How to test for botulism in food at home?

Table of Content

• What Is Botulism?

• Symptoms of botulism

• Botulism In Canning At Home

• Overview of Botulism Testing Methods

• Prevent Botulism From Home-Canned Foods

• Other Ways to Prevent Botulism

• How Common is Botulism Occurrence in Home-Canned Foods?

• How To Get Rid Of Botulism In Canning

• Take-Home Points

• FAQ on How to test for botulism in food at home

Introduction 

Botulism or botulinum toxin is produced by the bacteria Clostridium Botulinum. Botulism is rare, but a deadly illness. Home canned foods are some of the common causes of botulism. Other causes include wound-borne or infant botulism.

Home-canned foods are some of the common ways in which one can ingest botulinum toxin. In this blog, We’ll discuss what are ways to prevent botulism at home, How to prevent Botulism From Home-Canned Foods, and how commonly home-canned foods lead to botulism.

What Is Botulism?

Botulism or botulism poisoning is a rare but potentially deadly disease. Botulinum toxin is produced by Clostridium botulinum. Botulinum toxin attacks the nerves of our body. Spores of the bacteria are also present in fresh foods but these spores are only provided with necessary conditions like lack of oxygen and low acidity levels will make them germinate and produce botulism toxin. Home-canned foods if not canned properly can become  

Three types of botulism include:

1. Infant botulism

2. Wound borne botulism

3. Foodborne botulism

Symptoms of botulism

Symptoms of botulism toxicity appear usually 12 to 36 hours after ingestion but the appearance of symptoms can take a few hours to even a few days depending on the amount of toxin ingested.

1. Trouble swallowing or speaking

2. Dry mouth

3. Facial weakness on both sides of the face

4. Blurred or double vision

5. Drooping eyelids

6. Trouble breathing

7. Nausea, vomiting and stomach cramps

8. Paralysis

Botulism In Canning At Home

Clostridium botulinum spores are present even on fresh food, in conditions like anaerobic conditions(low oxygen), low acidic environment and temperature which makes it ideal for spores to germinate and produce toxins, this environment is provided in improper canning.

• Low-acid foods: Low-acid foods like meats, fish, poultry and all vegetables (except for most tomatoes) etc support the growth of Clostridium therefore canning these foods requires special measures like high pressure canning. A high-pressure canner heats the canned food to a high temperature to destroy spores.

• High-acid foods: In High-acid foods like Plums or rhubarb, a boiling water bath is used to kill moulds, bacteria and yeasts. A highly acidic environment prevents the growth of bacterial spores.

• Can I taste the food?: No, one should never try to taste to check for botulism as it has no taste or smell. Even a small dose of botulism can be deadly.

What to do when in doubt?

If you're not sure of whether your canned food is having botulism or not just throw it out. Both home-canned food or bought from stores can be contaminated. Here are some signs to look and discard the canned food immediately:

1. A container is looking swollen or the container is leaking.

2. A spurt of foam or liquid on opening the container.

3. Colour change of food or food looking mouldy.

Overview of Botulism Testing Methods

Unfortunately, there are no Botulism testing methods which are available at home. One should never taste a canned food if suspect of spoilage or botulism it should be immediately discarded. Overview of lab testing methods of botulism:

1. Mouse bioassay: Mouse bioassay is standard. In this method sample is injected into mice and we check for paralysis or death of mice. Involvement of specific muscles and paralysis indicated botulism.

2. ELISA(enzyme-linked Immunosorbent Assay): In this method, antibodies bind to a toxin(if present in the sample) and the colour change is observed if the toxin is present by the antigen-antibody reaction.

3. PCR(polymerase chain reaction): DNA samples of clostridium botulinum are amplified and increased DNA signals of clostridium confirm its presence.

Prevent Botulism From Home-Canned Foods

Although botulism is dangerous, one should note that it is not that common. Botulism can be prevented in home canned foods by using proper techniques:

1. Use Quality produce: Before canning opt for fresh, fruits and vegetables with no mould present

2. Cleanliness is the key before canning: Cleanliness before canning the foods is the key, wash them thoroughly before canning to avoid spoilage.

3. Acidifying low-acid foods: Low-acidic foods are more susceptible to botulism, therefore acidifying them is essential by adding lemon, vinegar or citric acid.

4. Using pressure Canner: Low-acid foods require high-pressure canning to destroy bacterial spores, heating it to 240-250 degrees Fahrenheit.

5. Maintain proper temperature: Maintain proper temperature while boiling, and check for pressure gauge accuracy while using pressure canning.

6. Label the date: Clearly label your jars, for later references and to check for suspicious jars.

7. Keep in cool and dark places: Store your canned foods in cool and dark places at about 50 degrees Fahrenheit.

Other Ways to Prevent Botulism

Following standard guidelines while canning prevents botulism. There many are other ways to prevent botulism:

1. Refrigerate any canned food after opening.

2. While preparing Alaska native foods use traditional methods.

3. Home oils which are infused with garlic and herbs should be refrigerated and unused oil in 4 days.

4. Baked potatoes should be wrapped in aluminium foil and kept at a temperature greater than 140 degrees Fahrenheit or refrigerated in foil.

5. Handle honey with care, honey is not safe for infants(age below 1 year).

6. Maintain wound hygiene to prevent wound-borne botulism.

How Common is Botulism Occurrence in Home-Canned Foods?

Botulism in home canned foods is quite rare, but it is not non-existent. Proper canning techniques and the use of pressure canning can help prevent botulism in home canned foods:

• There are about 2-3 outbreaks of home-canned food of botulism. (Not enough data available for India)

• Risk factors include improper storage, improper canning and low-acid foods.

How To Get Rid Of Botulism In Canning

Botulism can be get rid of by either increasing acidity of food or increasing temperature. One needs to increase the acidity of acidic foods. Here are some ways to get rid of botulism:

• High acidic foods: High acidic foods naturally inhibit botulism and growth of bacteria, high acidic can be water bath to prevent additional spoilage. 

• Low-acidic foods: Low-acidic foods have a high risk of botulism, these can be prevented by heating in a high-pressure canner to stop the spread and germination of spores of botulinum bacteria.

• Spores are destroyed at temperatures greater than 240 degrees Fahrenheit, this can only be achieved in high-pressure canners.

Take-Home Points

• Botulism or botulinum toxin is produced by the bacteria Clostridium Botulinum. Botulism is rare, but a deadly illness.

• Home canned foods are some of the common causes of botulism. 

• Botulism can be food-borne, infant botulism or wound-borne botulism.

• Symptoms of botulism include Trouble swallowing or speaking, Dry mouth, Facial weakness on both sides of the face, Blurred or double vision, Drooping eyelids, Trouble breathing, Nausea, vomiting and stomach cramps, Paralysis

• Methods of botulism testing include ELISA, mouse bioassay and PCR.

• Methods of preventing botulism include high acidic content, high-pressure canning, water baths etc.