If you have purchased a major brand of cold-pressed juice lately, chances are it has undergone the process of HPP (High Pressure Processing). Since there is some confusion about the technology I want to describe the process of HPP, dispel a few myths, and finally discuss why HPP is important and how it has helped our industry.
The Process of HPP
HPP is a processing step that extends shelf life and kills at least 99.999% of the microorganisms in juice. This is referred to as a “5 log reduction”. Here is the process:
- Raw juice is made on a juice press or other type of juicer, then bottled in plastic bottles. (HPP is not the process of making juice itself, but rather a secondary processing step).
- The plastic bottles of juice are loaded into a giant chamber that fills with water and pressurizes the bottles up to 85,000 PSI. To put this pressure in perspective, if you were to tie a rock to a bottle of juice and sink it to the deepest part of the ocean, the Mariana Trench, you would only achieve 1/5th of the pressure created in an HPP machine.
- The pressure maintains between one minute and several minutes depending on settings, then de-pressurizes.
- When the bottles come out the other end, they now contain almost no living microbial content, and now have a shelf life of about 30-45 days, instead of raw juice which is normally 3-5 days. The two major benefits are a safer juice product, and that retail stores can keep the juice on their shelf for much longer without it going to waste. Beyond these benefits, it is actually FDA law that juice must undergo a process like HPP or heat pasteurization in order to be distributed wholesale to re-sellers. If the maker is selling direct to consumer, this process is not required.
The 4 Myths:
Myth 1: Companies must put HPP on the label if it has been used to process the juice.
HPP, heat pasteurization, and other preservation methods are not required to go on the juice label in the US [EDIT: There is an exception for pasteurized orange juice]. Most juice companies choose to put it on the label so consumers know that what they are buying has been processed to make it safer than raw juice. There are many beverage companies who do not put HPP on the label, and some which refer to it under other names such as “Cold-Pressured” or “Pascalization.”
There were some lawsuits made public a few years ago when some cold-pressed juice companies were labeling the product as “100% Raw” and “Unpasteurized” even though it had been through HPP. Although it wasn’t against the law to label the product as raw, the plaintiffs claimed that the juice companies were deceiving their customers.
If you are unsure if juice is raw, look for this warning, as it is required by law to put on the label for raw juice:
“WARNING: This product has not been pasteurized and, therefore, may contain harmful bacteria that can cause serious illness in children, the elderly, and persons with weakened immune systems.”
Myth 2: HPP does not heat the juice.
When juice or any other liquid is pressurized, there is heat created. This type of heating is called “adiabatic heating.” According to the FDA, “HPP treatment will increase the temperature of foods through adiabatic heating approximately 3 °C per 100 MPa.” Juice is pressurized up to 600 MPa, which means that the juice is heated by up to 18 °C (32 °F) from its starting temperature. Note: To find the increase in °F, keep in mind that 1 °C = 1.8 °F, so multiply 18 °C x 1.8 °F = 32 °F.
Once the juice is depressurized, it immediately comes back down to its starting temperature (adiabatic cooling). For example, if the juice goes into the chamber at 45 °F then it can reach 77 °F for a few minutes while under pressure. This is still much less heat than thermal pasteurization temperatures, which are over 160 °F, although only for about 15 seconds.
Myth 3: HPP doesn’t affect nutritional or enzyme content.
According to some studies, HPP has at least a minor affect on nutrient content, with “remaining contents in the range of 87% to 100%.” Enzyme residual activity varies depending on the enzyme being tested and the settings of the HPP process, with majority of residual activity levels “lying in the 20%-60% range.”
It should also be noted that these tests were done immediately after the HPP process, and whether these numbers hold up several weeks later is questionable. Nutrients in raw juice begin to break down in a matter of days, so I assume this is the same with HPP juice, however I cannot find any data on this so it is only my opinion.
Myth 4: HPP juice is always cold-pressed.
As I stated above, HPP is not the process of actually making the juice, but rather a secondary processing step. Just because juice has gone through HPP does not mean it has been cold-pressed. In fact, many HPP “juices” contain purees, smoothies, powders, or other ingredients which are not cold-pressed at all.
Adding to this confusion is the new term “Cold-Pressured.” Within the last couple of years this term has been showing up on beverage products to refer to HPP. “Cold-Pressured” looks so similar to “Cold-Pressed” that I believe this is confusing consumers, and in my opinion should not be used to refer to HPP.
Whether or not I agree with the terms being used, I do think HPP is an important technology and has helped grow the cold-pressed juice industry in the US first, and now world-wide.
Why HPP is Important:
1. HPP makes cold-pressed juice more accessible.
Prior to the use of HPP in the juice industry, it was a mission to find cold pressed juice in most parts of the country, excluding the coastal cities. You had to either hunt down a specialty shop, or be satisfied with juice in the grocery store that had been heat pasteurized. HPP has allowed cold-pressed juice companies to distribute their juice to every part of the country without sacrificing too much of the desired qualities of the juice. The taste, color, texture, and nutrient content of the juice are generally better than heat pasteurized juice, while still extending shelf life substantially (although not as long as heat pasteurization).
2. HPP juice is safer than raw juice.
As discussed in the beginning of this article, HPP successfully achieves a 5 log reduction of microorganism in juice. These potentially harmful bacteria include E. Coli, salmonella, and other bad things. If harmful bacteria does exist in the raw juice, HPP can usually make it safe.
HPP Industry Links
Hiperbaric – HPP equipment manufacturer
Hiperbaric tolling centers – These facilities can HPP your products for a fee.
Avure – HPP Equipment Manufacturer
Avure tolling centers – These facilities can HPP your products for a fee.
Joyce Longfield – HPP industry expert and food regulation consultant. If you are looking for information on where and how to access HPP for your products, Joyce is the best resource I know of.
coldpressure.org – HPP trade organization
Agree or disagree with anything I’ve said here? Please comment below and join the discussion!