ResearchPhysics of Fluids· Jun 23, 2026
A University of Warsaw soft-matter group (Waszkiewicz, Lisicki and colleagues) instrumented a café-grade espresso machine and measured flow through pucks across a range of pump pressures. Up to about 5 bar the bed behaved like an ordinary porous medium (flow proportional to pressure), but above that the flow rate flattened and then fell as pressure rose: once the soluble fraction has dissolved (roughly 30-40 s in), the remaining bed is a poroelastic solid that compacts under load, and its permeability drops faster than the extra pressure can compensate. A minimal model reproduces the non-linear pressure-flow curve and the time evolution of flow during a shot. Caveat: one light-to-medium roast Brazilian coffee, one machine setup; the paper models flow and soluble concentration, not sensory outcome.
Why it matters: If your shots choke or run slow, cranking pressure above 6 bar is unlikely to help and may make the bed compact further; grind, dose and lower pressure profiles are the levers, which supports the trend toward 6-bar and declining-pressure espresso.
ResearchBeverage Plant Research· Jul 7, 2026
Haohao Yu and Faguang Hu's team at the Yunnan Academy of Agricultural Sciences split one batch of Catimor cherries from Baoshan, Yunnan, into four treatments (washed, natural, anaerobic-then-washed, anaerobic-then-natural), ran untargeted metabolomics on the green beans and cupped the roasted coffee. Processing method reshaped the green-bean metabolome, and the anaerobic natural treatment showed the strongest enrichment of amino acids, nucleotides, organic acids, flavonoids and tannins; 75 metabolites (including D-mannose, D-glucose, L-lactic acid, GABA, caffeic and sinapic acid) correlated with sensory attributes and were flagged as flavour precursors. Anaerobically fermented lots scored higher than conventional ones on dry/wet aroma, flavour, aftertaste, acidity, body and balance, while washed coffee scored higher on cleanliness and lower on sweetness. Caveats: a single variety, farm and season; the article gives correlations, not causal links between named compounds and cup attributes; the journal is a newer, lower-profile title.
Why it matters: When a bag says 'anaerobic natural', expect more sweetness and body and a busier aromatic profile than the washed lot from the same farm, and treat 'clean' washed coffees as a different, not lesser, target; it also explains why anaerobic Catimor from Yunnan is turning up on specialty menus.
ResearchJournal of Food Engineering· Jun 1, 2026
Francisco Trujillo's group at UNSW Sydney turned a portafilter basket into an ultrasonic sonoreactor, coupling high-intensity ultrasound directly into a loosely packed coffee bed while water percolates through it. Cavitation bubbles collapsing against the grounds pit and fracture particle surfaces, so espresso-strength concentrations are reached in 2-3 minutes without heat or 9 bar; the paper reports the ultrasonic brew used 24.3% of the energy of a conventional espresso machine (the university's press material rounds this to 'up to 75% less'). Brew ratio, grind size and sonication time were tuned, and beverages were characterised for colour, pH, caffeine and chlorogenic acids. In a blind test, 100 regular coffee drinkers could not distinguish the room-temperature ultrasonic shot from a conventional espresso, and an ultrasound-brewed filter coffee was preferred on bitterness. Caveats: a lab prototype with no consumer device; untrained consumer panel rather than descriptive analysis; the energy comparison depends on the reference machine's standby and heating losses.
Why it matters: Nothing to buy yet, but it is the clearest demonstration so far that heat and pressure are means, not ends: strength and flavour compounds can be pulled out of coffee at room temperature if you supply the mechanical energy another way, which reframes how we think about cold and low-temperature extraction.
ResearchMultisensory Research· Jun 3, 2026
Natsumi Kubo and Atsunori Ariga (Chuo University, Tokyo) had 92 blindfolded participants drink identical black coffee (a Nestlé 'Rich Blend' capsule, about 115 ml served at 68 °C) from cups fitted with either a sandpaper sleeve or a smooth kraft-paper sleeve and rate acidity. Coffee from the smooth cup was rated less acidic, and the effect persisted when the rough or smooth texture came from a separate object held at the same time, but disappeared when the touch and the sip were not simultaneous; the order also mattered (rough-then-smooth showed the effect, smooth-then-rough did not). Caveats: one commodity coffee, acidity only, a Japanese student-style sample, and an order-dependent effect that needs replication.
Why it matters: When comparing two brews or dialling in, hold the vessel, sleeve and surface constant, because what your hand feels at the moment of sipping measurably shifts how sour the coffee reads.
ResearchCrop Science
A University of Florida IFAS team (Suela and colleagues, Tropical Research and Education Center, Homestead) planted 48 arabica seedlings of four cultivars (Fronton, Limani, Typica and Obatã) in May 2023 and tracked them through 2025, the first year the trees were mature enough for representative yield data. Average fresh-cherry yield ranged from roughly 3 to 6 kg per tree across cultivars, and the beans showed some favourable physical and chemical traits, while the paper flags climate, soil, labour and management hurdles for any commercial Florida coffee. Caveats: a single lowland subtropical site, a tiny plot, one harvest, and no reported cup scores from a calibrated panel.
Why it matters: Do not expect Florida coffee in your grinder soon, but this is the first peer-reviewed yield data for arabica grown at sea level in the continental US, and the cultivars chosen (rust-resistant Obatã, Puerto Rican Fronton and Limani) hint at what 'climate-adapted' specialty varieties may look like.
ResearchJournal of Food Process Engineering
Mahima Bora and Heiko Briesen at the Technical University of Munich measured laser-diffraction particle size distributions of coffee ground on different grinders at several grind levels and from beans of different roast degrees, then compared ten two-component (five-parameter) distribution models for how well they describe the characteristic fines-plus-coarse bimodal shape. Lognormal/Weibull, Weibull/Betaprime and Gamma/Weibull fitted best across the dataset; fit quality depended strongly on grinder type and grind level and only minimally on roast degree. The point is methodological: reducing a full PSD to five parameters lets future extraction and sensory models use the whole distribution instead of a single median particle size. Caveat: no brewing or sensory measurements; the study characterises the powder, not the cup.
Why it matters: Nothing to change today, but it reinforces that a grinder's 'setting' is a poor description of what water sees; the fines-to-coarse shape differs by grinder even at the same median, which is why two grinders at the 'same' size brew differently.