Recognising Spoiled Parmesan Cheese
Identifying spoiled Parmesan is the first and most important step to prevent health issues. While its low moisture content makes it more resistant to bacteria than soft cheeses, it is not immune to going bad. A keen eye for visual cues and a sensitive nose can protect you from a ruined dish and potential sickness.
Obvious Signs of Spoilage
- Visible Mold: Although some molds are intentionally used in cheesemaking, any unexpected, fuzzy, off-color growth—such as green, black, or grey—on the surface of Parmesan is a sign of spoilage. While you might be able to salvage a hard block by trimming the mold, it's generally safer to discard pre-grated or shredded versions entirely if mold is present.
- Darker Colouration: Freshly grated Parmesan should be white to beige. If you notice it has become a darker, more yellow or darker beige hue, it is likely past its prime. This is a key indicator, especially for packaged grated varieties.
- Funny Odour: Fresh Parmesan has a nutty, savory smell. A tell-tale sign of spoilage is a strong, sour, or rancid smell. If the cheese emits an ammonia-like scent, it should be thrown out immediately.
- Texture Changes: Shredded or grated Parmesan that feels spongy or wet to the touch is likely spoiled. A block of Parmesan will lose moisture and become very dry and hard, but an unpleasant or slimy texture is a clear warning sign.
Health Considerations When Not to Eat Parmesan Cheese
Beyond simple spoilage, several health-related factors dictate when Parmesan should be avoided. These apply to specific individuals or dietary restrictions, regardless of the cheese's freshness.
Milk and Casein Allergies
For those with a cow's milk allergy, consuming Parmesan cheese can trigger a range of symptoms, from mild to life-threatening. This is because it contains casein, a protein found in milk that can cause an immune system reaction. Symptoms of a casein allergy can include hives, wheezing, swelling, and gastrointestinal issues. While Parmesan is virtually lactose-free due to its aging process, making it suitable for many with lactose intolerance, it is not safe for those with a true milk protein allergy.
High Sodium Content
Parmesan cheese, especially traditional Parmigiano-Reggiano, has a relatively high sodium content, which contributes to its flavour and preservation. For individuals with high blood pressure or other cardiovascular concerns, overconsumption of high-sodium foods is a risk factor. It is best to consume Parmesan in moderation or seek guidance from a healthcare provider regarding dietary intake.
High Fat and Calorie Density
As a calorie-dense food rich in saturated fat, Parmesan should be consumed in reasonable amounts. Excessive consumption can contribute to weight gain, which raises the risk of health issues like heart attack and stroke. A balanced diet is key, and Parmesan should be enjoyed as a flavorful supplement rather than a staple.
Use of Animal Rennet
Traditional Parmesan cheese is not vegetarian because it is made with animal rennet, an enzyme derived from the stomach of young mammals. Vegetarians should check the product label for confirmation that a non-animal-based rennet was used. Likewise, those observing Halal or Kosher diets should be aware of this and seek specifically certified products.
A Comparison of Cheese Types and Spoilage Risk
| Feature | Hard Cheeses (e.g., Parmesan) | Soft Cheeses (e.g., Ricotta, Mozzarella) |
|---|---|---|
| Moisture Content | Very low | Very high |
| Shelf Life (Opened) | 1-2 months or longer (block) | 1-2 weeks |
| Mold Risk | Low; mold stays mostly on the surface | High; mold can penetrate deeply |
| What to do with mold | Cut 1-inch away and discard the moldy portion. | Discard the entire product immediately. |
| Fridge Storage | Tightly wrapped in paper, then plastic or foil. | Airtight container or well-wrapped. |
How to Handle Moldy Parmesan
If you discover mold on a block of Parmesan, do not panic and do not immediately discard the entire thing. Because hard cheeses have a low moisture content, mold is less likely to penetrate deep into the interior. The U.S. Department of Agriculture (USDA) recommends a specific procedure to safely salvage the cheese. First, cut away at least one inch of cheese around and below the visible moldy spot, making sure your knife does not touch the mold. The rest of the block should be safe for consumption. However, this rule does not apply to grated or shredded Parmesan; if mold is present on these varieties, the entire container must be thrown out.
Proper Storage to Extend Freshness
Proper storage is critical to maximize the lifespan of your Parmesan cheese. A block of Parmesan should be wrapped in parchment or wax paper first to allow it to breathe, then in plastic wrap or foil to prevent moisture loss and absorption of other odors. Store the cheese in the crisper drawer of your refrigerator, which helps maintain a more consistent temperature. For long-term storage, Parmesan can be frozen. Shredded cheese can last for 3 to 6 months in the freezer, while a wedge can last even longer. For the best flavour and texture, always prioritize fresh Parmesan over prolonged storage.
Conclusion
Understanding when not to eat Parmesan cheese is a matter of both health and culinary quality. Paying attention to visible signs of spoilage, such as mold and color changes, along with offensive odors, is paramount for ensuring food safety. Additionally, individuals with specific dietary needs, such as milk protein allergies or a need to moderate sodium intake, should exercise caution. By following proper storage techniques and recognizing the difference between good and bad cheese, you can enjoy this beloved ingredient safely and extend its freshness, ultimately making better choices for your health and your meals.
Frequently Asked Questions
1. Is Parmesan cheese okay to eat after its expiration date?
Provided it has been stored correctly, a block of Parmesan can often be consumed weeks or even months past its 'best by' date due to its low moisture and high salt content, but you should always check for signs of spoilage first.
2. Can you get food poisoning from Parmesan cheese?
Yes, it is possible to get food poisoning from spoiled Parmesan, especially if it has visible mold or has been contaminated with harmful bacteria. However, the risk is lower than with softer cheeses.
3. What should I do if I find mold on my grated Parmesan?
Unlike a block, grated or shredded Parmesan should be discarded entirely if any mold is visible, as the mold spores can spread throughout the smaller pieces more easily.
4. Is Parmesan safe for people with lactose intolerance?
Yes, Parmesan is naturally very low in lactose due to its aging process, making it generally safe for individuals with lactose intolerance. However, those with a more severe dairy allergy (casein) should still avoid it.
5. Why do some people need to avoid Parmesan cheese?
Individuals with a cow's milk protein allergy (casein allergy), those monitoring high sodium intake for conditions like hypertension, and those on strict vegetarian, Halal, or Kosher diets (depending on the rennet used) should avoid or limit Parmesan.
6. Can pregnant women eat Parmesan cheese?
Yes, pregnant women can safely eat Parmesan cheese. As a hard, aged cheese, it is low in moisture and saltier, creating an environment inhospitable to bacteria like Listeria. However, always ensure you're consuming a pasteurized version if possible and consult with a healthcare provider if you have concerns.
7. How should I store Parmesan to keep it fresh longer?
For best results, wrap a block of Parmesan first in parchment paper, then in plastic wrap or foil, and store it in the crisper drawer of your refrigerator. For long-term storage, it can also be frozen.
8. What does spoiled Parmesan smell like?
Spoiled Parmesan may have a sour, rancid, or ammonia-like odour. If the smell is off in any way, it's best to discard it.
9. What are the benefits of Parmesan cheese?
When eaten in moderation, Parmesan is a good source of protein, calcium, and vitamins A and B12. Its long aging process makes it easily digestible for most people.
10. Can vegetarians eat all Parmesan cheese?
No. Traditional Parmigiano-Reggiano uses animal rennet, which is not vegetarian. Some brands use microbial or vegetable-based rennet, so it is important for vegetarians to check the label for a vegetarian certification.
