Is a preheating routine essential for coffee roasting?

Pavel Corena
November 11, 2022
Why is a preheating routine essential for coffee roasting?

Roasting is an essential part of unlocking the delightful aromas and exotic flavour notes within a coffee and defining the ideal cup profile. 

To develop a balanced and rich cup profile, there are many variables roasters must consider, as slight variations in the roasting process can alter the expected result. 

Therefore, consistency is key to maintaining high standards for product quality and satisfying consumer demand. 

While there are many actions roasters can implement in their processes to maintain consistency, one of the most effective is a preheating routine. 

Some roasters neglect to preheat the roasting equipment, which often results in them having to throw out the first batch of the day. However, preheating allows for better consistency when charging the roaster with green coffee and can help ensure consistency throughout the subsequent batches.

Read on to find out why a preheating routine is essential in coffee roasting, and how roasters can implement the ideal process. 

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An image of a coffee roaster implementing a preheating routine for the roaster in an article on why a preheating routine is essential for coffee roasting

Why is it essential practice to preheat the roaster?

Finding the perfect roast profile and maintaining an equilibrium between acidity, body, and sweetness can be challenging. 

By implementing a preheating routine, roasters can gain more control over the temperature and time of the roasting process. 

Additionally, this can help roasters reduce the risk of roast defects, such as scorching and tipping. Roast defects can impact the cup profile, affect the intensity or body of the coffee, and create unpalatable tasting notes.

Scorching refers to black or burnt spots on the flat side of the coffee bean. This happens when one side of the bean sits against the side of the drum for too long, or the charge temperature is too high. 

Scorched coffee often adds smoky, oily, or ashy bitter notes to the cup. 

Tipping is another common defect and is similar to scorching. Tipping is commonly caused when the coffee is heated too rapidly.

For instance, it occurs when the differential temperature between the green coffee and the drum is too high. This causes the moisture inside the bean to escape from the weakest structural point, which is usually the tip of the bean.

An image of a specialty coffee cupping session with coffee brewed in a chemex in an article on why a preheating routine is essential for coffee roasting

What are the key objectives of preheating the roaster?

Essentially, a preheating routine consists of warming up the roaster before charging the first batch of green beans. 

It should be common practice among roasters, as many variables can affect the roast process, such as location or season. These factors may cause the temperature of the roasting equipment to fluctuate. 

Applying a preheating routine can help roasters to control the temperature of the roaster and guarantee consistency.

There are two primary goals to achieve in a preheating routine: to store thermal energy and ensure it is evenly spread throughout the roaster. 

That said, many variables can affect the storage of thermal energy within the roaster. These include the ambient temperature, airflow, speed of the drum, and humidity, all of which can alter the result of the roast.

By standardising daily activities, such as a preheating routine, roasters can gain more control over these variables and ensure consistency in the final product. 

An image of coffee roasters preparing to preheat the coffee roaster at a coffee roastery in an article on why a preheating routine is essential for coffee roasting

How to implement an efficient preheating routine 

It is important to note that there are no golden rules to developing a preheating routine. 

To implement a preheating routine that works for the roastery, roasters must ensure they understand their equipment. 

For example, the bigger the roaster is, the more time it will need in order to reach a specific temperature. Depending on the equipment, there are several ways to accomplish a full preheat.

The first option is to allow the roasters burner to idle at a fixed gas percentage until the target charge temperature is reached. Depending on the size of the machine, this could range from 10 to 15 minutes. 

Another option is to overshoot the target charge temperature, flush the excess heat, and then back off until the target is reached again. 

It is possible to do this process more than once to ensure the thermal energy spreads evenly within the roaster. 

For roasters, it’s important to understand how changes in charge temperature can influence their roast. A good understanding can help improve consistency and ensure each batch delivers its full potential.

Once roasters have mastered charge temperature, the next step is to preserve the freshness of the roast coffee. For this, they will need high-quality bags with good barrier properties.

An image of a line of multilayer LDPE coffee bags with resealable zippers and PLA linings as sustainable coffee packaging for roast coffee in an article on why a preheating routine is essential for coffee roasting

Roast coffee has four age-old enemies: oxygen, moisture, heat, and light. While it should be given some time to “breathe” after roasting, long-term exposure to any one of these external factors will quickly cause it to lose freshness and become stale.

Today, flexible multilayer pouches have significantly extended the shelf life of coffee. Sturdy, versatile, and high barrier, they prevent exposure to external factors and protect the coffee on the journey between roastery and consumer.

However, not all specialty roasters will require the exact same packaging. The design and components of coffee pouches will largely depend on the way in which roasters plan to sell their coffee.

For example, those who plan to sell through supermarkets and grocery stores will need to factor in the relatively long period the coffee will sit on the shelf. Unlike coffee sold directly from the roaster to the consumer, it can take weeks, if not months, for the coffee to be bought and brewed.

At MTPak Coffee, we offer a range of 100% recyclable coffee packaging options made from renewable materials such as kraft paper, rice paper, or multilayer LDPE packaging with an environmentally friendly PLA lining, all of which minimise waste and contribute to a circular economy.

More so, we give our roasters complete control over the design process by allowing them to build their own coffee bags

Our design team is available to help you create the ideal coffee packaging. Plus, we are able to custom-print coffee bags using innovative digital printing technology, with a quick turnaround time of 40-hours and 24-hour shipping time. 

MTPak Coffee also offers low minimum order quantities (MOQs) to micro-roasters who are looking to remain agile while showcasing brand identity and a commitment to the environment.

For more information on sustainable coffee packaging, contact our team. 

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