In this episode, we meet with Dr. Arnold Mathijssen, Assistant Professor of Physics at U. Penn., and author of a paper recently published in Physics of Fluids, "Pour-over coffee: Mixing by a water jet impinging on a granular bed with avalanche dynamics". This paper just did the mainstream media rounds, so you may have heard about its findings on some other outlet. In this podcast we break it down and figure out whether physicists at U. Penn. revolutionized pour over.

The paper can be found here and is also available in the CLR library (link on instagram, @coffeelitrev).

Introduction featuring James Hoffmann.

Chris is joined by Dr. Alex Murray to discuss chlorogenic acid. We talk about how plants make it, what it does, what it tastes like, and how we might make it. We discuss a variety of papers, book chapter, and so forth. Check the library link on instagram for some of them.

Then, Alex and Chris spend some time on the year-end awards.

End of year awards: 23:52

Libation prize. 28:57

Spurlock award. 32:35

MTG tool of the year. 36:10

Fruit of the year. 39:49

Beast of the year. 45:03

Then, we shift to discussing movies of 2024 with Prof. Carl Brozek. Did anything released this year compete with Prof. Brozek or Chris' top three movies of all time?

About Dr. Alex Murray: He is from Hull, UK, and received his PhD from Bath. After a brief postdoc at MIT, followed by a professorship at Kent, he joined a startup Boston-based startup, Daqus. They specialize in creating novel battery materials. Chris and Alex lived together during their PhDs. and have been doing annual awards for a long time, but its the first time we put it on record.

About Prof. Carl Brozek: Prof. Brozek leads a materials chemistry research group at the University of Oregon. He is from Chicago, with a PhD at MIT and postdoc at Washington. Chris and Carl collaborate a lot.

Introduction preamble: Airplane 2.

Chris and Doran are joined by Emilee Bryant to discuss a pair of papers that probe whether latte art a) is perceived as more valuable and b) affects the perceived flavor of the drink.

Ordering a cappuccino is delightful. But is it more delightful with a rosetta? Would you be somehow compelled to pay more for it if it had one? Does it taste sweeter?

The papers are:

J. Sens. Stud., 2015, 30, 305

https://doi.org/10.1111/joss.12159

Br. Food J., 2021, 123⁠, 1931

https://doi.org/10.1108/BFJ-07-2020-0612

About Emilee: Originally from Houston, Emilee moved to live in a hippie tree house before finding her way to Brooklyn where she lives now. She is a latte art champion, YouTube content creator, and film maker. Check her out on instagram (emstagrim), and YouTube (EmileeBryant).

Introduction preamble: Lorelai Gilmore and Luke Danes

In this episode Chris and Doran discuss the age-old question of whether dark or light roast brewed coffees have more caffeine. The discussion was inspired by a paper published recently in Scientific Reports titled, "Caffeine content in filter coffee brews as a function of degree of roast and extraction yield".

So, do light and dark roast coffee extracts have different caffeine concentrations?

The paper is open access and available from the publisher:

Sci. Rep., 2024, 14, 29126

https://doi.org/10.1038/s41598-024-80385-3

Introduction preamble: Captain Janeway.

Chris and Doran are joined by Dr. Alex Dainis, a professional science communicator. We first met Alex through her work on "Chemistry Shorts", videos about sub-disciplines of chemistry supported by the Dreyfus foundation.

Today's paper is about microplastics. These are microscopic pieces of polymer that show up everywhere. In the case in single-serve coffee preparations. Alex is the perfect guest to discuss this because its a topic that is becoming increasingly studied, but to date we simply don't know all that much about whether they are bad for you. We get into that and much, much more. I hope you enjoy!

The paper:

Pouring hot water through drip bags releases thousands of microplastics into coffee

Food Chem., 2023, 415, 135717

⁠https://doi.org/10.1016/j.foodchem.2023.135717

The article can be found in coffee literature library: ⁠⁠⁠https://pages.uoregon.edu/chendon/coffee_literature/coffee_lit_rev/⁠⁠⁠

About Dr. Dainis: Blimp lover. She has a PhD in genetics from Stanford but is also trained in film and television. After she finished her PhD she founded Helicase media while also being a professional science communicator.

Introduction preamble: Pulp Fiction.

Chris and Doran are joined by Prof. Nicola Segata from University of Trento. Prof. Segata is a world famous professor of computational metagenomics, and is the senior author on a recently published study that strongly suggests that consuming coffee directly affects the population of some gut bacteria.

Metagenomics is far removed from our expertise. Instead of us fumbling around the paper, we decided to have the true world expert come talk to us about it.

Production note: The paper came out over the holiday period so we recorded remotely. The sound quality is not what we usually strive for, but the content quality is exceptionally high. We hope you enjoy.

The paper:

Nat. Microbio., 2024, 9, 3120

https://doi.org/10.1038/s41564-024-01858-9

The article can be found in coffee literature library: ⁠⁠https://pages.uoregon.edu/chendon/coffee_literature/coffee_lit_rev/⁠⁠

About Nicola Segata: Prof. Segata is from Trento, matriculated through Trento, spent a brief period as a postdoc at Harvard, and returned to Trento where he holds a position as Professor of Computational Metagenomics. He is one of the most highly cited scientists in all fields and has a staggering career of papers that merge computational biology with amazing experimental datasets. You can find his other works here.

Introduction preamble: Friends.

Chris and Doran are joined by Tonx (Tony Konecny) from YES PLZ from Los Angeles, CA. We discuss a paper from the Yeretzian lab out of ZHAW. The paper aims to address a common question for the home coffee consumer, "How should you store your coffee one the bag is open?".

We immediately thought of Tonx and YES PLZ, who have experimented with various packages for their subscription service. We hope you enjoy the episode.

The paper:

Food Packag. Shelf Life, 2022, 33, 100893.

https://doi.org/10.1016/j.fpsl.2022.100893

The article can be found in coffee literature library: ⁠https://pages.uoregon.edu/chendon/coffee_literature/coffee_lit_rev/⁠.

About Tonx: Legend of subscription coffee, Tonx started Tonx coffee and later a coffee/restaurant venture called LocoL. Pre-pandemic he rolled out his current subscription service, YES PLZ. Good timing — home coffee consumption exploded during the 2020-2021 years.

Introduction preamble: Steve Leighton

Chris and Doran are joined by David Yardley from Moongoat Coffee out of Costa Mesa, CA to discuss a series of papers discussing the emergence of mold in coffee.

Mold is bad. Ochratoxin A is bad. But how much of it is there, and how bad does it have to get?

The three papers:

Food Sci. Biotechnol., 2018, 27, 891.

J. Agric. Food Chem., 1998, 46, 673.

Food Chem. Toxicol., 1995, 5, 341.

The article can be found in coffee literature library: https://pages.uoregon.edu/chendon/coffee_literature/coffee_lit_rev/.

About David: Coming up from the entry level job at Starbucks, David is now the leader of Moongoat coffee, a roastery and series of cafes in the southern Californian region.

Introduction preamble: Don Pettit

Chris and Doran are joined by Alex Kaplan from Cometeer to discuss an old school paper titled, "An investigation into the relationship between freezing rate and mean ice crystal size for coffee extracts", appearing in Trans. IChemE, 2002, 80, 176. The paper is part of a conference proceeding which was published in the journal Food Bioprod. Process.

This paper looks at how freezing rate determines the ice crystal size. The paper itself is really about developing a model that correctly captures how brewed coffee freezes, but we used it as a platform to understand how coffee behaves when cooled.

The article can be found here:

About Alex: We couldn't have had a better guest, as Alex is the Head of Coffee Product for Cometeer, a company that manufactures frozen coffee extracts. Alex also has a degree in physics from Princeton, is a Q-grader, and was a pleasure getting nerdy with.

Introduction preamble: George Clooney

Chris and Doran are joined by Lance Hedrick to discuss, "A new Coffee Brewing Control Chart relating sensory properties and consumer liking to brew strength, extraction yield, and brew ratio", appearing in J. Food Sci., 2023, 88, 2168.

Today's paper is an attempt to revise and improve upon the seminal work of Lockhart: the empirical observation that coffee strength (%TDS) is related to the beverage refractive index. But do we need a new control chart?

The article can be found here:

About Lance: Lance is one of Youtube's most loved coffee professionals. He is also a competitor and coach in competitive coffee, handling the launch of Onyx EU, and an up-and-coming chess player.

Introduction preamble: Heisenberg