Originally Posted by midfielder5
If you meant liquid smack pack or vial of liquid yeast, yes you are underpitching. Run the numbers in Mr. Malty if you don't believe me. Just because the yeast "worked" [with airlock activity and FG numbers reached] does not mean it was an optimal fermentation. Underpitching has an effect on flavor. Wyeast website snip: "Under-pitching ..will produce an aroma and flavor profile that is less than desirable..".
Wow, I ran the numbers on Malty like you suggested and you're right. We usually use the dry packets but on occasion we have used the Wyeast smack packs. They may not have hit optimum fermentation but I havent noticed any off flavors so I guess we got lucky.
That is kind of misleading though, because right on the package Wyeast claims it "is designed to inoculate 5 gallons of wort with the same pitch rate recommended by professional brewers." And on their site they say that it is good for 5 gallons of wort up to 1.060og.
I wonder since you release the nutrient and let the pack incubate and swell up for 3+ hours if it acts as a makeshift starter to increase the count before you pitch? I cant imagine the count would double in a few hours though. Why would they claim that right on the package...?