Imagine reaching for a carton of oat milk, believing it to be a healthy choice, only to discover it might contain invisible toxic contaminants. This is the challenge food scientists face as plant-based milk alternatives (PBMAs) surge in popularity. With the global market projected to reach $29.5 billion by 2031, ensuring the safety of these products has never been more critical 1 4 .
Mycotoxins—toxic compounds produced by molds—can lurk in the raw ingredients used to make PBMAs. While laboratory testing methods exist, a 2022 German study revealed significant pitfalls in using rapid enzyme immunoassays (EIAs) for detecting these dangerous substances in plant-based milks 1 2 . This article explores the hidden challenges in keeping our plant-based beverages safe.
Mycotoxins are naturally occurring toxic compounds produced by certain types of fungi that can grow on various food crops. When these contaminated crops are used to make PBMAs, the toxins can carry over into the final product 7 .
Potent carcinogens linked to liver cancer
Causes kidney damage and may affect fetal development
Causes gastrointestinal issues and immune suppression
Poses significant health risks as a carcinogen
What makes mycotoxins particularly dangerous is their stability—they often survive food processing methods that involve heat, physical, and chemical treatments 7 . The problem is significant enough that global authorities have established strict limits for mycotoxin levels in food, typically in the microgram per kilogram range 6 .
Enzyme immunoassays are widely used for rapid detection of various contaminants in food products. Their appeal lies in their:
Compared to laboratory methods
Of use
For routine testing
For on-site quality control
For decades, similar immunoassays have been successfully used to test for aflatoxin M1 in conventional cow's milk 1 . Researchers naturally wondered: could the same approach work for plant-based milks?
A comprehensive 2022 study published in Mycotoxin Research set out to answer this question, investigating the applicability of EIA methods for directly testing PBMAs without sample extraction 1 2 .
Researchers acquired 54 different PBMA products from German retail stores, with the majority (34 products) labeled as organic. These represented various base ingredients including oats, rice, almonds, soy, and coconut 1 .
The study focused on detecting five mycotoxins: AFB1, STC, OTA, DON, and T-2/HT-2 toxin 1 .
Since no certified toxin-free PBMA material was available, scientists assessed matrix interference by comparing toxin standard curves made in EIA buffer solution with those made with diluted PBMA 1 .
As quality control, six PBMA materials were artificially contaminated with known mycotoxin concentrations to test recovery rates 1 .
Selected samples were additionally analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to validate the EIA results 1 .
The research revealed several significant challenges:
The diverse ingredients in PBMAs created substantial interference with the immunoassays 1 .
Diluting samples at least 1:8 was necessary, increasing detection limits 1 .
23 of the 54 samples showed positive results for at least one mycotoxin 1 .
| Mycotoxin | Detection Limit (µg/L) |
|---|---|
| Aflatoxin B1 (AFB1) | 0.4 |
| Sterigmatocystin (STC) | 2 |
| Ochratoxin A (OTA) | 0.08 |
| Deoxynivalenol (DON) | 16 |
| T-2/HT-2 toxin | 0.4 |
Data source: 1
Matrix interference occurs when other components in a sample affect the detection method's ability to accurately measure the target substance. In the case of PBMAs:
This variability means that a method working well for oat milk might perform poorly for almond or soy milk, creating a significant challenge for quality control laboratories.
| PBMA Base Ingredient | Content Range | Examples |
|---|---|---|
| Cereal/Pseudocereal | 8.7-17% | Oat, rice, spelt, millet, buckwheat |
| Nut-based | 2.3-8.4% | Hazelnut, almond, coconut, cashew |
| Legume-based | 4-10% | Soy bean, pea, lupine |
| Seed-based | 3% | Hemp |
| Mixed Ingredients | 4.9-21% | Oat + almond, rice + coconut |
Data source: 1
While EIAs face challenges with PBMAs, other technologies offer promise:
| Reagent/Material | Function in Research |
|---|---|
| Mycotoxin standards (AFB1, OTA, STC, DON, T-2) | Reference materials for calibration and quantification |
| Phosphate buffered saline (PBS) | Dilution buffer for sample preparation |
| Immunoaffinity columns | Selective clean-up and concentration of target mycotoxins |
| 13C-labelled standard solutions | Internal standards for precise LC-MS/MS quantification |
| Monoclonal antibodies | Specific recognition elements for immunoassays |
| Organic solvents (methanol, acetonitrile) | Extraction solvents for releasing mycotoxins from samples |
The 2022 study concluded that while EIA methods show potential for screening PBMAs, they're not yet reliable for routine analysis without further development of sample preparation methods specifically designed for these complex matrices 1 .
Future directions include:
The hidden challenge of detecting mycotoxins in plant-based milks reveals a broader truth about food safety: as consumer preferences evolve, our testing methods must adapt. The 2022 German study highlighted both the promise and limitations of current technologies, emphasizing that the diverse nature of PBMAs requires equally sophisticated detection approaches 1 .
While the findings might seem concerning, they represent the normal progression of scientific understanding—identifying problems is the first step toward solving them. Through continued research and method development, scientists are working to ensure that as the plant-based milk market grows, so too does our ability to verify its safety.
For consumers, the takeaway isn't to avoid plant-based milks, but to recognize the complex science behind food safety and appreciate the researchers working to develop better detection methods for these popular products.