Mold Risk: Chef Jordi Cruz on When to Toss vs. Save Food

A tiny green spot on your bread seems harmless. But according to Michelin-starred chef Jordi Cruz, that spot is just the surface. What you can't see—invisible spores and toxins—may have spread throughout the entire loaf, and inhaling or ingesting them can pose real health risks. In an era focused on reducing food waste, Cruz offers a necessary warning: not everything spoiled can be salvaged. Knowing when to toss is as important as knowing how to preserve.

The Science

Mold isn't just the fuzzy patch you see on bread. It's the visible fruiting body of a microscopic network of hyphae (threads) and spores that can penetrate deep into soft, porous foods. In sliced bread, the spongy structure allows spores to travel far beyond the visible spot, colonizing entire slices undetected. Moreover, some molds produce mycotoxins—toxic compounds that can withstand heat and survive toasting. The U.S. Department of Agriculture advises discarding the entire loaf if mold appears on soft bread, as the risk of hidden contamination is too high. A study from Cornell University found that mycotoxins like aflatoxin can remain stable even at 200°C, meaning toasting moldy bread does not make it safe.

Potatoes are a different case. When a potato sprouts, it can produce solanine, a glycoalkaloid toxin that acts as a natural pesticide. Solanine concentrates in the sprouts, skin, and green areas, but can spread to the rest of the tuber if deterioration is advanced. According to the European Food Safety Authority, solanine intake above 1 mg per kg of body weight can cause gastrointestinal and neurological symptoms. A firm potato with a small sprout has low levels, but a wrinkled, soft, heavily sprouted one may exceed safe limits. Chronic low-dose exposure to solanine has also been linked to inflammatory effects in the gut, according to recent research from the Norwegian Institute of Food Research.

“"Not everything that spoils in the kitchen can be used. Understanding this is key to avoiding risks." — Jordi Cruz”

Key Findings

• Moldy bread: Chef Cruz warns that removing the first few slices isn't enough. Spores and toxins can be spread throughout the entire product, even if not visible. The recommendation is to discard the whole package. Additionally, mycotoxins can cause long-term liver damage, as noted by the World Health Organization.
• Sprouted potatoes: A potato with a small sprout can be used after removing the sprout and surrounding area. But if it's wrinkled, soft, and heavily sprouted, it's better not to risk it due to possible solanine accumulation. Solanine levels can increase up to 10-fold in improperly stored potatoes, according to a University of Idaho study.
• Overripe tomatoes: Even if very soft or "soggy," tomatoes can still be used if they show no mold or off-odor. Texture alone doesn't indicate danger—only possible off-flavor. In fact, overripe tomatoes contain more lycopene, a beneficial antioxidant, according to Harvard University.
• Airborne spore risk: Cruz notes that mold spores can also be harmful when inhaled, potentially causing allergies or respiratory issues. Handling moldy bread without protection can release these spores into the air. Exposure to Aspergillus spores, common on bread, can trigger aspergillosis in immunocompromised individuals.

Why It Matters

In the age of eco-consciousness and zero-waste movements, the urge to "use everything" can conflict with food safety. Spanish households throw away over 1.2 billion kilos of food annually, according to the Ministry of Agriculture, but not everything discarded is dangerous, nor is everything saved safe. The key lies in educating the eye to distinguish between aesthetic deterioration (a soft tomato) and chemical or microbiological spoilage (mold, toxins). A 2025 study from the University of Barcelona revealed that 40% of consumers cannot correctly identify signs of dangerous spoilage in food.

For health optimizers, this knowledge is vital. Mycotoxins don't just cause acute poisoning; chronic low-dose exposure has been linked to liver damage, immune suppression, and cancer. Solanine poisoning, though rare, can cause nausea, vomiting, and diarrhea—especially dangerous for children and the elderly. Furthermore, Cruz's warning about airborne spores adds a layer of caution: how you handle contaminated food matters. Opening a moldy bread bag and sniffing it can release spores directly into your lungs. The safest approach is to discard it unopened, or wear a mask and ventilate the area.

Your Protocol

To apply these tips in your kitchen and reduce waste without risk, follow these guidelines:

1. 1Moldy sliced bread: Discard the entire package. Do not attempt to cut off affected slices. If you see mold on one slice, assume the whole loaf is contaminated. To avoid waste, buy smaller portions or freeze bread if you won't consume it quickly. Frozen bread maintains quality for up to 3 months.
2. 2Sprouted potatoes: Inspect each potato. If it has only a small sprout and remains firm, remove the sprout and about an inch of surrounding flesh. If wrinkled, soft, or heavily sprouted, discard it. Store potatoes in a cool, dark, dry place to delay sprouting. Avoid storing near onions, as gases accelerate spoilage.
3. 3Overripe tomatoes: Use them fully. If soft but mold-free, they are perfect for sauces, soups, or purees. Flavor may be sweeter or more acidic, but they pose no health risk. If mold appears, discard. For longer storage, keep at room temperature away from direct light.
4. 4Weekly pantry review: Organize foods by purchase date and consume oldest first. This prevents items from reaching advanced spoilage and reduces the need to discard. An inventory list can help with meal planning.
5. 5Safe handling: If you find mold on any food, do not sniff it. Discard in a sealed bag to prevent spore spread. Wash hands and surfaces that came into contact with hot soapy water. Wear a mask if you are allergic or have asthma.

What To Watch Next

Food safety science is advancing rapidly. In 2026, new studies are expected on portable sensors for early mycotoxin detection, potentially allowing consumers to know in seconds if a food is contaminated. Research into probiotics and enzymes that degrade toxins is also growing, though still experimental. Meanwhile, the zero-waste trend is driving investigations into safely using parts of foods typically discarded—like potato peels or broccoli stems—but always with safety criteria. The challenge will be balancing sustainability with scientific evidence, without risking toxin exposure to save a few cents.

The Bottom Line

Maximizing food use is a worthy goal, but safety must come first. As Jordi Cruz sums up, "Throwing away food is ugly," but uglier is risking your health. Learn to tell the difference between a past-prime tomato (safe) and moldy bread (dangerous). Next time you hesitate, ask yourself: is it a texture issue or a contamination issue? If there's mold, toxins, or advanced spoilage signs, don't think twice—toss it. Your body will thank you.