How Can You Tell Whether a Rose Product Is Safe and Stable?
Understanding Microbiological Safety, Stability Testing and Preservation Efficacy in Rose Water and Rose Distillates
When evaluating the quality of rose water, rose distillates, and rose-containing cosmetic products, another factor deserves just as much attention as fragrance, colour, and ingredients: microbiological safety.
Particularly in water-based products, controlling microorganisms is an essential part of product safety.
However, a common misconception must be addressed: the fact that a product is described as “natural,” has been obtained through distillation, or contains constituents with antimicrobial properties does not, by itself, demonstrate that it will remain microbiologically safe throughout its shelf life.
Microbiological safety must be evaluated by considering the product itself, its manufacturing process, hygiene conditions, packaging, storage conditions, and, where appropriate, microbiological analyses, stability studies, and preservation efficacy tests.
In this chapter of Akita Rose Academy, we will first distinguish these scientific concepts and then examine a real-world example involving Rosa damascena products and laboratory analyses performed on Akita Non-Deoiled Rose Water.
1. What Is Microbiological Safety?
Microorganisms are a natural part of our environment.
Bacteria, yeasts, and moulds may be found in the air, water, raw materials, manufacturing environments, and on the human body.
For cosmetic products, the important requirement is to meet acceptable microbiological quality criteria and be free from specified undesirable microorganisms, taking into account the characteristics and intended use of the product.
Laboratory testing may therefore include the assessment of:
Total aerobic microbial count
Yeast and mould count
Pseudomonas aeruginosa
Staphylococcus aureus
Escherichia coli
Candida albicans
However, there is an important distinction between a product meeting microbiological acceptance criteria at a particular point in time and remaining microbiologically stable throughout its intended shelf life.
Rose Academy Insight: Three Different Scientific Questions
Microbiological Testing
Are microorganisms present in the product at the time of testing, and do the results meet the applicable microbiological acceptance criteria?
Stability Testing
Does the product maintain its defined characteristics over time under different storage conditions?
Challenge Testing
When specified microorganisms are deliberately introduced into the product, can the product control their growth or reduce their populations?
These tests answer different scientific questions and cannot be used interchangeably.
2. Why Is Microbiological Safety Important in Rose Products?
Pure rose essential oil and rose water do not have the same physical characteristics.
Rose water and rose distillates are primarily water-based products.
Therefore, the general assumption that “a product has been distilled, so it cannot spoil” is not scientifically sufficient.
Although distillation provides an important opportunity for microbial control during manufacturing, additional conditions arise throughout the subsequent stages of a product's life cycle:
Filling → Packaging → Storage → Transportation → Opening → Consumer Use
At each stage, different factors may influence the product's microbiological quality.
We must therefore ask two separate questions:
Does the product meet microbiological acceptance criteria immediately after manufacturing?
And:
Can the product maintain those characteristics over time?
Answering the second question requires analytical evidence obtained directly from the finished product.
3. Not All Rose Waters Are the Same
Although the term “rose water” is commonly used as though it describes a single type of product, manufacturing methods and the resulting chemical compositions may differ considerably.
For example, traditional rose water obtained during rose essential oil production, after the oil phase has been separated, should not automatically be considered equivalent to a rose distillate in which the essential oil is not separately removed.
Several production factors may influence the finished product:
Quality and characteristics of the botanical raw material
Rose flower-to-water ratio
Distillation technique
Distillation duration
Retention of volatile compounds
Separation or retention of the rose essential oil
Manufacturing hygiene
Filling conditions
Packaging materials and procedures
For this reason, scientific findings obtained from a product described as rose water or rose hydrosol should not automatically be generalized to all rose waters.
The first step is to understand how the product used in the study was manufactured.
4. Can Microbial Spoilage Occur in Rose Water?
Yes.
The natural origin of rose water, or the fact that it is obtained through distillation, does not mean that every rose water product will remain microbiologically stable indefinitely.
This subject has also been investigated by researchers studying Rosa damascena in Türkiye.
Research conducted by Hasan Baydar and colleagues examined microbial spoilage in rose water and different approaches to controlling it.
The researchers evaluated methods including:
Pasteurization
Ultraviolet (UV) treatment
Chemical preservatives
Such studies highlight an important scientific principle:
The name “rose water” does not, by itself, guarantee microbiological stability.
However, the opposite assumption would also be incorrect.
The observation of spoilage in one rose water product does not necessarily mean that every rose distillate produced through a different process and possessing a different chemical profile will behave in the same way.
This is precisely why product-specific testing is essential.
5. “Antimicrobial” and “Microbiologically Stable” Do Not Mean the Same Thing
These two concepts must be clearly distinguished.
When a botanical extract, essential oil, or distillate demonstrates activity against a particular microorganism under laboratory conditions, the finding relates to its antimicrobial potential.
By contrast, the ability of a finished cosmetic product to maintain acceptable microbiological quality throughout its shelf life relates to product safety and stability.
For example, an antibacterial study conducted on Rosa damascena or one of its constituents cannot support the general conclusion:
“All rose waters are resistant to spoilage.”
Likewise, a satisfactory microbiological test result does not mean:
“This product kills all microorganisms.”
Understanding this distinction is fundamental to interpreting scientific evidence correctly.
An antimicrobial effect observed under specific experimental conditions does not automatically establish the long-term microbiological stability of a finished cosmetic product.
6. How Is the Microbiological Safety of a Product Evaluated?
Different laboratory methods answer different questions about microbiological quality.
Microbial Count and Specified Microorganism Testing
These analyses examine the microbiological condition of a particular sample at the time of testing.
They may include the enumeration of microorganisms and the detection of specified microbial species.
The results provide information about whether the sample meets the relevant microbiological acceptance criteria.
Stability Testing
During a stability study, the product is stored under defined conditions for a specified period.
Researchers may monitor microbiological characteristics alongside other parameters, including:
pH
Appearance
Fragrance
Density
Packaging condition
Stability testing therefore provides information about how a product behaves over time.
Preservation Efficacy Testing (Challenge Testing)
Challenge testing follows a different approach.
A defined quantity of selected test microorganisms is deliberately introduced into the product.
The microbial populations are then measured at predetermined intervals.
This approach goes beyond determining whether microorganisms were present in the product initially.
It evaluates how the product responds when exposed to a controlled microbial challenge.
7. Case Study: Akita Non-Deoiled Rose Water
We can now move beyond the general scientific literature on rose water and examine laboratory findings obtained from a specific finished product.
According to the manufacturer's formulation information, Akita Non-Deoiled Rose Water is a single-ingredient product, and no additional preservatives are introduced into its formulation.
Its declared ingredient is:
Rosa Damascena Flower Distillate
This makes the results of its stability and challenge tests particularly relevant to the scientific evaluation of its microbiological behaviour.
7.1. The 90-Day Stability Study
In a study conducted by the Bilim laboratory, Akita Rose Water samples were evaluated under several storage conditions.
The conditions included:
Room temperature with light exposure
Room temperature in darkness
Refrigerated storage at 4°C
Elevated-temperature storage at 45°C
Assessments were performed at defined intervals, including days 1, 28, and 90.
Reported Microbiological Results
| Microbiological Parameter | Reported Result |
|---|---|
| Total aerobic microbial count | <10 CFU/g |
| Yeast and mould count | <10 CFU/g |
| Candida albicans | Not detected |
| Pseudomonas aeruginosa | Not detected |
| Escherichia coli | Not detected |
| Staphylococcus aureus | Not detected |
According to the laboratory report, these microbiological findings were maintained during the monitored storage conditions.
The study also evaluated other product characteristics, including:
Colour
Fragrance
pH
Density
Packaging condition
The scientifically appropriate interpretation is:
The tested Akita Rose Water samples maintained low microbial counts and met the specified microbiological acceptance criteria during the 90-day study under the storage conditions examined.
This study does not, by itself, establish that the product has an unlimited shelf life.
However, it provides direct product-specific evidence about stability under the tested conditions.
8. A More Demanding Evaluation: The ISO 11930 Challenge Test
Akita Non-Deoiled Rose Water was also subjected to a Preservation Efficacy Test, commonly known as a Challenge Test.
The test was conducted according to the ISO 11930 protocol.
The key difference from routine microbiological testing is particularly important.
Rather than simply examining whether microorganisms were present in the product, the laboratory deliberately introduced selected microorganisms at relatively high concentrations.
Microorganisms Used in the Test
The test included five microorganisms:
Pseudomonas aeruginosa
Escherichia coli
Staphylococcus aureus
Candida albicans
Aspergillus niger
These organisms were introduced into the test samples under controlled laboratory conditions.
What Did the Results Show?
According to the laboratory report, the initial inoculation levels were approximately:
2 × 10⁷ CFU/g for the bacterial test organisms
3 × 10⁶ CFU/g for Candida albicans and Aspergillus niger
By day 7, all five tested microorganisms had been reduced to reported levels of:
<10 CFU/g
The reported logarithmic reductions were:
5.30 log reduction for the bacterial organisms
4.48 log reduction for the yeast and mould organisms
The same reported result of <10 CFU/g was maintained at days 14 and 28.
Laboratory's Final Assessment
The laboratory's final evaluation was:
“SUITABLE”
These findings indicate that the tested product demonstrated substantial microbiological control against the deliberately introduced microorganisms under the conditions of the ISO 11930 challenge test.
This is an important product-specific result.
However, it must not be interpreted as evidence that:
“The product kills every microorganism.”
The results provide evidence only for the specified test organisms, the tested sample, and the experimental conditions described in the report.
9. Does Akita Non-Deoiled Rose Water Contain Preservatives?
This question introduces another important scientific consideration.
According to the formulation information provided by the manufacturer, Akita Doğal Ürünler A.Ş., the product contains one ingredient, and no preservatives or alcohol are added during formulation.
In addition to the manufacturer's statement, an independent laboratory analysis is available.
In 2021, the Natural Products Application and Research Centre at Süleyman Demirel University conducted paraben and alcohol analyses on an Akita sample identified as Rosa Damascena Flower Water.
Paraben Analysis
The following substances were investigated:
Methylparaben
Ethylparaben
Propylparaben
Butylparaben
Isobutylparaben
Hexylparaben
Benzylparaben
Hexamidine paraben
Hexamidine diparaben
None of the listed substances was detected in the tested sample.
Alcohol Analysis
The laboratory also investigated:
Methyl alcohol
Ethyl alcohol
Isopropyl alcohol
None of these alcohols was detected in the tested sample.
Understanding the Limits of the Evidence
It is important to preserve the scientific distinction between a manufacturer's formulation declaration and an analytical test result.
The laboratory analysis demonstrates that the specific parabens and alcohols included in the analytical scope were not detected in the tested sample.
However, this was not a comprehensive screening for every possible preservative substance.
Therefore, it would be scientifically inaccurate to interpret these analytical results as proof that every potentially preservative chemical was absent.
The statement that no preservatives are added to the formulation is based on the manufacturer's formulation information.
The laboratory findings provide additional evidence concerning the specific substances examined.
10. How Can a Product Without Added Preservatives Demonstrate These Results?
From a scientific perspective, this may be one of the most interesting questions raised by the findings.
How can a single-ingredient Rosa damascena distillate, reportedly formulated without added preservatives, demonstrate such results in an ISO 11930 challenge test?
The available laboratory tests reveal how the product behaved under the experimental conditions.
However, they do not independently explain the biochemical mechanisms responsible for that behaviour.
Several factors may deserve further investigation:
The product's volatile chemical profile
Its water-soluble constituents
Its pH
The distillation method
Possible interactions among naturally occurring constituents
A particularly important scientific distinction must be maintained:
A challenge test demonstrates the product's response to a defined microbial challenge; it does not establish which molecule or mechanism is responsible for the observed effect.
Consequently, attributing Akita's microbiological stability to one particular volatile compound would require additional mechanistic research.
Such research could examine how the product's natural chemical composition and manufacturing conditions contribute to the microbiological behaviour observed in laboratory studies.
This represents a potentially valuable direction for future investigations into Rosa damascena distillates.
11. Why Do We Distinguish Between Deoiled and Non-Deoiled Rose Water?
This distinction is particularly important in Akita Rose Academy.
Akita Non-Deoiled Rose Water should not automatically be considered equivalent to traditional rose water from which rose essential oil has been separated.
The products differ in their manufacturing approaches.
These differences may influence their chemical composition and other characteristics.
Therefore, the results of a microbiological study conducted on traditional rose water cannot automatically be applied to Akita Non-Deoiled Rose Water.
Equally, the results of stability and challenge testing performed on Akita Non-Deoiled Rose Water cannot be generalized to all rose waters.
This scientific approach encourages us to ask a more precise question.
Instead of:
“Does rose water spoil?”
We should ask:
“Which rose-derived product, obtained through which manufacturing process and possessing which chemical composition, is being evaluated under which storage conditions and according to which laboratory results?”
This is a much more scientifically meaningful question.
12. What Should Consumers Look for in a Rose Product?
Terms such as “natural,” “pure,” and “traditional” do not independently demonstrate microbiological safety.
Consumers can make more informed choices by asking several questions.
How Was the Product Manufactured?
The distillation process and subsequent manufacturing stages matter.
A product obtained through a particular distillation method should be evaluated according to its own characteristics.
What Is the Product's Formulation?
A single-ingredient botanical distillate and a multi-ingredient water-based cosmetic formulation should not automatically be evaluated in the same way.
Has Microbiological Testing Been Conducted?
Laboratory findings obtained from the actual finished product provide more meaningful evidence than general assumptions based on botanical origin.
Have Stability Studies Been Performed?
Stability studies provide information about how the product behaves over time, rather than only describing its condition at a single point.
Has a Challenge Test Been Conducted?
For water-containing cosmetic products, preservation efficacy testing can provide particularly valuable information about how a formulation responds to deliberate microbial contamination.
Together, these questions help consumers understand why product-specific scientific evidence matters.
What Can We Conclude Scientifically?
The microbiological safety of rose-derived products cannot be established solely on the basis of the natural properties of the rose plant.
Manufacturing methods, product composition, hygiene, packaging, storage, and laboratory testing performed on the finished product must be considered together.
For Akita Non-Deoiled Rose Water, the available information provides three distinct layers of evidence.
1. Stability Study
The stability study showed that the tested samples maintained their reported microbiological characteristics over 90 days under different storage conditions.
2. ISO 11930 Challenge Test
The ISO 11930 challenge test demonstrated that five microorganisms introduced at high concentrations were reduced to <10 CFU/g by day 7.
The laboratory's final assessment was “SUITABLE.”
3. Paraben and Alcohol Analysis
The analysis conducted by Süleyman Demirel University showed that the specified parabens and methyl, ethyl, and isopropyl alcohol were not detected in the tested Akita sample.
According to the manufacturer's formulation information, the product contains one ingredient and no added preservatives.
When these findings are considered together, an important research question emerges:
What roles do the manufacturing method and natural chemical composition of a non-deoiled Rosa damascena distillate play in its observed microbiological behaviour?
The available analytical findings provide substantial product-specific evidence about the microbiological behaviour of the tested samples.
Explaining the underlying mechanisms, however, should remain the subject of future controlled scientific research.
Rose Academy Summary
Natural origin is not proof of microbiological safety.
Antimicrobial activity and shelf-life stability are not the same concept.
Results obtained from one rose water product cannot automatically be generalized to all rose waters.
Microbiological analyses, stability studies, and challenge tests answer different scientific questions.
The ISO 11930 challenge test performed on Akita Non-Deoiled Rose Water received a final laboratory assessment of “SUITABLE.”
What matters scientifically is not the strength of a claim, but measurable evidence obtained from the product itself.
Frequently Asked Questions (FAQ)
1. Can rose water undergo microbiological spoilage?
Yes.
The term “rose water” does not guarantee microbiological stability.
Manufacturing methods, chemical composition, hygiene, filling conditions, packaging, and storage can influence microbiological quality.
For this reason, rose waters obtained through different production methods should not automatically be assumed to have identical properties.
2. Can natural rose water remain microbiologically stable without added preservatives?
This question must be answered through product-specific testing.
According to the manufacturer, Akita Non-Deoiled Rose Water is a single-ingredient product with no preservatives added to its formulation.
The stability and challenge tests performed on this product provide direct laboratory evidence concerning its microbiological behaviour under the tested conditions.
3. Does Akita Non-Deoiled Rose Water contain preservatives?
According to the manufacturer's formulation information, the product contains a single ingredient, and no preservatives are added.
Furthermore, analyses performed by Süleyman Demirel University did not detect the specified parabens or methyl, ethyl, and isopropyl alcohol in the tested sample.
However, this analysis should not be interpreted as a comprehensive investigation of every possible preservative substance.
4. What is a challenge test?
A challenge test is a controlled laboratory procedure designed to evaluate how a product responds to microbiological contamination.
Specified microorganisms are deliberately introduced into the product, and changes in their populations are measured at defined intervals.
This differs from routine microbiological testing, which examines the microbial condition of a sample at the time it is tested.
5. Did Akita Non-Deoiled Rose Water pass the challenge test?
Yes.
The ISO 11930 challenge test involved:
Pseudomonas aeruginosa
Escherichia coli
Staphylococcus aureus
Candida albicans
Aspergillus niger
According to the report, all five test organisms were reduced to <10 CFU/g by day 7.
The same reported level was maintained at days 14 and 28.
The laboratory's final assessment was “SUITABLE.”
6. What did the stability test reveal about Akita Rose Water?
During the 90-day stability study, the product was evaluated under room-temperature light and dark conditions, as well as at 4°C and 45°C.
Under the examined conditions:
Total aerobic microbial counts remained below 10 CFU/g.
Yeast and mould counts remained below 10 CFU/g.
Candida albicans, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus were not detected.
These results provide evidence concerning the stability of the tested samples during the study period.
7. Are stability testing and challenge testing the same?
No.
Stability testing monitors how a product's characteristics change over a defined period under specified storage conditions.
Challenge testing evaluates how a product responds when selected microorganisms are deliberately introduced.
The two approaches are complementary but address different scientific questions.
8. Does the challenge test prove that Akita Rose Water kills microorganisms?
It would be scientifically incorrect to make such a broad claim.
The results must be interpreted in relation to the specific microorganisms and experimental conditions used.
The appropriate conclusion is that the tested Akita sample demonstrated the required microbiological control under the ISO 11930 challenge-test conditions and received a final assessment of “SUITABLE.”
9. What explains the successful challenge-test results of Akita Rose Water without added preservatives?
The available tests demonstrate the observed outcome, but they do not establish the underlying mechanism.
Factors requiring further investigation include:
Manufacturing process
pH
Naturally occurring volatile compounds
Water-soluble constituents
Interactions among different components
Additional controlled mechanistic studies would be necessary to identify which factors are responsible for the observed results.
10. Are traditional deoiled rose water and Akita Non-Deoiled Rose Water the same?
No.
They must be distinguished according to their manufacturing methods.
In Akita Non-Deoiled Rose Water, the rose essential oil is not separated from the distillate after production.
Consequently, findings obtained from traditional rose water after oil separation cannot automatically be applied to Akita's product.
Similarly, results obtained from Akita's stability and challenge tests cannot be generalized to all rose waters.
11. Does antimicrobial activity mean that rose water cannot spoil?
No.
Antimicrobial activity and microbiological stability are different concepts.
Demonstrating activity against a particular microorganism under laboratory conditions does not, by itself, establish that a finished cosmetic product will remain microbiologically stable throughout its shelf life.
12. Does distillation automatically make rose water microbiologically safe?
Distillation provides important opportunities for microbial control during manufacturing.
However, the finished product subsequently undergoes filling, packaging, storage, transportation, and use.
For this reason, microbiological safety should not be assessed solely on the basis of the statement that a product has been distilled.
13. What should be examined when evaluating the microbiological safety of a rose product?
In addition to manufacturing methods and formulation, the evaluation should include:
Microbiological analyses
Stability studies
Challenge-test results, where appropriate
Descriptions such as “natural,” “pure,” or “preservative-free” do not independently demonstrate microbiological safety.
14. Do Akita's test results apply to all rose waters?
No.
These findings are product-specific results obtained from the Akita product and samples examined.
This is one of the most important scientific principles in the evaluation of rose-derived products.
Rose waters produced through different methods may exhibit different microbiological behaviours and should therefore be evaluated individually.
Scientific References and Laboratory Reports
1. Baydar, H., Kuleaşan, H., Kara, N., Seçilmiş-Canbay, H., & Kineci, S. (2013). The Effects of Pasteurization, Ultraviolet Radiation and Chemical Preservatives on Microbial Spoilage and Scent Composition of Rose Water. Journal of Essential Oil Bearing Plants.
2. Bilim Sağlık ve Laboratuvar Hizmetleri Tic. Ltd. Şti. (2019). Akita Rose Water – Stability Analysis Report. Report No. A-2018-000177.
3. Bilim Sağlık ve Laboratuvar Hizmetleri Tic. Ltd. Şti. (2018). Akita Rose Water – Preservation Efficacy (Challenge) Test, ISO 11930. Report No. A-2018-000177.
4. Süleyman Demirel University, Natural Products Application and Research Centre. (2021). Rosa Damascena Flower Water – Paraben and Alcohol Analysis. Report No. 2104001.
Scientific Interpretation and Scope of Evidence
The findings discussed in this article come from distinct sources of evidence.
The published research by Baydar and colleagues concerns microbial spoilage and preservation approaches in rose water.
The stability and challenge-test findings concern specific Akita Rose Water samples evaluated under defined laboratory conditions.
The paraben and alcohol results concern only the substances included in the analytical scope of the 2021 university report.
Statements concerning the product's single-ingredient formulation and absence of added preservatives are based on information provided by the manufacturer.
These different categories of evidence should be interpreted separately.
The test results demonstrate observed microbiological behaviour under specified conditions. They do not establish unlimited shelf life, universal antimicrobial activity, or the precise biochemical mechanisms responsible for the findings.