Intro to Product Shelf Life

For many shelf stable products, acidity is a very important aspect of development, as it can help ensure shelf life stability. During the process Low pH and heat act together as the protection to prevent pathogenic bacteria, yeast and mold growth. In small batch food manufacturing, pH is a critical factor enabling your product to be shelf-stable.

The pH scale is a 14-point reference scale from 0 to 14, where 0 is the most acidic and 14 is the most alkaline. 7 is considered neutral with acidic below that value and alkaline above. Most microbes prefer a neutral or near-neutral environment. Acidity is measured with a pH meter. There are many types of pH meters, but generally, a digital unit with a probe is more accurate. They can cost $250 or more, and a good meter is worth the investment. The meter must be calibrated frequently to give accurate measurements and requires buffering liquid for this procedure. As a standard operating procedure (SOP), we calibrate our pH meter at the beginning of every day. This equipment can be purchased from a reputable company such as Cole Parmer.

The most dangerous pathogen as far as shelf stability is concerned is Clostridium botulinum (botulism) which cannot grow below a pH of 4.5. As a reference, vinegar and lemon juice have an approximate pH of 2. Tomatoes have an approximate pH of 4 and most vegetables have a pH between 6 and 7, which is close to neutral. In contrast, soapy water has a pH of approximately 12, which is alkaline. Ingredients with a low pH are sour and any additions of acid – lactic, malic, citric, vinegar, lemon juice, or any other acids – will make your product more tart.

To be safely packed, the product has a general pH of less than 4 and a filling temperature of greater than 175F to prevent the growth of mold, bacteria or yeast. When pH and heat are used together and evaluated by a recognized process authority, your product may be stored at ambient temperatures and will be safe for an extended time. This can be done without the addition of dangerous chemicals.

This type of processing is called “hot fill and hold” and this control is essential to ensure that your product is safely manufactured, will have a long shelf life stability, and will be safe for your customers.

You can continue to read: What is a Scheduled Process?