High-pressure processing destroys harmful pathogens that cause disease and deteriorate food. It is more effective than other treatments and ensures food safety. It is a nonthermal technique for food preservation that uses extreme pressure ranges between 100-1000mPa for specific time and temperature, with less effect on the nutritional values and sensory characteristics of food.
1. Principles of High Pressure Processing (HPP)
HPP high-pressure processing works on the Le-Chatlier principle. This principle describes that when pressure is applied to a system in equilibrium, it reacts to resist the changes in equilibrium. This reaction decreases the volume with the increase in pressure and inactivates the enzymes and microorganisms.
Another essential principle of HPP is Isostatic Processing. This describes how when pressure compresses the food from every direction, it returns to its original shape after the pressure is released. High pressure also affects the food’s chemical, biochemical, microorganism, enzymatic, and functional properties.
1.1 Uses of High Pressure Processing to Improve Food Safety and Quality
High pressure (100-1000mPa) is applied to food with or without heat to inactivate the microbes and change the food characteristics to meet consumer satisfaction and ensure food safety.
- Food processors use high-pressure processing to treat a variety of foods, including semi-solid food, solid food, and value-added liquids, to ensure a high-quality and safe end product. They treat food products such as seafood, ready-to-eat meals, juices, deli meats, guacamole, and beverages with high pressure.
- Salsa, James, pet food, baby food, vegetables, and fruit products are some categories treated by high pressure.
- HPP applies mainly to acidic food with a pH of less than 4.6.
- HPP extends the shelf life of food up to 4 months, depending on processing parameters such as pressure, temperature, and time. This enhances the quality of food, makes it microbial-free, and makes it safe for consumption.
- Compared to thermal processing, HPP has less effect on food properties such as vitamins, pigments, and flavor compounds. It does not break the covenant bond either. So, the quality of HPP food is equal to that of fresh food products.
- HPP provides the conditions for developing new food textures in starch—or protein-based foods. Without thermal treatment, pressure is applied to make protein gels and high-viscosity products.
1.3 Effect of High Pressure on Food Quality
High pressure inactivates the microbes, vegetative cells, yeasts, and molds that cause food-borne illness. Consumers highly demand the inactivation of harmful microbes in food with safety.
HPP increases food’s shelf life, and food with a long shelf life is considered high-quality food. High pressure has a low effect on food properties, such as flavor compounds and pigments of flavor. It doesn’t break the covalent bond that makes its quality equal to that of fresh food.
1.4 Other Applications of High Pressure on Food
- Food processors use high-pressure processing to preserve the freshness of foods such as dairy products (yogurt, milk, and cheese), juices, beverages, and smoothies, maintaining their flavor and nutritional properties.
- HPP extends the shelf life of cured or cooked meat by inactivating microbes. It is also used to preserve sea foods such as shellfish and fish.
- Pressure application is used in the industry to prepare ready-to-eat meals by killing pathogens like Salmonella, Listeria, and E. coli.
- HPP is also used to prepare functional foods that provide bioactive compounds and to process probiotic products.
1.5 Modeling of HPP
Modeling of HPP is modeled using computational and mathematical models to stimulate the HPP effect on food. It helps to evaluate the parameters in the HPP and how pressure, time, and temperature affect the chemical, physical, and biochemical properties. It involves the physical models to distribute pressure and temperature changes and the effect of cooling.
Microbial Inactivation Models
It involves applying different rates of pressure and temperature to inactivate the microbes.
Enzyme inactivation model: It involves the denaturation of enzyme by applying high pressure.
Nutritional and chemical changes: The modelling of HPP involves the high-pressure application to the chemical and nutritional profile of the food, such as vitamin degradation and lipid oxidation.
Structural and textural changes: HPP modelling evaluates the flow behavior and deformation of the food product under the application of high pressure and compression and decompression effect
Steps in HPP modeling
- Collecting Data
- Formulating mathematical validating models
- Estimating Parameter
- optimization and stimulation
- implementation
1.6 Outlook for High Pressure Processing of Food
Various food industries apply HPP to prepare products such as salads and ready-to-eat meals. The food industry requires HPP to meet consumer demands for extended shelf life, high quality, and stable food. It involves the trends and opportunities for the outlook of HPP:
- Consumers demand food without additives and artificial preservatives. HPP meets this trend by preserving food through natural treatment.
- Food that is distributed to the consumers should be safe for consumption. HPP aligns with this trend.
- HPP applies to a variety of food products. It contributes to food processing by reducing waste, extending shelf life, and enhancing sustainability.
- HPP contributes to developing unique products with unique flavor and texture, such as extended-life smoothies and innovative plant-based food.
- HPP has significant opportunities to expand in the current market with its aligning trends. HPP provides functional and nutritional foods that are health-oriented.
- The challenges HPP can have could be: The initial cost of installing HPP equipment is high, which can be problematic for small business investors. However, since consumers should be educated about the high-pressure processes of food, HPP products will be in high demand in the market.
2. HPP Salads and Ready Meals
The food industry uses High-Pressure Processing (HPP) to prepare ready-to-eat meals with extended shelf life without compromising quality. HPP also extends shelf life and maintains freshness and crispiness in fresh-cut vegetables. Food processors treat salads like tomatoes, cucumbers, leafy green vegetables, and dressings with HPP.
Food processors also treat fruit salads with high pressure. They treat cold meals such as deli-style meals, sushi, and poke bowls to maintain their quality and freshness. Additionally, they use high pressure in the processing of beef, chicken, and seafood.
2.1 Importance of Salads and Ready-to-Eat Meals
HPP food salads and ready-to-eat meals undergo treatment to inactivate harmful microbes that can cause food-borne diseases. People consume these salads without further cooking. The salads and ready-to-eat meals preserve freshness and minimize waste, contributing to food safety and sustainability. HPP salads and ready-to-eat foods retain their nutritional profile and functional properties.
In salads and foods, there are no excessive preservatives and additives. So, all these properties are beneficial for the consumer’s health. The availability of ready-to-eat meals and highly nutritious foods meets customers’ demands.
2.2 Pressure Effect on Microorganisms
HPP disrupts the cell structure and function. Pressure ruptures the cell membrane and leads to cell death, effectively preventing the growth of yeasts and molds. Pressure denatures the protein and enzymatic activity that can cause microbial growth.
High pressure also disturbs the nucleic acid that retards the transcription process and microbes reproduction. Vegetative cells, spores, and viruses are sensitive to high pressure but can be inactivated by applying 300-600 mPa pressure. Salads and ready-to-eat meals with cooked protein and nutritional ingredients are safe for consumers.
2.3 Pressure Effect on Enzymatic Activity
High pressure denatures proteins and enzymes by changing their structure to inactivate them. Inactivation is essential to prevent food spoilage—for example, polyphenol oxidase results in browning in vegetables and fruits. Pressure is set according to the sensitivity of enzymes because each enzyme has a different level of sensitivity. Inactivating enzymes to avoid browning in vegetable and fruit salads extends their shelf life.
2.4 Pressure Effect on Texture
HPP maintains the crispiness and freshness of fruits and vegetable salads, but excessive pressure destroys cell structure and soft texture. So, it is necessary to maintain selective parameters.HPP in meats denatures the protein and produces a gel, producing a juicy and firm texture product. Pressure inactivates the pectin methylestrate and enzyme degradation essential for the crispiness of salad.
Moisture retention prevents dryness and maintains juiciness in food. HPP leads to the gelatinization of starch, which improves the texture of starch-based food products. Food processors should manage and maintain parameters of HPP, such as temperature, pressure, and timing, for the optimal implementation of the process because each profile requires different parameters.
2.5 Pressure Effects on Nutrients
Pressure also affects the nutritional properties of food. HPP doesn’t break down covenant bonds and preserves the antioxidants, vitamins, and flavor compounds. Pressure is applied correctly to not affect pressure-sensitive compounds such as vitamins B and C . HPP degrades the enzymes that disturb the nutritional value of food. The high pressure processing- HPP retains lipids and fats’ oxidative stability, lead, which has an extended shelf life.
3. Microbial Effect of HPP
HPP is a food preservation method to inactivate harmful microbes and extend the shelf life for better quality food products. Bacteria like Salmonella, listeria, and E.coli are destroyed by high pressure processing. High pressure inactivates the yeasts, spores, and vegetative cells for the extended shelf life of food products. Enzymatic activity is retarded by HPP to prevent spoilage. HPP results in the most minor chemical changes, retains flavor, and extends the shelf life of food products.
3.1 Factors Affecting the Effectiveness of Treatment
Many factors affect the effectiveness of the treatment of HPP:
Temperature: HPP is not a thermal process, but temperature high or low can affect its effectiveness.
Timing: Pressure application for a specific period is crucial for accurately implementing the treatment for the least microbial growth.
Food composition: The content of fats, carbohydrates, lipids, water activity, and pH affects the inactivation of microbes.
Pressure: The application of HPP to food must be specialized according to the food for effective microbe inactivation.
Species of microbes: Different species have different sensitivity levels to pressure. So, optimal pressure should be applied for effective results.
Regulatory requirements: while implementing HPP on food, the process should meet compliance with regulatory requirements.
3.2 Effects of High-Pressure
High-pressure processing affects the microbes and results in safe food products. HPP inactivates harmful pathogens that can deteriorate food and cause sickness, such as yeasts, molds, and viruses. Pressure destroys the structure of cells and stops their growth.
High pressure destroys cell membranes, nucleic acid, and proteins, leading to cell death and impaired growth. HPP ensures uniform food treatment for a sustainable product. HPP damages bacterial growth, reduces food quality damage, and maintains the integrity of the product.
4. Conclusion
High-pressure processing (HPP) is a significant advancement in food preservation, offering numerous benefits over traditional methods. HPP effectively destroys harmful pathogens, ensuring food safety and extending shelf life while maintaining the nutritional and sensory qualities of the food.
Key Points:
- Principles and Mechanisms:
- HPP operates on the Le-Chatelier principle, inactivating enzymes and microorganisms through pressure application.
- Isostatic processing ensures uniform pressure distribution, allowing food to retain its shape post-processing.
- Applications:
- Suitable for various foods, including seafood, ready-to-eat meals, juices, and fruits.
- Particularly effective for acidic foods with a pH of less than 4.6.
- Benefits:
- Enhances food safety by inactivating harmful microbes.
- Preserves nutritional and sensory qualities.
- Extends shelf life and reduces the need for artificial preservatives.
- Challenges:
- High initial equipment costs.
- Need for consumer education on HPP benefits.
- Future Outlook:
- Growing potential in the food industry due to demand for natural, additive-free products.
- Supports innovative food textures and functional foods.
In summary, HPP is a versatile and effective method for improving food safety, extending shelf life, and maintaining food quality, positioning it as a valuable future technology in food processing.