The motivation of using high pressure in dairy products lies on physical and chemical changes induced by pressure. For instance, HPP disrupts casein micelles, denatures whey proteins and alters the mineral balance. Thus, some quality attributes and functional properties are the result of the way in which these three phenomena are affected by pressure.
In addition to food preservation, pressure treatment also has potential applications in structural modifications of the dairy proteins and other components. This will help processors develop dairy products with high-value nutritional and functional properties. For example, pressure treatment may be used as an alternative to heat for the preparation of novel milk protein gels. Selected potential dairy applications of pressure treatment reported in the literature are summarized below.
Cheese. It has been reported that moderate pressure treatments could increase cheese yield, ripening characteristics and functionality possibly due to complex interactions between whey proteins and casein micelles. The cheese ripening time has been accelerated by the application of HPP due to conformational changes within the cheese matrix that enhances the action of native enzymes.
Yogurt. Combined pressure-thermal treatment can yield gel with desirable properties, including rigidity, smooth surface, texture and viscosity.
Colostrum. Pressure treatment eliminates harmful bacteria without modifications to nutritional attributes. This has been exemplified in human colostrum where the application of HPP showed that the concentration of bioactive compounds did not change as opposed to that found in thermal pasteurization at conditions of the same microbial reduction efficacy.
Fluid milk. Ultra-high temperature (UHT) conditions may potentially alter milk composition, resulting in a cooked or burnt flavor. On the other hand, pressure- assisted thermal treatment can help to create a milk profile closer to that of thermally pasteurized milk. In addition, the treatment can enhance the retention of bioactive compounds in milk. An investigation showed that milk rich in conjugated linoleic acid, a bioactive compound naturally found in milk, can be treated with PATP, resulting in minor losses of CLA compared with the control treatment.
Ice cream. Application of pressure alters the water freezing and melting point temperature (-22C at 30,000 psi). Pressure shift freezing and thawing application in improving ice crystallization and texture have been reported.
Conclusion
High-pressure-based technologies have the potential to preserve natural freshness as well as the intricate sensory and nutritional quality of a variety of dairy products. The higher initial equipment cost and the relatively lower throughput of this technology likely limit its use to high-value-added niche products, such as organic milk, premium ice cream and cheese products.
Nevertheless, significant opportunity also exists in formulating novel milkbased beverages containing naturally enriched bioactive compounds that are preserved by PATP treatment.
Combined pressure-thermal treatment provides a new tool for dairy processors to innovate and introduce new value-added dairybased beverages which may not be available in the market today.
