Some program guides titled this episode “Pretzels Logic” instead of the correct “Pretzel Logic.” Program guides occasionally pick up alternate names from the FoodTV site, which uses them for a number of episodes, but in this case, it’s strictly an error.

The yeast saccharomyces cerevisiae mentioned in this episode is, of course, only one of many species of yeast. However, it is the one most people mean when this discuss bread yeast, brewers’ yeast, ale yeast, or top fermenting yeast. Not all yeasts are benign. Some, such as candida albicans can colonize humans – this species is responsible for the infection called variously candidiasis (the proper medical name) and thrush.

Stewardess: Ladies and gentlemen, we’re starting our descent into Philadelphia, so sit down, buckle up and turn off all your electronic equipment... NOW!

Alton: Although most of the great American street foods – oysters, waffles, ice cream penny licks – are sadly gone, street pretzels – the big, salty, soft type – remain an icon of the northeastern metropoli.

Alton: (opening his briefcase at a street pretzel cart) Fill it up, my good man!

Alton: Yeast are fungi, which is why they get invited to all the best parties! (All the yeast sock puppets groan at the terrible pun.)

Alton: If you start to see a twist right in the middle of the dough, you know that you do not have your hands coordinated and that twist could become a break point, so be watching for that.

Alton: Why look – it’s my legal team, Itchy and Twitchy. You guys pass the bar yet?

Alton: (about his legal team) Who would have thought those guys would have a problem with a little lye?

Alton: You could play around with mixing in the water first but unless you’ve got steel sinuses, you want to be very careful!

Stewardess: Pretzels?
Alton: Oh, no thanks, miss! I brought one from home.
Stewardess: Whatever.

Alton uses the word “metropoli” as a plural of metropolis. The actual plural of metropolis is metropolises. In the original Greek it is possible that the plural was something like metropoli, but Good Eats isn’t broadcast in Old Greek...

Alton’s pH explanation is close, but incorrect. The value of pH actually refers to the relative concentration only of positively charged hydrogen ions. In pure water not exposed to air, this is roughly 1E-7. The negative common logarithm of this value gives the pH of 7. Increasing concentration of such ions results in smaller numbers – acid with a concentration of 1E-2 would have a pH of 2, for example. A more technical and complete explanation may be found here.

It is a common misconception, repeated here, that mustard gas was developed from mustard seeds. Mustard gas is actually bis(2-chloroethyl sulfide) which is a fancy way of saying it contains two ethane molecules joined by a sulfur atom, and on which the end hydrogen atoms are replaced by chlorine. The earliest certain synthesis of sulfur mustard occurred in 1886 when Albert Neiman reacted sulfur dichloride and ethane and recorded the noxious properties of the resultant. Other chemists experimented with these compounds as early as 1822 but failed to record the noxious properties, making it impossible to know for certain whether they produced sulfur mustard or not. Mustard gas is a powerful vesicant (blister causing chemical) and has carcinogenic properties. These unwholesome properties relate to its ability to readily bind to guanine, a DNA nucleotide. That damages or destroys DNA and causes immediate cell death or neoplastic mutation. Isothiocyanates found in mustard seed, on the other hand, inhibit carcinogenesis and can even trigger apoptosis (programmed cell death) in neoplastic cells resistant to other chemotherapeutic agents. Apoptosis is a process in which malfunctioning cells detect their faults and destroy themselves. Failure of the apoptotic mechanism is a precondition for the development of neoplasm, the malignant variety of which is cancer.

The episode takes its title, Pretzel Logic, from the name of a 1974 album by musical group Steely Dan. The album featured Rikki Don’t Lose That Number, which would go on to become the band’s greatest hit. Alton is a known Steely Dan fan.

Alton likens the extreme fecundity of yeast to that of tribbles. Star Trek’s 1968 episode “The Trouble with Tribbles” centered around the problems that arose when a species of animal called tribbles were removed from their natural environment. The creatures reproduced extremely rapidly (according to Dr. McCoy, they were born pregnant) and consume all food in their vicinity.

Alton calls his dough hook “Captain Hook.” Captain Hook is the pirate villain of the play Peter Pan (and its numerous adaptations). Peter Pan, the titular boy who wouldn’t grow up, severed Hook’s right hand, which was then devoured by a crocodile. Hook replaced his missing appendage with an iron hook. Along with the peg leg, iron hooks of this sort are stereotypical equipment for pirates, who lived a dangerous lifestyle that often cost them limbs.

Alton mentions Johnny Depp in connection with the skull and crossbones that appears on a bottle of lye. This symbol indicates a poisonous substance (it is used internationally) and is so well recognized that a bottle with nothing save the skull and crossbones is accepted as poison when it appears in cartoons and other media. The skull and crossbones also appear as a white device on a black field on the Jolly Roger, the traditional flag flown by pirate ships. Johnny Depp’s most recent and arguably most famous role is Captain Jack Sparrow, one of the Pirates of the Caribbean in a series of recent Disney films. Usually when the crossed bones appear behind the skull, the symbol means poison, whereas when they appear beneath the skull the symbol means piracy, so the symbol on Alton’s bottle is more pirate than poison, but this is not a standard.

Alton slips up when he mentions the first rule of Fight Club. This rule, which is simply, “You don’t talk about Fight Club,” comes from the 1996 Chuck Palahniuk novel and 1999 film Fight Club. Soap manufacture, a process that commonly uses lye, plays a key role in the plot of the novel. To say more about the rules or the soap risks harming the experience for a new reader...

Alton directs viewers to repeat the same baking instructions for a new batch of pretzels by saying, “same pretzel time, same pretzel temperature.” This phrase spoofs the phrase “Same Bat-Time, Same Bat-Channel,” that frequently ended episodes of the 1966 Batman show. The music that follows Alton’s comment contains elements of the show’s theme song.