Vintage Maltexo

A mate of mine was digging around in his garage, found a couple of tins from his uncles homebrewing days.

#1 is a metal tin of Maltexo, looks in pretty good nick, few spots of dust on it.

#2 is a plastic container, no label. Has a much thinner consistency than the Maltexo.

Both containers are thought to be at least 20 years old. My question is, will they still be any good? Is there any point running a test batch, or are they definitely useless?

Cheers,

Jake