Chapter 20 - High Hydrostatic Pressure and High-Pressure Homogenization Processing of Fruit Juices

Abstract

Both high hydrostatic pressure (HHP) and high-pressure homogenization (HPH) processes are nonthermal, nonconventional, emerging technologies, first studied as food-preservation techniques. Although similar in name, the technologies are completely different in relation to principles and processes. The HHP process is based on the isostatic principle and the principle of Le Chatelier; where the pressure is equally applied in all directions of the foods, being responsible for the observed reaction. It can be used for solid, fluid, or particulate food, being conducted in-package and discontinuously. On the other hand, different from the HHP process, in the HPH process it is the shear stress distribution across the product, and not the pressure, which is the responsible for the obtained results. The HPH process is continuous and available only for fluid products. Even so, both products cannot be used alone to guarantee the required microbial inactivation; a complementary preservation technology, such as refrigeration or mild thermal process, is necessary. On the other hand, the positive changes in fruit juices structure and properties are highly relevant, with great industrial potential. This chapter describes the principles and equipment for both technologies, as well as their effects on microorganisms, enzymes, food constituents, juice structure, physical and technological properties. Finally, it describes the industrial perspectives, commercial use and future challenges.