)-CN, beta-CN, kappa-CN, alpha-lactalbumin, or beta-lactoglobulin. The effect of the coating on fat globule structure, free oil formation, and cheese rheology was investigated to determine if globule coating affected the physical structure of cheese. Fat globule size and shape were determined in cheese using confocal laser scanning microscopy, and the rheological properties measured by uniaxial compression after maturation for 35 and 70 d. Fat globules were elongated and clustered in the control cheese coated with native membrane material and in cheese where the globules were coated with alpha(s2)-CN, but were more circular and distinct than all others. Cheese containing globules coated with alpha(s2)-CN fractured at a lower strain and with a lower stress than other experimental cheeses. Free oil decreased in cheese as the stress at fracture of the cheese protein matrix increased. Strain at fracture increased as pH increased from 4.7 to 5.3. There was no correlation between free oil and fat globule circularity. Cheddar cheese aroma was not evident in experimental cheeses.