How to know if the grapes are spoiled? (7 methods)

In this brief article, we are going to answer the question “how to know if the grapes are spoiled”, discuss the different methods of identifying spoiled grapes and the potential health effects of eating spoiled grapes.

How to know if the grapes are spoiled?

If you want to know if your grapes are spoiled or not, the following seven signs will help you to take a smart decision:  

Important: Be aware that eating spoiled grapes can be harmful to your health as they may contain harmful bacteria or mold, which can cause food poisoning (1-3).

1. Check the appearance of your grapes: Look for any discoloration or shriveling. If the grapes are turning brown, black, or appear to be dried out or wrinkled, they are likely spoiled. You should not eat them!
2. Check the presence of molds: Check for any visible molds on the grapes. Molds can grow on grapes that have been sitting around for too long, producing powerful harmful toxins that can seriously ill you (3).
3. Check the texture: If the grapes are slimy or sticky to the touch, they may have started to spoil, and it is best that you throw them out. Remember that the texture of a fresh grape should be firm, plump, and smooth.
4. Smell your grapes: Take a whiff of the grapes. If they have a sour or fermented odor, they may have started to spoil.
5. Be aware of changes in the taste: If the grapes taste sour or off, it’s a sign they have gone bad. Stop eating them! A fresh grape should taste sweet, juicy, and refreshing.
6. Look for fruit flies around your grapes: If you see fruit flies or other insects hovering around the grapes, this is a clear sign that they are overripe or spoiled and you must throw them out immediately.
7. Determine how juicy they are: If your grapes are leaking juice or feel squishy, they may have started to spoil. Fresh grapes should be dry to the touch.

Once a grape starts to spoil the different harmful microorganism growing on it could quickly spread to other grapes, so it is always recommended to discard any grape that appears to be spoiled and regularly check the remaining ones.

It is highly recommended to store grapes in the refrigerator to help extend their shelf life by reducing the growth of harmful bacteria (4-5).

Can you get sick from eating spoiled grapes?

Yes, eating spoiled grapes can make you sick and lead to foodborne illness (3,6).

Spoiled grapes can harbor different harmful microorganisms that can be potentially toxic to humans. These include:

• Photogenic bacteria: Various types of dangerous bacteria can grow on your spoiled grapes, including Salmonella, Escherichia coli (E. coli), and Listeria monocytogenes, among others (7). These bacteria can cause severe food poisoning- you should not eat spoiled grapes!
• Molds: Molds can grow on spoiled grapes, and some types of molds produce toxins that can cause illness (8). For example, the mold Aspergillus can produce a toxin called aflatoxin (a potent carcinogen), which can increase the risk of liver cancer if consumed in large amounts (1).
• Yeast: Different species of yeast can also grow on your grapes and cause spoilage. While most types of yeast are harmless, some can produce toxins that can cause illness. For example, Candida can produce a toxin called candidalysin, which can cause tissue damage and inflammation when consumed (9).

You may experience different symptoms from eating spoiled grapes including nausea, vomiting, diarrhea, stomach cramps, abdominal pain, fever, headache, and fatigue, which are regular symptoms of food poisoning (10).

The severity and duration of these symptoms can vary from one individual to another, and the specific pathogens or toxins present in your spoiled grapes as described before.

If you experience severe or prolonged symptoms after consuming spoiled grapes, you must seek medical attention immediately.

What should you do if you suspect you have consumed spoiled grapes?

If you suspect that you have eaten spoiled grapes, you can follow the next tips to minimize the risk of illness:

• Stop eating the grapes: You should stop eating the grapes immediately to avoid consuming more potentially harmful bacteria or toxins and increase the severity of the disease (1).
• Drink plenty of fluids: To avoid dehydration and flush out any toxins in your system, you should drink plenty of fluids such as water, clear broths, or sports drinks (11).
• Monitor your symptoms: Keep track of any symptoms you experience, such as nausea, vomiting, diarrhea, or fever – their severity and duration. If your symptoms are severe or persist for more than a few days, seek medical attention immediately!
• Practice good hygiene: To prevent the spread of any potential bacteria or toxins, wash your hands frequently with soap and warm water before and after handling your grapes or any food.
• Contact your healthcare provider: If your symptoms are severe and you are concerned about your health, contact your healthcare provider as soon as possible. They will find the best treatment for you!
• Check for recalls: If you suspect that the grapes you consumed may be part of a larger recall due to contamination or spoilage, check the FDA or USDA website for any updates or alerts.

Remember that it is best to err on the side of caution and discard any grapes that appear to be spoiled. This will help you to avoid the risk of any foodborne disease.

How should you handle grapes to prevent spoilage?

You can follow the next tips to better handle your grapes and reduce the risk of spoilage:

• Choose fresh grapes: When purchasing grapes, look for plump, firm, and smooth-skinned grapes with no signs of mold, decay, or discoloration.
• Store grapes properly: Grapes are best stored in the refrigerator at 32-40°F (0-4°C) and can last up to 1-2 weeks (4-5, 12). If you want to keep them longer, you can freeze them in an airtight container or freezer bag for up to 10-12 months.
• Handle with care: Grapes are delicate and can easily bruise or become damaged, which can lead to spoilage. Handle them gently and avoid dropping or crushing them.
• Rinse before eating: Wash grapes thoroughly under cool running water before eating to remove any dirt or bacteria.
• Avoid moisture: Grapes should be kept dry as excess moisture can promote the growth of molds and bacteria (12). Before storing, remove any excess moisture with a paper towel.
• Check for signs of spoilage: If you notice any signs of molds, decay, or discoloration, discard the grapes immediately.

It is important that you know that the shelf life of grapes varies depending on the type of grape and how they are stored. For example, red and black grapes can last up to 1-2 weeks in the refrigerator, while green grapes can last up to 1-3 weeks in the refrigerator (4-5, 12).

The above-mentioned tips could help to ensure the longest possible shelf life of your grapes and safely eat them.

References

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2. Zhang X, Li Y, Wang H, Gu X, Zheng X, Wang Y, et al. Screening and Identification of Novel Ochratoxin A-Producing Fungi from Grapes. Toxins 2016, Vol 8, Page 333 [Internet]. 2016 Nov 12 [cited 2023 May 11];8(11):333. Available from: https://www.mdpi.com/2072-6651/8/11/333/htm  

3. Drusch S, Ragab W. Mycotoxins in Fruits, Fruit Juices, and Dried Fruits. J Food Prot. 2003 Aug 1;66(8):1514–27. https://pubmed.ncbi.nlm.nih.gov/12929850/  

4. de OLIVEIRA CCM, de OLIVEIRA DRB, Silveira Junior V. Variability in the shelf life of table grapes from same batch when exposed under different ambient air conditions. Food Sci Technol [Internet]. 2020 Oct 9 [cited 2023 May 11];41:290–300. Available from: http://www.scielo.br/j/cta/a/sJDHbM9QFfk4zRsC9pw9xxr/abstract/?lang=en  

5. Gorrasi G, Bugatti V, Vertuccio L, Vittoria V, Pace B, Cefola M, et al. Active packaging for table grapes: Evaluation of antimicrobial performances of packaging for shelf life of the grapes under thermal stress. Food Packag Shelf Life. 2020 Sep 1;25:100545. https://www.sciencedirect.com/science/article/pii/S2214289420301848  

6. Lawrence DT, Dobmeier SG, Bechtel LK, Holstege CP. Food Poisoning. Emerg Med Clin North Am [Internet]. 2007 May 1 [cited 2023 Apr 24];25(2):357–73. Available from: https://pubmed.ncbi.nlm.nih.gov/17482025/   

7. Newell DG, Koopmans M, Verhoef L, Duizer E, Aidara-Kane A, Sprong H, et al. Food-borne diseases — The challenges of 20 years ago still persist while new ones continue to emerge. Int J Food Microbiol [Internet]. 2010 May 30 [cited 2023 May 3];139(SUPPL. 1):S3–15. Available from: https://pubmed.ncbi.nlm.nih.gov/20153070/  

8. Pleadin J, Frece J, Markov K. Mycotoxins in food and feed. In: Advances in Food and Nutrition Research. Academic Press Inc.; 2019. p. 297–345. https://pubmed.ncbi.nlm.nih.gov/31351529/  

9. Naglik JR, Gaffen SL, Hube B. Candidalysin: discovery and function in Candida albicans infections. Curr Opin Microbiol. 2019 Dec 1;52:100–9. https://www.sciencedirect.com/science/article/pii/S1369527418300948  

10. Milaciu M V, Ciumărnean L, Orășan OH, Para I, Alexescu T, Negrean V. Semiology of food poisoning. Int J Bioflux Soc [Internet]. 2015 [cited 2023 May 10];8(2):108–13. Available from: http://hvm.bioflux.com.ro/docs/2015.108-113.pdf  

11. McRobert GR. THE TREATMENT OF BACTERIAL FOOD POISONING. Br Med J [Internet]. 1934 Aug 8 [cited 2023 May 10];2(3841):304. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2445530/  

12. Rodriguez Assaf LA, Pedrozo LP, Nally MC, Pesce VM, Toro ME, Castellanos de Figueroa LI, et al. Use of yeasts from different environments for the control of Penicillium expansum on table grapes at storage temperature. Int J Food Microbiol. 2020 May 2;320:108520. https://www.sciencedirect.com/science/article/abs/pii/S0168160520300143