It is not because we, readers, are unfamiliar with center that all known Toriko characters are unfamiliar with it too.
But I doubt Yuda or the others would know about Center.
Best guess would be Setsuno or the two high ranking chef's not of an Igo Nation, Livebearer and Tyran.
My guess is as good as yours, but I'm hoping that Teppei really is dead. Let's face it, he isn't an important character, just a very likeable one.
With his death, Jirou might as well go on a rampage and steal the spotlight for himself.
Well, maybe Teppei isn't one of the main cast, but he is still quite an important character. And I do hope he will come back due to Center. I hope Toriko and Co will get Center sooner. Maybe not in the upcoming Arc, but in the first Arcs of Gourmet World.
I agree with Koen that top Chefs should know some tips on where or how to find Center, so I believe at some point they or maybe Ichiryu might show them the way to find it.
Whats the point of killing him if hes just gonna be revive with Center... After that gruesome death let just let him rest in peace... Don't get me wrong I like Teppei and if the author decided to kill him thats fine with me and it kinda suck to see a revival bullcrap in this manga... And I don't think Toriko and the others will want to search for Center just to revive Teppei they rather just find and eat delicious food... And we don't know a lot about Center maybe you need a body to be able to revive it or DNA and if Teppei is eaten they be no trace of him...
Well, why bother to introduce the legendary reviving ingridient Center if you don't want your characters to use it? For me it would be at least strange.
Also Teppei is just a great person to be revived. He is not some old jizzer who is already close to his last breath, but he is from the same generation as Toriko and Komatsu and was supposed to become one of the greatest characters of Torikoverse, so I believe it would be better to show Center's powers on him, than on some nameless characters noone cares about...