re: Canning Pesto Sauce

I am a food technologist and I want to respond to your question. I was looking for some recipe's on Pesto Sauce for a project I am working on. I ran across your question, and I thought I would answer the question for you. The reason why you do not want to can pesto sauce is that most pesto recipes do not call for an acidulant, except a little lemon juice. Lemon juice (citric acid is the natural acidulant) cannot be relied upon to properly acidify the product.

The primary concern is botulism (yes, the big bug-a-boo!). Any food which has a finished pH of greater than 4.6 must be treated under Federal Law as a low acid food. This means, it must be retorted under temperature and pressure to kill botulism spores.

If enough acid is added to the food to drop it's "equilibrium pH" to below a pH of 4.6, then it is considered an "acidified food." An acidified food is one in which the majority of ingredients have an initial pH of greater than 4.6. Enough acid is added to the product so it's equilibrium pH is less than 4.6 (hopefully, 4.0 or lower). This is coupled with a heat process of about 180F for 5 - 10 minutes. You would want to use 50 Grain (5% acidity) vinegar as the acidulant. You could use Red Wine, White Wine, Balsamic or another vinegar to drop the product's pH to less than pH 4.6. My recommendation would be a pH of 4.0 or less. The product would then receive a heat treatment to bring the center of the container to 180 F for 5 minutes, using a standard canning thermometer. The product would then be treated as any other canned good, inverting jars and letting cool. This is important in canning, as the cooling down period adds additional cook time.

Now here is my advice to you. FIRST and FOREMOST, you must contact your local land grant college or university which has an agricultural extension agent, or a department of Food Science with an ag extension agent or a Department of Human Nutrition with a nutritionist. Preferably, speak to a food science ag extension specialist who is familiar with canning and acidified foods.
Take your recipe to the ag extension specialist and have them verify the pH and the process temperature and time. The extension agent will be able to verify to you the proper cook time and temperature and pH. Secondly, you must know, that this time and temperature changes for standard sized jars...the reason being, larger jars require a longer cook time for the center of the jar to be penetrated and cooked for the appropirate temperature and time. Time and temperature are critical. So once you have established it, do not change jars or size of jar until you have re-validated the process with the specialist. Doing this will ensure that you don't produce a product which has botulism in it.

For people residing on the East Coast, they should contact the Department of Food Science at Cornell University, in NY State.

For people in the mid-west, they should contact the Department of Food Science at Purdue University in Indiana, Michigan State University or Ohio State University.

For people in the South, they may contact the University of Kentucky or Texas A&M,

For people in the West, they can contact UC Davis in California, Oregon State University or Washington State University.

You may also call your local regional office of the Federal Food and Drug Administration to ask their guidance or advice.

Do not experiment on your own! Work with an ag specialist or home economist who will be happy to assist you in developing a healthy and safe food product.