Optimizing Brewed Coffee Quality Through Proper Grinding Daniel Ephraim

Transcription

1 Optimizing Brewed Coffee Quality Through Proper Grinding Daniel Ephraim President Modern Process Equipment

2 First and foremost Is there a particular grinding problem or issue that you would like to see addressed today? THERE S S NOTHING WORSE THAN SITTING THROUGH A PRESENTATION AND WALKING AWAY EMPTY HANDED!

3 The Coffee Quality Cycle Brewing Theory: Key factors in Coffee Brewing or Extraction: Particle size Particle uniformity Time Presentation Outline The Big Picture in Coffee Brewing Effect of Temperature on Ground Coffee Analyzing and Testing Ground Coffee Grinding for Pods and Espresso Coffee Questions and Discussions

4

5 Proper coffee grinding is a most essential, and often neglected, part of the coffee quality process. So let s explore the process from the beginning with selected coffee quality tipping points

6 Theoretical Coffee Quality = 100% Maximum Possible Coffee Beverage Quality = 100%

7 Theoretical Coffee Quality = 100% Maximum Possible Coffee Beverage Quality = 100% We cannot improve on Mother Nature!

8 Coffee Processing Tipping Point Poor Preparation Quality Decreases

9 Coffee Transportation Tipping Point Exposure to Adverse Conditions Quality Decreases

10 Coffee Roasting Tipping Point Over/Under Roasted Quality Decreases

11 Coffee Grinding Tipping Point Improper Grind Size/ Poor Uniformity Quality decreases, including the value of all processes up to this point

12 Theoretical Coffee Quality = 100% Maximum Possible Coffee Beverage Quality = 100% Tree Cup Processing The Coffee Brewing Quality Cycle Transportation Grinding Warehouse Roasting

13 The great thing about cupping coffee is that it pretty well defines the quality of the bean.

14 BUT, the tough part is grinding the coffee to achieve the same quality of the bean to the brew.

15 We don t t brew whole bean coffee! X

16 Proper Extraction and Strength Coffee beans are composed of soluble solids, which must be extracted into the coffee brew.

17 Proper Extraction and Strength The amount of soluble solids extracted from the coffee bean into the brew must be the correct amount or percentage.

18 This is a much magnified view of a ground coffee particle using an electron microscope. The cellular walls are about 30 microns in diameter, and the colloidal material fills the voids within the ground coffee and cellular structures. Part of this colloidal material is what we want to extract, but with a limit.

19 Proper Extraction and Strength 18% 22% Approx. 98.5% Water 1.35% 1.15% Ideal Extraction of the coffee particle s soluble solids is 18-22% Ideal Brew Strength is % brewed solids

20 One Example of Overextraction is Turkish Coffee Where the entire bean is ground and dissolved into hot water. 100% Excess solids settle on the bottom of the cup, which is typically considered undrinkable.

21 The Center of the Universe for Coffee Grinding is EXTRACTION! Specifically PROPER EXTRACTION! The key to PROPER EXTRACTION is creating, through GRINDING, the IDEAL EXPOSED COFFEE SURFACE AREAS

22 Effect of Grind Size on Surface Area 1 Bean = 3.4 cm 2 2 Particles = 4.4 cm 2 4 Particles = 5.4 cm Particles = 34 cm 2

23 Grind Comparison particles French Press, Coarse particles Drip, Filter Legend = One Coffee Bean 1,000 3,000 particles Vending, Filter Fine 3,500 particles Espresso 15,000 35,000 particles Turkish

24 Grind Sizes Typically expressed in: Mesh Microns (um) 25,400 microns = 1 inch or 100 microns = Inch = Thickness of One Hair!

25 Average Particle Size by Grind Average Particle Size by Grind 1,200 1, E.P. Urn ADC Drip Fine Pod Espresso Medium Vending Espresso Fine Turkish-Coarse Turkish-Fine 0 Average Size in Microns

26 Average Size vs. Surface Area (1 Bean = 3.4 cm 2 = Size of a Postage Stamp) Surface Area Increases as Brewing Time Decreases! Average Size in Microns 1,200 1, E.P. Size of a Business Card Urn ADC Drip Fine Pod Espresso Medium Size of a Business Envelope Vending Espresso Fine Turkish-Coarse Turkish-Fine Exposed Surface Area (cm2)

27 Micro Analysis of Extraction Ideal Grind Size (drip) H2O 4 min. brew cycle 600 particles (850 um avg.) 850 um 1 particle RESULT: 20% Ideal Extraction (Good Taste)

28 Micro Analysis of Extraction Ideal Grind Size (drip) H2O 4 min. brew cycle 600 particles (850 um avg.) 500 um Factors: 1) 1) Time Time is is consistent. 2) 2) Particle size size has has decreased. 1 particle Result: Since Since the the coffee coffee particle is is smaller than than ideal, ideal, the the surface area area is is greater and and the the extraction rate rate will will be be excessive. RESULT: 30% Overextraction (Poor/Bitter Taste)

29 Micro Analysis of Extraction H2O Conclusion #1: Ideal extraction is is a function of proper particle size for the brew time.

30 The Importance of Grind Uniformity Typical Ground Coffee Particle Size 24,500 microns = 1 inch E.P. Regular ADC Drip Fine Espresso Coarse Espresso Medium Vending Espresso Fine Turkish-Coarse 1,200 1, Particle Size Average Size in Microns Turkish-Fine

31 The Importance of Grind Uniformity Typical Ground Coffee Particle Size 24,500 microns = 1 inch E.P. Regular ADC Drip Fine Espresso Coarse Espresso Medium Vending 1,200 1, Particle Size Particle Uniformity Average Size in Microns Espresso Fine Turkish-Coarse Turkish-Fine

32 Grind Uniformity Comparison Non-Uniform Particle Size Uniform Particle Size

33 Uniform vs. Non-Uniform Coffee Grind % Retained (Non-Cumulative) Worn Roller Grinder Poor Quality, Non-Uniform, Coffee Grind Properly Maintained Ideal, Uniform Roller Grinder Coffee Grind Oversize Desired Size Undersize

34 Roller vs. Disc Grinder % Retained (Non-Cumulative) Roller Grinder Disc Grinder Oversize Desired Size Undersize

35 Impact of Improper Grinding Practice on Grind Quality (Poor Methodology, Excessive Wear, etc.) % Retained (Non-Cumulative) 650 um/ 3.0 σ 645 um/1.35 σ Uniform ground coffee distribution (good) Non-uniform ground coffee distribution (bad) Oversize Desired Size 650 um Undersize

37 Micro Analysis of Extraction Ideal Grind Size (drip) H2O 4 min. brew cycle 600 particles (850 um avg.) 500 um 850 um Factors: 1) 1) Time Time is is consistent. 1,000 um 2) 2) Particle uniformity is is inconsistent. RESULT: 30% Overextraction (Poor/Bitter Taste) RESULT: 20% Ideal Extraction (Good Taste) RESULT: Underextraction (Tea-Like Taste) Result: Result: Since Since some some of of the the coffee coffee particles particles are are smaller smaller and and larger larger than than ideal, ideal, the the surface surface areas areas are are greater greater and and lesser lesser and and the the extraction extraction rates rates will will be be excessive excessive or or insufficient. insufficient.

38 Micro Analysis of Extraction H2O Conclusion #2: Ideal extraction is is a function of proper particle size uniformity.

39 Optimal Brew Time vs. Particle Size Brew Time vs. Particle Size to Achieve 20% Extraction Rate Particle Size (microns) % Extraction Rate Particle Size Dictates Brew Time! Brew Time Dictates Particle Size! 300 Espresso Pod Fine Drip Urn Brewing Time (minutes)

40 Effect of Extraction Time on Taste

41 Effect of Cycle Time on Taste Courtesy of the Coffee Brewing Center

43 Micro Analysis of Extraction Ideal Grind Size (drip) H2O 8 min. brew cycle 600 particles (850 um avg.) 850 um Factors: 1) 1) Particle size size is is consistent. 2) 2) Time Time has has changed. Result: Since Since the the brewing time time is is too too long long for for the the relative particle size, size, the the extraction rate rate is is excessive. 1 particle RESULT: 30-35% Overextraction (Poor/Bitter Taste)

44 Macro Analysis of Extraction Espresso Brewer 225 um grind H2O 20 sec. H2O Optimum Brew

45 Macro Analysis of Extraction Espresso Brewer 225 um grind H2O H2O 20 sec. 1 min. H2O Optimum Brew Over Extracted Brew

46 Macro Analysis of Extraction Espresso Brewer 225 um grind Filter Basket Brewer 850 um grind H2O H2O H2O H2O H2O H2O 20 sec. 1 min. 4 min. Optimum Brew Over Extracted Brew Optimum Brew

47 Macro Analysis of Extraction Espresso Brewer 225 um grind Filter Basket Brewer 850 um grind H2O H2O H2O H2O H2O H2O 20 sec. 1 min. 4 min. 2 min. Optimum Brew Over Extracted Brew Optimum Brew Under Extracted Brew

48 Macro Analysis of Extraction Espresso Brewer 225 um grind Filter Basket Brewer 850 um grind H2O H2O H2O H2O H2O H2O 20 sec. 1 min. 4 min. 2 min. 8 min. Optimum Brew Over Extracted Brew Optimum Brew Under Extracted Brew Over Extracted Brew

49 Micro Analysis of Extraction H2O Conclusion #3: Ideal extraction is is a function of proper brew time for the method and grind.

50 Macro Grind Challenge 64 oz. H2O H2O Extract for 4 min. Approx. 6 oz. water retention in grounds 3.75 oz. Good Grind Goal: Good Grind Goal: 20% extraction of soluble solids 58 oz. liquid (64 oz. 6 oz.) Soluble Solids: 1.3% (0.75 oz./58 oz.) 58 oz. brew 20% * 3.75 =.75 oz.

51 The Gold Cup Standard Calculation Strong Under- Developed Strong Strong Bitter Too Fine so Extraction Rate Too High How do we calculate brewed solids? Too Coarse so Extraction Rate Too Low Under- Developed Weak Under- Developed Optimum Balance Weak Bitter Weak Bitter 1. Use 64 oz. of water for brewing 2. Subtract water absorbed in coffee grounds (6 fl/oz.) 3. Use 3.75 oz. of ground coffee to extract 20% solids 4. Brew to Gold Cup Standard that will extract 20% of solids: 20% x 3.75 oz. = 0.75 oz. 5. Calculate brewed solids as percentage of liquid: 0.75 oz./58 oz. = 1.3%

52 Evaluation of the same grind (average particle size) but different uniformities Particle Size/Particle Uniformity: Strong Under- Developed Strong Strong Bitter 645 um/1.35 σ (Good Quality Grind) Under- Developed Optimum Balance Bitter 650 um/ 3.0 σ (Poor Quality Grind) Weak Under- Developed Weak Weak Bitter

53 The Key Principals of Coffee Extraction The rate of soluble solids extraction from a coffee particle is directly related to the amount of exposed surface area to the hot water. The time that the hot water will be exposed to the coffee particle must be directly proportional to the exposed surface area, or particle size, of the ground coffee. If particle size, uniformity and brewing time are matched correctly, with all other factors being equal, a 20% extraction rate can be achieved.

54 Ideal Matrix of Grind vs. Time Grind Coarse Optimal Fine Excessive Strong Under- Developed Strong Strong Bitter Brew Times Optimal Too Short Under- Developed Weak Under- Developed Optimum Balance Weak Bitter Weak Bitter Brewed Coffee Taste Profiles

55 Ideal Matrix of Grind vs. Time Grind Coarse Optimal Fine Excessive Strong Under- Developed Strong Strong Bitter Brew Times Optimal Too Short Most Common Problems Under- Developed Weak Under- Developed Optimum Balance Weak Bitter Weak Bitter Brewed Coffee Taste Profiles

56 Heat vs. Grinding Goal: We only want to roast coffee once, and that is in the roaster! = OK! Challenge: Maintain low temperatures during grinding. = NOT OK!

57

58 Temperature Rise During Grinding 170 Increasing Loss of Flavors & Aromatics Coffee Temperature (Deg F) Disc-Style Coffee Grinder w/o Water-Cooling Grinder Run Time (Minutes) High Temperature/Vapor Pressure Flavors and Aromatics Medium Temperature/Vapor Pressure Flavors and Aromatics Low Temperature/Vapor Pressure Flavors and Aromatics Coffee Darkens

59 Temperature Rise During Grinding 170 Increasing Loss of Flavors & Aromatics Coffee Temperature (Deg F) Disc-Style Coffee Grinder w/ Water-Cooling Disc-Style Coffee Grinder w/o Water-Cooling High Temperature/Vapor Pressure Flavors and Aromatics Medium Temperature/Vapor Pressure Flavors and Aromatics Low Temperature/Vapor Pressure Flavors and Aromatics Grinder Run Time (Minutes) Coffee Darkens

60 One Example of the Results from a Water-Cooled Disc-Style Grinder Temperature (F) Temperature (F) Ground Coffee Discharge Temperatures Over Time Ground Coffee Discharge Temperatures Over Time (Standard Drip Grind Size = Approx. 700 um) (Standard Drip Grind Size = Approx. 700 um) Time (min.) Time (min.) Log. Without (W/OWater- Log. Without (W/OWater- Water-Cooling) Water-Cooling) Log. With Log. With (With Water- (With Water- Water-Cooling) Water-Cooling) Model GPX.WCI (Water-Cooling Integrated) Disc-Style Coffee Grinder

61 Questions?

62 Is Evaluating Ground Coffee By Eye Reliable?

63 What do you see?

64 What do you see?

65 Which Line is Longer?

70 They re the same length.

71 Which box is bigger?

72 They re both the same size.

73 Is this line straight?

74 Nope.

75 Which grind is smaller? This one.

76 Analyzing and Testing Ground Coffee

77 The Ro-Tap Method

78 The Ro-Tap Method % Retained (Non-Cumulative) Screen Size Pan Oversize Desired Size Undersize

79 The Ro-Tap Method % Retained (Non-Cumulative) Screen Size Pan MESH Weight (Tyler) (grams) PAN Oversize Desired Size Undersize

83 The Ro-Tap Method % Retained (Non-Cumulative) Screen Size Pan MESH Weight (Tyler) (grams) PAN 23.9 Oversize Desired Size Undersize

84 Ro-Tap Calculation TEST # DATE: N O T E S 1 25-Apr-03 Fine Drip Grind Sample MESH grams % (Tyler) % % % % PAN %

85 Ro-Tap Graph 45.0% 40.0% % Retained (Non-Cumulative) 35.0% 30.0% 25.0% 20.0% 15.0% 10.0% 5.0% 0.0% PAN Drip Grind 0.6% 4.4% 28.9% 42.2% 23.9% Screen Size (Tyler Mesh)

86 Laser Particle Size Analysis

87 Principle of Laser Particle Size Analysis Focusing Lens Scattered Light Laser Beam Central Detector Particles Main Detector f

88 Laser Analysis Results % Particle Diameter (µm.) 100 D(v,0.1) = 306 um 90 Path: Coffee C:\SIZERX\DATA\ Result: Sieve ASTM E11:61 Table ID: Run No: 1 Measured: File: EXAMPLE2 Rec. No: 2 Analy sed: 3/5/01 11:50AM Source: Input 10% Percentile Range: 1000 mm Beam: mm Sampler: Obs': 20.0 % Presentation: 2RHA Analy sis: Poly disperse Residual: % Modif ications: None D(v,0.5) = 478 um Conc. = %Vol Density = g/cm^3 S.S.A.= m^2/g Distribution: Volume D[4, 3] = um D[3, 2] = um D(v, 0.1) = um D(v, 0.5) = um D(v, 0.9) = um Span = 9.760E-01 Unif ormity = 3.054E-01 Average Particle Size Mesh No Aperture um Volume In% Volume Below% D(v,0.9) = 772 um 90% Percentile Mesh No Aperture um Volume In% Volume Below%

89 Two Different Fine Grinds % Retained (Non-Cumulative) Average Particle Sizes are the same. Brew Qualities are different! Oversize Desired Size Undersize

90 Use about 50 grams 24 mesh/700 um screen size The MPE Single Sieve Hand Ro-Tap Method Shake and rotate for five minutes, occasionally tapping on a table Percentage Above Pan Use Single Sieve chart to determine the average particle size by referencing the percentage of coffee retained on the sieve. Percentage Below

91 The MPE Single Sieve Hand Ro-Tap Method Weigh your results using a portable scale.

92 The The MPE MPE Single Single Sieve Sieve Reference Reference Chart Chart Disc-Style Disc-Style Coffee Coffee Grinder Grinder % Retained Retained on on Screen Screen Sample result was % retained on top of 24 Mesh screen 30 Mesh Mesh Mesh Calculated Particle size: um Euro Fine Fine/Drip Average Average Particle Drip Particle Size Size (um) Coarse/Drip Perc/Urn (um) Average Particle Size (um) 30 Mesh 24 Mesh 20 Mesh Note: Use Roller-Style Reference Chart for Roller-Style Coffee Grind Results Copyright MPE, 2009

93 % Retained Retained on on Screen Screen The The MPE MPE Single Single Sieve Sieve Reference Reference Chart Chart Sample result was 60% retained on top of 24 Mesh screen Disc-Style Disc-Style Coffee Coffee Grinder Grinder Mesh Mesh Mesh Calculated Particle size: um Euro Fine Fine/Drip Average Average Particle Drip Particle Size Size (um) Coarse/Drip Perc/Urn (um) Average Particle Size (um) 30 Mesh 24 Mesh 20 Mesh Note: Use Roller-Style Reference Chart for Roller-Style Coffee Grind Results Copyright MPE, 2009

94 Size Conversion and Grind Reference Table Available online at: SIZE CONVERSION AND GRIND REFERENCE TABLE U.S. Mesh Tyler Mesh Inches Microns Grind* Extract Grinds and French Press SIZE CONVERSION AND GRIND REFERENCE TABLE U.S. Mesh Tyler Mesh Inches Microns Grind* Fine Grind E.P and Regular Grind Drip Grind Fine Grind Euro Filter Fine Espresso Coarse Vending Espresso Fine Coarse Turkish Medium Turkish Fine Turkish Modern Process Equipment, Inc. Chicago, Illinois USA *=Average Particle Size

95 Segregation Once coffee is ground, care must be taken so that the particles don t declassify between the grinder and the package, pod or other delivery container.

96 Segregation Segregation Video Courtesy of Jenike and Johanson, Inc.

97 Espresso and Single-Cup Serving methods are the toughest grinds to achieve!

98 Brewer Examples Flavia Tassimo Keurig Flavia Filter Pack Tassimo T-Discs Keurig K Cup

99 Filter-Type Packages

100 or shaped like these

101 Pod vs. Fresh Brew Performance Comparison Brewing Dynamics 1 Pod/8 oz. cup Equivalent Coffee Pack for 64 oz. Brew Ratio Coffee Weight 9 grams 3.75 oz. 1/12th the weight Water Pressure (psi) Gravity: Brew Time sec. 3 6 min. Grind Size (microns)

102 Pod vs. Fresh Brew Performance Comparison Brewing Dynamics 1 Pod/8 oz. cup Equivalent Coffee Pack for 64 oz. Brew Ratio Coffee Weight 9 grams 3.75 oz. 1/12th the weight Water Pressure (psi) Gravity: times the water pressure Brew Time sec. 3 6 min. Grind Size (microns)

103 Pod vs. Fresh Brew Performance Comparison Brewing Dynamics 1 Pod/8 oz. cup Equivalent Coffee Pack for 64 oz. Brew Ratio Coffee Weight 9 grams 3.75 oz. 1/12th the weight Water Pressure (psi) Gravity: times the water pressure Brew Time sec. 3 6 min. 1/20th the time Grind Size (microns)

104 Pod vs. Fresh Brew Performance Comparison Brewing Dynamics 1 Pod/8 oz. cup Equivalent Coffee Pack for 64 oz. Brew Ratio Coffee Weight 9 grams 3.75 oz. 1/12th the weight Water Pressure (psi) Gravity: times the water pressure Brew Time sec. 3 6 min. 1/20th the time Grind Size (microns) /2 the grind size

105 A pod grind is one of the most technical and challenging grinds, yet is typically produced on the most basic, limited grinder as a matter of convenience. The grind must be the correct size and uniformity to produce a comparable coffee brew!

106 Now let s take a closer look at Espresso Grinding: Two apparently contradictory needs must be satisfied to prepare a good cup of espresso: 1) On the one hand, a short percolation time is required; 2) On the other hand, a high concentration of soluble solids must be reached.

107 Both requirements can only be attained if a close contact between solid particles and extraction water can be achieved. Thus, espresso percolation needs a plurimodal particle size distribution, where the finer particles enhance the exposed extraction surface (chemical need) and the coarser ones allow the water flow (physical need). 40 um (20%) 280 um (80%)

108 Let s look at an espresso particle distribution using an electron microscope. Upon further magnification, we can see the cellular structure and hexagonal structure in more detail, as well as the fines which are an essential and integral part of espresso grinding. We can also see the rupture of the cellular walls, which are 30 um in diameter, which is the same size as the superfines that are a required element in espresso grinding.

109 Ideal Espresso Grinding It is typically desirable to generate fines (20-40 um) when grinding for espresso to promote the proper infusion. Optimum Espresso Grind w/ um fines

110 Basic Illustration of Bimodal/Plurimodal Concept Modern Roller Grinding with EFT*

111 How do you determine the optimal grind for your application? 1) Use a grind reference document (SCAA, MPE, etc.) to determine the correct grind for your application or, alternatively: 2) Perform a grind test using the ro-tap, hand ro-tap or laser method to ensure that your actual grind matches your target. 3) In conjunction with the above, utilize a soluble solids tester* to establish: - Your brewed solids and; - Your desired grind to achieve or maintain those brewed solids. * Either a hydrometer or soluble solids Ultrameter can be used for the above.

112 Questions?

113