Reference

What this advice is built on

Last updated: 20 August 2026

Most coffee writing online cites nothing, which means an error introduced once gets copied forever. This page exists so you can check the claims on this site rather than take my word for them — and so I have something to check my own writing against.

The rule I work to: anywhere a page explains why something happens — why skim milk foams badly, why old milk won’t stretch, why a shot pulled in fifteen seconds tastes sour — that mechanism gets checked against a published source before it goes up. Practical technique advice comes from my own pours and is labelled as such. More about how this site is made.

Dairy and foam chemistry

  • Walstra, P., Wouters, J.T.M. & Geurts, T.J. (2006). Dairy Science and Technology, 2nd ed. CRC Press. ISBN 0-8247-2763-0.

    The standard reference on how milk actually behaves. Underpins everything on this site about protein, fat, and why milk foams the way it does.

  • Deeth, H.C. (2006). “Lipoprotein lipase and lipolysis in milk.” International Dairy Journal 16(6):555–562. Link

    Why older milk foams badly. It is not the proteins breaking down — it is enzymes cleaving fat into free fatty acids, which kill foam long before the milk tastes off. This page corrected an earlier version of our milk guide.

  • Barista Hustle, Milk Science series — including “MS 3.03 Anti-Foams” and “A New View of Milk Foaming”.

    Proteins stabilise foam; fats destabilise it. This is the opposite of what most latte art tutorials imply, and it is why skim milk over-foams into something stiff and unpourable rather than under-foaming.

Brewing, extraction, and water

  • Hoffmann, J. (2018). The World Atlas of Coffee, 2nd ed. Firefly Books. ISBN 9780228100942.

    General brewing reference — ratios, grind, and method fundamentals behind the recipe pages.

  • Rao, S. Everything but Espresso (2010); Espresso Extraction: Measurement and Mastery; The Professional Barista’s Handbook.

    Extraction theory, and the source for why a 1:2 espresso belongs in the 25–30 second range rather than anywhere faster.

  • Specialty Coffee Association — Coffee Standards and Water Quality Standard.

    Brew temperature and water composition targets. Where a recipe on this site specifies 93 °C rather than boiling, this is why.

  • Hendon, C.H., Colonna-Dashwood, L. & Colonna-Dashwood, M. (2014). “The Role of Dissolved Cations in Coffee Extraction.” J. Agric. Food Chem. 62(21):4947–4950. Link

    Why the minerals in your water change how coffee tastes, and why distilled water makes a flat cup.

Cold brew

  • Rao, N.Z. & Fuller, M. (2018). “Acidity and Antioxidant Activity of Cold Brew Coffee.” Scientific Reports 8:16030. Link

    Cold brew is not meaningfully less acidic than hot coffee — measured pH sits at 4.85–5.13 for both. A widely repeated claim that does not survive measurement.

  • Fuller, M. & Rao, N.Z. (2017). “The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee.” Scientific Reports 7:17979. Link

    Extraction times and caffeine levels for cold brew — including that coarse-grind cold brew can carry more caffeine than its hot equivalent.

Latte art technique

  • Lance Hedrick — two-time World Latte Art Champion; public tutorial catalogue.

    Pouring mechanics: pitcher height through the phases of a pour, and the pull-through that finishes a heart.

  • World AeroPress Championship — official winning-recipe archive, 2008–present.

    Reference point for AeroPress steep times and ratios.

Corrections

If something here is wrong, I want to know. Send it through the contact form — a page reference and what you think is wrong is plenty. I will check it against the literature and fix it if it stands up.

This has already happened more than once. The milk guide previously said old milk foams badly because its proteins degrade; that was wrong, and the Deeth paper above is what corrected it. The heart guide previously treated a high pour as always a mistake, when in fact it is correct at the start of a pour and only wrong once the design begins.