{"id":238,"date":"2026-08-22T12:06:24","date_gmt":"2026-08-22T12:06:24","guid":{"rendered":"https:\/\/www.avventuracaffe.it\/?p=238"},"modified":"2026-08-22T12:06:25","modified_gmt":"2026-08-22T12:06:25","slug":"quando-lacqua-incontra-il-caffe-3-livelli","status":"publish","type":"post","link":"https:\/\/www.avventuracaffe.it\/en\/quando-lacqua-incontra-il-caffe-3-livelli\/","title":{"rendered":"When Water Meets Coffee \u2014 3 Levels"},"content":{"rendered":"<style>\n.ac-wrap{--ink:#202124;--teal:#31c3bb;--dark:#096c69;--coral:#ff603b;--yellow:#ffd161;--cream:#fff8ed;color:var(--ink);font-family:Arial,sans-serif;max-width:1180px;margin:0 auto}.ac-hero{display:grid;grid-template-columns:1.05fr .95fr;background:var(--cream);min-height:480px}.ac-hero-copy{padding:70px 7%;display:flex;flex-direction:column;justify-content:center}.ac-tag{display:inline-block;width:max-content;background:var(--yellow);padding:10px 17px;border-radius:999px;font-size:12px;font-weight:900;letter-spacing:.12em}.ac-hero h1{font-size:clamp(45px,6vw,78px);line-height:.98;letter-spacing:-.05em;margin:28px 0 22px;font-weight:900}.ac-hero h1 span{color:var(--coral)}.ac-hero p{font-size:18px;line-height:1.65}.ac-image{background:url('https:\/\/www.avventuracaffe.it\/wp-content\/uploads\/2026\/08\/exec-3baf04fc-7aef-4ff1-8852-425c17fc106e-1536x864.png') center\/cover;min-height:380px}.ac-nav{position:sticky;top:32px;z-index:4;display:grid;grid-template-columns:repeat(3,1fr);background:white;border:1px solid #eadfce}.ac-nav a{padding:18px;text-align:center;text-decoration:none;color:var(--ink);font-weight:900;border-right:1px solid #eadfce}.ac-nav a:nth-child(1){border-top:7px solid var(--yellow)}.ac-nav a:nth-child(2){border-top:7px solid var(--teal)}.ac-nav a:nth-child(3){border-top:7px solid var(--coral);border-right:0}.ac-level{scroll-margin-top:120px;display:grid;grid-template-columns:180px 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p,.ac-factor p{font-size:15px;margin:7px 0 0;line-height:1.6}.ac-factor{display:grid;gap:3px}.ac-number{list-style:none;padding:0;display:grid;gap:12px;counter-reset:item}.ac-number li{counter-increment:item;display:grid;grid-template-columns:55px 1fr;gap:8px 15px;border-color:var(--coral)}.ac-number li:before{content:'0' counter(item);grid-row:1\/3;font-size:30px;font-weight:900;color:var(--coral)}.ac-cta{display:block;margin-top:45px;padding:25px 28px;background:var(--coral);color:white!important;text-decoration:none;font-weight:900}.ac-next{margin-top:55px;padding:32px;background:var(--teal);border-left:9px solid var(--yellow)}.ac-next h3{margin:10px 0}.ac-next b{display:inline-block;background:var(--yellow);padding:8px 11px;font-size:10px;letter-spacing:.12em}@media(max-width:760px){.ac-hero{grid-template-columns:1fr}.ac-level{grid-template-columns:1fr;gap:30px;padding:65px 22px}.ac-pair{grid-template-columns:1fr}.ac-nav a{font-size:12px;padding:14px 6px}.ac-hero-copy{padding:60px 24px}}\n.page-id-231 .has-tertiary-background-color:has(.wp-block-post-title){display:none!important}<\/style>\n<div class=\"ac-wrap\">\n<section class=\"ac-hero\"><div class=\"ac-hero-copy\"><span class=\"ac-tag\">ESPRESSO SCIENCE \u00b7 ARTICLE 01<\/span><h1>When water<br><span>meets coffee.<\/span><\/h1><p>A three-level journey to understand what happens inside the coffee puck, from the first drop to the physics of flow.<\/p><\/div><div class=\"ac-image\"><\/div><\/section>\n<nav class=\"ac-nav\"><a href=\"#panoramica\">01 \u00b7 Overview<\/a><a href=\"#approfondimento\">02 \u00b7 In Depth<\/a><a href=\"#tecnico\">03 \u00b7 Technical<\/a><\/nav>\n<section class=\"ac-level\" id=\"panoramica\"><aside class=\"ac-side\"><b>01<\/b><span>OVERVIEW<\/span><small>Understand what happens<\/small><\/aside><div class=\"ac-text\"><h2>What happens when water reaches the coffee puck?<\/h2><p class=\"ac-lead\">This is the first question in our journey through espresso extraction: what happens to the ground coffee at the exact moment hot water reaches the puck?<\/p><p>Complex physical and chemical processes take place during extraction. To understand them, the first step is to examine some characteristics of ground coffee and the way water reaches it and flows through it.<\/p><p>The coffee puck is a porous medium. It contains void spaces between the particles, and water must move through these spaces. Two concepts therefore become essential: porosity and permeability.<\/p><div class=\"ac-pair\"><div><strong>Porosity<\/strong><p>The void space available within the puck.<\/p><\/div><div><strong>Permeability<\/strong><p>The ability of the medium to allow a fluid to pass through it.<\/p><\/div><\/div><p>These two characteristics are closely related, but they are not the same. The puck structure changes according to particle shape and size, grind setting and the pressure applied during tamping.<\/p><p>The way water initially permeates the coffee bed also plays a crucial role. This is where pre-infusion comes into play: the very first moments of brewing, when water begins to interact with the grounds.<\/p><p>Understanding these first seconds helps explain why water does not always travel through the puck in the same way and why small changes in preparation can alter extraction behaviour.<\/p><a class=\"ac-cta\" href=\"#approfondimento\">Want to understand why it happens? Continue with In Depth \u2192<\/a><\/div><\/section>\n<section class=\"ac-level deep\" id=\"approfondimento\"><aside class=\"ac-side\"><b>02<\/b><span>IN-DEPTH<\/span><small>Understand why it happens<\/small><\/aside><div class=\"ac-text\"><h2>Inside the puck: porosity, permeability and grinding<\/h2><p class=\"ac-lead\">To understand the first contact between water and coffee more precisely, we must consider the puck as a porous medium whose structure controls fluid flow.<\/p><h3>Permeability<\/h3><p>Absolute permeability is an intrinsic property of porous media such as ground coffee and expresses the medium\u2019s ability to allow a fluid to pass through it.<\/p><p>During extraction it can vary significantly depending on the blend, grind setting, roast profile and pressure applied during tamping. The way and timing with which water initially permeates the coffee bed are also decisive.<\/p><h3>Porosity<\/h3><p>Porosity is defined as the ratio between the volume of voids, or pores, and the total volume of the material considered: in our case, the ground-coffee puck.<\/p><p>Pores can be classified as macropores, mesopores and micropores. Their presence and distribution depend on particle shape, arrangement and size.<\/p><h3>What changes the puck?<\/h3><div class=\"ac-factor\"><div><strong>Particle shape<\/strong><p>It determines pore shape and size and depends greatly on the type of grinder used and the grind setting.<\/p><\/div><div><strong>Particle arrangement<\/strong><p>It is related to particle shape and tamping level. Stronger tamping compacts the particles, reduces porosity and restricts water flow between layers.<\/p><\/div><div><strong>Particle size<\/strong><p>It depends on the grind setting and affects both porosity and permeability. For Italian Espresso, the document normally indicates a range between 300 and 400 \u00b5m, with an unavoidable fraction of extremely fine particles known as fines.<\/p><\/div><div><strong>Puck tamping<\/strong><p>The force used to compress the puck with the tamper is crucial in establishing the relationship between permeability and porosity.<\/p><\/div><\/div><h3>The key distinction<\/h3><p>In short: porosity represents the volume of available void spaces; permeability represents the fluid\u2019s ability to pass through those spaces.<\/p><p>When water reaches the puck, it does not encounter a uniform mass but a complex structure whose geometry influences flow. To describe this phenomenon more precisely, we must enter the physics of permeability.<\/p><a class=\"ac-cta\" href=\"#tecnico\">Want to explore the physics of the phenomenon? Continue with the Technical level \u2192<\/a><\/div><\/section>\n<section class=\"ac-level tech\" id=\"tecnico\"><aside class=\"ac-side\"><b>03<\/b><span>TECHNICAL<\/span><small>Study the physical phenomenon<\/small><\/aside><div class=\"ac-text\"><h2>The physics of flow: permeability, viscosity and Darcy\u2019s law<\/h2><p class=\"ac-lead\">In technical terms, puck permeability does not simply describe the presence of void spaces, but the behaviour of the porous medium as fluid passes through it.<\/p><p>Unlike porosity, permeability is described in the document as a vector quantity and is the geometric factor in the proportionality constant that, according to Darcy\u2019s law, links the pressure gradient to fluid flow rate.<\/p><h3>The two elements of fluid flow<\/h3><ol class=\"ac-number\"><li><strong>Viscosity<\/strong><span>It depends on the physicochemical characteristics of the fluid\u2014in our case, water at specific temperatures and pressure gradients.<\/span><\/li><li><strong>Intrinsic permeability<\/strong><span>It is determined solely by the structure of the porous medium\u2014in our case, ground coffee.<\/span><\/li><\/ol><h3>The microscopic structure<\/h3><p>The factors affecting absolute permeability are closely linked to the microscopic structure of the medium, including tortuosity and pore size.<\/p><p>Porosity is a scalar quantity. Permeability is instead described mathematically as a tensor, because resistance to water flow can vary with flow direction.<\/p><p>This distinction leads to a fundamental point: knowing the volume of void spaces is not enough. We must also consider the fluid\u2019s ability to pass through them and the direction in which flow develops.<\/p><h3>From first contact to pre-infusion<\/h3><p>The document emphasises that the way and timing with which water initially permeates the coffee bed play a crucial role. This phenomenon is summarised by the term pre-infusion.<\/p><p>This leads to the next topic: when water saturates the coffee bed, the system\u2019s behaviour requires us to consider non-Newtonian fluids, soft matter, anisotropy, temperature and pressure gradient.<\/p><div class=\"ac-next\"><small>CONTINUE THE JOURNEY<\/small><h3>Pre-infusion and changes in the puck<\/h3><p>Next topic: the first seconds of brewing.<\/p><b>IN PREPARATION<\/b><\/div><\/div><\/section>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>SCIENZA DELL\u2019ESPRESSO \u00b7 ARTICOLO 01 Quando l\u2019acquaincontra il caff\u00e8. Un percorso in tre livelli per capire cosa accade nel pannello, dalla prima goccia alla fisica del flusso. 01 \u00b7 Panoramica02 \u00b7 Approfondimento03 \u00b7 Tecnico 01PANORAMICACapire cosa succede Cosa succede quando l\u2019acqua tocca il pannello di caff\u00e8? Questa \u00e8 la prima domanda da cui parte il [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[21],"tags":[],"class_list":["post-238","post","type-post","status-publish","format-standard","hentry","category-articoli"],"_links":{"self":[{"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/posts\/238","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/comments?post=238"}],"version-history":[{"count":1,"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/posts\/238\/revisions"}],"predecessor-version":[{"id":239,"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/posts\/238\/revisions\/239"}],"wp:attachment":[{"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/media?parent=238"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/categories?post=238"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.avventuracaffe.it\/en\/wp-json\/wp\/v2\/tags?post=238"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}