Which fruits aren't acidic enough for jam without added acid?

Most fruits are acidic enough for jam on their own, but a handful sit near or above pH 4.6, the line above which botulism becomes possible. Figs range right around 4.6, elderberries average 4.92, white peaches are above 4.6, and the federal acidified food definition lists tropical fruits, which include bananas and mangoes, among its examples of low-acid foods. Tomatoes and Asian pears are borderline and need added acid whenever they are canned. For these fruits, a tested recipe adds a measured amount of bottled lemon juice, citric acid or, for elderberries, extra sugar, and you must not reduce it. White peaches and elderberries have been taken out of the fruit canning chapters altogether. This page gives the numbers and tested routes.

The fruits, one by one

Fruit with only a mild shortfall of acid for the set (blueberries, sweet cherries, peaches, apricots, pears) is a different case. Those fruits are acidic enough to be safe, but they need lemon juice to gel well; Pomona's Pectin requires 1 tablespoon lemon or lime juice per cup of mashed fruit for them [2]. That side of acid, the set, is explained on acid, lemon juice and the set.

Rhubarb is a puzzle for sellers. It tastes sharply sour, yet Penn State's commercial primer lists it with peppers, tomatoes and figs among the low-acid ingredients that call for pH verification in a product for sale [9]. For home use, follow a tested rhubarb recipe as written; if you sell a rhubarb product, take Penn State's caution and confirm its pH. The fruit itself is covered on rhubarb jam.

Why elderberry jam is the exception

Penn State Extension describes the change plainly: the fruit canning chapters no longer include white peaches and elderberries, because elderberries' average pH of 4.92 raises the same safety problem as other low-acid foods [5]. The exception is jam or jelly, where a high, precisely weighed sugar content does the protective work:

That is more sugar than fruit by weight. It means elderberry is never a candidate for low-sugar jam, honey-sweetened jam or a fruit spread. Use a kitchen scale; measuring cups are not accurate enough for this. If you want elderberry with less sugar, freeze the berries or the juice and make small refrigerator batches.

How much acid tested recipes add

The amounts below are not interchangeable rules. Each belongs to its source's method, and they are gathered here so you can see the scale of what a tested recipe asks for.

Pomona's Pectin contains no added acid, which is why the company stresses adding lemon or lime juice where its table requires it [2].

Bottled lemon juice, citric acid and vinegar

Use bottled lemon juice when a recipe says so. USDA's jam and jelly recipes and remake procedures specify bottled lemon juice [10], because its acidity is consistent from bottle to bottle while fresh lemons vary. Citric acid can replace lemon juice only where the recipe gives a citric acid amount, as the fig and tomato directions above do. Do not swap vinegar for lemon juice in a fruit jam; it changes the flavor and is not what the recipe tested.

Fruits taken out of canning guidance

Old recipe cards and cookbooks still include all three. If yours does, the recipe predates the change.

A fruit that is not on any list

Pawpaws, persimmons, loquats, prickly pears, kiwi, guava, lychee, unusual heirloom apples: if you cannot find a tested recipe for a fruit, assume nothing about its acidity. You have three honest routes.

1. Look again for a tested recipe. NCHFP publishes some unusual ones (loquat jelly, butia palm fruit jelly, mayhaw jelly, strawberry-kiwi jam) [4].
2. Make freezer jam or refrigerator jam from it, kept cold rather than on the shelf, so it does not depend on a canning process nobody tested for that fruit. How to make freezer jam has the method.
3. Measure the pH, and if you sell, get a process authority's review. A pH meter reading tells you where your fruit sits; it does not by itself give you a safe recipe. Measuring pH explains what a reading can and cannot tell you.

Fig jam is the most-made of the fruits on this page, and the details of making it well, including fresh versus dried figs, are on fig jam.

References

1. National Center for Home Food Preservation, Preserving the Fickle Fig, October 8, 2013. https://nchfp.uga.edu/blog/preserving-the-fickle-fig
2. Pomona's Universal Pectin, Create Your Own Recipe, modified August 24, 2023. https://pomonapectin.com/?p=21164
3. Oregon State University Extension Service, Preserving Fruits: Figs (SP 50-648), rev. March 2020. https://extension.oregonstate.edu/sites/default/files/documents/8836/sp50648preservingfigs.pdf
4. National Center for Home Food Preservation, Jams and Jellies (recipe index), accessed October 2026. https://nchfp.uga.edu/how/make-jam-jelly
5. Penn State Extension, Hassani, Why some old canning recipes are no longer safe, updated September 13, 2024. https://extension.psu.edu/why-some-old-canning-recipes-are-no-longer-safe
6. Penn State Extension, Morrow, Preserving White Peaches, updated March 22, 2024. https://extension.psu.edu/preserving-white-peaches
7. Oregon State University Extension Service, Preserving Foods: Asian Pears (SP 50-694), rev. May 2024. https://ccfruitandnuts.ucanr.edu/sites/default/files/2025-07/sp_50_694_preservingasianpears.pdf
8. Code of Federal Regulations, 21 CFR 114.3, Definitions (Cornell LII), current. https://www.law.cornell.edu/cfr/text/21/114.3
9. Penn State Extension, LaBorde, Food for Profit: Commercial Production of Jams, Jellies and Fruit Butters, updated May 24, 2024. https://extension.psu.edu/food-for-profit-commercial-production-of-jams-jellies-and-fruit-butters
10. USDA and National Center for Home Food Preservation, Guide 7: Preparing and Canning Jams and Jellies, rev. July 2015. https://nchfp.uga.edu/papers/guide/GUIDE07_HomeCan_rev0715.pdf
11. National Center for Home Food Preservation, Beware: Pumpkin Butter, December 7, 2012. https://nchfp.uga.edu/blog/beware-pumpkin-butter