Computer Vision and Color Measurement Techniques for Inline Monitoring of Cheese Curd Syneresis

Schematic of computer vision system coupled to the cheese vat with twin corotating stirrers.CCD= charge-coupled device.

Computer vision images of the curd/whey mixture at a) 5 min, b) 15 min, c) 35 min, and d) 85 min after cutting, in the 10-L vat. The curd/whey mixture is being stirred by twin stirrers (Figure 1).

a) Red (♢), green (□), and blue (△) (i.e., RGB, values on a scale of 0 – 255 for a trial) and b) the corresponding ΔE_m values (———; RGB model) fitted to ΔE_RGB values (□) vs. time.

Changes in M_C (curd moisture) over the course of syneresis (t = 5min to t = 85min) for different treatments: pH, 6 and stirring speed, 12.1rpm (average of 3 replicates, ——); pH, 6 and stirring speed, 27.2rpm (average of 3 replicates, — — —); pH, 6.5 and stirring speed, 12.1 revolutions per minute (average of 3 replicates, – – –); pH, 6.5 and stirring speed, 27.2 (average of 3 replicates, — – — – —).

Graph of log a_wy (log of ratio between white and yellow areas) vs. time after cutting the coagulum for a typical trial, using the computer vision system. It is apparent that log a_wy decreases in a linear manner up to t_linear, the vertical bar indicating the point of departure from this first linear section.

Plot showing trend of W_M (yield of whey) vs. a_wy (ratio between white and yellow area): t = 5 (♢); t = 15 (□); t = 25 (△).

Fit of Eq. [7] to the experimental values of MC (curd moisture content) at time t showing the effect of stirring speed on prediction consistency. Two different stirring speeds (12.1 and 27.2rpm) were used to promote syneresis. Thin line, diagonal line; thick line, regression line. a) Fit for the 12 tests, which constituted the 3 whole replications of the experiment; Regression line: Predicted M_C = 0.985×Measured M_C; b) Fit for the 6 tests at low stirring speed; Regression line: Predicted M_C = 0.972×Measured M_C; c) Fit for the 6 tests at high stirring speed. Regression line: Predicted M_C = 1.000×Measured M_C. Prediction equation coefficients were: b₀ = 92.63, b₁ = −0.150, b₂ = 0.000851, b₃ = 33.2, b₄ = −0.0171.