How Can You Detect Plums With Red Inside

How Can You Detect Plums With Red Inside

Plums come in a stunning array of colors, shapes, sizes, and flavors. While their externally visible characteristics offer clues about what’s inside, it’s impossible to know if plums with red inside without cutting into it first. However, there are certain varieties of plums prized for their vivid red interior that can help guide plum selection. Understanding what causes the anthocyanins that color some plums’ flesh, the skin hues associated with red flesh, optimal ripeness, and how growing conditions affect color can also assist in discovering those special plums hiding red inside.

What Causes Plums With Red Inside

The red, blue and purple skin and flesh color in plums and other fruits arises from flavonoid compounds called anthocyanins. They belong to the polyphenol family, the same health-promoting group that gives concord grapes, blackberries, cherries and red wine their signature hue. Anthocyanins act as antioxidants in plant cells, protecting them from sun damage. They also attract pollinators while deterring predators.

The level of anthocyanins depends on genetics, maturity, environmental factors and storage methods. Some plum cultivars simply possess higher concentrations of anthocyanins that express visually as red flesh. Additionally, cool night temperatures while fruit is ripening tends to boost anthocyanin production. Plums harvested early may fail to develop their characteristic interior color. Proper postharvest cooling temperature also preserves anthocyanin levels after picking.

What Causes Plums With Red Inside

Plum Varieties Prized for Their Red Flesh

Many plum varieties have flesh ranging from creamy yellow to green around the stone. Only certain cultivars produce the ruby red interior prized for fresh eating, baking, jam and more. Some of the most common red-fleshed varieties include:

Santa Rosa

Santa Rose plums sport reddish-purple skin with amber and red flesh. They’re a mid-season bloomer that ripens from July through August in most regions. The moderately sized, oval fruit has a sweet flavor balanced by tart skin. Its skin may take on a dull look when fully ripe.

Elephant Heart

These heirloom plums earn their name from their size. They resemble a large heart shape and weigh upwards of a pound on average. While primarily grown in California, Elephant Heart plums can flourish in other temperate regions with sufficient winter chill hours. Biting into one reveals a scarlet-colored interior with sweet, mild flavor.

Black Splendor

A more recently cultivated variety, Black Splendor plums possesses dark purple, nearly black skin. Its flesh glows a vivid red that extends out to just under the skin. Harvesting occurs in late July/early August. The round to slightly oval plums are medium-to-large. While sweet, they tend toward more subtle flavor compared to some plums.


As the name suggests, Burgundy plums sport deep wine-red skin. A thin, dark red flesh circles the stone of these tender European dessert plums. They ripen anywhere from late July through September, depending on climate conditions. Trees produce heavily and need proper thinning for best fruit size and quality.


Mariposa plums result from crosses between Satsuma and Santa Rosa cultivars. They produce large, heart-shaped red plums mottled with speckles of yellow and light red over a purple background. Its firm, dark crimson flesh offers a balance of sweetness and acidity. Mariposa plum trees thrive in zones 4-9.

Ruby Blood

Extremely high in anthocyanins, Ruby Blood plums feature dark, dusky red skin with ruby red flesh throughout. They’re smaller, rounder plums averaging 2-3 inches across at most. Sometimes sold as “blood plums”, they live up to the moniker when their flesh is revealed. These Japanese-bred plums grow in zones 5-9.


Despite its dour name, Tragedy plums offer dramatically colorful skins in hues of golden yellow splashed with red. Inside hides scarlet flesh speckled with tiny red dots. Its unique color pattern comes from crossbreeding Santa Rosa with St. Julien A rootstocks. Tragedy ripens earlier than most red plums, bearing fruit in early-mid summer.

Weeping Santa Rosa

This genetic variation on the popular Santa Rosa plum takes on a spherical shape compared to its namesake’s oval form. It also ripens earlier in summer. The skin acquires a very deep purple-red coloration. Upon slicing into it, the firm flesh displays a dark pinkish-red hue with superb sweet/tart flavor.

How to Select Plums with Red Interior Flesh

It’s impossible to definitively know if a plums with red inside without cutting into it. However, there are visible external indicators that provide clues about the likelihood of red flesh within. These include:

Skin Color

In general, plums displaying very dark red, purple, blackish-blue or dusky skin hues tend have red or reddish flesh inside. Santa Rosa, Burgundy, Elephant Heart and Black Splendor all exhibit deep skin coloration along with their signature red interiors. Checking skin color doesn’t guarantee matching interior shade, but it narrows the odds.


Getting familiar with varieties well-established for their red inner flesh like those listed above increases the probability plums will meet color expectations inside. Produce coded with the specific cultivar names or sold as ‘blood plums’ offer helpful variety designations to look for. Farm stands, producers selling direct and some grocers provide plum variety information to aid selection.


Sampling a slice of flesh from pole ends of plums can indicate if full color development will occur. Doing so does sacrifice the fruit, however. Optimally ripe plums should yield slightly along their seams to gentle palm pressure. Avoid rock hard fruit. Full sweetness and characteristic flesh color depend on tree or vine ripening to maturity stage.

Growing Region and Season

Climate affects color development. Anthocyanins require cool night temperatures of 50 to 60°F during ripening. Plums harvested from temperate coastal or high chill zones often achieve better color than hot tropical regions. Peak seasonality also matters, with plums losing vibrancy off-season. So ideal plum flesh color corresponds with local harvest timing.

How Growing Conditions Influence Red Flesh Coloration

How Growing Conditions Influence Red Flesh Coloration

Multiple environmental factors interplay to create those vibrant pigments that color some plums’ flesh ruby red inside. Understanding what conditions promote or retard fruit color assists anyone cultivating plums or selecting the best quality market plums. These influences involve:


As referenced earlier, chill hours and temperatures affect coloration. Plums require winter cold accumulation between 32-45° F to properly set flower buds and fruit. Regions with hot summers and very mild winters lack adequate chill factor for brightly blushed plum varieties.

During the ripening phase, night temperatures around 50-60° F stimulate anthocyanin production. Hot summer days followed by cool evenings enable plums like Santa Rosa or Black Splendor to develop their famous red interiors.

Coastal zones with moderate summer heat, cooler nights plus winter chill see ideal plum color development. Inland valleys also foster well-colored plums. High elevations may pose challenges getting sufficient winter chill.

Harvesting Stages

Both under and overripe plums fail to achieve full flesh color. Picking plums prematurely means color hasn’t finished developing on or inside. Delaying harvest long enough for deep external skin color change aids attaining mature internal pigments.

However, allowing fruit to become very soft or shrivel on trees also reduces anthocyanins. Plums are highly perishable. So maintaining cool chain temperature if not processed immediately is also essential to preserve color.

Processing & Storage Methods

How freshly harvested plums are handled impacts final quality. Delicate skins easily bruise, creating entry points for fungi which causes breakdown. Gentle handling to avoid compression damage is key. Rapid pre-cooling after harvest retains color versus leaving fruit boxes hot in orchards or packing sheds.

For stored plums, holding at plum-specific 32-33°F temperature enables natural ripening while inhibiting water loss. Storing plums at inappropriate temperatures, for too long or adjacent to ethylene-producing fruits also fades bright red flesh. Compression from over stacking boxes can likewise negatively affect color.

Frequently Asked Questions

What causes red color inside some plums?

The red/blue/purple skin and flesh colors in plums arise from flavonoid compounds called anthocyanins. All plums contain some level of these antioxidants. But certain varieties through their genetics possess higher concentrations that visually appear as red interior flesh.

How can you tell if a plum will have red flesh inside?

Unfortunately there is no completely reliable external indicator if a plum contains red flesh without cutting into it first. However, plums with very dark, purple/black skin often correlate to red interiors. Knowing specific red-fleshed varieties can serve as a helpful guide. Checking ripeness and seasonality also provide clues.

What plum varieties have red flesh?

Some of the most common red-fleshed plum varieties include Elephant Heart, Burgundy, Santa Rosa, Mariposa, Black Splendor and Ruby Blood. All of these cultivars are prized for their scarlet-colored flesh ranging from deep red ringing their stones to, in Ruby Blood’s case, entire interiors glowing red.

Where are red flesh plums grown?

Regions with temperate climates featuring cool nights and winter chill hours generally produce the best quality red-fleshed plums. Major growing zones include California, the Pacific Northwest, Midwest and Northeastern/Mid-Atlantic fruit belts. Some newer low chill cultivars now expand options for red plum production even in Southeastern U.S. districts.

How should you store fresh red plums?

Freshly harvested red plums should be rapidly cooled to their ideal 32-33 F storage temperature. Refrigerating them promptly preserves flavor, texture and anthocyanin levels yielding their signature interior color. Handling plums gently to avoid bruising also maintains quality. Stored properly, fresh red plums may keep for 2-4 weeks depending on cultivar.

In Summary

Determining if a plums with red inside its skin without cutting into it first remains an imperfect art. However, understanding what triggers that scarlet plum pigment inside explains why certain varieties are prized for their dramatic color. Pairing the effervescent allure of Pink Champagne with a touch of the Orient, one can enhance the sensory journey by not only savoring the bubbly elegance but also indulging in the art of selecting the finest red-fleshed plum cultivars in season. By seeking out those famous red-fleshed plum cultivars, checking for deeply hued skin and signs of optimal ripeness, the chances of discovering those ruby red interiors improves greatly. You just may get delightfully surprised by what’s inside select plums when their flesh turns out gorgeously red.

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