The most effective way to significantly reduce calcium oxalate in taro, particularly in the stems, is through cooking, specifically boiling for 20 minutes.
Calcium oxalate crystals are naturally present in taro (Colocasia esculenta) and are responsible for the itchy, irritating sensation often experienced when handling or consuming raw or improperly prepared parts of the plant. While it's difficult to remove calcium oxalate completely, cooking methods, especially boiling, are known to break down these crystals and reduce their levels, making taro safe and pleasant to eat.
Why Boiling is Effective
Research has shown that cooking taro dramatically reduces its oxalate content. According to studies focusing on taro stems:
- Boiling for 20 minutes was identified as the most effective method among tested cooking treatments.
- This process significantly reduces both total and soluble oxalate contents.
- It also decreases the amount of calcium bound to the insoluble oxalate fraction. In raw taro stems, about 39% of the total calcium was bound to insoluble oxalate. After boiling, this was reduced to a mean of 17.2% ± 2.6%.
This indicates that heat and exposure to water help to leach out or break down the calcium oxalate crystals, thereby mitigating their irritating effects.
Practical Steps for Reducing Calcium Oxalate
To minimize calcium oxalate and make taro edible, follow these preparation methods:
- Peel Carefully: Wear gloves when peeling taro corms or handling stems and leaves to prevent skin irritation from the crystals.
- Thorough Cooking: Always cook taro components thoroughly. Boiling is highly recommended, particularly for stems, for at least 20 minutes as shown to be effective.
- Discard Cooking Water: After boiling, drain and discard the cooking water, as it may contain leached oxalates.
- Use Acidic Ingredients: Some traditional methods suggest cooking taro with acidic ingredients like tamarind, lime juice, or vinegar, which may help further break down the crystals.
- Combine Cooking Methods: Combining boiling with other cooking methods like simmering in stews or curries for extended periods also helps ensure the crystals are neutralized.
Comparing Raw vs. Cooked Taro (Illustrative based on reference principles)
While the reference specifically quantifies the effect on stems' bound calcium, the principle of oxalate reduction through cooking applies broadly to taro corms, leaves, and stems.
| Taro Form | Oxalate Level (Relative) | Bound Calcium (Relative, based on stems) | Edibility Recommendation |
|---|---|---|---|
| Raw | High | ~39% bound to insoluble oxalate | Not recommended (causes irritation) |
| Cooked (e.g., Boiled 20+ min) | Significantly Reduced | ~17.2% bound to insoluble oxalate | Recommended |
Always ensure taro is cooked until very tender before consumption. Any lingering itchiness after cooking indicates that the calcium oxalate has not been sufficiently reduced.
