The preservation of food has been practiced for centuries; drying and freezing for instance are two of the earliest methods. During the winter, the ancient man placed his fresh hunt under the snow and during the summer, under the sun. There were plenty of other ways to conserve food items such as curing, sugaring, fermenting, and pickling. Most of these methods, however, had many disadvantages, such as altering the flavor of the foods or using a large amount of expensive resources. One of the most recent methods of preserving food was pioneered in the late 18th century by a French confectioner, Nicolas Appert. He observed that sealing a glass bottle with heat prevented the food inside from spoiling. It was an efficient and inexpensive way to preserve food for extended periods of time and it truly became a sensation. This method of conservation is now commonly known as canning. Despite its great discovery, the scientific reasoning as to why canning was successful remained a mystery for more than fifty years! It was not until the mid 19th century that microbiologist Louis Pasteur deciphered the relationship between microorganisms and food spoilage. Having access to the scientific basis for canning, together with modern technology, today’s canning methods have certainly evolved. Although these may be fast and precise, nothing beats the simplicity and efficiency of the art of canning in the 19th century. In the following blog, the reader will take a first glance as to how housewives meticulously canned in the 19th century and the variety of food items that they were able to preserve by doing this. The reader will also have an insight into the science behind canning; something that took more than half a century for scientists to figure out. Finally, the modern methods of canning will be discussed and compared with those from the previous century. However, it is important to first discuss the history of this fascinating method of preserving food and why it is so popular today.
It all began in 1795, when Napoleon Bonaparte offered an enticing cash prize to anyone that came up with a method to keep food from spoiling for extended periods of time. What was his reasoning? Napoleon was afraid that his constantly-traveling army was lacking the nutrition necessary for a powerful battle. Having to rely on invaded countries to sell or provide him and his army with food was always a disadvantage. Thus, the long quest for the undiscovered method of canning began. It took 15 years for Napoleon’s prize to be collected and the lucky man was Nicolas Appert, a candymaker now known as “The Father of Canning”. His incredible discovery was recognized in a letter in 1810 from The French Minister, “As the preservation of animal and vegetable substances may be of the utmost utility in Seavoyages…I deem your discovery worthy an especial mark of the good will of the government. I have in consequence acceded to the recommendation made me by my council to grant you a recompence of 12,000 francs” (Appert 1812). Appert obtained inspiration from the process of bottling wine; He began placing food in jars, placing a cork over their opening, and sealing the cork to the jar with hot wax. Then, he would wrap the sealed jar with canvas, a smooth fabric, and place the wrapped jar in a pot of boiling water. Appert’s work became a phenomenon. J. Miriel, secretary of the Council of Health sent a letter to a general describing the condition of three-month old food preserved by the Appert method, “The broth in bottles was good…the bouillon in a vessel was also good…The Beans and green peas…had all the freshness and flavour of recently gathered vegetables” (Appert 1812).
Image 1: Nicolas Appert’s “bottling” method for the preservation of food. Photograph from The Smithsonian Magazine.
Appert had a basic idea as to why his method was successful; he knew that the application of heat prohibited animal and vegetable products from decomposition. Additionally, he was aware that completely sealing the jars was essential as it deprived the food inside from all contact with the air achieving, “a perfect preservation of those same productions, with all their natural qualities” (Appert 1812). In Appert’s description of the equipment needed for proper canning, he mentions the importance of using glass bottles as this container, “is the most impenetrable by air”. There was no mistake in his basic understanding of how canning works, as the lack of air inside the sealed bottles is precisely what keeps the food from perishing. While Appert understood the process of canning and sealing food from contaminants he lacked the understanding of microbial and atomic science to improve and refine his methods much further. So, why exactly is the deprivation of air so essential in canning? What happens if the bottle is not heated enough or sealed properly?
In 1864, Louis Pasteur, a chemist and microbiologist, realized that microorganisms were the main cause for food spoilage, and their absence kept food fresh for a surprising amount of time. Knowing this, Pasteur developed a method of killing harmful bacteria thus extending the shelf life of perishable products. This process is known as “pasteurization” which involves heating liquids to high temperatures in order to kill any bacteria found within the product. Even though pasteurization is mainly used for milk and dairy products, the same reasoning can be applied to canning. The only difference between canning by Appert’s water bath and Pasteur’s pasteurization is the temperature and the amount of time the jar is kept in the hot water. Therefore, Appert’s first hypothesis stating that heat prohibited food and animal products from deteriorating was confirmed by Pasteur to be correct.
The reasoning behind the necessity of securing the jars completely to prevent air contact is quite straightforward. Foods that contain a high quantity of water (moisture) are extremely perishable for a number of reasons. Moisture for one, causes the growth of unwanted bacteria and mold as it is used by microorganisms as a source of energy to grow and reproduce. In addition, the presence of air (oxygen) causes the food to undergo the process of oxidation. During oxidation, foods change chemical composition as they are broken down and begin to produce an undesirable smell as they spoil. It is therefore important to properly seal the glass jars by boiling them and then letting them cool, so a strong vacuum seal can be created. This, in turn, completely deprives the item from all contact with moisture and oxygen from the atmosphere, resulting in a longer shelf-life due to the jar’s sterile environment.
The extended storage-life of food that canning provided was only one of numerous reasons why it became a sensation among housewives in the 19th century. Canning provided additional nutrition to families during the harsh winter months, when hardly any fruits or vegetables could be harvested. Seasonal fruits and vegetables could now be enjoyed out of season for a longer duration. It also diminished the waste of food, as housewives would can when a surplus of fruit was available that would otherwise spoil if uneaten. This in turn saved a significant amount of money. As mentioned previously, other food preservation methods such as drying and sugaring either negatively affected the taste and texture of the product or required expensive ingredients. Canning, although it may alter a food’s texture, does not significantly impact its taste, which is what many people are concerned about. Additionally, this method of food preservation is inexpensive as it only utilizes a glass jar with a proper lid, and if taken proper care of, can be reused indefinitely.
The Perfect Art of Canning and Preserving, written by Edna Witherspoon for housewives at the end of the 19th century, explains how to make jams, marmalades, and jellies for canning and preserving food. She mentions that canning is no easy task for a housewife as, “the thermometer is almost certain to be somewhere in the nineties, while in the kitchen it often reaches one hundred” (Witherspoon 1891). In spite of this, all the hard work done during the spring and summer pays off during the long winter months, and canning begins all over again after the winter ends. Before she describes her endless number of recipes, Witherspoon writes something interesting that is worth taking note of, “Our grandmothers…they usually kept their jams in earthen crocks. Now this is not a good plan, for jams kept in these jars are apt to ferment by Spring”. Earthen crocks were cheap containers made out of clay or stone that were used to store perishable items. Image 2 displays some examples of antique earthen crocks. By simply observing these containers and now having the knowledge of what makes canning successful, one can determine why Witherspoon described preserving food in these pots as “not a good plan”. The multiple holes in the crocks as well as their loose lids would allow air and moisture inside, affecting the perishable item by fermentation. The clay itself is a material that is known to absorb water and moisture; think of plant pots, clay pots are used precisely because they can absorb and retain water for a certain period of time, keeping plants hydrated. This is certainly not what a housewife wants to do if she’s trying to preserve food for the entirety of the winter! Therefore, Witherspoon recommends to, “Use instead the glass jar with metal screw – top and rubber” and goes on to say that even though it is a big investment, with proper care these jars will last for years. In fact, Witherspoon describes everything that Appert, “The Father of Canning,” had explained years before, and the science confirms all of it, making Witherspoon a reliable source.
Image 2: Antique Earthen Crocks. Left photograph obtained from True Legacy Homes. Right photograph obtained from Chairish.
The way Witherspoon describes canning is extremely similar to the Appert canning method. “Just before the time is ended, place the jars in water as hot as the glass will stand without cracking; drain them and at once adjust the rubbers…fill it to overflowing. As the jam runs out of the top, screw down the metal cover tightly. Use the wrench that comes for this purpose, as the top can thus be made perfectly tight…set away to cool. After they are cold, tighten the tops a little more… Jam made in this way may be kept for an indefinite period”. She emphasizes the tightening of the lids, “On the following day, when the jars are perfectly cold, tighten the tops more if possible” which, again, is essential for successful preservation. She also recommends avoiding shaking the jars once they are cooled to prevent the fermentation of the fruit, something that Appert never mentioned. It is true however, as shaking the jars increases the probability that gas will be produced inside the container, causing fermentation to occur. Witherspoon mentions something else that is interesting and accurate, “Canned fruit should always be opened two or three hours before it is needed, as the flavor is much finer when the oxygen, of which it has been so long deprived, is thus fully restored”. Although Appert does not consider this, it makes perfect sense that jams and marmalades would taste better after being left out for a while. She goes as far as to describe in detail how to best care for the glass jars:
Image 3: Excerpt from The Perfect Art of Canning and Preserving.
In this way, she was able to produce canned jams, jellies, marmalades, preserves, butters, syrups, and branded fruits. Withserspoon clearly understood what she was talking about and truly considered canning and preservation to be an art.
Finally, let’s consider modern canning methods that utilize the same basic principle but take advantage of modern technology. The two most common being pressure canning and atmospheric steam canning. Pressure canning, which is mainly for low acid foods such as vegetables and meat, uses pressure to create temperatures above boiling capable of effectively heating foods that carry more potent bacteria. Achieving higher temperatures creates a higher sterile environment inside the can, ensuring that there is no unwanted growth of bacteria. Pressure canning would have been a housewife’s dream in the 19th century as she would be able to preserve all kinds of nutritious meats for winter. On the other hand, atmospheric steam canners are mainly used for high acid foods like in water bath canning. It is currently the newest canning method and differs from pressure canning in that it operates under atmospheric pressure and at the boiling point of water instead of above. Both of these canning methods use expensive appliances with pressure cookers being the least pricey at approximately 200 dollars and atmospheric pressure cookers can cost up to 10,000 dollars! There is no doubt that water bathing remains the cheapest and safest way of canning, and it all started with a contest to win 12,000 francs.
Image 4: Pressure Cooker vs Atmospheric Pressure Cooker. Both photographs obtained from Amazon.
- Adamant, Ashley, Tarre B Smith, Beth, Lisa Smith, Lourdes, Timmy, Leslie, et al. “Pressure Canning: Beginners Guide.” Practical Self Reliance, October 27, 2022. https://practicalselfreliance.com/pressure-canning/.
- Appert, Nicolas. The Art of Preserving All Kinds of Animal and Vegetable Substances for Several Years. Seconded. London: Cox and Baylis, 1812.
- “Canning Techniques.” Twice as Tasty, March 2, 2018. https://twiceastasty.com/canning/techniques/.
- “Historical Origins of Food Preservation.” National Center for Home Food Preservation | NCHFP Publications. Accessed December 3, 2022. https://nchfp.uga.edu/publications/nchfp/factsheets/food_pres_hist.html.
- “How to Use an Atmospheric Steam Canner.” Penn State Extension. Accessed December 4, 2022. https://extension.psu.edu/how-to-use-an-atmospheric-steam-canner.
- Martin, Kalea. “How Napoleon Influenced the Canned Food Industry.” Tasting Table. Tasting Table, May 12, 2022. https://www.tastingtable.com/861564/how-napoleon-influenced-the-canned-food-industry/.
- Meredith, Leda. “The Brief History of Canning Food.” The Spruce Eats. The Spruce Eats, October 2, 2019. https://www.thespruceeats.com/brief-history-of-canning-food-1327429.
- “Pasteurization.” Environmental Health, February 24, 2017. https://www.vdh.virginia.gov/environmental-health/food-safety-in-virginia/milk-safety/pasteurization/#:~:text=Pasteurization%20involves%20heating%20liquids%20at,%3D%20all%20bacteria%20are%20destroyed).
- Witherspoon, Edna. The Perfect Art of Canning and Preserving. London: Butterick Pub. Co., 1891.