The central vein of the kaffir lime leaf is not bitter

If you ask Google, "Is the central vein of a kaffir lime leaf bitter?" the answer is, "Yes, the central vein of kaffir lime leaves is particularly bitter and tough. In cooking, it is strongly recommended to remove it before chopping." However, if you ask the question using AI, the answer is, "No, the central vein of the kaffir lime leaf is not particularly bitter. However, it is very hard, fibrous, and tough. It is for this textural reason that it is always removed."

The source in both cases is the same page on the mamscook blog. A page that doesn't

mention leaf bitterness at all.

When asked the same question in English, Google always answers, "Yes, the central vein (or stem) of the kaffir lime leaf is very tough and can carry a bitter, sometimes muddy or soapy flavor." The source is a Reddit discussion whose scientific basis is non-existent, but where a speaker makes an unfounded assertion. "It's the stem that's bitter."

Chatgpt also replies, “Yes. The central vein of kaffir lime leaves is generally tougher and more bitter than the rest of the leaf.” It says this is based on “common culinary uses of kaffir lime.” Only one of its sources mentions bitterness and that concerns the kaffir lime fruit juice not leaves.

If you ask the question in Thai, Google answers "yes", but its source doesn't say that,. It says "However, excessive use of the leaves or fruit can give a bitter taste and a pungent odor."

There is no academic source that states that the central vein of the leaf is bitter the naringin content of the leaves is not reported to be heterogeneous.

The origin of the false information : Saturday Kitchen Cooking Bible (2013). It is the only source that mentions that the central vein may taste bitter.

In short, the central vein of the kaffir lime leaf is removed before slicing the leaf for culinary use and consumption, because its tough. Otherwise, it is fine to use the whole leaf in sauces, cooked dishes, and herbal teas.

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