Yes, Granny Smith apples are acidic, and they’re usually the most acidic apple in the grocery store. In a 2018 study comparing 11 apple varieties, Granny Smith had the highest total acid, about 10.3 grams per liter of juice, roughly double that of Red Delicious, and a pH of just 3.12 to 3.20 (Mezey and Serralegri, 2018). USDA physiologist Dr. Jim Mattheis puts Granny Smith’s titratable acidity at 0.7% to 1.0% at harvest, compared with just 0.2% to 0.3% for Red Delicious (Good Fruit Grower).

That sharp, mouth-puckering bite is exactly why people love Granny Smith for pies, salads, and snacking with peanut butter. But if you deal with heartburn, sensitive teeth, or a touchy stomach, it’s worth knowing just how tart this green apple really is, and how to enjoy it without regret.

Key Takeaways

• Granny Smith apples are acidic, with a pH of about 3.1 to 3.2 in one study.
• They’re the tartest common apple. Granny Smith had the most total acid of 11 varieties tested: about 1.5 times as much as Fuji or Gala, and about twice as much as Red Delicious.
• They’re also a little lower in sugar than many popular apples, so the acid isn’t masked as much.
• Green color doesn’t make an apple acidic. Granny Smith is tart because of its variety, not its color.
• Apples aren’t on the NIH’s list of common reflux triggers, but Granny Smith’s high acid makes it the apple most likely to bother sensitive people.
• Tartness is a strength in the kitchen. It’s why Granny Smith shines in baked desserts.

For context, see our main guide, Are Apples Acidic?, plus our variety profiles for Pink Lady and Honeycrisp.

Are Granny Smith Apples Acidic or Alkaline?

Granny Smith apples are acidic. On the pH scale, anything below 7 is acidic, 7 is neutral, and anything above 7 is alkaline. Granny Smith juice measured pH 3.12 to 3.20 in the 2018 study (Mezey and Serralegri, 2018), which puts it firmly on the acidic side.

The main acid is malic acid, the same acid found in all apples. Granny Smith simply has a lot of it. In the 2018 study, Granny Smith had the highest malic acid content of every apple tested, about 9.8 grams per liter (Mezey and Serralegri, 2018).

What about “alkaline-forming”?

You may have read that apples are “alkaline” foods. That idea refers to the estimated acid load a food leaves after digestion, not its pH. Most fruits and vegetables, including apples, are considered alkaline-forming because they’re rich in potassium and other minerals (Remer and Manz, 1995). Neither fact affects your blood pH, which your body keeps steady at about 7.35 to 7.45 (Hopkins et al., StatPearls).

How Acidic Are Granny Smith Apples? The Numbers

Here’s what the research shows.

Granny Smith in a side-by-side apple study

The 2018 study published in the Athens Journal of Sciences tested apples from both organic and conventional farms. Granny Smith had the most total acid of any apple in both groups (Mezey and Serralegri, 2018):

Granny Smith’s acid range at harvest

According to USDA physiologist Dr. Jim Mattheis, quoted in Good Fruit Grower, Granny Smith’s titratable acidity typically runs 0.7% to 1.0% at harvest. For comparison, he gives 0.3% to 0.7% for Honeycrisp and 0.2% to 0.3% for Red Delicious (Good Fruit Grower). That means a Granny Smith can contain three to four times as much acid as a Red Delicious.

Does Granny Smith get less acidic over time?

A little. Mattheis notes that all apples lose acid during storage, but the ones that start highest stay highest (Good Fruit Grower). So a Granny Smith bought months after harvest may be slightly milder, but it will still be among the tartest apples on the shelf.

Why Are Granny Smith Apples So Tart?

Granny Smith’s tartness comes down to two things: lots of acid and less sugar than many popular apples.

USDA FoodData Central lists raw Granny Smith apples at about 10.7 grams of sugar per 100 grams (USDA FDC 1750342), compared with about 12.4 grams for Honeycrisp (USDA FDC 1750343). With more acid and less sugar to balance it, the sourness shines through.

Compare that with Pink Lady, which also has high acid but more sugar, so it tastes sweet-tart instead of sour. You can read about that balance in Are Pink Lady Apples Acidic?

A tart apple with a famous history

Granny Smith is named after a real person. According to the City of Ryde in New South Wales, Australia, Maria Ann “Granny” Smith grew the first Granny Smith apples on her family’s farm in Eastwood, near Sydney, in 1868. She died in 1870, but in 1895 a New South Wales agriculture official, Albert H. Benson, named “Granny Smith’s Seedling” a suitable apple for export and began growing it on a large scale at a government experimental station (City of Ryde).

From that accidental seedling came one of the world’s best-known apples, and its tart flavor is a big part of its fame.

Granny Smith vs Other Apples: Acidity Chart

How much more acidic is Granny Smith than other apples? Here are the conventionally grown results from the 2018 study, ranked from most to least total acid (Mezey and Serralegri, 2018):

Source: Mezey and Serralegri, Athens Journal of Sciences, 2018, Table 4 (conventional production).

Notice two things:

1. Granny Smith had about 25% more total acid than Pink Lady, the next most acidic apple, and roughly double the acid of Red Delicious.
2. The pH differences are small, all between about 3.1 and 3.3. In apples, total acid tells you more about tartness than pH does.

For a mid-range apple, see Are Honeycrisp Apples Acidic?

How does Granny Smith compare with other sour foods?

Granny Smith is tart, but it’s far from the most acidic food in your kitchen. Using FDA pH values:

Source: FDA, Approximate pH of Foods and Food Products; Granny Smith value from Mezey and Serralegri, 2018.

Because each pH step is a tenfold change, lemon juice is still roughly 3 to 10 times more acidic than a Granny Smith. For a complete list, see our guide to acidic foods.

Are Green Apples More Acidic Than Red Apples?

Not because they’re green. Color isn’t what makes an apple acidic; the variety is. Granny Smith happens to be both green and very tart, which is why people link the two.

But look at Golden Delicious, a yellow-green apple. Its breeders’ data show only about 0.32% titratable acidity, less than half that of Pink Lady (Cripps et al., 1993). Meanwhile, Pink Lady, a red-pink apple, is much more acidic than Golden Delicious.

So if you’re choosing apples for a sensitive stomach, choose by variety, not color.

Are Granny Smith Apples Bad for Acid Reflux?

For many people, Granny Smith apples are fine. Apples aren’t on the National Institute of Diabetes and Digestive and Kidney Diseases’ (NIDDK) list of foods that commonly worsen reflux, which names citrus fruits, tomatoes, alcohol, chocolate, coffee and caffeine, high-fat foods, mint, and spicy foods (NIDDK).

But Granny Smith is the most acidic common apple, so if acidic fruit tends to bother you, it’s the apple most likely to cause trouble. The American College of Gastroenterology’s 2022 guideline recommends that people with GERD identify their own trigger foods (Katz et al., 2022).

Are Granny Smith apples good for acid reflux?

There’s no scientific evidence that Granny Smith apples, or any apples, treat or prevent reflux. Online claims that green apples “neutralize stomach acid” aren’t supported by research. A fruit with a pH around 3.1 doesn’t neutralize acid.

Tips if you love Granny Smith but have reflux

1. Eat smaller portions. Try a few slices instead of a whole apple.
2. Eat them with food. Pair slices with oatmeal, cottage cheese, or a little nut butter rather than eating them alone.
3. Mix varieties. Combine Granny Smith with a sweeter, lower-acid apple like Golden Delicious or Fuji in salads and baking.
4. Avoid late-night snacking. NIDDK suggests eating meals at least 3 hours before lying down if you have nighttime symptoms (NIDDK).
5. Skip extra acid. Don’t add lemon juice or vinegar dressings to a Granny Smith salad if you’re sensitive.
6. Watch apple drinks. Apple juice has a pH of 3.35 to 4.00 (FDA). See Is Apple Cider Safe for Acid Reflux?

For a broader list, see foods to avoid with GERD. If you have frequent heartburn (more than twice a week), trouble swallowing, or symptoms that don’t improve, talk with your doctor.

Gentler apple choices

If Granny Smith bothers you, try a lower-acid apple. Based on the 2018 study and USDA’s acid ranges, Red Delicious, Red Chief, Envy, Golden Delicious, Fuji, and Gala contain noticeably less acid. We rank them in our guide to GERD-friendly apple varieties.

You can also mix in lower-acid fruits like cantaloupe (pH 6.13 to 6.58) or pears (Bartlett, pH 3.50 to 4.60) (FDA).

Are Granny Smith Apples Hard on Digestion?

Some people worry that a sour apple will “add acid” to their stomach. Here’s the reality:

• Your stomach is far more acidic than any apple. The acid your stomach makes for digestion is much stronger than the malic acid in a Granny Smith, so an apple doesn’t meaningfully change the acidity inside your stomach.
• Fiber is the bigger factor for digestion. Granny Smith provides about 2.5 grams of fiber per 100 grams (USDA FDC 1750342). Fiber supports regular digestion, but eating a lot of raw fruit at once can leave some people feeling bloated.
• Discomfort is usually about sensitivity and portion size. If a whole raw Granny Smith bothers you, try half an apple, eat it with a meal, or try it cooked.

If you have ongoing stomach pain or digestive symptoms, talk with your doctor rather than cutting out foods on your own. For gentle eating ideas, see our 7-day meal plan for gastritis.

How to Make Granny Smith Taste Less Sour

You can’t change a Granny Smith’s acid content, but you can change how tart it tastes. These tricks mainly soften the flavor. They won’t make the apple low-acid, so they may not help much if acid triggers your symptoms.

1. Pair it with something rich or creamy. Cheese, yogurt, or peanut butter soften the sharp edge, and dairy is also good for your teeth.
2. Slice it thinly. Thin slices in a salad or sandwich give you the crunch without a big sour bite.
3. Add warm spices. Cinnamon and nutmeg make tart apples taste sweeter and cozier.
4. Combine it with sweeter fruit. Mix Granny Smith with Fuji, Gala, pears, or grapes in a fruit salad.
5. Cook it with a little sweetness. Baking or sautéing Granny Smith with a touch of maple syrup or brown sugar mellows the flavor, though the acid remains.

Granny Smith Apples and Your Teeth

Because Granny Smith is so acidic, frequent snacking on it can expose your enamel to acid. The American Dental Association recommends:

• Eating acidic foods as part of a meal, not by themselves
• Rinsing with water, drinking milk, or eating cheese afterward to help neutralize acid
• Waiting about an hour after eating acidic foods before brushing

Source: American Dental Association, MouthHealthy.

A classic pairing, Granny Smith slices with cheddar, actually follows this advice. Read more in Are Apples Good for Your Teeth?

The Tart Truth in the Kitchen: Cooking and Baking with Granny Smith

Granny Smith’s acidity isn’t just something to manage; it’s a big reason the apple is so useful in the kitchen.

• Balance in sweet desserts: Pies, crisps, and cakes contain a lot of sugar. A tart apple keeps them from tasting flat or overly sweet.
• Bright flavor in salads: Thin Granny Smith slices add crunch and tang to green salads, slaws, and grain bowls.
• Mix and match: Many bakers combine Granny Smith with a sweeter apple for a more rounded flavor.

Cooking doesn’t remove the acid. The FDA lists applesauce at pH 3.10 to 3.60 (FDA), so baked or cooked Granny Smith dishes are still acidic. Adding dairy, oats, or nuts can make them taste milder.

Recipes to try

• Mom’s apple cake: A tart apple keeps the cake from being too sweet.
• Little Brown Bettys: A baked apple dessert similar to an apple crisp.
• Pie pops: Mini pies on a stick, perfect for a tart apple filling.
• Apple pie donut holes: Bite-size apple pie flavor.
• Apple cider mini donuts with maple glaze: A fall favorite.
• Honeycrisp apple salad: Swap in Granny Smith for extra tang.

A sprinkle of cinnamon pairs beautifully with tart apples.

Are Granny Smith Apples Healthy?

Yes. Granny Smith apples are a low-calorie, fiber-rich fruit, and they’re a little lower in sugar than many popular varieties. Here’s what USDA FoodData Central lists for 100 grams of raw Granny Smith with skin (USDA FDC 1750342):

A few notes:

• Lower sugar than Honeycrisp: about 10.7 g vs. 12.4 g per 100 grams, according to USDA (USDA FDC 1750343).
• Keep the skin on for the most fiber.
• Managing blood sugar? Pair apples with protein or healthy fat. See Are Apples Good for Diabetics?

Frequently Asked Questions

Are Granny Smith apples acidic or alkaline?

They’re acidic, with a pH of about 3.1 to 3.2 in one study. Like most fruits, apples are considered alkaline-forming after digestion, but that doesn’t change your blood pH.

Are Granny Smith apples the most acidic apple?

Among common grocery-store apples, yes. Granny Smith had the most total acid of 11 varieties in a 2018 study, and USDA data put its acid at 0.7% to 1.0%.

Are green apples more acidic than red apples?

Not because of their color. Granny Smith is very tart, but Golden Delicious, another green-yellow apple, is low in acid. Variety matters more than color.

Are Granny Smith apples bad for acid reflux?

Not for everyone, but they’re the apple most likely to bother people who are sensitive to acidic fruit. Eat smaller portions with meals, or choose a lower-acid apple.

Do Granny Smith apples neutralize stomach acid?

No. There’s no evidence that green apples neutralize stomach acid. They’re acidic themselves, with a pH around 3.1 to 3.2.

Which apple is less acidic than Granny Smith?

Almost all of them. Red Delicious, Golden Delicious, Envy, Fuji, Gala, and Honeycrisp all contain less acid than Granny Smith.

Are Granny Smith apples good for baking?

Yes. Their strong tartness balances the sugar in desserts, which is why they’re a favorite for pies and crisps.

Are Granny Smith apples healthy?

Yes. They’re low in calories, provide fiber, and have slightly less sugar than many popular apples.

The Bottom Line

Granny Smith apples are acidic, and they’re the tartest common apple you can buy. In a side-by-side study, they had the most total acid of 11 varieties, about double that of Red Delicious. Their lower sugar content lets that tartness shine.

That’s great news for bakers and anyone who loves a sharp, crisp bite. If you have reflux or sensitive teeth, you don’t necessarily need to give up Granny Smith, but it helps to eat smaller portions with meals, pair it with gentler foods, or switch to a lower-acid apple when your symptoms flare.

Want to compare more apples? Read Are Pink Lady Apples Acidic?, Are Honeycrisp Apples Acidic?, and Are Apples Acidic?

Medical disclaimer: This article is for general information only and isn’t a substitute for professional medical or dental advice. If you have frequent heartburn, GERD, or dental sensitivity, talk with your doctor, dentist, or a registered dietitian.

References

1. Mezey J, Serralegri D. Selected quantitative parameters comparison of apples from bio- and conventional production. Athens Journal of Sciences. 2018;5(4):343–354. https://doi.org/10.30958/ajs.5-4-3
2. Good Fruit Grower. How to measure Honeycrisp qualities (quoting Dr. Jim Mattheis, USDA-ARS). https://goodfruit.com/how-to-measure-honeycrisp-qualities
3. Cripps JEL, Richards LA, Mairata AM. ‘Pink Lady’ apple. HortScience. 1993;28(10):1057. https://journals.ashs.org/downloadpdf/view/journals/hortsci/28/10/article-p1057.pdf
4. City of Ryde (NSW, Australia). Granny Smith. https://www.ryde.nsw.gov.au/Events/Granny-Smith-Festival/Granny-Smith
5. USDA FoodData Central. Apples, granny smith, with skin, raw (FDC ID 1750342, Foundation Foods). https://fdc.nal.usda.gov/fdc-app.html#/food-details/1750342/nutrients
6. USDA FoodData Central. Apples, honeycrisp, with skin, raw (FDC ID 1750343, Foundation Foods). https://fdc.nal.usda.gov/fdc-app.html#/food-details/1750343/nutrients
7. U.S. Food and Drug Administration, CFSAN. Approximate pH of Foods and Food Products. 2007. Copy used: https://riverstonehealth.org/wp-content/uploads/FDA-Approximate-pH-of-Foods.pdf
8. NIDDK. Eating, Diet, & Nutrition for GER & GERD. https://www.niddk.nih.gov/health-information/digestive-diseases/acid-reflux-ger-gerd-adults/eating-diet-nutrition
9. Katz PO, Dunbar KB, Schnoll-Sussman FH, et al. ACG Clinical Guideline for the Diagnosis and Management of GERD. Am J Gastroenterol. 2022;117(1):27–56. https://doi.org/10.14309/ajg.0000000000001538
10. American Dental Association, MouthHealthy. Dietary Acids and Your Teeth. https://www.mouthhealthy.org/all-topics-a-z/dietary-acids-and-your-teeth
11. Remer T, Manz F. Potential renal acid load of foods and its influence on urine pH. J Am Diet Assoc. 1995;95(7):791–797. https://pubmed.ncbi.nlm.nih.gov/7797810/ 
12. Hopkins E, Sanvictores T, Sharma S. Physiology, Acid Base Balance. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK507807/