DISADVANTAGES OF STANDARD TREATMENTS

Heat treatments uses are so wide-ranging because they inactivate bacteria and/or inhibit bacterial growth,  thus extending the shelf-life even for a year as in the milk powder. However, they have several major drawbacks:

• The conventional thermal methods applied in the food industry (e.g. pasteurisation or thermal sterilisation) can induce negative effects in micronutrients and essential biomolecules of dairy products such as degradation, denaturation and inactivation of alkaline phosphatase, lactoperoxidase and especially whey proteins.
• Temperature also promotes the interaction between amino acids and sugars in a process well-known as Maillard reactions. These reactions lead to several modifications in color and taste, and also diminish the bioavailability of essential amino acids, since some vitamins, like tocopherol (vitamin E) are degraded.
• Heat pasteurisation inactivates lactic acid bacteria (LAB) preventing their beneficial effect.

To increase the shelf-life of dairy products without the negative effects that come with high-temperature, the food industry has tried other methods like ultraviolet radiation, thermosonication or pulsed electric fields but none of them has been so accepted as high pressure processing (HPP).

WHAT DOES HPP BRING TO DAIRY INDUSTRY?

High Pressure Processing (HPP) also known as high pressure pascalisation or cold pasteurisation is a non-thermal (5 deg C – 20 deg C) food and beverage preservation method that guarantees food safety and achieves an increased shelf-life, while maintaining the optimum attributes of fresh products.

But what different things does HPP bring to the dairy industry and why is growing between worldwide companies?

FOOD SAFETY & CLEAN LABEL

Mario González explains that according to several studies, HPP inactivates foodborne pathogens and spoilage microorganisms and clarifies us "for instance, Lactococcus sp. and yeasts were inactivated below the detection limit (10² CFU/g) in fresh curd cheeses processed at 600 MPa for 5 min and L. monocytogenes can be effectively controlled as well in fresh cheese, causing reductions below the detection limit (0.91 log CFU/g) when processing at 600 MPa. In addition, HPP in-pack technology eliminates the risk of cross-contamination when processing products in their final packaging."

It also decreases or can eliminate the need for chemical preservatives, which allows a clean label and premium quality standards that consumers and manufacturers demand nowadays.

PRODUCT DEVELOPMENT & SHELF-LIFE EXTENDED

Mario clarifies that "if we focus on probiotics, it is interesting to note that some LAB strains are pressure resistant and can survive after processing at 600 MPa (87,000 psi) for various minutes". Obviously, this opens a wide range of possibilities in developing probiotic products with a long shelf-life, since pathogens and spoilage microorganisms can be controlled while probiotic cultures remain alive. Mr. González adds that "HPP also helps to preserve sporulated probiotic cultures, such as Bacillus coagulans what is a great news for all food producers who are planning or already inoculating their products with spores of probiotic bacteria."

The shape and integrity of dairy products packaged in flexible materials remain unchanged because pressure transmission is uniform and instantaneous, regardless of packaging dimensions, allowing a wide variety of presentations for convenient commercialisation.

NUTRITIonAL VALUE & ADDITIonAL CHARACTERISTICS

The yogurt industry can also benefit from HPP in various ways. For instance, processing milk before fermentation improves the viscosity of the yogurts and significantly reduces syneresis. The application of HPP to yogurt after fermentation has other advantages in terms of shelf-life extension.

The destabilisation and disruption of some proteins that HPP causes on milk components do not affect the functionality of bioactive molecules. This allows developing functional products like the colostrum.

WHY IN NOW AND NOT BEFORE?

Despite the numerous and potential applications that high pressure processing offers to the dairy industry, it is estimated that only around two percent of the global HPP machines are working on dairy applications.

The main factor is that milk and dairy products follow worldwide very strict regulations, which sometimes restrict the innovation capacity of producers.

According to FAOs Codex Alimentarius, "raw milk" is defined as "milk which has not been heated beyond 40ºC or undergone any treatment that has an equivalent effect". In the European unio, HPP is considered as a processing step with an effect on microorganisms equivalent to heat pasteurisation. Guidance for the implementation of Regulation (EC) No 852/2004 clearly indicates that "HPP with the purpose of decontamination should be considered as processing". For this reason, labeling and claiming HPP milk as "fresh" or "raw" seems complicated in the European market. Nevertheless, HPP milk would keep its fresh attributes as HPP juice does.

In the United States, the commercialisation of milk is only possible when an equivalent treatment to heat pasteurisation is applied to the product, which would include a 5 log CFU/ml reduction of Coxiella brunetii. Currently, there are no scientific reports on the lethal effect of HPP against C. brunetii on milk.

"Despite of that, well-known brands around the world have taken risks and have won with very different dairy products: cheese, raw milk, smoothies and functional beverages, yogurt, dressings and spreads or probiotic products, among others", points out Mario.

Without a doubt, HPP is the new revolution in the dairy industry worldwide.