Effect of a bacteriocin-producing lactic culture and high pressure treatment on the colour of Hispanico cheese

The effect of the addition of a bacteriocin-producing (BP) culture to milk, individually or combined with high pressure (HP) treatment (400 MPa, 5 min, 10 degrees C) applied on day 15 of ripening, on the colour of Hispanico cheese was investigated. Objective colour parameters L* (lightness), a* (green to red), b* (blue to yellow), colour saturation (C) and hue angle (h) of freshly cut samples were determined using a spectrophotometer, after 15, 25 and 50 d of ripening. Addition of BP culture increased L*, b* and C values of cheeses, moving their hue angle towards the yellow direction. HP treatment of cheese made without BP culture decreased cheese L* values, and increased b* and C values. On the other hand, HP treatment of cheese made with BP culture decreased L*, and diminished b* and C values up to 25 d of ripening. In general, colour changes caused by BP culture addition or HIP treatment could be related with the colour of older cheeses. Ripening time increased b* and C values, and shifted hue angle of all cheeses but the control cheese to the yellow direction. Short exposures (15 min) of cheese samples to room air/light conditions generally reduced L * and a* values, and increased b* and C values.