Some shelf-stable foods are classified as acid, acidified or low-acid based on the natural acidity of the product. 

• Acid foods are foods that have a natural pH of 4.6. or below. "Natural pH” means the pH prior to processing.
• Acidified foods are low-acid foods to which acid(s) or acid food(s) are added and which have a water activity (a_w) greater than 0.85 and a finished equilibrium pH of 4.6 or below.
• Low-acid canned foods are foods with a finished equilibrium pH greater than 4.6 and a water activity (a_w) greater than 0.85 that are packed in hermetically sealed containers. Low-acid canned foods include shelf-stable canned soups, canned meats and canned vegetables. Tomatoes and tomato products having a finished equilibrium pH less than 4.7 are not classified as low-acid food.

Why Is pH Important When Manufacturing Acidified Foods?

The regulations for acidified foods require pH controls for Clostridium botulinum (botulism). This organism grows in canned and vacuum-packaged products and produces a very deadly neurotoxin that can cause paralysis and death if not treated.

Determining the Classification

Acid, acidified and low-acid canned foods should be evaluated by a food processing authority for proper classification and identification of any critical factors that must be monitored, such as pH and cook time/temperature.

What Is a Process Authority?

A Process Authority is a recognized food safety expert who has the training, experience and access to the resources necessary to determine the appropriate processing conditions and critical factors to produce a commercially sterile food product. The regulations for acidified foods state that you must work with a Process Authority to determine an appropriate scheduled process for each product that you manufacture. After analyzing your ingredients and processing methods, a Process Authority will provide a document or “letter” that specifically outlines each critical factor. This document is used to file your scheduled process with the U.S. Food and Drug Administration (FDA) and will also be used by the inspector during each inspection. View a list of Process Authorities.

Steps to Complete Before Starting a Business Manufacturing Acidified or Low-Acid Food

1. The operating supervisor who will oversee processing must receive training in pH controls and critical factors from an approved Better Process Control School. Do a web search for "Better Process Control School" for numerous choices.
2. Find a commercial processing facility that meets the Food Establishment Minimum Construction Standards [ 273.9 kB ] . 
3. Register as a Food Facility with FDA.
4. Work with a Process Authority to validate and schedule your processes.
5. Register as a Food Canning Establishment with FDA.
6. File your scheduled process for each product with FDA.
7. Submit a Food Establishment Permit application to the Florida Department of Agriculture and Consumer Services.

What Regulations Apply?

In addition to Chapter 500, Florida Statutes, and Rule 5K-4, Florida Administrative Code, the following rules apply:

• Acid food products are subject to the requirements in Title 21, Part 117, Code of Federal Regulations (CFR).
• Acidified foods are subject to the requirements in 21 CFR 108.25, 21 CFR 114 and 21 CFR 117.
• Low-acid canned foods are subject to the requirements in 21 CFR 108.35, 21 CFR 113 and 21 CFR 117.

Note: Qualified facilities that meet the modified requirements under 21 CFR 117.201 are subject only to 21 CFR 117 subparts A, B and F (training records) when determining which subparts of 21 CFR 117 apply.

Additionally, the FDA has issued: Guidance for Industry: Low-Acid Foods Packaged in Hermetically Sealed Containers (LACF) Regulation and the FDA Food Safety Modernization Act.

What Should You Expect During an Inspection?

Inspections are a careful, critical, official examination of your process and final product. Your facility and equipment will be inspected to assess sanitation practices and your implementation of Good Manufacturing Practices. The inspector will observe processing activities to assess your adherence to the scheduled process that was filed with the FDA. A comprehensive review of the required records is necessary to determine compliance with the regulations. At the end of the inspection, a report will be provided.