From Field to Fruit: How Microplastics Affect Strawberry Quality and Food Safety
Following our previous blog posts, where we examined the effects of microplastics on soil and general plant health, we now turn to a specific and highly relevant case: strawberries. Within the InPlasTwin project, strawberries (Fragaria × ananassa) are used as a model crop to better understand how microplastics interact with edible fruits and what this means for agricultural production and food safety. This focus is particularly important because strawberries are consumed fresh, often without processing, making them a direct pathway for potential human exposure.
Why Strawberries Matter in Microplastic Research
Strawberries are not only economically important but also uniquely exposed to microplastic contamination. Their cultivation frequently involves plastic-based practices such as mulching, which contributes to microplastic accumulation in agricultural environments. At the same time, strawberries grow above ground and are directly exposed to atmospheric deposition of particles. Unlike root crops or grains, the edible part of the strawberry is the fruit itself, which develops in direct contact with the surrounding environment. This makes strawberries an ideal system for studying whether microplastics can move beyond soil and vegetative tissues and enter edible fruit structures, a question that has only recently been addressed in scientific research (1).
Direct Uptake of Microplastics into Strawberry Fruits
Recent experimental evidence shows that microplastics can enter strawberry fruits directly through the fruit surface. In controlled studies using fluorescently labeled polystyrene particles, both micro-sized (2 μm) and nano-sized (80 nm and 200 nm) plastics were observed to penetrate the fruit epidermis. The mechanisms of uptake are strongly dependent on particle size. Larger particles (around 2 μm) primarily enter through stomatal openings, which are small pores on the fruit surface typically ranging from 3 to 10 μm in width. These openings, known for regulating gas exchange, can also act as entry points for external particles. Smaller particles, particularly those in the nanoscale range, can enter not only through stomata but also via endocytosis, a cellular process in which the cell membrane engulfs external material. Imaging studies have revealed membrane invaginations and vesicle-like structures in strawberry epidermal cells, indicating active internalization of these particles. This dual pathway highlights that strawberries are susceptible to microplastic uptake across a range of particle sizes, with smaller particles having greater flexibility in how they enter plant tissues (1, 2).
Translocation and Accumulation Within Fruit Tissues
Once microplastics enter the fruit, they do not remain confined to the surface. Experimental observations show that particles initially accumulate on the epidermis but gradually move into the internal tissues. Within just two days of exposure, microplastics have been detected inside the fruit, and their concentration increases over time. Particle size again plays a critical role. Smaller particles (80 nm and 200 nm) show significantly higher mobility and deeper penetration into fruit tissues compared to larger particles. After prolonged exposure (up to 21 days), nanoscale particles were found distributed throughout the fruit, including within individual cells. Microscopic analyses confirm that microplastics are present both in intercellular spaces and inside cells, suggesting that biological barriers such as the cell wall can be altered or bypassed. The typical pore size of plant cell walls (around 5–20 nm) is smaller than many of the observed particles, indicating that microplastics may induce structural changes in the cell wall to facilitate entry. These findings demonstrate that fruit tissues are not passive barriers but dynamic systems capable of taking up environmental contaminants (1).
Impacts on Strawberry Yield
Microplastic exposure has measurable effects on strawberry production, particularly in terms of fruit yield. One of the most consistent observations is a reduction in fruit weight following exposure to microplastics. Fruit weight is a key indicator of yield and market value. In experimental conditions, strawberries exposed to microplastics showed significantly lower weights compared to unexposed controls, with certain particle sizes (e.g., 200 nm and 2 μm) having more pronounced effects. Although the exact mechanisms were not directly measured in these experiments, previous research suggests that such reductions are likely linked to physiological stress, including oxidative damage and disruptions in photosynthesis. Microplastics are known to induce reactive oxygen species (ROS), which can impair metabolic processes and limit plant growth. This indicates that microplastics have the potential to reduce agricultural productivity, even when exposure occurs at the fruit surface rather than through the root system (1).
Effects on Fruit Quality and Flavor
Beyond yield, microplastics also influence key quality parameters that determine consumer acceptance. One of the changes is an increase in fruit acidity, which directly affects taste. At the same time, changes in sugar composition have been observed. While total sugar content may increase under certain conditions, the balance between sugar and acid commonly expressed as the sugar-to-acid ratio is altered. This ratio is a critical determinant of strawberry flavor, and its reduction can lead to less desirable taste profiles. These findings suggest that microplastics can influence not only how much fruit is produced, but also its sensory quality, with potential implications for marketability and consumer preference (1).
Changes in Nutritional and Antioxidant Composition
Strawberries are widely recognized for their nutritional value, particularly their high content of vitamin C and polyphenols. Microplastic exposure has been shown to affect both of these important components. Vitamin C levels exhibit a complex response. In early stages of exposure, there may be a temporary increase, likely reflecting an initial stress response. However, with prolonged exposure (14 to 21 days), vitamin C content decreases significantly across all particle sizes. This decline suggests that sustained microplastic exposure leads to chronic oxidative stress, overwhelming the plant’s antioxidant defense system. Polyphenols, another group of antioxidant compounds, show a different pattern. After an initial decrease, their levels increase over time, indicating activation of secondary metabolic pathways as the plant attempts to adapt to stress. Together, these changes indicate that microplastics can affect the nutritional and functional properties of strawberries, and potentially their health benefits (1).
Implications for Food Safety
The direct uptake and accumulation of microplastics in strawberry fruits raise important concerns for food safety. Since strawberries are typically consumed fresh, without peeling or processing, any contaminants present in the fruit are likely to be ingested directly. A key finding is that atmospheric deposition alone can lead to contamination of fruit tissues , even without soil-mediated uptake. This highlights the importance of considering multiple exposure pathways when assessing risks. The presence of microplastics in edible tissues suggests a direct route for these particles to enter the human food chain. While the long-term health implications are still under investigation, this pathway highlights the need for further research and monitoring (3).
The Role of InPlasTwin
The InPlasTwin project builds on these findings by focusing specifically on strawberries as a model system for understanding microplastic contamination in fruit crops. By investigating uptake mechanisms, translocation pathways, and impacts on fruit quality, the project aims to bridge the gap between environmental contamination and food safety.
Through this work, InPlasTwin seeks to:
- Quantify how microplastics accumulate in edible fruit tissues
- Understand their effects on crop yield and quality
- Assess potential risks for consumers
- Support the development of mitigation strategies in agricultural systems.
Microplastics are no longer confined to soil and water they can directly enter and accumulate in fruits such as strawberries. Their presence affects fruit development, reduces yield, alters flavor, and changes nutritional composition. These findings highlight a significant shift in how we understand microplastic pollution. It is not only an environmental issue but also a food system challenge, with direct implications for agriculture, consumer health, and sustainability.
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References
- Zhang, C., Li, S., Wang, H., Li, X., An, L., & Jin, F. (2026). Microplastics enter strawberry fruit tissues directly through the epidermis. Journal of Hazardous Materials, 141994.
- Zhao, J., Stenzel, M.H., 2017. Entry of nanoparticles into cells: the importance of nanoparticle properties. Polymer Chemistry. https://doi.org/10.1039/c7py01603d.
- Liu, K., Wang, X., Song, Z., Wei, N., Li, D., 2020. Terrestrial plants as a potential temporary sink of atmospheric microplastics during transport. Sci Total Environ. https://doi.org/10.1016/j.scitotenv.2020.140523.
