The objective of this study was to evaluate the color change of cottage cheese made with different processes of acidification (enzymatic and chemical) over time. The research was conducted at Universidad del Valle (Cali, Colombia) laboratories, between 2014 and 2015. Microbial rennet and lactic culture (CC) were used for enzymatic coagulation method (control cheese), and solutions of citric acid (CA) and phosphoric acid (PA) were used for the chemical method. The physicochemical properties were determined, and color behavior was analyzed over nine days of storage. Significant differences in acidity and moisture for the three coagulants were found. In the color plane, it was observed that the final and initial points of the coordinates a * and b * are close together; changes in color were mostly due to changes in brightness. The speed at which brightness decreased in the three cheeses matches kinetics order to zero and one. The first order kinetics displayed in higher values of linear correlation coefficients (R), AC: 0.8410 ± 0.0533; AF: 0.8390 ± 0.0847, and CC: 0.8717 ± 0.0256. The kinetics of change in color also adjusted correctly to zero and the first order kinetic model; that is, no significant difference (p <0.05) between these results. However, the speed of color change for the three cheeses had a slightly higher setting for zero order kinetics, as evidenced by the linear correlation coefficient (R) results, AC: 0.8800 ± 0.0205; AF: 0.8543 ± 0.0099, and CC: 0.7982 ± 0.0605.

Keywords: processed cheese, milk products, lactic fermentation, cheese making, preservatives.