Summary of European Patent EP3253232B1: Antimicrobial Compositions

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07 Mar 2026 • 7 min read

Summary of European Patent EP3253232B1: Antimicrobial Compositions

This patent, granted on August 12, 2020, and assigned to Naturex S.A., protects a specific antimicrobial composition designed to extend the shelf life of food products, particularly meat, fish, and poultry. The invention addresses two critical aspects of food spoilage: microbial growth (e.g., Listeria monocytogenes) and color deterioration (the conversion of red oxymyoglobin to brown metmyoglobin).

The core of the invention is the surprising synergistic effect achieved by combining two specific, highly refined natural ingredients: a highly purified hesperidin extract from citrus fruits and a deodorised extract from plants of the Lamiaceae family (such as rosemary, thyme, or oregano). The key innovation lies not just in the combination, but in the specific processing of these components to maximize antimicrobial efficacy while minimizing negative sensory impacts on the food.

1. Technical Problem and Prior Art

The patent document begins by outlining the significant challenges faced by the food industry, especially meat processors. There is a constant need to ensure food safety and prevent spoilage to meet consumer demand for high-quality, natural products with a guaranteed shelf life. A major target for spoilage control is the problematic bacterium Listeria monocytogenes, known for its resistance to conventional preservation methods.

While plant-derived antimicrobials are desirable due to their "natural" and "generally regarded as safe" (GRAS) status, the prior art, as cited in the patent, highlights a major obstacle. The antimicrobial activity of herbs from the Lamiaceae family was traditionally attributed to their volatile essential oil components (e.g., thymol, carvacrol, borneol). However, as the patent explains (citing Davidson & Naidu, 2000), the concentrations of these essential oils required for effective antimicrobial protection in food are high enough to cause serious off-flavors, making the products sensorially unacceptable to consumers. This is the central problem the invention seeks to solve: providing effective, natural antimicrobial protection without negatively impacting food taste or smell.

Furthermore, the patent notes that meat discoloration is a primary driver of consumer rejection at the point of sale. Therefore, an ideal solution would also preserve the desirable bright red color of fresh meat.

2. The Inventive Solution: A Synergistic Combination of Refined Extracts

The patented invention overcomes the limitations of the prior art by moving away from crude extracts or essential oils. Instead, it claims a composition comprising two specific ingredients, processed in a particular way to achieve a synergistic effect far greater than the sum of their individual parts.

The composition is defined by the following two essential components:

A Pure Hesperidin Extract: This is a highly concentrated extract derived from citrus fruits (the patent mentions Citrus aurantium, C. sinensis, and C. reticulata as examples). The defining characteristic is its purity: it must contain from 80% to 99% hesperidin. This distinguishes it from less refined citrus extracts that contain a complex mixture of many different flavonoids and compounds.
A Deodorised Lamiaceae Extract: This extract is obtained from plants of the Lamiaceae family, such as rosemary (Rosmarinus officinalis), thyme (Thymus vulgaris), oregano (Origanum vulgare), or sage. The critical processing step is that a majority of the volatile oil components have been removed. These volatile compounds are precisely the ones responsible for the strong, undesirable flavors noted in the prior art. By deodorising the extract, the invention retains the non-volatile, antimicrobial phenolic compounds while eliminating the sensory negatives.

The composition can exist in various forms, including a liquid, a powder, or a suspension, depending on the application needs. The ratio of the two components can be adjusted, but the patent emphasizes that the combination is key to the synergistic effect.

3. Synergistic Effects and Key Findings

The patent provides extensive experimental data to demonstrate the unexpected and superior performance of the combined composition. The core finding is the synergy between the two components, which allows for lower overall concentrations of active ingredients to achieve the desired preservation effect.

a) Antimicrobial Synergy:
The most dramatic evidence of synergy is presented in experiments targeting Listeria monocytogenes in ready-to-eat (RTE) meat products, specifically sliced cooked ham.

An experiment tested the pure hesperidin extract (at 0.15%) and the deodorised rosemary extract (at 0.15%) individually against a control.
Individually, both extracts showed very limited to no ability to inhibit the growth of L. monocytogenes over a 28-day storage period. The bacterial counts in samples treated with the individual extracts were nearly as high as in the untreated control.
However, when the same concentrations of the two extracts were combined (0.15% hesperidin + 0.15% deodorised rosemary extract), a potent antimicrobial effect was observed. The bacterial growth was almost completely suppressed throughout the entire 28-day storage period. This result is not merely additive; it is a clear demonstration of synergy, where the combined effect is exponentially greater than the sum of the individual effects. This allows for effective food preservation with minimal additive usage.

b) Color Stabilization:
The composition also proves highly effective at preserving the desirable red color of fresh meat, a critical factor for consumer appeal.

An experiment was conducted on fresh ground beef patties stored under conditions simulating retail display.
The color was measured over time using a colorimeter, tracking the "a*" value (red-green coordinate), where a higher a* value indicates a redder color.
The results showed that patties treated with the combined hesperidin/Lamiaceae extract composition maintained a significantly higher a* value (i.e., stayed redder) for a longer period compared to untreated patties.
This effect is attributed to the antioxidant properties of the phenolic compounds in both extracts. They inhibit the oxidation of oxymyoglobin (the red pigment) to metmyoglobin (the brown pigment), thereby extending the visual freshness of the meat.

c) Overcoming Sensory Issues:
By using the deodorised Lamiaceae extract, the invention directly addresses the flavor problems associated with prior-art essential oil-based preservatives. The removal of volatile terpenes and other aromatic compounds means the composition can deliver its antimicrobial and antioxidant benefits without imparting an "herbal" or "medicinal" taste to the food product. This is a crucial advantage for consumer acceptance of "clean label" preserved foods.

4. Key Claims of the Patent

The legal protection of the patent is defined by its claims. The key independent claims summarize the scope of the invention:

Claim 1: Defines the fundamental composition. It claims an antimicrobial composition comprising (a) a pure hesperidin extract containing 80-99% hesperidin and (b) a deodorised Lamiaceae extract (e.g., from rosemary, thyme, oregano, or sage) from which the majority of volatile oil components have been removed.
Claim 8: Defines a method for extending the shelf life of a food product (specifically meat, poultry, or fish). The method involves applying an effective amount of the claimed composition to the food.
Claim 9: Defines a food product (specifically meat, poultry, or fish) that comprises the claimed composition.
Claim 14: Defines a method for manufacturing the composition, which involves simply mixing the pure hesperidin extract and the deodorised Lamiaceae extract.
Claim 15: Defines the use of the combination of these two extracts for extending the color shelf life and/or microbial shelf life of a food product.

5. Conclusion

In conclusion, EP3253232B1 protects a novel and non-obvious solution to long-standing problems in food preservation. By moving beyond the reliance on crude, flavorful essential oils and instead combining a highly purified hesperidin extract with a deodorised Lamiaceae extract, the inventors achieved a powerful synergistic effect. This synergy provides dual-action protection against microbial spoilage (especially L. monocytogenes) and color deterioration, all while avoiding the negative sensory impacts that plagued previous natural preservation attempts. The patent successfully enables food manufacturers to meet consumer demand for safer, fresher-looking, and more natural products with an extended shelf life.

Advantages of the patented antimicrobial compositions

The attractiveness of these new ingredients comes from their ability to navigate the "Preservation Trilemma"—the constant struggle to balance Efficacy, Sensory Quality (Taste/Appearance) , and Consumer Perception (Naturalness) .

Here’s a breakdown of why this invention is more attractive, directly addressing the weaknesses of other agents:

1. It Solves the "Flavor Problem" of Natural Alternatives (Sensory Superiority)

This is the single biggest advantage and the core problem the patent was designed to solve.

The Problem with Existing Natural Agents: As the patent's background section heavily emphasizes (citing Davidson & Naidu), the most potent natural antimicrobials from herbs are the essential oils (e.g., thymol, carvacrol from oregano or thyme). While they kill microbes, they do so at concentrations that make the food taste like "herbal medicine" or spices. A meatball with oregano oil might be safe, but it won't taste like a plain meatball. This makes them unusable for the vast majority of applications where a neutral flavor is desired.
The Attractive Solution: This invention uses a deodorised Lamiaceae extract. By removing the volatile, smelly essential oil components, they've kept the antimicrobial power but thrown out the bad taste. It's like having decaf coffee—you get the enjoyment without the stimulant you don't want. This allows a manufacturer to protect a neutral-flavored product like cooked ham or fresh chicken breast without telling the consumer "this now tastes like rosemary."

2. It's a "Clean Label" Solution for a Difficult Pathogen (Consumer & Regulatory Appeal)

The Problem with Synthetic Agents: Traditional preservatives like nitrites, benzoates, or sorbates are effective and cheap. However, consumer demand for "natural," "clean label," and "free-from" artificial ingredients is a massive, global trend. These synthetic chemicals are increasingly viewed negatively by consumers, who are willing to pay a premium for products without them. Food manufacturers are under immense pressure to reformulate.
The Attractive Solution: The composition is made from two plant extracts: citrus peel (hesperidin) and common herbs (rosemary/thyme). This gives it a powerful marketing advantage. It can be listed on an ingredient label as something like "citrus extract, rosemary extract," which consumers recognize and accept as natural. It directly helps a manufacturer achieve a "clean label" while still tackling a serious pathogen like Listeria.

3. It's a "Dual-Action" Ingredient (Economic & Functional Efficiency)

The Problem with Single-Purpose Agents: Many preservatives do one thing well. An antimicrobial might stop bacteria but does nothing for color. An antioxidant (like Vitamin C or synthetic BHA/BHT) might preserve color but not stop pathogen growth. A manufacturer would have to buy, store, and add two or more different ingredients to achieve both goals. This adds complexity and cost.
The Attractive Solution: This composition is a "two-in-one" solution. The experimental data proves it not only stops Listeria (antimicrobial effect) but also maintains the red color of meat (antioxidant effect). For a meat processor, this is highly attractive. One ingredient, added at one point in the process, tackles two of the biggest shelf-life limitations: safety and appearance.

4. It's More Potent, So You Use Less (Economic & Sensory Advantage)

The Problem with Dose-Dependent Side Effects: Even "natural" extracts can have a sensory limit. If you use too much of a standard rosemary extract (even a non-deodorised one), you might start to taste it. High doses also increase cost.
The Attractive Solution: The core of the patent is the synergistic effect. The data shows that 0.15% of hesperidin extract alone does almost nothing. 0.15% of the deodorised rosemary extract alone does almost nothing. But combine them at the same low concentrations, and you get powerful protection. This synergy means the total amount of "additives" going into the food is minimized. This is attractive because it keeps costs down and further reduces any remote risk of sensory impact.

Summary: The Attractiveness in a Nutshell

You wouldn't "bother" with this ingredient if you were making a strongly spiced sausage where the flavor of oregano oil would fit right in. But for the massive market of neutral-tasting, high-value products like fresh meat, poultry, and ready-to-eat meals, this invention is a game-changer.

It's attractive because it successfully combines:

High Efficacy (proven synergy against Listeria and color loss)
Excellent Sensory Profile (deodorised, so it doesn't taste like herbs)
Consumer-Preferred Image (made from two simple plant extracts)

It offers food manufacturers a way to navigate the Preservation Trilemma, giving them a product that is safe, looks good, tastes right, and has a label the consumer will trust and buy. d

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