Heat Treatment of Milk | Non-Thermal Technologies: High Pressure Processing

Abstract

Of all the nonthermal technologies, high-pressure processing has attracted most interest. Although first researched (on milk) in the nineteenth century, it was not until the 1990s that it was adopted commercially. There are now 130 high-pressure plants in the world, but still none is devoted to the industrial production of a dairy product. High-pressure processing involves subjecting products to pressures of ~300-600. MPa for ~2-30. min at around ambient temperature, although each of these parameters can be varied. Its major attraction is its ability to 'pasteurize' foods without significantly changing their color, flavor, and nutritional value.High pressure has some dramatic effects on milk, the major one of which is the disintegration of the casein micelles leading to the production of a clear, almost transparent product when skim milk is treated. Thus, it changes the distribution of proteins and minerals between the colloidal and soluble phases. Its other major effect is the destruction of bacteria, particularly vegetative cells, thus extending the shelf life of the product. Recently, pressure-assisted thermal processing (PATP) and its more specific form of pressure-assisted thermal sterilization (PATS) have been actively researched with respect to destruction of barotolerant microorganisms, particularly bacterial spores.