**3. Ultra high pressure homogenization (UHPH)**

High pressure homogenization (HPH) is a continuous treatment in which a food liquid is pumped at high pressure and later depressurized when the fluid passes through a special valve. It is normally called HPH when pressurization occurs at 100–200 MPa (**Figure 5A**) and ultra high pressure homogenization (UHPH) when the pressure range is higher than 200 MPa (**Figure 5B**) [7, 9].

The "UHPH sterilization system" is a novel process, patented in Europe (EP2409583B1) by UAB (Autonomous University of Barcelona), extended to a lot of countries and exclusively exploited and manufactured by Ypsicon Advanced

#### **Figure 5.**

*Valve components in HPH (A) and UHPH (B) systems (Ypsicon [28]). HP: high pressure, UHP: ultra high pressure, AP: atmospheric pressure.*

**33**

**Figure 6.**

*UHPH industrial machine (Ypsicon [28]).*

*Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2*

Technologies (Barcelona, Spain) (www.ypsicon.com). It consists of a continuous device capable of working from 200 to 400 MPa and applying shear, impact, cavitation, and turbulence forces in a special valve at high speed (Mach 2). As a consequence, the particles size is reduced from 100 to 300 nm, microorganisms are destroyed, enzymes inactivated and stable emulsions are produced without additives,

UHPH is highly efficient in controlling microorganisms. The antimicrobial effect is produced by the strong impact forces together with the shear stresses and the complementary effect of local cavitation and friction [7–9]. This process produces intense heating in the in-valve time but during a really short period of time of 0.02 and 0.2 s for the global residence time. The temperature in the valve can reach 100°C when the inlet temperature is 20°C, being reduced to 25°C after the valve [8] by adiabatic-expansion chilling. Even when high temperatures are reached instantaneously in the valve, as a whole it can be considered a gentle technology with no thermal effect on sensory degradation. After the UHPH process, no formation of thermal markers such as furfural or 5-hydroxymethylfurfural is observed, probably because of the very low residence time. UHPH processing using suitable in-valve temperatures can produce sterilization capable of destroying even sporulated bacteria. Because of this feature, it can be considered a gentle alternative to UHT, since in this thermal technique a temperature of 140°C for 3–4 s is necessary.

In contrast, UHPH only requires a total processing time of less than 0.2 s. UHPH can be applied to liquids containing particles, but the particle size must be lower than 500 μm. The average particle size range at the valve outlet is 100–300 nm. The valve design is a critical point, as well as the performance of the UHPH process, but especially the antimicrobial effect depends on the geometry and materials of the valve piston and seal. Especially, efficient designs are manufactured by Ypsicon [44] (**Figure 6**). UHPH systems are currently available with flow rates of up to 10,000 L/h [28]. The processing rate can be increased in a modular way by using several systems working in parallel. Some UHPH pumps can work up to

Concerning the elimination of microorganisms, UHPH has proven to be highly effective with 6-log reductions for *Saccharomyces* and non-*Saccharomyces* yeasts

400 MPa continuously with a pressure oscillation of 1 MPa.

*DOI: http://dx.doi.org/10.5772/intechopen.92035*

and consuming less energy than thermal treatments.
