Monday, July 21, 2014
Exhibit Hall AB (Kansas City Convention Center)
Rodrigo A Ibanez , University of Wisconsin-Madison, Madison, WI
Paul L. H. McSweeney , University College Cork, Cork, Ireland
Abstract Text:

The appearance of cheese is greatly influenced by its composition. Low fat content is usually related to an increase in translucency. Many alternatives have been proposed to modify translucency of cheese, such as the addition of ingredients or through the modification of manufacturing protocols. Colorimetric methods have been used extensively to determine the degree of translucency. The Kubelka-Munk index (K/S) measures the relationship between the reflectance of a thin layer of sample above black and white backgrounds, which indicates the reflectance of a sample of infinite thickness. A method based on the measurement of L* values and the application of K/S was proposed to investigate the effect of titanium dioxide, annatto and homogenisation on the translucency of reduced-fat Cheddar cheese during ripening. Three reduced-fat Cheddar cheeses were manufactured in parallel experiments. For titanium dioxide, levels of 0, 20 or 40 g of TiO2/100 kg were added to cheesemilks. For annatto, levels of 0, 8.25 and 16.50 ml/100 kg were added to cheesemilks. Cheesemilks were also homogenised at 0, 10 or 20 MPa, using a two stage homogeniser (4:1 ratio) at 40°C. L* values and K/S were obtained with a colorimeter at 20°C for all experimental cheeses during six months of ripening. A high correlation was observed between K/S and L* values (r>0.90). Titanium dioxide, annatto and homogenisation significantly (P<0.05) modified K/S values compared to the control. Ripening significantly increased translucency (i.e., reduced K/S) for all treatments (P<0.05). An increase in K/S was observed when TiO2 was added (P<0.05). A reduction of the K/S value was observed following addition of annatto (P<0.05). An increase of K/S was observed when milk was homogenised (P<0.05). However, no differences in K/S values were found between homogenisation pressures of 10 and 20 MPa. These results suggest that K/S is a useful tool to determine changes in the translucency of Cheddar cheese. Addition of titanium dioxide and homogenisation reduced translucency. On the other hand, the use of annatto increased translucency in experimental cheeses.

Keywords: Translucency, L* value, Kubelka-Munk.