Ten questions and ten answers, detailed interpretation of UHCL processing HPP technology

  Ultra-high pressure processing (HPP) is becoming increasingly popular among food and beverage manufacturers who want to ensure food safety, authenticity, lock in nutrients and freshness, zero additives, and effectively extend shelf life. However, consumers and food industry professionals still create confusion when referring to concepts related to this technology or comparing it with other methods. The following is an introduction to the frequently asked questions (FAQs) about HPP.

  UHP is a non-thermal food safety solution* that uses water and high pressure to inactivate harmful foodborne bacteria while maintaining the quality, nutrition, and freshness of the food. Its additional advantages include the absence of preservatives and the extended shelf life. The product is subjected to high levels of hydrostatic pressure (300-600) from a few seconds to a few minutes MPa)。 Another less common but equally valid way to refer to the technique is "high hydrostatic pressure" and "pascalization".

  What foods are suitable for using HPP technology?

  HPP technology is a hydrostatic process that relies on the compression of water to transfer pressure. Therefore, it is recommended that the water activity (AW) of food be above 0.96 to maximize the sterilization effect. In other words, HPP is more effective in high-aw products because the product will have a higher content of free water that can be used to transfer pressure, resulting in higher microbial inactivation and extended shelf life. Please note that the moisture content is different from that of AW. Products can have high moisture content and low AW.

  What are the main applications of HPP technology?

  HPP has been applied to a wide range of foods and beverages: from integrated HPP applications, such as juices and beverages, meat and avocado products, to trends such as ready-to-eat meals (RTEs), plant-based food dips, baby food, and pet food. We recommend visiting the HPP app on our website for a deeper understanding of where to find the business case and the variety of documents and materials where to find each product category.

  What foods should not be HPP technology?

  In order to give full play to the advantages of HPP, the product should have a high water activity content to maximize the killing effect on microorganisms. In addition, this technique alters the texture of food that lacks free water molecules or water molecules that encapsulate food. Therefore, spices, powders, dried nuts, dried fruits, cereals, whole fruits, leafy vegetables, leafy salads, bread, pastries, etc. should not use HPP technology.

  Does HPP affect the composition of food or its organoleptic properties?

  HPP has minimal effect on vitamins, antioxidants, and other micronutrients, flavor, and aroma-forming compounds. HPP retains these compounds better than traditional heat treatment processes. Because HPP does not break covalent bonds, it only affects relatively weak non-covalent interactions, such as hydrogen bonds, van der Waals forces, electrostatic and hydrophobic interactions. These interactions are only responsible for stabilizing the secondary and tertiary structures of proteins, complex carbohydrates, and biological structures (e.g., cell membrane lipid bilayers).

  What are the advantages of HPP over other non-thermal technologies?

  HPP is commonly used in non-thermal food processing technologies (e.g., pulsed electric fields, UV radiation, ionizing radiation, or membrane filtration) in the United States, Europe, Asia, and Oceania. Unlike other non-thermal technologies, HPP is completely non-thermal and can be used on both liquid and solid foods. In addition, as a post-packaging intervention, it removes additives and obtains a clean-label product.

  Can HPP ensure food safety?

  Indeed, HPP ensures food safety and extends shelf life while maintaining the ** attributes of fresh products. In addition, HPP technology is highly recognized by many food safety agencies (e.g., FDA, EFSA). Apply 400 MPa from a few seconds to 6 minutes (4000bar/58000psi) to 600 MPa (6000 bar/87000 psi) pressure inactivates pathogens (bacteria, viruses, molds, yeasts, and parasites). However, due to the presence of some pressure-resistant microorganisms and enzymes, spores will not be inactivated even at the ** working pressure of industrial equipment (600MPa/6000bar/87,000psi), so it can be used in conjunction with other operations, such as lowering the pH value (<4.6), adding natural antibacterial agents, refrigeration (4-6°C), etc. to ensure food safety.

  Does food need to be packaged?

  Generally, food is required to be packaged. The packaging should be waterproof, flexible and elastic to ensure that the food can be placed in water, withstand a certain pressure, and return to its original appearance after processing. Plastic is a common choice. Hiperbaric has developed HPP In-Bulk technology, a groundbreaking innovation that allows liquids to be handled unpackaged, which opens up a range of other packaging solutions that can be used, such as carton bricks, glass bottles, and metal cans.

  Is HPP really a non-thermal process?

  HPP is a non-thermal technique because the temperature during treatment is below 40 °C/100 °F。 However, during this process, there is a slight increase in temperature inside the container. This phenomenon is called adiabatic heating and is associated with water compression. In the special case of water, the temperature rises by about 2-3 for every 100 MPa/1000 bar/15,000 psi of pressure applied °C。 Therefore, considering the ** working pressure of industrial equipment (600MPa/6000bar/87,000psi), the food/water temperature will only increase by 18 °C/64 during holding time °F, usually 2-6 minutes. In addition, adiabatic heating is completely reversible when the pressure is released, and the original temperature level can be restored after treatment.

  Can HPP replace hot pasteurization or sterilization?

  HPP technology inactivates microorganisms, parasites, and viruses by applying pressures of 400 MPa (4000 bar/58,000 psi) to 600 MPa (6000 bar/87,000 psi) for a few seconds to about 6 minutes. However, as with hot pasteurization, some pressure-resistant microorganisms can survive in the product after processing, as well as bacterial spores that are not inactivated by HPP. In addition, HPP does not completely inactivate most enzymes, therefore, HPP does not allow the development of stable foods that are sold at room temperature. On the other hand, HPP-treated products retain their organoleptic and nutritional properties better than traditional heat treatment processes.

  In conclusion, HPP technology offers products with microbiological results similar to thermal pasteurization, but it is not a sterilization technology.

  Can HPP food be stored at room temperature?

  It is recommended to store HPP products refrigerated (4-6°C) as cold chains slow down unwanted microbial growth enzyme activity and chemical reactions during shelf life. Because some microorganisms can resist high pressure and recover within the shelf life. The same happens with enzymes that are not completely inactivated: if they are kept in the cold chain, their residual activity will decrease. Similarly, chemical reactions that are not related to HPP but cause sensory or trophic changes occur in temperature abuse (temperature abuse) (10°C) or at room temperature levels.