Seven letter words change one or two letter to make a new word

storage

zygotes

zygomas

mangoes

[del]zymurgy[/del]

No, really, what word was it?

In play:
gnashes

Hessian

[Webster’s 2nd Unabridged, in the “obsolete words” section at the bottom of the pages, lists “mazurgy” as a variant spelling of “mazurka”, a Polish folk dance, which is one step away from “zymurgy”.]

Russian

ruffian

Saffian

raffias

raffles

fluffs

fluffy

Missing letters from last two entries. Playing off of raffles:

staffer

flatter

platted

plaster

cluster

Munster

umpires