What exactly is the chemical reaction that occurs when you cook Star Anise with Onions?

According to Heston Blumenthal doing this intensifies the flavour of meat.

Ultimately what I want to know is can you use this on any meat based recipe? Won't the flavour of the Star Anise be overpowering?

1 Answer 1


It is basically the anethole (a phenol) of the star anise that react with the sulfur in the onion to create sulfur-phenolic aromatics. In Chinese cuisine the same family of reactions is used with duck and pork.

The sulfur-phenols are also produced during the Maillard reaction, the reaction that gives grilled meat its characteristic flavor, so adding star anise to the onions will give your dishes more of that grilled, browned flavor. The reactions of the compounds in the star anise with those in the meat are not the relevant reactions for flavor or texture.

From averaging a few recipes, I would say 1 star anise for every 250g of chopped onion. Too much star anise will highlight the other aromas in star anise, so one has to use it in moderation and allow enough time for the reactions to take place.

Garam masala, a common Indian spice combination that is used in meat dishes, may have star anise. Star anise is sometimes used in French onion soup — it intensifies the caramel flavor of the onions — and in Vietnamese cuisine, which today incorporates French elements.

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    I guess the main thrust of my question what exactly does the sulphur aromatic do to the meat? Does it just add flavour? Will it tenderize the meat? Can this technique be used for instance in French or Indian cookery?
    – Pram
    Oct 1, 2010 at 18:54
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    Excellent answer, I really appreciate it when we get detailed scientific explanations. @Pram - @Papin's answer is saying it is the flavor, not tenderization or anything else, that is affected. You could use it in any kind of food where you don't mind tasting onion and a little star anise. Oct 1, 2010 at 20:13
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    I just happened to be reading about this in the Fat Duck cookbook. He says that compounds in the anise such as anisaldehyde and anisidine combine with the sulfur in the onions to produce sulfur heterocyclics that are responsible for the delicious new flavors. Put that in your pipe and smoke it :). Aug 11, 2011 at 5:36
  • Stupid question--how much is "1 star anise"? Is it the whole "flower", or just one "petal"?
    – Ray
    Jan 8, 2014 at 23:26
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    @Ray I'm sorry it took so long for someone to answer that. One star anise is one whole "flower" or "star".
    – Jolenealaska
    Mar 7, 2015 at 15:30

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