Pink in McIntosh Apple?

Some apple varieties always have solidly red-pigmented flesh

Certain apple varieties like Lucy, Mountain Rose, Pink Pearl and Almata apples have been breed to have red flesh. I’ve never seen these at my Mid-Atlantic farmers market or grocery store, though, according to a website promoting Lucy apples, they are available at some stores in my region. Since these apples reliably have red flesh, Marini, who specializes in tree fruits, said they’re a different scenario than the apple pictured here (which was submitted to us by Deborah S., of Washington, D.C. Thanks Deborah!). 

What is the red color?

Whether it’s a normally red-fleshed apple or one with surprise red or pinkish areas in its flesh, Marini said the color comes from natural plant pigments called anthocyanins. They’re antioxidants that are also found in a number of foods, from blueberries to red onions to purple cauliflower. Anthocyanins, like other antioxidants, are widely known for their health benefits.

Could the red color have diffused from the skin?

If you search online, you may also see theories on various forums about the color from the apple skin diffusing into the flesh. Marini was skeptical that that was what was happening in the apple pictured here, noting that the pigment molecules were probably too big to migrate from the skin to deep within the apple. Here’s what he told me:

“Although anthocyanins are water-soluble, the molecules are pretty big, so I question this because the pigment would have to leach through two membranes – the membrane of the vacuole and the membrane of the epidermal cell containing the vacuoles. If the cell is healthy, I don’t think the membranes would be permeable enough to allow anthocyanin to leak out into the flesh. Also, if red coloration was due to leakage from the epidermal cells, I would expect the intensity of red color to be highest just under the skin and become lighter towards the core.”

So how did the red color get there?

Likely due to a genetic quirk, but the rest remains a mystery. Marini points out that the genes that prompt apples to produce this red pigment are controlled by different combinations of light and temperature. While light is normally involved in producing the red color we see in an apple’s skin, he said it is possible for other fruits to produce anthocyanin pigments without light so perhaps these apples have the same ability. 

Could this be a new type of apple?

Nope. All apples of a single variety are clones of each other, so it’s not as if these apples grew from fresh seeds with rescrambled genetic instructions. In fact, rather than plant new trees, growers typically graft whatever variety they’re looking for onto a rootstock. Grafting generally replicates the exact genetic combination that gives us the characteristics of flavor, color, crispiness, sweetness and other qualities that we associate with different types of apples.

But if all apples of a certain variety are clones of each other, how do we explain these pink splotches, which seem to reflect something that might be programmed by an apple’s genes? Here’s how Marini explained it: 

“All McIntosh trees are clones, but there are a few different strains that have resulted from mutations over the years. Some strains develop more red color in the peel than others. I would guess that some strains are more prone to red color in the flesh.”

Would a McIntosh with pink inside taste different?

Deborah reports that her apple was still sweet and tangy, just as she expected a McIntosh to be. She did note that it felt a step away from being mealy or mushy, but that could have just been her particular apple. Also notable? At least one other apple from that batch also had the pink spots, confirming Marini’s take that some strains might be more prone to red color in the flesh.