Coffee Freshness Dr. Marco WELLIGE Dr. Alexia GLÖ Dr. amo MKE Barbara EDELMA Chahan YEETZIA 1 Every step matters to obtain a good cup of coffee Why focus on freshness? erving temperature Cup size and shape Black, with milk, sugar or other ingredients Water temperature, pressure, mineral content Extraction technique (espresso, filter, ) The Barista Particle size distribution Temperature of burs rientation, diameter, material of burs Consumption Brewing Grinding Technology (drum, tangential, fluidized bed ) oast degree / weight loss Time temperature profile oasting pecies (C. arabica, C. canephora) Varieties (Bourbon, Typica, ) tripping, picking, mechanical harvesting Dry, semi-dry, wet processing pecial PH treatments (Monsooned, Kopi Luvak) Propagation & Irrigation Input of chemicals (fertilizers, ) Farm management Genetics Agronomy Harvesting, Post- Harvest Treatment 2 1
The secret to great coffee is the people who make it It All Began when Alfred Peet opened a coffee store in Berkeley, April 1, 1966 Few noticed but a revolution was brewing. His coffee was unlike anything Americans had ever tasted before small batches, fresh beans,. His philosophy: there should be the shortest distance possible between the roaster and the customer Alfred Peet's inspired and guided founders of tarbucks. 3 In 1971, Jerry Baldwin, Gordon Bowker and Zev iegl founded tarbucks in eattle, selling fresh-roasted whole beans to local customers 4 2
«pecialty Coffee» origin of the wording The phrase «pecialty Coffee» was first used by Erna Knutsen, a small oaster, in 1974 in an article of the Tea & Coffee Trade Journal. The concept: special geographic microclimates produce beans with unique flavor profiles, which she referred to as 'specialty coffees.' Underlying this idea of coffee appellations was the fundamental premise that specialty coffee beans would always be well prepared, freshly roasted, and properly brewed. Erna Knutsen 1982: pecialty Coffee Association of America 1998: peciality Coffee Association of Europe 5 6 3
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Freshness is at the heart of pecialty Coffee Make freshness measurable! During roasting: Formation of coffee aroma compounds Formation of C 2 (Carbon dioxide) Barely created they already start do evaporate and degrade H H 9 (Loss of) Freshness Make freshness visible Make freshness measurable During roasting Aroma is generated and already starts degrading C 2 is generated and already starts being lost nce roasting is completed Aroma starts degrading Evaporation xidation / chem. reactions Temp., humidity, light Loss of C 2 Measure freshness Measure changes in aroma compounds during storage: freshness indices Measure degasing during storage: loss of C 2 and C 1 5
Coffee aroma formation during roasting H H Furaneol C 2 H + icotinic acid H H H Quinic acid oasted Coffee C 2 H H Quinic + acid lactone C H HMF Pyridine and derivatives C 2 E- -Damascenone Coffee Aroma Precursors (Green Coffee) LIPID UGA ucrose, glucose, fructose (arabinogalactans) + AMI ACID (trecker-active AA) TIGELLIE CHLGEIC ACID Chlorogenic acid lactones CATEID GAIC ACID C 2 H C 2 H Formic C H 3 C 2 H acetic H C 2 H H C 2 H glycolic C H 3 lactic Maillard, trecker 2 1 1 3 2 3 Diketones Aldehydes Pyrazines H H H 2-Furfurylthiol 3-Mercapto-3-methylbutyl-formate Carbonyls oasted Coffee Caffeic + Ferulic acids C H H Vanillin H Guaiacols 11 The aroma of coffee 1 volatile compounds 5 % have odour 25 are important coffee aroma compounds 12 6
ome important coffee aroma compounds H 2 CH 3 H H H H 13 Chemical markers: Freshness indices related to coffee aroma atio 1: Dimethyl disulfide / Methanethiol Compounds Compounds CA # dor CA # dor Volatility Volatility eactivity eactivity buttery, creamy, buttery, fatty, creamy, oily, fatty, oily, 2,3-Butanedione 2,3-Butanedione 431-3-8 431-3-8 low sweet, vanilla, sweet, caramel vanilla, caramel Dimethyl disulfide Dimethyl 624-92- disulfide sulphurous, sulphurous, onion, garlic, onion, garlic, 624-92- medium burnt rubber burnt rubber sulphurous, sulphurous, rotten eggs, rotten fish, eggs, fish, Methanethiol Methanethiol 74-93-1 74-93-1 high cabbage, garlic, cabbage, cheesy garlic, cheesy burnt, ethereal, burnt, gasoline, ethereal, gasoline, 2-Methylfuran 2-Methylfuran 534-22-5 534-22-5 very high acetone, chocolate acetone, chocolate low low medium high (ox.) high very high (ox.) very high (ox. very high low low high (ox.) very low Processes that lead to changes in aroma compound: Evaporation xidation ther reaction / intrinsic reactivity 14 7
I (Methanthiol) * g I (Dimethyldisulfid) * g atio 1 Dimethyldisulfid and Methanthiol (Medium roast degree: Pt 95) 25' 2' 9' 8' 7'.6.5 atio 1: Dimethyldisulfid / Methanthiol 6'.4 15' 5' 1' 4'.3 3'.2 5' 2' 1'.1 1 2 3 torage time / weeks 1 2 3 torage time / weeks 15 torage of whole beans: Aluminium packaging with valve Ethiopian Limu, Washed, Grade 2, Arabica oasted on a 1-kg batch size Probatino oast degree 93 Pt (Colorette), medium roast 65 g roasted whole beans in each pack Packaging: plastic composite film with thick aluminum layer Valve Heat sealed tored at 22 C (room temperature) and at 5 C 16 8
atio atio The evolution of the ratio dimethyl disulfide / methanethiol stored at room temperature and at 5 C.7.6 Dimethyl disulfide / Methanethiol at 22 C 6 5 Dimethyl disulfide / Methanethiol at 5 C.5.4.3.2 4 3 2.1 Charge 3 Charge 4 1 2 3 4 torage/ weeks 1 Charge 3 Charge 4 1 2 3 4 5 torage/ weeks 1-fold acceleration of degradation when going from 22 C to 5 C Very sensitive freshness index : significant changes within 1 week 17 The chemistry of freshness index Dimethyl disulfide / Methanethiol Methionine Methional H 2 C H 3 H C H 3 DM + DMT C H 3 CH 3 C H 3 DMD Freshness Index Me Dimethyldisulfid (DMD) Methanethiol 18 9
Freshness roasted whole beans Chemical markers Freshly roasted coffea arabica from Guatemala, 25 g roasted whole beans, stored at room temperature Packed in four different packaging materials (with valves except for paper packaging) 19 Freshness in single serve capsules (ground coffee / hermetically sealed) Chemical markers Code Capsule Material Delizio (Ø4x26) Body: PP/EVH/PP Cover: PP/EVH/PP; thickness:.1 mm Barrier-properties integrated into capsule and cover Dolce Gusto (Ø53.5x39) Denner (Ø37x31) Body: PP/EVH/PP Cover: PP/EVH/PP; thickness:.12 mm Barrier-properties integrated into capsule and cover. Extraction system (perforation points & aluminum foil) and outlet for extract are integrated in cover-material Body: PP (injection molding without barrier-properties) Cover: Paper with aluminum coating; thickness:.3 -.5 mm econdary packaging: aluminum; each capsule is individually packed; barrier-properties integrated into secondary packaging espresso (Ø37x31) Body: 99% aluminum, with thin coating of food-grade shellac Cover: aluminum foil; thickness.3 -.5 mm Barrier-properties integrated into capsule and cover 2 1
Freshness Index = DMD / Me for espresso Lungo Fortissio 21 During roasting: Drying Formation of C 2 (a few percent are C) C 2 : % weight, 1-2 H 2 : 12 1-2 22 11
Measuring Freshness by Weighing Coffee Physical freshness marker VT 15 g basket filter Probat drum roaster Probatino (1kg per batch) 23 The story of C 2 from green to old coffee (Arabica coffee) Loss from roasting to grinding (.15 mg/g) Freshly roasted coffee &G 1 Whole beans 8 Loss during grinding (7.6 mg / g) Loss from grinding to first measurement (.2 mg / g) C 2 degassing in &G ( 2.7 mg /g) 6 4 2 pecific mass loss / (mg/g) 2 4 6 8 1 12 14 16 18 2 Time / h 24 12
pecific mass loss / (mg/g) Weight Loss of Arabica Whole Beans 12 18 days 1 1 days 8 6 4 2 Medium to dark roast (85 Pt; Colorette) 18 days of degassing 1 mg/g corresponds 1 % weight loss 48 96 144 192 24 288 336 384 432 Time / h 25 13