High-Pressure Processing to Extend Shelf Life

High-pressure processing (HPP), also known as high-pressure pasteurization, is a food preservation technique that uses elevated pressure to extend the shelf life of food products.

The process works by applying pressure evenly and uniformly throughout the food product. Pressure is transmitted through a liquid medium, usually water, which surrounds the food. The food is typically placed in a high-pressure chamber, where pressure is increased to the desired level for a predetermined period, typically a few minutes. The pressure is later released, and the food is removed from the chamber.

The packaged or sealed food product is subjected to high levels of hydrostatic pressure, typically between 300 and 600 megapascals (MPa) or 43,500 and 87,000 pounds per square inch (psi).

Food preservation techniques are devised to serve a threefold purpose – minimize microbial and enzymatic activity, ensure pack integrity, and extend shelf life.

Extending the shelf life can help curtail food wastage, which would help remove one-quarter of the total greenhouse gas emissions from the global food system. Preservation techniques, like HPP, play a part in ensuring customer confidence by the maintenance of clean labels without compromising product quality or safety.

The high pressure exerted during HPP has several effects on microorganisms, enzymes, and other components of the food:

1. Microbial inactivation: HPP effectively kills or inactivates most types of bacteria, yeasts, molds, and parasites that can spoil food or cause foodborne illnesses. It disrupts their cellular structure and enzymatic systems, rendering them unable to grow or cause spoilage.

2. Enzyme inactivation: Many enzymes responsible for food deterioration and quality degradation are sensitive to pressure. HPP can inactivate these enzymes, including those that cause browning, texture degradation, and off-flavors in food.

3. Extended shelf life: By controlling the microbial load and enzyme activity, HPP helps to extend the shelf life of food products. It can significantly slow down the natural deterioration processes, maintaining the freshness, quality, and nutritional value of the food for an extended period.

HPP is commonly applied to meat, poultry, seafood, fruits, vegetables, juices, soups, sauces, dips, ready-to-eat meals, and even certain dairy products. It is a non-thermal preservation method and so does not rely on high temperatures, which can negatively impact the sensory and nutritional qualities of the food. Instead, HPP allows food manufacturers to achieve microbial safety and quality preservation while minimizing the need for additives or excessive heat treatment

Proper storage conditions, such as refrigeration, are still necessary to maintain the safety and quality of HPP-treated products as the process does not make the food completely shelf-stable but rather, helps extend shelf life.