How to set minimum cart weight for specific product collections?

[rawquestions]

I've got a store with Frozen and Ambient products. Recently, I'm in need of setting a minimum weight of frozen products for any order to pass the cart.

Ideally, I can inform my customer that "You've got only 3 Kilos of frozen products in your order, please add 2 more to proceed" regardless of the ambient products.

For this I should be able to gather the total weight of the cart PER collection. So far, my use of liquid hasn't been enough to get there and I'd like to avoid javascript as much as possible.

Any ideas?

Thanks in advance guys