Frost Burn on plants???

Hello,

A friend and myself order some plants from across the country (Canada)... and they were shipped with two heat packs as the weather was REALLY cold. Needless to say when I opened up the box the heat packs were long dead...

the package did not sit on my doorstep for very long... and the plants looked fine (besides cold to the touch) when opening it.

However, we have cleaned the plants and have put them in our tanks...

They are all bromes... and some of the leaves are now turning brown on them... I am not talking one or two brown leaves... like half the brome is turning brown... the colour in the leaves look dead.

Is this because of frost burn?
What can we do to save these plants before they all turn brown?
Should we cut the brown leaves off?

Thanks,

Frank