Canned or jarred foods are products that have been preserved and packaged in airtight containers, usually made of metal (such as tin-plated steel) or glass, to prevent spoilage and maintain their quality over an extended period of time. The canning process involves sealing food in a container, often with a liquid or sauce, and then subjecting the container to heat to destroy microorganisms that can cause spoilage and foodborne illnesses.
Canning provides several benefits, including extended shelf life, convenience, and the ability to enjoy certain foods even when they are out of season. Canned foods can also be used as ingredients in various recipes and are often relied upon during emergencies or when fresh foods are not readily available.
What is the history of canning food?
The history of canning food is a fascinating journey that spans centuries and involves multiple inventors and innovations. Here are some brief key milestones in the development of canning as we know it today:
- Early Preservation Techniques: Before the invention of canning, humans relied on various methods to preserve food, such as drying, salting, smoking, and fermenting. While these methods were effective to some extent, they often didn’t provide long-term preservation and were limited in their ability to prevent spoilage.
- Nicholas Appert (Late 18th Century): The concept of canning food began to take shape with the work of Nicolas Appert, a French chef and confectioner. In the late 18th Century, he conducted experiments to preserve food by sealing it in glass jars and heating it to kill bacteria. In 1809, he published a book detailing his methods and success in preserving various foods. Although he didn’t fully understand the role of heat in the preservation process, Appert’s work laid the foundation for future developments.
- Peter Durand (1810): A few years after Appert’s experiments, Peter Durand, an Englishman, applied for and received a patent for preserving food in tin-plated iron cans. Metal containers, as opposed to glass, are more durable and suitable for commercial production.
- Early Challenges: While the idea of preserving food in cans gained traction, early canning processes faced challenges. The preservation methods were inconsistent, leading to issues like spoilage, off-flavors, and safety concerns. Additionally, the lack of proper understanding of the role of microorganisms contributed to these challenges.
- Louis Pasteur and Germ Theory (19th Century): Louis Pasteur’s discoveries in microbiology and his formulation of the germ theory of disease in the mid-19th Century significantly improved the understanding of the role of microorganisms in food spoilage. This laid the groundwork for better food preservation techniques.
- John L. Mason and the Mason Jar (1858): John L. Mason created and patented the Mason jar, a glass container with a threaded metal lid. This innovation allowed for easier sealing of containers and became a popular choice for home canning.
- Appertization and Commercialization: By the mid-19th Century, the canning industry had begun to grow as companies adopted improved sealing techniques and a better understanding of heat processing. Appertization, the term used for heat processing to preserve food, became more refined, leading to better-quality canned products.
- Modern Advances: Throughout the 20th Century, advancements in materials, sealing techniques, and understanding of food science continued to improve the quality and safety of canned goods. Innovations like vacuum sealing, better can coatings, and more precise temperature control contributed to the development of a wide range of canned products.
- Home Canning and Industrial Production: Canning became popular in households for preserving fruits, vegetables, jams, and more. At the same time, industrial-scale canning allowed for mass production of canned goods, making them widely accessible.
- Diversification of Canned Products: As technology and food science advanced, the range of canned products expanded to include soups, meats, fish, ready-to-eat meals, and more. Convenience and long shelf life made canned goods a staple in many households.
How long do canned goods last?
Before we proceed with this article, please note that improperly canned foods can cause serious illnesses. Please consult reliable sources such as the USDA or the National Center for Home Food Preservation if you have any questions about the safety of canned foods.
The shelf life of canned goods varies widely depending on factors such as the type of food, the canning process used, the storage conditions of the canned food, and more. Typically, canned goods have a relatively long shelf life, particularly when compared to other forms of food preservation, due to the airtight seal that prevents the entry of bacteria, yeast, and molds.
Low-acid foods, such as vegetables, meats, and fish, typically have a longer shelf life than high-acid foods, often ranging from 2 to 5 years or even longer. Properly canned low-acid foods can remain safe to eat for several years, though the quality and taste may gradually decline over time.
High-acid foods like fruits and tomatoes have a slightly shorter shelf life than low-acid foods. They generally last 1 to 1.5 years or more. Over time, the acidity can lead to the deterioration of the can and potential changes in flavor and texture.
Either way, remember that while canned foods usually have a long shelf life, consuming them within a reasonable time frame is recommended to ensure optimal quality and safety. Over an extended period, the food’s nutritional content, flavor, and texture may degrade. Factors such as temperature, humidity, and exposure to light can also affect the shelf life of canned goods.
As we touched on above, improper canning can lead the growth of harmful bacteria inside of the can. One indication that your canned food has a problem is a bulging can. Bulging cans should be tossed out immediately because that can indicate the presence of harmful bacteria, such as Clostridium botulinum, which causes botulism. This bacteria produces gas as it multiplies, causing the can to swell. Consuming food from bulging cans can lead to severe food poisoning, characterized by symptoms like nausea, vomiting, fatigue, dizziness, and even paralysis or death in extreme cases. To ensure safety, it’s crucial to discard any cans that show signs of bulging, rusting, or damage.
Spoiled Canned Foods
If you are ever in doubt about the safety or quality of a canned product, it’s best to err on the side of caution and avoid consuming it. To ensure the safety and quality of canned goods:
- Check for External Damage: Before consuming canned goods, inspect the cans or jars for any signs of damage, such as cracks, dents, bulges, rust, leaks, or changes to the food product inside (if you can see it). Damage can compromise the seal and lead to spoilage or contamination.
- Follow Recommended Storage Guidelines: Store canned goods in a cool, dry place away from direct sunlight. Extreme temperatures can affect the integrity of the containers and potentially lead to spoilage. Avoid storing them in areas prone to temperature fluctuations, such as garages or attics.
- Rotate Your Stock Regularly: When purchasing canned goods, try to use the “first in, first out” rule, meaning you should consume the oldest cans first and replace them with newer ones. This helps prevent canned foods from sitting on your shelves for too long.
- Use By or Best Before Dates: Some canned goods may have “use by” or “best before” dates printed on them. While these dates provide a general guideline for quality, they might not always accurately reflect the product’s safety. If the container is undamaged and has been stored correctly, it might still be safe to consume after the indicated date.
Can you can food at home?
Of course! Canning food at home can be a fun and rewarding way to preserve seasonal produce and create your own shelf-stable foods. Jars of homemade foods also make great gifts! There are two main home canning methods: water bath and pressure canning. The method you choose depends on the type of food you are canning, as low-acid foods require pressure canning for safe preservation.
Before reading further, please keep in mind that canning food at home requires strict adherence to safety guidelines to prevent the risk of foodborne illnesses, such as botulism, and ensure personal physical safety. It is crucial to use tested recipes and appropriate equipment, including pressure canners for low-acid foods. If in doubt, consult reliable sources such as the USDA or the National Center for Home Food Preservation to ensure safety.
Water Bath Canning
Water bath canning is suitable for high-acid foods, like fruits, jams, jellies, pickles, and tomatoes with added acid. The high acidity helps prevent the growth of harmful microorganisms.
Equipment needed:
- Large pot with a lid and a rack (designed to hold jars off the bottom)
- Canning jars with two-piece lids (jars and metal bands with flat lids)
- Jar lifter
- Canning funnel
- Wooden or plastic spatula
- Clean kitchen towels
- Acid (like lemon juice) if required by the recipe
How to water bath can:
- Prepare Your Jars: Wash jars, lids, and bands with hot, soapy water. Sterilize jars by placing them in simmering water or in the oven at a low temperature. Keep lids and bands in warm water to soften the sealing compound.
- Prepare Your Food: Prepare the food you want to can according to your chosen recipe. Blanch, peel, and cut fruits and tomatoes as needed.
- Fill The Jars: Use a canning funnel to fill your jars with the prepared food, leaving the recommended headspace (space between the food and the jar’s rim).
- Remove Air Bubbles: Gently run a spatula along the sides of the jars to release any trapped air bubbles.
- Wipe The Rims: Use a clean, damp cloth to wipe the rims of the jars to ensure a clean seal.
- Apply The Lids and Bands: Place the flat lids on the jars and secure them with the metal bands. Tighten the bands until they are fingertip-tight, not overly tight.
- Process The Jars: Place the filled and lidded jars on the rack in the canning pot. Add water to cover the jars by at least one inch. Bring the water to a boil and then start the timer for the recommended processing time (specified in your recipe).
- Complete The Processing: After processing, turn off the heat and let the jars sit in the water for a few minutes. Then, carefully lift the jars out of the water using a jar lifter and place them on a clean kitchen towel.
- Cool and Seal The Jars: As the jars cool, you’ll hear a “ping” sound, indicating that the lids are sealing. This process creates a vacuum seal that prevents contamination.
- Check The Seals: After the jars are completely cool, press the center of each lid. The jar is sealed if the lid is firm and doesn’t move. If it pops, the jar didn’t seal, and you should refrigerate or reprocess the contents.
Pressure Canning
Pressure canning is used for low-acid foods like vegetables, meats, poultry, and seafood. The higher temperature reached in a pressure canner is necessary to destroy harmful bacteria like Clostridium botulinum.
Equipment needed:
- Pressure canner
- Canning jars and two-piece lids
- Jar lifter
- Canning funnel
- Clean kitchen towels
How to pressure can:
- Prepare Your Jars: Follow the same steps as for water bath canning to prepare and sterilize the jars, lids, and bands.
- Prepare Your Food: Prepare the low-acid food according to your recipe.
- Fill The Jars: Fill jars with the prepared food, leaving the recommended headspace.
- Remove Air Bubbles and Wipe Rims: Similar to water bath canning, remove air bubbles and wipe jar rims clean.
- Apply The Lids and Bands: Apply lids and bands to the jars.
- Process The Jars: Place the jars in the pressure canner, following the manufacturer’s instructions for water level and pressure settings. The canner should be properly vented before sealing and pressurizing.
- Start A Timer: Once the canner reaches the recommended pressure, start the timer for the specified processing time.
- Cool and Check The Seals: After processing, turn off the heat and let the pressure naturally release. Once the canner is depressurized, carefully open it. Allow the jars to cool, and check for proper seals.
A Word of Caution
Though canning at home can be fun, it can also be a bit dangerous, and there are a few things you should keep in mind before you begin. Canning is a skill that requires proper techniques and understanding of food safety principles. If you’re new to canning, consider learning from experienced canners, attending workshops, or consulting reliable resources and guides.
- Always follow a trusted and up-to-date canning recipe to ensure safety and proper processing times.
- Always use jars specifically designed for canning, as they are tempered to handle the temperature changes during canning.
- Be sure to adjust processing times and pressure settings based on your altitude. Higher altitudes require longer processing times.
The steps outlined above provide a basic overview of home canning. Refer to authoritative sources such as the National Center for Home Food Preservation or reputable canning guides and books for more detailed instructions and safety guidelines.
Do you can food at home? What are your favorite foods to can? Do you give them as gifts? Let us know in the comments!
