What five years on a shelf taught us about our own juice
By Florita S. Maslog, PhD
Scientific Advisor Emeritus, Philippine Morinda Citrifolia, Inc.
Adapted for general readers by the PhilNONI editorial team from Dra. Maslog’s research, and reviewed and approved by the author.
Before I tell you about bacteria, I want to tell you about a bottle.
Every food manufacturer must do stability testing. It is unglamorous work. You keep samples, and at intervals you open them and check whether they have become something other than what you sold. We test for sterility by standard plate count, for pH, for sugar content by Brix, and for the plain sensory qualities — taste, color, odor. We hold the samples at 25–30°C and 65% humidity, which is to say, the ordinary conditions of a Philippine storeroom. No refrigeration. No special handling.
We have examined twenty samples this way. Among them: a bottle one month old, a bottle three years and six months old, a bottle five years old, and a bottle of our stevia variant at one year.
The five-year-old bottle met specification. Sterility below 10 colony-forming units per milliliter. pH between 3.4 and 4.0. Brix between 7 and 9. It was, by every measure we apply, still PhilNONI juice.
I have spent a career in microbiology, and I want to be clear about why this is unusual. Our juice is never pasteurized and never sterilized. There is no step in our process that kills microorganisms — not one. The fruit ripens, it is sun-cured, it rests in sealed vats for months, it is separated, and it is filled at room temperature. A juice made this way, sitting on a shelf for five years in tropical humidity, has every opportunity to spoil.
It did not.
Something in the juice was doing that work. I wanted to know what.
Why we opened a bottle instead of picking a fruit
There is a good deal of published research on Morinda citrifolia, and most of it studies the fruit. Researchers prepare an extract in a laboratory — concentrated, controlled, fresh — and test that.
That work is valuable. But it does not answer the question a customer would actually ask. A customer does not want to know what is in the noni fruit. She wants to know what is in the bottle she just bought.
Those are not the same question. Our juice is not fruit. It is what fruit becomes after six to seven months of natural transformation at ambient temperature. A great deal happens in that time. It is entirely reasonable to wonder whether the compounds that make noni interesting are still present at the end of it, or whether we are selling a bottle of pleasantly sour liquid with nothing left in it.
So when we designed this study, we did not use fresh fruit and we did not prepare an extract. We took a 500ml bottle of 100% PhilNONI juice — the same bottle any buyer would find on a shelf, sealed and ready for market — and treated it as our unknown sample. This bottle came from a batch ready for market; unlike the stability samples described above, its exact age at the time of testing was not separately recorded.
If the phytochemicals did not survive the journey into the bottle, I wanted to be the one to find out.
The three organisms, and why them
There are millions and millions of microorganisms that can cause disease in humans. We chose three: Staphylococcus aureus, Escherichia coli, and Salmonella typhi.
We chose them because they are the organisms that food safety monitoring is built around. Every batch of juice we release is tested for their absence before it leaves us. They are the pathogens a Philippine food manufacturer thinks about constantly, and they are behind a great deal of the food- and water-borne illness reported in this country.
If our juice was going to be tested against anything, it made sense to test it against the organisms we already spend our lives trying to keep out of it.
What we did
Two standard methods, both long established.
The first is the minimum inhibitory concentration test, done by tube dilution. The principle is simple. You take your sample and cut it in half with nutrient broth, then cut that in half, and again — seven times over. Into each tube you introduce a known quantity of bacteria, standardized by the McFarland method to 1.5 × 10⁸ colony-forming units per milliliter. Then you incubate everything at 37°C for one to two days and look to see which tubes stayed clear.
A clear tube means the bacteria did not grow. The question is how far down the dilution series the clarity holds.
But “the juice inhibited growth” means nothing without a scale to measure it against. So we ran a second series alongside, identical in every respect, using chloramphenicol — a broad-spectrum antibiotic — diluted down the same ladder: 250 µg/ml, then 125, 62.5, 31.25, 15.62, 7.8, and 3.9. This gave us a laboratory yardstick. Not a rival, and not a claim of equivalence. A ruler.
Our organisms came from the Philippine National Collection of Microorganisms at BIOTECH, UPLB — Salmonella typhi (1756), Staphylococcus aureus (1582), and Escherichia coli (1634). We included tubes with no organism added, and plates carrying broth and organism but no juice, so we could be confident that what we were seeing was the juice and not the glassware.
What we found
All three organisms — Salmonella typhi, Staphylococcus aureus, and Escherichia coli — were inhibited down through the 1:32 dilution, the same step at which chloramphenicol’s series still held. Growth resumed for both the juice and the antibiotic at the next dilution, 1:64.
We confirmed the result by a second, independent method — the streak method, plating three replicates of each organism on Mueller Hinton agar. All three again showed inhibition. The control plates — broth and organism, no juice — grew as they should have.
Two methods, run separately, agreeing with each other is itself worth noting. It is a small piece of evidence that what we were seeing was real, and not an artifact of one particular technique.
What might explain it
In a separate study, we isolated the phytochemical components present in Philippine Morinda citrifolia and found glucosides, anthraquinones, phenolic compounds, tannins, alkaloids, flavonoids, organic acids, and iridoids.
Several of those classes of compound are known in the literature to have antibacterial activity. Their presence in the finished juice is, at minimum, a plausible explanation for what we observed in the tubes — and for the five-year-old bottle that would not spoil.
I would put it no more strongly than that. We have not isolated which compound is responsible, and we have not measured how much of each is present.
What this study does not show
This is the section I care most about, and I would ask you to read it as carefully as the rest.
A test tube is not a person. What happens when juice meets bacteria in a glass tube on a laboratory bench tells us nothing about what happens when a person drinks it. Drinking involves dilution, stomach acid, digestion, absorption, and a body that is already doing a great deal on its own. None of that was modeled here. This study cannot tell you what noni juice does inside a human being, and I will not pretend otherwise.
We did not separate acidity from chemistry. Our juice sits at pH 3.4 to 4.0. Acid alone inhibits bacterial growth — this is why vinegar preserves food. This study did not include a pH-adjusted control, which means we cannot yet say how much of what we observed came from the phytochemicals and how much came simply from the juice being acidic. That is an honest limitation, and it points directly at the next experiment worth doing.
The antibiotic is a ruler, not a rival. We used chloramphenicol to give our dilution series a scale. Nothing in this study suggests that noni juice can be used the way an antibiotic is used, and nobody should treat it that way. If you have an infection, you need a physician and you need proper medicine.
We make no health claims. PhilNONI is a food. It is not a drug, it is not a treatment, and it is not a substitute for medical care. What we have described here is laboratory work on a bottled beverage, and that is all it is.
This describes a retained sample, not your bottle at home. The bottles in this study were unopened, sealed, and kept under controlled conditions for testing purposes. That is different from a bottle that has been opened, or stored somewhere hot, or kept for an unknown length of time. This finding is a signal about our manufacturing and formulation and not an instruction to disregard the date printed on your bottle. Please follow the shelf life on your label.
Why we are publishing it anyway
Some years ago I would have kept a study like this in a folder until every question had been closed. I have changed my mind about that.
Noni juice has been surrounded by claims for as long as I have known it — many of them enthusiastic, most of them unsupported, and a good number of them made by people who never opened a bottle in a laboratory. The remedy for that is not silence. It is showing your work: what you tested, what you found, what you did not find, and where you are still uncertain.
This is where we are still uncertain. We know that our juice inhibited three organisms in a tube. We do not know why with precision, and we do not know what it means for anyone drinking it.
But we know the bottle on the shelf still has something in it. After five years, it still has something in it. That seemed worth telling you.
Read the full study and Dra. Maslog’s other research →
References
- Maslog, F. (2023). Antibacterial susceptibility of PhilNONI juice versus Salmonella typhi, Staphylococcus aureus, and Escherichia coli. Silliman Journal, 64(1), 106–119. Silliman University, Dumaguete City, Philippines.
- Maslog, F. (2023). Isolation of phytochemical components in Philippine Morinda citrifolia variety (PhilNONI). Silliman Journal, 64(2), 9–24. Silliman University, Dumaguete City, Philippines.
- Henry, J. B. (1979). Todd, Sanford, Davidson: Clinical Diagnosis and Management by Laboratory Methods. London.
- Lima, A., et al. (2017). Biotechnological potential assessment of noni fruit (Morinda citrifolia Linn). MOJ Food Processing & Technology, 5(2), 337–341.
- McFarland standard method for matching turbidity of liquid bacterial suspensions.
- Minimum Inhibitory Concentration and Minimum Bactericidal Concentration (broth tube dilution method). BSCI424 Pathogenic Microbiology, University of Maryland College Park.
No approved therapeutic claims. This product is a food supplement and is not intended to diagnose, treat, cure, or prevent any disease.
MABISANG PANG-KALUSUGAN / PAALALA: Ang produktong ito ay food supplement at HINDI GAMOT, at hindi dapat gamiting panggamot sa anumang uri ng sakit.