Sweet potatoes, with their sweet flavor and vibrant orange flesh, are a popular root vegetable used in many dishes. However, when you cut open a raw sweet potato, you may notice some white sticky material oozing out. This unique substance is actually a natural feature of sweet potatoes. But what exactly is it and why is it there?
The White Substance is Called Latex
The white sticky stuff on sweet potatoes is a milky liquid called latex. Latex is found just under the skin of raw sweet potatoes and acts as a protective seal. When a sweet potato is cut or peeled, the latex oozes out as the protective barrier is broken.
Latex contains a collection of proteins, alkaloids, resins, and raphides. It is produced in the latex vessels within the flesh and skin of the sweet potato. These latex vessels run throughout the root, which is why liquid latex seeps from any point where the sweet potato is cut open.
Purpose of Latex in Sweet Potatoes
So why do sweet potatoes produce latex? Latex actually serves a few very important protective purposes:
- Seals wounds – When a sweet potato root gets cut, scraped, or punctured, the latex helps seal off the damaged area and protects it from infection.
- Deters pests – Many insects and other pests are deterred by the taste and substance of latex. So it helps prevent the sweet potato from being eaten by various bugs, rodents, and molds.
- Reduces water loss – The latex seals in moisture and prevents the sweet potato from drying out.
Overall, the main role of latex is to act as a protective barrier for the sweet potato root. It helps keep it intact, pest-free, and full of moisture.
Latex Contains Beneficial Compounds
While latex may seem like nothing more than plant juice, it actually contains some very beneficial compounds:
- Protein – Latex is full of protein, containing all essential amino acids. The protein helps heal wounds.
- Antioxidants – The white sticky stuff is packed with antioxidants like vitamin C and vitamin E. These help fight disease and oxidative damage.
- Resins – Resins provide a natural pest-deterring substance.
- Raphides – These are tiny needle-like crystals that deter fungi and also provide a bitter taste to deter pests.
So while the function of latex is primarily protective, it also provides a range of beneficial nutrients and compounds.
Is Latex Harmful?
While latex serves great protective purposes for the sweet potato plant itself, is it actually harmful if consumed by humans?
The answer is no. Latex from sweet potatoes is entirely edible and safe to ingest for humans. And since it contains beneficial protein, antioxidants, and more, it can actually provide health benefits.
Some people claim online that sweet potato latex is toxic. However, there are no scientific studies or evidence indicating harm from consuming it. The only risk would be for those with latex allergies triggered by the proteins in the latex.
Cooking Removes Latex
You may notice that when you cook sweet potatoes, the baked or roasted flesh no longer has white latex oozing out. This is because heating sweet potatoes denatures the latex proteins, turning the liquid into a harmless gel.
So cooking eliminates any concerns of texture or flavor from the latex. By baking, frying, or roasting sweet potato wedges, slices, or fries, you render the latex inactive.
This is why the sweet potato dishes we eat do not contain liquid latex – it has been destroyed by cooking. The only place you will notice the raw white substance is on uncooked, freshly cut sweet potatoes.
Is Latex Unique to Sweet Potatoes?
While sweet potatoes have a very conspicuous latex oozing out when cut open, other fruits and vegetables also produce latex. It is just far less noticeable in most produce.
Some examples of foods that contain latex include:
- Figs
- Papaya
- Avocado
- Banana
- Kiwi
- Mangos
- Cucumber
- Eggplant
- Asparagus
So latex itself is not unique to sweet potatoes. But the large amount and highly visible nature of it is far more pronounced in sweet potatoes than other produce.
What About Latex Allergies?
Since many fruits and vegetables contain latex, you may wonder if this poses a danger to those with latex allergies.
First, it is important to understand that a latex allergy is not the same as a food allergy. It is an allergy to the proteins found in natural rubber latex from rubber trees.
Some individuals experience cross-reactivity between the latex in rubber and the latex in certain foods. But this depends on the specific proteins involved.
According to research, sweet potato latex contains proteins that do not appear to be allergenic. So sweet potatoes are not considered to pose any latex allergy risk.
However, latex in bananas, avocados, kiwis, and chestnuts may cause reactions in some cases. So individuals with latex allergy should be cautious when eating those foods until they know how they respond.
Is Latex Related to Cyanide in Sweet Potatoes?
Some people wonder if the scary sounding cyanide produced in sweet potatoes is related to or produced by latex. But cyanide actually has no connection to latex.
Cyanide occurs from the breakdown of glycosides into hydrogen cyanide by the enzyme linamarase when sweet potato cells are damaged. It does not come from the latex.
And the cyanide levels are only dangerous if you eat extremely large quantities of raw sweet potato or extract and consume the enzymes. Cooked sweet potatoes contain no cyanide risk.
Conclusion
The white sticky substance oozing out of raw sweet potatoes may seem strange, but it is a completely normal and healthy feature of the plant. The latex acts as a protective mechanism for the sweet potato root.
While visually unappealing in its raw form, latex poses no risks to humans when cooked along with the sweet potato flesh. And it actually provides nutritional benefits from its proteins, antioxidants, and vitamins.
So there is no need to worry about the function or safety of the unique white latex within sweet potatoes. It is simply another one of the root’s natural protective components that churns out when the cell structure is broken into.
| Point | Description |
|---|---|
| What is it? | White sticky latex that oozes out when raw sweet potato is cut open |
| Other Names | Sweet potato juice, sweet potato liquid, milk |
| Composition | Proteins, resins, antioxidants like vitamin C and E, raphides |
| Purpose | Protective sealant – seals wounds, deters pests, reduces water loss |
| Safety | Edible and safe when cooked, not harmful unless latex allergy |
| Occurrence | Found in raw sweet potatoes and other fruits/vegetables |
Frequently Asked Questions
Is sweet potato latex toxic?
No, sweet potato latex is not toxic to humans. There are no studies showing any toxicity or harm from consuming cooked sweet potato latex.
Why do sweet potatoes ooze white stuff?
Sweet potatoes ooze white latex as a natural protective sealant whenever the root is cut open or peel is damaged. It helps prevent infection, water loss, and pests.
Should you wash sweet potatoes?
Yes, you should wash sweet potatoes to remove any dirt or debris before cooking. Washing will not remove the latex, which will still ooze out when cut.
Do all sweet potatoes have latex?
All varieties of sweet potatoes contain latex. However, some varieties produce lower amounts than others.
Is it OK to eat the white stuff on potatoes?
Yes, the white latex on sweet potatoes is perfectly safe to consume after cooking. It contains beneficial nutrients like protein, vitamins, and antioxidants.
Why are my potatoes oozing a white liquid?
Oozing white liquid from potatoes is caused by latex, the natural protective substance produced by sweet potatoes whenever the skin/flesh is cut open or damaged.
Do I have to remove the white stuff from sweet potatoes?
No, you do not need to remove the white latex from sweet potatoes before cooking. It becomes harmless when cooked and provides nutritional benefits.
Similar Foods with Latex
Sweet potatoes are not the only food that produce latex. Many other fruits and vegetables also contain latex, but it is less visible or pronounced. Some examples include:
- Figs
- Papaya
- Pineapple
- Avocado
- Banana
- Kiwi
- Mango
- Passionfruit
- Asparagus
- Carrots
So while sweet potato latex may seem unique, many other plant foods also contain it for protective purposes.
Using Sweet Potatoes
Wondering how to cook sweet potatoes after seeing the white latex? Here are some tips:
- Wash thoroughly before peeling or cutting to remove dirt and debris
- Peel or cut as desired – latex will ooze out from any nicks or cuts
- Bake, fry, roast or boil sweet potato pieces to render the latex harmless
- Season baked sweet potatoes with cinnamon, brown sugar, nut butter, etc
- Use mashed sweet potatoes in pancakes, breads, smoothies, etc
- Top sweet potato fries with Cajun seasoning, rosemary, or parmesan
The white latex should not deter you from reaping the many nutritional benefits of sweet potatoes. Just be sure to cook them thoroughly before enjoying their sweet flavor.