Exploring coffee chemistry and a roadmap to purposeful profiling

John Laird

Nordic Roaster Forum November 8, 2013

Purpose To develop a greater understanding of the

relationship between our roasting systems, our coffees, and the chemical and physical changes that occur during the roasting process.

To understand the relationship of roast progression at specific periods during the roasting process and the effects on the roasted coffees

To translate this to intentional proactive profiling and greater control over the outcome of our roasts.

Think Differrently.

Profiling?

What do we mean by the term Profiling? Profiling is a description of the inputs and results of

our process. A plan for controlling the development path of our

roasts. A method of ensuring consistency of our roasts. Timing is everything

Our Role as a Roaster

Understanding our customers. Understanding our product. Develop our stylistic approach. What are our objectives? Filter coffee / Espresso Roast delicious tasting coffee. There is no such thing as a perfect roast. As soon as we decide that we’ve got it all figured out

is the time that we stop learning.

Coffee Terminology Acidity. Acidity is the essential quality of coffee that that

can be either over or underwhelming, but when crafted into a balanced roast often defines the overall character of a coffee.

Acidity can be used to describe both the actual chemical acidy present in the coffee or to describe the perception of the remaining transformed acids that more clearly fit with the term perceived acidity.

Coffee Terminology

Aroma. Aromas are the sensations perceived through our sense of smell which also contribute greatly to the perceived flavors of brewed coffees. Aromatics released during the roasting process can range from dry grass or hay, to caramel or buttery during the various stages of the roast.

Coffee Terminology

Body. Body is a physical sensation that refers to the perception of weigh on the palate or “mouthfeel”. Body can be an inherent quality of a particular coffee as well as a roast induced characteristic.

Balance. That point in a roast where the favorable characteristics of the cup are harmonious to each other. An aggressively acidic low body coffee, or a flat dull and heavy bodied coffee that would be considered unbalanced however could possibly be considered enjoyable by some.

Roasting - Terminology Air Flow: Refers to the total volume of air passing through

the roasting chamber measured as standard air at ambient temperature. US measure is cubic feet per minute ( ft3/min) and metric is cubic meter per hour (m3/hour).

Bean Temperature: Refers to the temperature recorded by a thermocouple or RTD which is immersed in a steady stream of coffee contained in the roasting chamber. Bean temperature measurements vary widely depending on probe placement and are different from machine to machine.

Roasting Terminology Cont’d

Charge Temperature: Is the temperature of the roasting chamber immediately prior to releasing the green coffee in to the roasting drum at the start of the roast.

Drop Temperature: Is the temperature recorded by the bean probe at the termination of the roast.

Environment Temperature: Refers to the temperature of the air exiting the roasting chamber after has transferred its heat energy to the roasting coffee.

Roasting Terminology Cont’d

Rate of Rise: The rate of temperature rise of the bean mass, usually expressed in degrees per minute.

Roast Development Time: The period of time the roast continues from the start of first crack until the completion of the roast.

Roasting Systems

Purpose of a Coffee Roasting System Various Types of Roasting Equipment Impact on Profile Description Understand relationship between Environment temp

and bean temp. Coffee temperature / heat capacity.

Probat -Single Pass

Probat Recirculating

Carbohydrates

Carbohydrates – (Sugars) Monosaccharides Ogliosaccharides Polysaccharides

Simple Sugars Necessary component of Maillard reaction.

Melting point:160C -200C range,(320-392F)

Proteins

Account for roughly 10 to 13% of coffee’s dry weight Amino acids that are a necessary component in

producing Maillard reaction. Critical for development of : Color Aroma Flavor

Chlorogenic Acids

Chlorogenic acids are the large family of esterified compounds present in green and roasted coffee. During roasting, CGA's slowly decompose to form caffeic and quinic acid. Roughly 50% of the original CGA will decompose in a medium roast

Make up 7% of dry weight of green coffee. Degrade as roast progresses. Total concentration of acids degrade from 1.6% at a

light roast to 0.71% in dark roasts.

Quinic Acid

Quinic acid along with citric and malic represent a significant portion of coffee's total acid content. During roasting quinic acid progressively increases as the levels of chlorogenic acid decrease

Increases as roast progresses

Citric Acid

During roasting, citric acid reaches a maximum at light to medium roasts then quickly diminishes as roasting levels progress. A typical medium roast will lose about 50% of its initial citric acid concentration and with progressive destruction in latter stages of roasting progresses. Boiling pt.153oC (307oF)

Increases initially then rapidly decreases as roast progresses

Maillard Reaction

The primary Browning reaction of many cooked foods.

Results from a chemical reaction between an amino acid and a reducing sugar.

Reaction promoted by heating, Virtually no amino acids remain after 5 minutes at

220˚C (428 ˚C) Occurs in the presence of melted sugars 160C -

200C range,(320-392F)

Carmelization

An entirely different process from Maillard browning. Results are sometimes similar Visually and taste. Caramelization may sometimes cause browning in

the same foods in which the Maillard reaction occurs.

They both are promoted by heating Caramelization is basically the pyrolysis of certain

sugars.

Proactive Profiling

So what does all of this mean? Consider your objectives. Know your green - Sample roasting Importance of the Rate of rise Hit your targets Roast development time End of roast Timing is everything Think outside the box - Interpolation

Costa Rica – PR-0024

Costa Rica – PR-0025

Costa Rica – PR-0026

Costa Rica – PR-0027

Kenya – PR-0028

Kenya – PR-0029

Kenya – PR-0030

Kenya – PR-0031

Costa Rica – Roast Defect

Kenya – Overlay