Effect of ultra-high pressure homogenisation of milk on the texture and water-typology of a starter-free fresh cheese.

摘要

Fresh starter-free cheeses were made from ultra-high pressure homogenised (300 MPa and inlet temperature of 30 degrees C), pasteurised (80 degrees C for 15 s) or homogenised-pasteurised (15 +3 MPa at 60 degrees C, 80 degrees C for 15 s) milks to compare their textural, microstructural, colour and water-related characteristics by means of uniaxial compression and dynamic oscillatory tests, confocal laser scanning microscopy, spectrocolorimetry, and thermogravimetry, respectively. Sensory analysis was performed by a sensory panel. Major differences among treatments were revealed by both instrumental and sensorial methods. Cheeses from homogenised milks were firmer, less deformable, grainier, pastier, whiter, and had higher water-holding capacity but lower water-mouth feeling than cheeses from pasteurised milk. The effect of ultra-high pressure homogenisation (UHPH) was greater than that of conventional homogenisation. Differences in the composition, i.e. water typology and protein content, and the microstructure could explain the sensory characteristics of the cheeses. Industrial relevance: UHPH treatment of milk is being studied as an alternative to conventional heat-treatment since it reduces microbial load and inactivates enzymes. Moreover, UHPH has been proven to affect protein interactions resulting in an increase of curd-firming rate and gel firmness during coagulation. Thus structural changes intrinsically related to the arrangement of cheese components, such as texture, syneresis and colour, are expected in fresh cheeses produced from UHPH-treated milk