roasting for coffee

Hirofumi Yamamoto

INTRODUCTION OF ROASTING COFFEE

Roasting • Roasting is the method that makes green coffee beans to be ready for brewing by using manual or automatic roasting machine that produces certain heat (Cal.) • Roasting dose not require well-trained skills, it is easy to roast coffee beans. If you felt difficulties, that would be because you do not have any standard for roasting• There are no royal road for roasting

Roasting Machine• Roasting machine is that rotates or shakes to stir beans in constant interval with several heat sources: pipe burner, bunsen burner, etc.• Manual roasting tends to be inconsistent coloring, while machinery roasting can be consistent in color• Among roasting machines, there are several types. However, almost all machines is not so different in taste and flavor, if the roasting machine is enclosed type with ventilations.• The centerpiece in roasting is that being familiar with the machine: heat source, temperature alteration, gas pressure, ventilation and capacity, etc.

Machine Type• Types of heat sourcepipe burner, bunsen burner, gun burner, charcoal fire, infrared, etc.

Machine Type• Types of cylindersDirect-fired cylinder, Semi hot blast cylinder, semi hot blast dual cylinder, far infrared coated cylinder, etc.

• Types of structuresEnclosed type that can control ventilation and open type that can not control ventilation

Roasting Procedure• Roasting is consisting of sorting green beans, pre-heating, roasting, cooling and resorting roasted beans• Sorting – Sort defect beans and uniform beans size. Particularly, black and fermented beans should be culled out (detail later)• Pre-heating – Before start roasting, warm up the container that confine coffee beans so that roasting profile can be consistent• Roasting – Roast beans up to decided roasting level (detail later)• Cooling – Cool down roasted beans immediately after finishing roasting to avoid from over-cooked beans• Resorting – Soring discolored and malformed beans• Recoding as numerical values in a profiling sheet should be done at every batches

Roast Profiling Table

Roasting• Roasting dose not require special skill, everyone can do• There are no royal method

• There are 3 major methods that are based on roasting timeshort-time roasting – 10℃/min raisingstandard roasting – 5℃/min raisinglong-time roasting – 2-3℃/min raising• Short-time roasting is good for acidity and rich flavor• Standard roasting is good for sweetness, medium acidity and flavor• Long-time roasting is good for tasting mildness and sweetness

Premises • The temperature to put beans in machine should be same every time• The volume for roasting should be same every time• The bottom temperature and duration up to bottom temperature after putting beans should be almost same• The temperature raising should be almost same every time• The timing of changing ventilation should be same• The temperature of beginning of cracks should be almost same• Roasting should be finished at the pre-decided roasting level•Write records as numerical values, temperature and gas pressure, every minutes

Short-time Roasting• Pre-heating should take around 15min up to 180℃• Close ventilation during pre-heating• Put beans into the drum at 180℃• Open 1/3 ventilation at the timing of putting beans• Control gas pressure after reached bottom temperature so that it will raise 10℃ in a minute• Open 2/3 ventilation immediate before the first crack• Open ventilation completely immediate before the second crack• Finish

Record the bottom temperature and duration up to it

Record the temperature of beginning and finishing of first and second crack

Standard Roasting• Pre-heating should take around 25min up to 180℃• Close ventilation during pre-heating• Put beans into the drum at 180℃• Open 1/3 ventilation at the timing of putting beans• Control gas pressure after reached bottom temperature so that it will raise 5℃ in a minute• Open 2/3 ventilation immediate before the first crack• Open ventilation completely immediate before the second crack• Finish

Record the bottom temperature and duration up to it

Record the temperature of beginning and finishing of first and second crack

Long-time Roasting• Pre-heating should take around 25min up to 180℃• Close ventilation during pre-heating• Put beans into the drum at 180℃• Open 1/3 ventilation at the timing of putting beans• Control gas pressure after reached bottom temperature so that it will raise 2-3℃ in a minute• Open 2/3 ventilation immediate before the first crack• Open ventilation completely immediate before the second crack• Finish

Record the bottom temperature and duration up to it

Record the temperature of beginning and finishing of first and second crack

Important Notices• Every before first batch, clean up the roaster to avoid fire• Understanding of bottom temperature and duration up to the

temperature is important• Being familiar with temperatures of beginning of 1st and 2nd crack

and finishing of 1st and 2nd crack is important• Understanding for duration of during 1st and 2nd crack and from end

of 1st and commencement of 2nd crack is important• Changing gas pressure cannot reflect immediately, it will take

around 0.5-1 minute• The temperature raising is fluctuating up to 6-7 minutes after

putting beans• Ambient temperature sometimes affect roasting

Relative humidity >70% - roasting speed will decreaseTemperature > 30℃ - roasting speed will increase• It should cool down the drum temperature up to 160-170℃ after

finishing then tune on fire to raise the temperature up to 180℃

Roasting Level• Cinnamon Roast – from immediate after starting the first crack to

during the first crack• Light Roast – from immediate after finishing the first crack to a

few tens of seconds after finishing the first crack• Medium Roast – immediate before the second crack• City, Full city – during the second crack, 10-80 seconds after

starting the second crack• French Roast – from last some tens of seconds of second crack to

immediate after finishing second crack• Italian Roast – a few tens of seconds after finishing second crack

Important Notices• There are no exact definitions for each roasting level• You can define each roasting level’s definitions that correlates to

your roasting method

Determination of roasting level• It should be tested by each roaster and determine what levels is good• The yardstick for test roasting is city or full cityTaste the coffee and evaluate it whether the roasting level should be lighter, stronger or as it is

• In general speaking, roasting level for Philippines arabica coffee is ranging from light to full city• It is not recommendable to roast up to italian level except the beans for iced coffee

Complements • Those roasting methods are just yardsticks. To create flavors and tastes, sometimes it is required to deviate from the yardsticke.g. changing roasting duration up to 1st crack changing temperature for putting beans• Products should be consistent always. The consistency is attributed　 or come down to numerical values: temperature and thermal power. Namely, it is recommendable to implement temperature and gas pressure gauge, if there were not installed• Roasting method for merchandisers should be inheritable to other staffs as numerical values not relies on senses or only experiences• Its not advisable to roast by a pan. It cause discoloration that is uncooked

Creating Flavors and Tastes • By changing roasting methods and roasting levels, creating flavors and tastes can be accomplished in same coffeee.g. blending different roasting level coffee with same coffeeLight roast and full city roast 1:1 ratio• How to create blends?Test different ratio blends. e.g. prepare 3 roasted coffee. Then brewed each by each. Make different ratio blends by using a spoon in other cups. Evaluate and determine what ratios are good.

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Creating Flavors and Tastes • The tastes or flavors should be compatible to local people or your targeting market, understanding local preference or buyer’s preference is important• Aside from be closer to consumer demand, it is also advisable to introduce new flavor tendency in the marketit will expand market volumeit should be based on certain reasons

e.g. light roast as specialty coffee with scored point, blend of light and city roast with description of flavor tendency, Italian roast blend for iced coffee

Pre-mix or After-mix• Pre-mix – mix beans for a blend before roasting• After-mix – mix beans for a blend after roasting• Once the ratio of the blend was fixed, roasters can consider pre-mix roasting, if the characters in roasting process was almost same each other• In CAR, it is advisable to pre-mix so that economize preparation time, if each blending parts was all arabica or all robusta in same postharvest method• The advantages of after-mix roasting is that can be prepared several kinds of coffee beans as blend partsIn the case of café, barista can make any kind of coffee flavor along customers’ preferences by blending each coffee as they ordered• it can reduce the amount of discarding of coffee beans after expired

Sorting• Roasted beans for merchandiser, it should be consistent and free from danger of health (e.g. mycotoxin - mold)• Ideally, roasted beans should be consistent in color and sizeIf the defect content was very high, the result, roasted coffee beans, would be inconsistent in color • Sorting can be done before and after roasting• After sorting, the sorted beans should be scaled for understanding the portion of defects and good beans. Usually, good beans are defined that has defects less that 10~15%

Black beans

Black beansCause• Lack of water during development of cherries• Over fermentation• Overripe cherries picked from the ground• Bas drying process or humidity on the beans

Description• Brown to black beans• Shrunken•Wrinkled• Flat faced• Crack too opened

Sour beans

Sour beanCauses• Delay in between coffee picking and depulping• Overextended fermentation process• Use of dirty water• Storage of beans with high moisture content

Description• Light brown to dark brown beans• Crack free of tegument• Silver skin can be reddish-brown

Mold bean

Mold beanCauses• Over fermentation• Long interruptions during drying process• Storage of beans with high moisture content

Description• Coffee beans infested by mold presenting yellowish or reddish spores

Faded - Streaked Bean

Faded - Streaked BeanDescription•Stained bean, showing an irregular greenish color

Causes•Usually due to uneven drying or re-wetting after drying

Faded - Oldish Bean

Faded - Oldish BeanDescription• Coffee beans with alterations in the normal color, white coffee beans, cream, yellow to brown

 Causes• Long time in storage• Storage in bad conditions (high temperature and humidity)

Faded - Amber or Buttery Bean

Faded - Amber or Buttery BeanDescription•Yellow, semi-transparent beans Causes•Iron deficiency in the soil

Faded - Over dried

Faded - Over driedDescription•Amber to yellow beans Causes•Excessive time in the dryer, or high temperature during drying

Broken - Pressed or Crushed Bean

Broken - Pressed or Crushed BeanDescription•Bruised beans with partial fractures Causes•Bruised beans during depulping, drying and milling process•Milling parchment with high moisture

Broken - Cut or Nipped bean

Broken - Cut or Nipped beanDescription•Cut or nipped bean and rusty

Causes•Bean broken by the depulping machine during wet process•Cherries harvested prior to maturity

Broken – chipped bean

Broken – chipped fragmentsDescription•Tiny fragments

Causes•Bean broken by the depulping machine during wet process•Bean broken by the hulling machine after drying

Immature bean

Immature beanDescription

• Green or light grey beans

• Beans tend to have a very adherent silver skin and  size smaller than normal

• Whither surface

• Smaller size than normal

• In this group low density beans are included 

Causes

• Cherries picked before ripeness.

• Cultivation in marginal zones for coffee production.

• Lack of fertilizer

• Beans affected by drought and rust disease

Insect damage

Insect damageDescription• Beans with small holes caused by insects. Causes• Attack on cherries by Hypothenemus haempei  (coffee berry borer)• Attack by Araecerus Fasciculatus during storage, due to inadequate storage conditions

Wet or Underdried Bean

Wet or Underdried BeanDescription•Beans with dark green color and soft texture

Causes•Bean with high humidity. Lack or incomplete drying

Malformed – shrunken bean

Malformed – shrunken beanDescription•Wrinkled bean

Causes•Beans affected by drought conditions•Lack of fertilization

malformed

malformedDescription•The beans that can not form completely

Cause•Genetic inheritance•Nutrient deficiency•Separated from shells

shell

shellDescription• Shell like shape•Non-content

Cause•Genetic inheritance•Nutrient deficiency• Climate factor

Dry cherry

Dry cherryDescription•Dried black cherry

Cause•Improper pulping in wet method•Improper hulling after drying

parchment

parchmentDescription•Whole parchment•Parchment fragments

Cause• Improper hulling• Improper sorting

Floater

FloaterDescription• The beans that can float on the surface of water• Light density• Color in whitish or yellowish

Cause• Improper storage and dying • Parchment coffee that was stored in excessive humid environment

Impurities

impuritiesDescription• From small to large stones• Sticks• Twigs• Others

Cause• Drying parchment or cherry on the ground directry• Drying on old patio• Improper sorting

Good configuration bean

Good configuration beanThank You Very Much