Impact of microplastics originating from formula preparation on protein digestion in infant digestion models

Project Information

Microprot

Grant agreement ID: 101090313

DOI

10.3030/101090313

Project closed

EC signature date 20 October 2022

Start date 1 April 2023

End date 31 March 2025

Funded under

• Widening participation and spreading excellence

Total cost

No data

EU contribution

€ 140 187,84

Coordinated by

HEMIJSKI FAKULTET, UNIVERZITET U BEOGRADU
Serbia

Periodic Reporting for period 1 - Microprot (Impact of microplastics originating from formula preparation on protein digestion in infant digestion models)

Reporting period: 2023-04-01 to 2025-03-31

Summary of the context and overall objectives of the project

The MICROPROT project was initiated in response to the growing concern over human exposure to micro- and nanoplastics (MNPs) through food, particularly in vulnerable populations such as infants. Polypropylene (PP), a common material used in food packaging and infant feeding bottles, can release MNPs during heating and sterilization processes. These particles may interact with nutrients, particularly proteins, potentially altering their digestibility and bioavailability. Despite the increasing detection of MNPs in food systems, limited data existed on how these particles affect protein digestion under physiologically relevant conditions, especially those simulating the infant gastrointestinal tract.
The project thus aimed to fill a critical gap in knowledge by investigating the interaction between cow’s milk proteins (CMPs) and MNPs in adult and infant digestion models. This aligns with broader concerns about food safety, sustainable packaging, and the need for informed regulatory policies under the European Green Deal and the Zero Pollution Action Plan.
Scientific aim of the project was to evaluate the impact of polypropylene micro- and nanoplastics (PP-MNPs) on the digestibility of cow’s milk proteins, with a focus on infant and adult gastric digestion.
The project set specific objectives to investigate effect of particle size on digestion, to compare digestibility across milk types and to investigate the effect of microplastic aging on protein digestion.
In addition to scientific objectives, project set the training objectives.
The project included a strong capacity-building component, aimed at equipping the researcher with advanced skills in:
• Simulated digestion models
• High-resolution protein analysis (e.g. 2D PAGE, proteomics)
• Microplastic production, aging, and characterization
• Open science practices, gender aspects of research, and project management
All scientific and training objectives were fully achieved, with outcomes contributing to new knowledge, improved technical capabilities, and enhanced career prospects for the researcher.
The project thus aimed to fill a critical gap in knowledge by investigating the interaction between cow’s milk proteins (CMPs) and MNPs in adult and infant digestion models. This aligns with broader concerns about food safety, sustainable packaging, and the need for informed regulatory policies under the European Green Deal and the Zero Pollution Action Plan.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The MICROPROT project carried out a comprehensive investigation into the effects of polypropylene (PP) micro- and nanoplastics (MNPs) on the digestion of cow’s milk proteins (CMPs) under conditions simulating adult and infant gastric digestion. The work encompassed:
1. Material Preparation and Characterization:
Synthesis of PP microplastics (MPs) and nanoplastics (NPs), including oxidized/aged particles to reflect real-world exposure scenarios (e.g. sterilized baby bottles).
Characterization conducted using FTIR, laser diffraction, differential light scattering, and zeta potential measurements.
2. Development of In Vitro Digestion Models:
Simulated adult digestion (pH 3.0 high pepsin activity) and infant digestion (pH 5.0 law pepsin activity).
Applied models to test cow's milk protein digestion in full-fat milk, skimmed milk, and infant formulas in the presence and absence of MNPs.
3. Experimental Work:
Conducted time-dependent digestion studies.
Analyzed protein breakdown using SDS-PAGE, 2D electrophoresis, and nLC-MS/MS.
Investigated aggregation behavior of plastics and proteins in gastric fluids using laser diffraction.
4. Protein–Plastic Interaction Studies:
Characterized soft and hard protein coronas formed around PP-MPs and NPs.
Identified major milk proteins (e.g. β-lactoglobulin, α-lactalbumin, caseins) consistently bound to plastic particles.
Data Processing and Interpretation:
Generated proteomic datasets, visualized results, and assessed digestion efficiency and molecular impacts.

Main Scientific Results Achieved
• Protein digestion was significantly slower in the infant model than in the adult model in the presence of PP-MPs.
• Oxidized MPs and nanoplastics showed the strongest inhibitory effect on cow's milk protein digestion, particularly on allergenic proteins like β-lactoglobulin.
• Six milk proteins were consistently adsorbed to plastic surfaces, indicating that MNPs may affect their digestibility and function.
• Aggregation of proteins and particles in digestive fluids suggests additional physical mechanisms contributing to digestion impairment.
All scientific objectives and deliverables were successfully achieved.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The MICROPROT project has produced several novel and impactful results that significantly advance the current state of knowledge in the fields of food safety, protein digestion, and microplastics research:
1. First in-depth study using an infant-specific digestion model (pH 5.0 low pepsin activity) to examine the impact of polypropylene micro- and nanoplastics (PP-MNPs) on the digestion of cow’s milk proteins (CMPs).
2. Demonstrated impaired digestion efficiency in the presence of MNPs, especially in the infant model, with a particular reduction in the breakdown of allergenic proteins like β-lactoglobulin.
3. Revealed protein–plastic interaction mechanisms through detailed analysis of soft and hard protein coronas, identifying six milk proteins consistently adsorbed onto MNP surfaces.
4. Established real-world relevance by simulating exposure to aged (oxidized) PP-MPs, representing conditions encountered during infant bottle sterilization and reuse.
5. Generated proteomic and physicochemical datasets, open for reuse and validation, following FAIR data principles.
Potential Impacts
Scientific and Technological Impact
- Provides first mechanistic insights into how MNPs interfere with nutrient bioavailability in vulnerable populations like infants.
- Opens new avenues for research in food allergy, infant nutrition, and gastrointestinal health.
- Supports the design of safer packaging materials, potentially triggering material innovation in the food and baby care industries.
Societal and Policy Impact
- Reinforces the need for regulatory control of microplastics in contact materials, especially those used for infant nutrition.
- Raises public awareness and supports evidence-based policymaking in food safety and packaging regulations.
Capacity Building and Career Development
- Equipped the researcher with advanced skills and tools in proteomics, digestion modeling, and microplastics analysis.
- Resulted in the researcher’s career advancement to a Senior Researcher position at the University of Johannesburg.
Key Needs for Further Uptake and Success
To fully capitalize on the results of MICROPROT and ensure wider adoption and impact, the following are recommended:
Further Research:
- Extend findings to intestinal digestion models and absorption studies using cellular or organoid systems.
- Investigate the long-term health effects of chronic MNP exposure in infants and other sensitive groups.
Standardization and Regulation:
- Support development of standardized methods for testing MNP migration and bio-interference in digestion.
- Inform EU policy bodies to integrate such data into food contact materials regulation (e.g. EFSA, ECHA).
Access to Markets and Innovation Support:
- Foster collaboration with industry to develop biodegradable, non-toxic packaging alternatives.
The MICROPROT project has laid a strong foundation for further scientific advancement, policy influence, and commercial innovation in the area of microplastics, food safety, and infant health. Continued interdisciplinary collaboration and support mechanisms will be key to translating these findings into tangible societal benefits.

Microprot project overview