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Why do strawberries have white in the middle?


Strawberries with white in the middle are a common sight in strawberry baskets. The white or pale green flesh at the center of strawberries is perfectly normal and natural. This white interior is simply the result of how strawberries grow and ripen. Understanding the anatomy and development of strawberries helps explain why some strawberries have more white flesh than others.

Anatomy of a Strawberry

A strawberry is an aggregate accessory fruit, meaning that the fleshy part is derived not from the plant’s ovaries but from the receptacle that holds the ovaries. Each apparent “seed” (called an achene) on the outside of a strawberry is actually one of the ovaries of the flower, with a seed inside it.

The fleshy, edible part of the strawberry is the swollen receptacle, while the tiny, yellow, seed-bearing achenes cover the surface.

The Receptacle

The receptacle is the thickened, swollen base of the flower that remains attached to the plant after fertilization occurs. This forms the fleshy red part of the strawberry that is eaten. As the receptacle grows, it becomes conical or heart-shaped.

The size of the receptacle determines the overall size of the mature strawberry. The development of the seeds does not directly affect strawberry size.

The Achenes

The small, seed-containing achenes are the actual fruits of the strawberry plant. These tiny fruits dot the exterior of strawberries and contain the seeds. Each achene has one seed within it.

The number of achenes depends on the variety and can range from around 200 to 600 per berry. Achenes are usually yellow or white.

Development and Ripening

Understanding how strawberries develop and ripen helps explain why unripe or under-ripe strawberries often have more white flesh.

Flowering

The flowering process begins when temperatures increase in spring. The flowers have both male and female parts. Once pollinated, the ovules become achenes and the receptacle starts expanding.

Enlargement

After pollination and fertilization, cells in the receptacle start rapidly dividing and expanding. This enlargement forms the fleshy part of the developing berry.

As the receptacle expands, it takes on a conical or heart-shape. The achenes adhere to the surface.

Ripening

As the strawberry continues to grow, it remains pale green and hard. Only when ripe does it turn red and soft.

Ripening occurs from the outside in. The outermost part of the receptacle ripens first.

The center is the last part to ripen. This explains why under-ripe strawberries often have white centers.

Why Strawberries Have White Inside

There are a few main reasons why ripe, red strawberries may still have some white or pale green flesh towards the middle:

Under-ripe Berries

Strawberries are often picked before fully ripe. Since ripening happens from the outside in, under-ripe strawberries will have white centers. Fully vine-ripened strawberries will be completely red through to the core.

Over-sized Berries

Larger strawberries can sometimes have trouble fully ripening, leaving the innermost flesh under-ripe and white. Smaller berries tend to ripen more evenly.

Dense Foliage

Lack of sunlight penetration can hinder complete ripening. Strawberries grown in dense foliage don’t receive full sun exposure, impeding ripening, especially of the interior.

Cold Temperatures

Cool weather and temperatures below 45°F (7°C) can halt the ripening process. The insides of strawberries fail to ripen and turn red in cold conditions.

Excess Moisture

Too much rainfall or irrigation during ripening can cause incomplete color development. The achenes absorb moisture and remain hard. This inhibits ripening hormones from reaching the receptacle.

Poor Pollination

Without proper pollination and fertilization, the receptacle does not develop properly. The resulting berries remain partially white or misshapen.

Nutrient Deficiencies

Lack of important nutrients like nitrogen, phosphorus, or potassium can affect ripening and color. Deficiencies cause the inside to remain hard, pale and underdeveloped.

Varietal Characteristics

Some varieties are more prone to having white centers, especially large, showy types. These prioritize size over perfect ripening. Older varieties and alpine strawberries usually have the best uniform ripening.

Is it Harmful?

A white or pale center is completely harmless in an otherwise normal, fresh strawberry. The unripened interior has the same texture and minimal flavor. Leaving the tops on strawberries until eating can allow additional ripening.

When to Avoid

Avoid strawberries with white centers that are also mushy, moldy or damaged. Signs of rotting or unusual textures indicate spoilage.

Very hard, white centers that resist cutting may also be overly unripe with poor texture and flavor.

Improving Ripening

Growers and home gardeners can take steps to encourage complete ripening:

Choose Smaller Varieties

Compact, smaller-fruited varieties like Alpine strawberries ripen the most evenly. Larger commercial types emphasize size over perfect ripening.

Allow Adequate Sun

Ensure strawberry plants receive at least 6 hours of direct sun daily for the fruit to fully ripen. Avoid shade and dense foliage.

Wait Until Fully Red

Allow strawberries on the plant to ripen completely before harvesting. Pick when fully red for best texture and flavor.

Keep Beds Weeded

Weeds compete for sunlight, water and nutrients, inhibiting ripening. Keep the area around plants free of weeds.

Use Drip Irrigation

Water strawberries at ground level to keep foliage and fruit dry. This prevents excess moisture from interfering with ripening.

Protect Flowers from Frost

Cold temperatures below 45°F (7°C) during flowering and fruit set can damage fruit development. Cover plants when frost threatens.

Fertilize Properly

Apply balanced fertilizer each spring and follow soil test recommendations. Proper nutrition ensures good receptacle development.

Remove Old Leaves

Prune off old leaves to improve air circulation and sunlight exposure. This opens up the center of plants.

Frequently Asked Questions

Are white centers safe to eat?

Yes, white centers are completely edible and harmless, as long as the berry is fresh and not mushy or moldy. The white flesh is simply unripe with a milder flavor.

Should I remove the white parts?

This is unnecessary. The white flesh can be safely eaten or left behind based on personal preference. Cutting off white centers does not improve flavor.

Is under-ripeness the only reason for white centers?

No, other factors like large berry size, shading, inadequate pollination and nutrient deficiencies can also cause unripened white flesh, even in fully red strawberries.

Can white centers be ripened after picking?

To a limited extent. Leaving caps on and holding at room temperature may allow the white flesh to redden slightly after harvest. But strawberries do not ripening significantly off the plant.

Does white flesh affect strawberry quality?

Beyond appearance and milder flavor, white centers do not negatively affect nutritional value, texture or juice content. But full red color is desired for peak sweetness and flavor.

Conclusion

White centers in strawberries are normal and harmless. This interior flesh is simply the last area to ripen. Under-ripeness explains most instances of white flesh, though other growing conditions like shade or poor pollination can also be factors. While less colorful, the mild-tasting white centers are perfectly edible. Allowing berries to vine-ripen and optimizing growing conditions helps minimize unripened white centers. With improved ripening, strawberries will achieve that perfect, fully red center.