In Modernist Cooking Made Easy: Getting Started the recipe for mango noodles (and other recipes) includes locust bean gum, but the Modernist Pantry kit I bought does not include it. How can I substitute it? The recipe asks for locust bean gum and agar. Can I use xanthan gum or carrageenan?
Hi Alejo, that's a good question. In general, agar gels are brittle (they fall apart) while locust bean gum adds elasticity (makes them chewier and stay together). For gels that are being shaped, especially the gel noodles, the elasticity is critical, otherwise they tend to fall apart. For things like cubes or softer gels, you don't have to have the locust bean gum, the gels will just be less chewy.
As for substitutions, there's not a real good one for locust bean gum, it works really well with agar and they combine in ways that other ingredients don't. You could try using a gelatin-agar mixture, it has more elasticity, though it's not quite as strong, maybe something like these gelatin-agar gel sheets.
Or a combination of iota carrageenan with either agar or kappa carrageenan might work, though the carrageenan tends to be used for more tender preparations. You can also try making it without the locust bean gum, especially for gels besides the noodles, and see how it holds together.
I'd say if you plan on making gels more often, then purchasing a small packet of locust bean gum is worth the $8.00 investment.
I hope this helps out. Thanks and happy cooking!