The Big Bang Theory Wiki

"The Fermentation Bifurcation" is the twenty-second episode of the ninth season of the American sitcom The Big Bang Theory. The episode aired on Thursday, April 28, 2016.


The gang goes to a wine tasting and run into Penny’s old boyfriend, Zack. Also, Bernadette gets stuck spending the evening with Sheldon when she can’t drink alcohol, and things don’t go as planned when Raj introduces his new friend, Claire.

Extended Plot[]

While fixing dinner, Penny tells them that she won a night of wine tasting at work. Leonard wonders why scientists don't win things. Howard claims that they are in it for the groupies. Sheldon claims that he is just pursues science for the intrinsic joy of discovery. Amy reminds him that he always says that he wants to win a Nobel Prize. Howard, Amy, Raj and Leonard plan on going; however, Bernadette is pregnant and Sheldon has had enough of wine. Sheldon then tells Bernadette that it'll just be the two of them. "Me? How? Why?", exclaimed a shocked Bernadette. Sheldon wanted her to join him and explained that all the things she has to avoid, he never liked in the first place. She decides to give it a try. Sheldon tells her to come and "party hardly".


Me? How? Why?

Working on their invention, the infinite persistence gyroscopic navigation system, in the Mechanical Engineering Lab, Raj wonders if he can bring Claire. Leonard wondered if he was still dating Emily. Raj concurs and says that he is keeping the two casual relationship|relationships casual. Howard is ready to start up their gyroscope while Sheldon documents it on video. The three rotating rings start up successfully. Raj thinks it looks beautiful, while it makes Howard and Leonard dizzy. Sheldon falls down dizzy while trying to video tape it.

Raj calls up Claire and invites her to the winery. She is fine with it as long as meeting his friends is not too big a step. Claire wants to know if she'll be introduced as his girlfriend and what happens if they don't like each other.

Leonard is reading a scratch-and-sniff book about wine tasting. Leonard can't really smell anything because his sinuses are acting up. Sheldon tells Penny that he is going to prove that you can have fun without alcohol, tobacco, caffeine, sushi, soft cheese, processed meats, Jacuzzi's or anything else that is harmful to a pregnant lady. Then Sheldon drives Leonard and Penny out of the apartment after his list of verboten things get more disgusting.


E=MC squared.

At the wine tasting, Howard and Amy are the first to arrive. At first they are nervous with nothing to say; then they remember that the last time they were together. It was three years ago during the scavenger hunt. Even though they said should do it again, they never did. Amy mentions about Bernie and Sheldon hanging out together and she has no idea what they are going to talk about. Leonard, Penny and Raj show up. Claire is going to meet them there and Raj doesn't want them to ask too many questions since they are keeping it casual. Leonard then won't ask her about how it is being in his harem. Amy then notices Zack, Penny's old boyfriend; however, Penny doesn't know whether she want to talk to him. Peeved, Raj wants her to ask who was better in the sack.

Bernadette shows up with some bubbly apple cider which unfortunately tickles Sheldon's nose. Sheldon has a fetus friendly festival of fun discussing trains and types of toast that thrills Bernadette.


I was always rooting for you.

The guys are describing what they smell in the wine, except for stopped-up Leonard. Zack comes by to say hello. He sees that they are married and wonders if it's to each other. Despite breaking up with Leonard and keep coming back to Zack, he was always rooting for them. The guys tell Zack about their navigational system and he wonders if it could be misused by the military. Zack then asks if it's better than the one they're using now. "Yea!" they exclaim as they realize that the military would want it. Zack then wonders if they really are smart.

Sheldon is describing the various model train gauge scales. The smallest gauge railroad engine he accidentally swallowed and had to pass. Bernie wondered why he liked trains. Life was confusing when he was young and trains represented order. He could line them up, categorize them, etc. They gave Sheldon a sense of calm in a world that did not.

Leonard is talking to Howard that he is worried about the military applications ever since Zack mentioned it. Raj adds that any scientific advancement can be used for destructive purpose. Amy cites Einstein's theory and the development of the atomic bomb. Penny knows the Mass-energy equivalence equation (E = mc2) and what the letters mean. Claire then joins them and is introduced as a causal friend who needs no other questions. Leonard asks her if she would like some wine. Raj shouts that he said no questions.


Bernadette getting into her D&D game.

Now Sheldon has laid out all the different types of toast including Star Wars toast. It has a light side and a "dark side". Next on the evening's agenda is D & D. Bernadette says that she might play for a little while. Sheldon doesn't think that she will want to stop or will be allowed to. The game was designed for her. Her character's name is Bernadetrix, a tall brave warrior queen. She likes being tall. Also only the men get pregnant in this universe. She thinks it might be fun. She starts out having a drink at the tavern. Bernadette says that she storms into the tavern, throws down her sword and wants his strongest ale in the skull of a goblin.

Penny tells Claire that they have heard nothing, but good things about her. Claire stumps them by asking what they had heard. Zack comes over and then hits on Claire. Raj counters that she is seeing him. Zack asks why she was introduced as his friend since she is so great. Claire says that she doesn't know, so Zack then asks Raj who is stumped. Leonard is still worried about their project and wants to take another look at it. Howard doesn't want to stop because he needs the money. How do they know that their invention is not going to be used to destroy the world? Howard retorts that no one has come back from the future to kill them.

Back at D&D, Bernadette is killing the ogre that attacked her. After being in a hot spring, the ogre is reduced to sushi and begs to be eaten. Bernadette enjoys the sushi, bathes in the hot spring and does not have swollen ankles. The end. The night was much more fun than she thought it would be. She thanks him since for one night she didn't have to be "pregnant Bernadette". Sheldon tells her that if she ever needs another break, Bernadetrix the Warrior is there for her. Only unto the third trimester because he can't risk getting amniotic fluid on his spot.


Claire getting hit on by Zack.

Raj asks Zack to not come onto Claire since he is bigger and more handsome. Zack apologies. Raj doesn't want him to talk about how great Claire is. That's fine with Zack. Claire then asks Penny and Amy if he brings around other girls. The girls are stumped. Leonard calls Raj loyal to a fault. Zack comes over and tells everyone that Raj is right that Claire is not so great. Raj counters with that he says crazy things all the time. So what had they been talking about while he was gone? Claire kids him that they were discussing all of the girls he had been dating. Raj complains that he didn't want them to mention that. Penny tells him that they didn't, he did.

Leonard wakes up, walks into the kitchen and tells Sheldon that he over did it that previous night. Sheldon did too, but it was making too much toast. Leonard then inquires if Sheldon has ever thought about the military applications. It first bothered him and then he talked to Alicia and Fred about it and they put it into perspective. Leonard wondered who these people were. Sheldon tells him that friends are like toilet paper since it's always good to have a couple of extra under the sink.



  • Title Reference: The splitting of the group where one set goes to a wine tasting while Sheldon and Bernadette share an evening together.
  • Taping date: April 5, 2016
  • This episode was watched by 14.13 million people with a rating of 3.4 (adults 18–49).
  • The Big Bang Theory was ranked #2 for the week ending May 1, 2016.
  • This episode aired in Canada  April 21, 2016.
  • Chuck Lorre's vanity card [1]
  • Episode transcript [2]


  • Jesse Schedeen of IGN - For a show as formulaic and set in its ways as The Big Bang Theory, the best episodes are often the ones that push the characters out of their comfort zones...Most importantly, the wine tasting story line addressed the growing problem that is Raj and his generally obnoxious behavior this season. On one hand, his desire to invite Claire and formally introduce her to the group was a rare sign of maturity. There was a sense that Raj generally does care about this woman and wants to move the relationship forward, even if he can't bring himself to cut ties with Emily...Back home, the Sheldon/Bernie story definitely lived up to its potential...Several times over the past few seasons, Sheldon has shown signs of emotional maturity and a desire to do something nice for his friends for no other reason than because it's the right thing to do. This was one of those cases. [3]
  • IMDb user reviews [4]


  • Zack Johnson returns in this episode and brings up the gyroscope being useful for the US Army, making Leonard and Howard think about how their invention might be used by the military. 
  • Claire meets some more of the gang.
  • Sheldon's first official bonding with Bernadette.
  • Zack still loves science and has gotten slightly smarter and wiser since his last appearance. 
  • Howard and Amy stated that they last hung out together 3 years ago. This could be a reference to "The Scavenger Vortex" (S7E3), when they both bonded over their love of Neil Diamond. It's unclear if they went to the Neil Diamond concert together.
  • When describing toast, Sheldon doesn't mention Cylon ("Battlestar Galactica") toast from "The Cornhusker Vortex".
  • Penny also demonstrated her limited knowledge of the E=mc2 equation in "The Roommate Transmogrification".
  • While filming the preliminary trial of the infinite persistence gyroscopic navigational system, Sheldon wonders if he can overdub Leonard's voice in the video with that of James Earl Jones, whom he met and became friends with in "The Convention Conundrum".


Sheldon: Leonard, friends are like toilet paper; it's good to have extras under the sink.

Penny: Oh, hey, if you guys are free this weekend, I won a night of wine tasting from work.
Leonard: That sounds fun. Mmmmm. How come scientists don’t win free stuff like salespeople do?
Howard: ‘Cause we’re not in it for the stuff. We’re in it for the groupies.
Sheldon: Personally. I find the notion of external rewards demeaning. I pursue science for the intrinsic joy of discovery.
Amy: But you always say that you want to win a Nobel Prize.
Sheldon: I also say don’t contradict me in front of my friends, but that you don’t remember.
Raj: I would love to. I do enjoy the complexity of an aged Pinot noir.
Leonard: I’m sure that would pair nicely with your fried nuggets if chicken.
Amy: Well, it sounds like a nice night. We should go.
Sheldon: Wine again? Yeah, no, thank you. I like my grapes the old-fashioned way in a juice box.
Amy: Well, I’m going. You couldn’t stop me from getting a massage in the mall, and you’re not stopping me now.
Sheldon: I shouldn’t have to see my girlfriend get groped by another man in public.
Amy: And I shouldn’t have to see my boyfriend riding on a train for children around the mall.
Penny: The little choo-choo for toddlers?
Amy: And now you know why I needed the massage.
Howard: Well, we’re out. Bernie can’t drink ‘cause she’s pregnant. And she’s pregnant because we had sex. And we had sex because…. [laughs] well, come on.
Bernadette: It’s okay. You should go.
Howard: You sure?
Bernadette: Of course.
Penny: Yeah, give her a break from, “Well, come on.”
Sheldon: Well, Bernadette, looks like Saturday night, it’s just you and me.
Bernadette: Me? How? Why?
Sheldon: Well, it makes perfect sense. Because you’re an expectant mother, you can’t drink alcohol. I don’t like to. You can’t have sushi. I don’t like to. You can’t go in hot tubs. I consider them vats of sweaty people soup.
Bernadette: Gee, Sheldon. I don’t know.
Sheldon: Oh come on. Roller coasters, caffeine, runny eggs- I’ve been avoiding those things all my life. And now, because you’re pregnant, you have to.
Leonard: The difference is she’s bringing life into the world, and you suck it out.
Bernadette: I guess we could give it a try.
Sheldon: Well, little lady, you’ve heard of party hearty; get ready to party hardly.
Howard: I bet you’d like a drink now.

Raj: Hey, you think it’d be okay if I brought Claire to the wine tasting?
Leonard: Sure. I’d like to meet her.
Raj: Oh, that’s great. I’ve been wanting her to meet you guys, too, so this seems like the perfect opportunity.
Shelden: Oh, but I won’t be there.
Raj: Funny how that worked out.
Leonard: Does this mean Emily’s not in the picture anymore?
Raj: No, I’m still dating her.
Leonard: Okay, help me out. How are you doing this? Do they know about each other?
Raj: They know that we’re not exclusive, and we don’t ask too many questions.

Raj: Hey, guys, do me a favor and don’t ask too many questions about our relationship. We’re just keeping it casual.
Leonard: Oh, so I shouldn’t ask her how she feels about being a member of your harem?

Bernadette: So what do you want to do tonight?
Sheldon: Oh, I have quite an evening planned. Our fetus-friendly festival of fun begins with an in-depth look at the world of model trains, and then we’ll kick things up a notch and explore all the different ways you can make toast.

Zack: Hey, did you two get married?
Penny: We did.
Leonard: Yeah, mmm.
Zack: To each other?
Penny: Yes.
Zack: Cool. Cause other than when you broke up with him and dated me, then broke up with me, and then dated me one more time before getting back to him, I was rooting for you two.

Zack: Are you kidding? I love science. Einstein. Stephen Hawking. Mike deGrasse Tyson.
Amy: Mike deGrasse Tyson?
Howard: Yeah, you know, the boxer who grew a mustache and became a scientist.

Bernadette: What is it about trains that you like so much?
Sheldon: What an interesting question. Well, when I was a child, life was confusing and chaotic for me, and trains represented order. I could line them up, categorize them, control them. I guess you could say that they gave me a sense of calm in a world that didn’t.

Sheldon: And last, but not least, this is one I like to call Star wars toast because…it has a light side and a “Dark Side”.

Amy: So Claire, we’ve heard so many wonderful things about you.
Claire: Really? Like what?
Amy: Uh, mostly, Penny’s heard them.
Zack: Boy, you get some dirty looks over there when you ask for ice.
Raj: Zack, this is my friend Claire.
Zack: You’re hot. You seeing anybody?
Raj: Uh, she’s seeing me.
Zack: Why’d you say she’s your friend?
Raj: We’re just keeping it casual.
Zack: Why is he being casual with you? You seem great.
Claire: I don’t know. Ask him.
Zack: Why are you being casual with her? She seems great.

Bernadette: Wow, this night turned out to be so much more fun than I thought.
Sheldon: Oh the fun doesn’t stop. You’re still going home with a goodie bag full of toast.
Bernadette: Thank you for this. You know, ever since people found out I’m having a baby, I feel like I became “Pregnant Bernadette”. It was nice to take a little break tonight.

Zack: I see what you’re saying. She’s not so great.
Raj: Don’t listen to him. He says crazy things all the time. Uh watch. Marco!
Zack: Polo!
Raj: So, uh, what are you guys talking about?
Claire: Your friends were just telling me about all the other girls you’re dating.
Raj: Why would you do that? I specifically asked you not to do that.
Penny: We didn’t.
Amy: You just did.
Zack: Wow. Maybe none of you guys are smart.