Yes, it’s true that the direction you slice an onion can affect its taste. This is due to the onion’s cellular structure and the release of sulfur compounds when the cells are damaged.
Slicing with the grain (pole to pole):
When you slice an onion from root to stem, following the grain, you rupture fewer cells. This results in a milder flavor since less of the sulfur compounds responsible for the onion’s pungent taste and tear-inducing properties are released. This method is ideal for raw preparations like salads or sandwiches, where a milder onion flavor is preferred.
Slicing against the grain (through the equator):
Slicing an onion across its equator, against the grain, damages more cells. This leads to a greater release of sulfur compounds, resulting in a more pungent and intense flavor. This method is often used in cooking when you want the onion flavor to be more pronounced, such as in stir-fries or caramelized onions.
Why does this happen?
Onions contain sulfur-containing compounds called amino acid sulfoxides. When you cut an onion, these compounds are converted into sulfenic acids by an enzyme called alliinase. Sulfenic acids are unstable and quickly rearrange into a variety of volatile sulfur compounds, including those responsible for the onion’s pungent taste and tear-inducing effects.
When you slice an onion with the grain, you create cleaner cuts that damage fewer cells. This limits the amount of amino acid sulfoxides exposed to alliinase, resulting in less conversion to sulfenic acids and a milder flavor.
Slicing against the grain, on the other hand, crushes more cells, releasing more amino acid sulfoxides and leading to a greater production of pungent sulfur compounds.
Additional factors:
- Onion variety: Some onion varieties are naturally milder or stronger than others, so the slicing direction will have a more pronounced effect on some onions than others.
- Cooking method: Cooking can mellow the flavor of onions, so the difference between slicing directions might be less noticeable after cooking.
I hope this article provides a clear explanation of how slicing direction affects onion flavour and that you will experiment in order to cook the best curry of your life.
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