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Low-acid canned foods are shelf-stable foods in hermetically sealed containers whose finished equilibrium pH is above 4.6 and water activity is above 0.85, and they are regulated under 21 CFR 113. Acidified foods are low-acid foods with acid added to bring the pH to 4.6 or below, regulated under 21 CFR 114. Both require FDA registration, a filed scheduled process and a trained supervisor.
This guide explains the definitions, how to tell which rule applies, what a process authority does, and the registration and filing steps. It sits beside our overview of 21 CFR Part 117 and the wider FSMA framework. This is general information, not legal advice; confirm requirements for your product with FDA and your process authority.
Low-Acid Canned Foods vs Acidified Foods: Definitions
| Term | Definition | Main rule |
|---|---|---|
| Low-acid food | A food other than an alcoholic beverage with a finished equilibrium pH above 4.6 and water activity above 0.85. Tomatoes and tomato products with a finished equilibrium pH below 4.7 are excluded (21 CFR 113.3) | 21 CFR 113 when thermally processed in hermetically sealed containers |
| Acid food | A food with a natural pH of 4.6 or lower (21 CFR 114.3) | Not an acidified food |
| Acidified food | A low-acid food to which acid or acid food is added, with water activity above 0.85 and a final equilibrium pH of 4.6 or below. Carbonated drinks, jams, jellies and preserves are excluded, as are foods kept refrigerated through storage, distribution and retail (21 CFR 114.3) | 21 CFR 114 |
| Commercial sterility | The condition reached when heat, or heat with water activity control, eliminates microorganisms that could grow in the food under normal non-refrigerated storage, including spores of public health significance (21 CFR 113.3) | Goal of the scheduled process for low-acid canned food |
Examples of acidified foods in the regulation include beans, cucumbers, cabbage, peppers and artichokes, which are often sold as pickles. A pickle that stays refrigerated from production through retail falls outside the acidified food definition, which is why storage conditions matter as much as pH.
What a Process Authority Does
A scheduled process is the thermal process a processor chooses as adequate for a given product under its own conditions. For low-acid foods it must be at least equivalent to a process set by a competent processing authority, according to 21 CFR 113.3. In practice a process authority is a person or laboratory with expert knowledge of heat penetration, acidification and your equipment, who establishes and documents the scheduled process for each product and container size. If you later lower the starting temperature, shorten the time or change the formulation or container in a way that affects the process, 21 CFR 108.35 calls for a qualified scientific authority to confirm the change is adequate, with the confirmation recorded and kept on file.
FDA Registration and Process Filing
Commercial processors register with FDA and file each scheduled process. Under 21 CFR 108.25 (acidified foods) and 21 CFR 108.35 (low-acid canned foods), the sequence is:
- Register the establishment. Within 10 days of first processing, file Form FDA 2541, the food canning establishment registration (commonly called the FCE registration). Foreign processors of acidified foods must register before offering food for import.
- Get a scheduled process. Have your process authority set it for each food and container size.
- File the scheduled process. Within 60 days of registration, and before packing a new product, file on the form for your method (commonly called the SID filing). The forms are 2541e for acidified foods, and 2541d (retort), 2541f (water activity or formulation control) and 2541g (aseptic) for low-acid canned foods. A separate filing is needed for each food and container size.
- Use a trained supervisor. Operators of the thermal system, container closure inspectors and acidification operators must work under a supervisor who has completed an FDA-approved course (21 CFR 114.10), which is commonly delivered as a Better Process Control School.
- Run at or above the filed process and keep processing, deviation and closure-inspection records.
FDA's receipt of a filing is not an approval of the process, and filed information is treated as a trade secret. If you stop processing, notify FDA within 90 days; temporary seasonal or emergency shutdowns do not trigger the notice. Check FDA's acidified and low-acid canned foods page for the current forms and the filing method.
Records and Deviations
Both rules require records of processing, of deviations from the scheduled process and of container closure inspections, and they require those records to be reviewed. Retention periods are set in the regulations, so check 21 CFR 113.100 and 114.100 for your case. A deviation from the scheduled process, such as a retort temperature drop, needs a documented evaluation of the affected product, usually with your process authority.
How These Rules Fit With FSMA
Acidified and low-acid canned food plants follow 21 CFR 113 and 114 for the thermal process and the container integrity hazards those parts address. For other hazards, plants generally remain subject to current good manufacturing practice under Part 117 and the preventive controls requirements, as the regulations describe. Confirm the scope that applies to your facility with FDA.
Keeping the Supporting Records Together
The thermal process itself is controlled by your retort, your process authority and your process records. What surrounds it is lot-level evidence: which ingredient lots and container lots went into each batch, when each check was done and what happened on a deviation. In IONI, batches, ingredient lots, scheduled monitoring checks, logs and deviations with corrective actions can be kept in one place alongside your own process records. IONI does not control a retort or replace a process authority. See IONI's food safety software.
FAQ
What is a low-acid canned food?
A shelf-stable food in a hermetically sealed container, with a finished equilibrium pH above 4.6 and water activity above 0.85, thermally processed to commercial sterility under 21 CFR 113.
What is the difference between low-acid canned and acidified foods?
Low-acid canned foods are sterilized by heat. Acidified foods are low-acid foods that have acid added to reach pH 4.6 or below, which allows a less severe process, and they are regulated under 21 CFR 114.
Do I need a process authority?
Your scheduled process must be adequate and, for low-acid foods, at least equivalent to one set by a competent processing authority, so in practice yes.
What is FCE registration and SID filing?
The FCE registration is Form FDA 2541, which registers the establishment. The SID filing is the scheduled process submission for each product and container size, on the form matching your process.
Do refrigerated pickles count as acidified foods?
The regulation excludes foods that are kept refrigerated through storage, distribution and retail from the acidified food definition. Confirm your product with FDA.
Last updated: October 14, 2026
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