Canning and bottling are sometimes distinct methods for preserving foods, although the terms occasionally might refer to the same process. Some key differences between canning and bottling are their particular contents, their composition and their implementation methods. Canning, for example, generally uses sealed tin cylinders to store solid foods, and bottling usually uses glass containers.
Preserving foods is important for a number of reasons. For one, proper preservation prevents foods from becoming infected with potentially harmful microorganisms such as fungi and bacteria. A process called fat oxidation is also slowed down, which delays the food becoming spoiled and inedible. In addition, preservation methods can prevent unsightly discoloration of foods.
Canning involves preparing food, placing it in airtight containers such as canning jars and then adding hot or cold syrups. After sealing, the canned contents are often boiled or frozen to further hinder some of the dangers. Food that has been preserved using the canning method typically can stay fresh for five or more years. In many regions, this process is known as bottling, so canning and bottling are sometimes synonymous, particularly if non-commercial canning and bottling are being referenced.
In most commercial manufacturing situations, bottles are primarily used for liquids, whereas cans are used for solid foods. When considering commercial settings, bottles are differentiated from cans by their smaller opening, their larger height and their glass or plastic composition. Bottles also must be filtered before use, and sometimes they must be infused with carbon dioxide to stabilize the air contents and pressure the inside of the bottle. Production lines are used in both canning and bottling facilities.
Commercial canning, unlike bottling, typically uses tin cylinders as containers rather than glass or plastic containers. This tradition began in the early 19th century when the French government called for an effective food preservation method. Although a successful method emerged via cooking foods in airtight jars, manufacturers found difficulties in producing and distributing glass containers. Tin cans were more durable, less costly and more quickly produced, so they emerged as attractive alternatives. Modern canning procedures use a double seaming method by which lids are welded to the tin cylinders.
Different opening methods are used for canning and bottling as well. The welded sealing that is typical of cans means that an object such as a can opener is often needed to access the contents. Bottles, on the other hand, typically have a lid or holder that is detached from the bottle. Bottle caps, for example, are twisted onto the bottle to seal the contents and can be twisted off the bottle for access.
The freshness and nutritional value of foods is maintained in both canning and bottling. In addition, both means of preservation are prominent during hard economic times. Individuals often stockpile canned and bottled foods for later use, particularly when household income is compromised. Further, the cans and bottles themselves can often be used to generate income and help environmental causes when they are recycled.