Changes in microbiology, proteolysis, texture and sensory characteristics of raw goat milk cheeses treated by high-pressure at different stages of maturation

Abstract

The influence of high-pressure (HP) treatment (400 MPa or 600 MPa for 7 min) on microbiology, proteolysis, instrumental texture and sensory parameters was investigated in the Ibores raw goat milk cheese. Treatments were applied at three different stages of ripening (1, 30 or 50 days) and analyses were carried out after the treatment or at the end of maturation. Treatments at 600 MPa at the three stages of cheese maturation decreased the counts of undesirable microorganisms in mature Ibores cheese (day 60), such as psychrotrophics bacteria, Enterobacteriaceae and Listeria spp. SN/TN (soluble nitrogen/total nitrogen) was increased after HP treatment at day 1 (accelerating effect on cheese maturation), in contrast to the decrease of SN/TN level found after pressurisation at day 30 (arresting effect on cheese maturation). However this effect was reduced throughout cheese maturation. Mature cheeses (day 60) pressurized at the beginning of ripening showed a higher variation of texture profile analysis. In the sensory analysis, cheeses treated at day 1 showed a significant change of appearance, odour and texture. They had less “eyes”, odour intensity and hardness and more springiness than the other ones while the treatments applied at the end of maturation did not affect sensory characteristics.