Testing the pH of Salsa

Down here in the southwest, we like our salsa. Naturally, we’ve found a way to work some science-talk into salsa-making because well, that’s what we do. If you’re a fan of canning and making salsa, or if you’re looking to pick up a new hobby, then there are a few things you should know about acids and pH in this process. It’s important in understanding both taste and food safety, so before summer begins and you start getting all of your fresh produce, let’s learn about testing the pH of salsa!

Let’s Salsa!

When making salsa, your primary ingredient is the tomato. Tomatoes have a pH of 4.30-4.90, and when you start to make changes to tomatoes, the pH changes, too. For example, tomato juice has a pH of 4.10-4.60, tomato paste has a pH of 3.50-4.70, and strained tomatoes have a pH of 4.30-4.47. As you add other ingredients to your salsa, such as onions, garlic, and basil, you are continually changing the pH. All the ingredients in salsa must be taken into account when balancing the pH.

Here is a list of the approximate pH values of some common ingredients in salsa:

• Garlic – pH 5.80
• Yellow Onions – pH 5.32-5.60
• Red Onions – pH 5.30-5.80
• Peppers – pH 4.65-5.45
• Green Peppers – pH 5.20-5.93
• Vinegar – pH 2.40-3.40
• Lemon Juice – pH 2.00-2.60
• Lime Juice – pH 2.00-2.35

Here is another list of general pH ranges for various foods from the FDA.

Salsa recipes designed for canning often contain much more lemon or lime juice, or vinegar to balance the pH. These three ingredients are very acidic, and have a pH closer to 2.00. So why would you want to make your salsa more acidic? It’s the age-old answer we always give, and we’re betting you can guess it. High acid levels inhibit bacteria growth. However, too acidic and your salsa may not be pleasing to the palette.

So, if the average pH of our main ingredients is 5, and we want to add vinegar, lemon or lime juice (pH of about 2) to lower the overall pH, what is the ideal final pH? If something has a pH of 4.6 or below, it is deemed high in acid and is safe for boiling water bath canning.

If the pH of your salsa is close to 4.6, but you’re a little high, you can add more acid, such as vinegar, lemon or lime juice, to bring it into the safe zone.

Testing Salsa pH

About 12-24 hours after you have made your jars of salsa (or other canned food), open a jar and take a sample of your product. It’s important to test each different batch you make, and the waiting period is to make sure the salsa has cooled. Sampling after processing and cooling gives you an accurate reading of the equilibrium pH, whereas sampling immediately after heat processing will result in a highly acidic reading.

The next step depends on how you like your salsa. If your salsa is more smooth/saucy and less chunky, you can measure the pH directly by dipping our pH 3-6 test strip into the salsa sample. For a chunky salsa (our personal preference), you need to blend the sample in a blender to make it a smoother consistency. If necessary, you can add distilled water to smooth it out even more, as distilled water will not change the pH. You can then dip the pH 3-6 test strip into the salsa sample to get a reading.

Just dip the strip into the sample for 1-2 seconds, remove and shake off any excess salsa. Then compare it immediately to the included color chart, shown below.

If your results are at 4.5 or below, consider yourself in the safe zone! If not, add a little more of your acidic ingredient to the whole batch, take another sample and test again. And, equally as important, don’t forget to do a taste test!