what is locust bean gum?

Do you ever look at the ingredients of the pre-prepared foods you eat?   Occasionally I do.  And thus begins our story.

My wife recently acquired a coupon for a free package of Starbucks’ caramel macchiato ice cream.  It’s a mix of vanilla and coffee ice cream, with swirls of caramel.  I don’t care much for coffee, but she liked it.   We happened to look at the ingredients on the back of the label, and noticed that the last ingredient was “locust bean gum”.  I don’t know what that is, but the name of it doesn’t sound appealing.

Normally the lower-tier ingredients have scientific names, such that the average consumer has no idea what it stands for (and is too lazy to bother looking it up).   But with a name like locust bean gum, that just opens the door to a lot of questions.  Let’s start with, “What does that mean?”  Is it locusts ground up into beans, or do the locusts eat the beans and then “extract” the gum (a la a certain coffee), or is it locust-flavored beans?  I have no idea, apart from rampant speculation.

So it’s time for some research*.  I found that it’s a galactomannan consisting of a B-D-mannopyranose backbone with 6 branchpoints linked to a-D-galactose.  A detailed explanation of what that means is WAY beyond the scope of this article.  However, a quick summary in English is that it retards ice crystal growth by forming a structured gel at a solid/liquid interface.  I suppose it has to do with the texture and viscosity of the ice cream.  But that still doesn’t answer where it comes from.

But I’m not sure I want to know…  Sometimes it’s good to not ask too many questions.  Just enjoy your ice cream…  🙂

* My research consisted of a single search and looking at one link on the first page of results.