Is it safe to eat green sweet potatoes? (How to prevent)

In this handy guide, we will answer the question, “Is it safe to eat gree­n sweet potatoes?” We also will explore the re­asons why sweet potatoes can turn gre­en and talk about the health benefits they offer. In addition, we will touch on how to identify if they’ve gone bad.

Is it safe to eat green sweet potatoes?

Yes, green sweet potatoes are safe to eat. The presence of an unpleasant green color in cooked sweet potatoes is caused by the presence of epoxides.

Epoxides are produced by the oxidation of β-carotene, which also degrades into apocarotenoids and apocarotenoids. These compounds, oxidize into lower molecular weight carbonyl compounds, which are volatile. These compounds do not affect the quality or flavor of sweet potatoes. (1, 2)

How to prevent green sweet potatoes?

Cooking sweet potatoes in slightly alkaline water can help prevent or improve the development of a green color. The unappealing green hue that can appear in some cooked sweet potatoes results from the presence of carotene epoxides.

These compounds are pH-sensitive and take on a greenish appearance when combined with a yellow pigment found in sweet potatoes, particularly in an acidic solution. (3)

What is the nutritional content of sweet potatoes?

Sweet potatoes are rich in macronutrients like starch, dietary fiber, and protein. They also offer a wide array of micronutrients, including minerals such as manganese, copper, potassium, and iron, as well as vitamins, primarily from the B complex, vitamin C, and vitamin E. Additionally, they provide provitamin A in the form of carotenoids, along with anthocyanins (in purple sweet potatoes), flavonoids, and coumarins.

When compared to other root and tuber crops, sweet potatoes stand out due to their higher content of carbohydrates, proteins, specific vitamins, and minerals. They boast elevated levels of provitamin A, vitamin C, and minerals in comparison to staples like wheat or rice.

Sweet potatoes are a notable source of various bioactive compounds, with a prominent presence of (poly)phenols, terpenoids, tannins, saponins, glycosides, alkaloids, and phytosterols. The varying colors of the skin and flesh can be attributed to the differing concentrations of (poly)phenols and carotenoids. (4)

How does cooking affect sweet potatoes?

Sweet potatoes can be prepared using various cooking methods, including steaming, baking, roasting, boiling, and microwave roasting. Throughout these cooking processes, carotenoids, and food processing can influence their levels. Frying and boiling sweet potatoes, for instance, preserve more than 90% of their β-carotene content.

Additionally, boiling has been observed to reduce trans-β-carotene while increasing cis-β-carotene. Notably, anthocyanins are known for their sensitivity to heat, light, pH variations, and the presence of oxygen. However, the impact of cooking on anthocyanins depends on the specific cooking technique employed.

As for the phenolic compounds in sweet potatoes change, is primarily due to heat-induced degradation, oxidation by polyphenol oxidase, the leaching of water-soluble phenolics, and the isomerization or release of compounds resulting from cell wall rupture. Cooking almost always intensifies the color. Cooked sweet potatoes may be white, gray, greenish, yellowish, yellow, or orange. (1, 4)

What are the health benefits of sweet potatoes?

Traditionally, sweet potatoes have served as a vital source of carbohydrates and energy for both humans and livestock due to their high starch content. In modern times, sweet potatoes are acknowledged as a highly nutritious and beneficial food with the potential to prevent chronic diseases.

This recognition is primarily attributed to their significant dietary fiber, natural sugars, and protein, as well as vitamins A and C, potassium, iron, and calcium, all while being low in fat, particularly saturated fat, sodium, and cholesterol.

Furthermore, sweet potatoes are known for their antioxidant properties, hepatoprotective effects, and potential to improve cognitive function and memory. Additionally, the potential benefits of anthocyanin and carotenoid-rich extracts from sweet potatoes may be valuable as supplementary ingredients for addressing obesity and related health conditions. (4, 5)

How to properly store sweet potatoes?

The optimal storage conditions for sweet potato roots involve maintaining a temperature range of 13–16 °C and relative humidity between 80–95%. Storing sweet potatoes for extended periods ensures year-round availability but can lead to various physicochemical changes.

The shelf-life of sweet potatoes during storage can vary from a few days to several months, contingent upon the specific cultivar and storage environment. Generally, sweet potatoes can be safely stored in a pantry for approximately 3–5 weeks, while refrigeration extends their shelf-life to around 2–3 months.

The postharvest quality of sweet potatoes tends to deteriorate due to factors such as sprout growth, postharvest damage, microbial spoilage, and the loss of nutritional properties. (6)

What are the signs of spoiled sweet potatoes?

Affected roots will exhibit signs of discoloration, emit unpleasant odors, undergo changes in texture, or display visible contaminants, ultimately leading to decay. Sweet potato rot results in a decrease in nutritional quality. It’s important to take into account the accumulation of toxins within the roots caused by rot during storage, as this can pose a significant health risk when consumed.

The postharvest deterioration of sweet potato roots can be attributed to various types of pathogenic microorganism infections, including fungi, bacteria, or viruses, with the majority of cases being fungal. (6)

Conclusion

In this handy guide, we’ve answered the question, “Is it safe to eat gree­n sweet potatoes?” We also explored the re­asons why sweet potatoes can turn gre­en and talked about the he­alth benefits they offer. In addition, we touched on how to identify if they’ve gone bad. In my perspective as a food scientist, green sweet potatoes are perfectly safe to eat and don’t offer any risk to the consumer.

References