Sourcing and buying green coffee is certainly a big part of this, but efficient inventory management is also paramount. When stored and used improperly, green coffee will quickly lose its freshness, and thereby its quality as well.

However, with many medium or larger-sized roasters often having anywhere up to a year’s supply of green coffee, how can they manage their inventories as effectively as possible?

To find out, I spoke with Giorgio Mosca, the Export Manager at IMF Roasters. Read on for more of his insight.

You may also like our article on how coffee roasters can design an appealing and efficient roasting space.

Why is preserving coffee freshness and quality so important?

Many coffee professionals often talk about coffee freshness in terms of roasted coffee – and rightly so.

The roasting process (essentially applying high temperatures to green coffee) causes a great number of chemical reactions. These reactions then create irreversible changes within the cell structure of the coffee beans – helping to develop flavours and aromas.

Roasting also enables us to grind and brew coffee as the beans become more brittle. However, at the same time, roasting makes coffee a much less stable product. Green coffee can stay fresh for between six months and one year after harvest. Roasted coffee, however, only remains fresh for a matter of weeks.

Once roasted, coffee is more susceptible to a number of environmental factors, such as heat, light, moisture, and oxygen. Ultimately, when exposed to these variables for a significant amount of time, coffee loses its distinctive flavours and aromas more quickly. Eventually, it will taste stale and flat.

Green coffee freshness

However, despite having a longer shelf life, we also need to remember that green coffee can lose its freshness, too. Prolonged exposure to oxygen, water, and extreme temperatures will have adverse effects on green coffee quality and freshness. 

“During roasting, the moisture content of green coffee beans will influence the chemical reactions, and therefore the formation of flavour,” Giorgio tells me.

According to the International Coffee Organisation, the ideal moisture content for green coffee is between 8% and 12.5%. In turn, if the moisture content was to fall outside of this range, roasters wouldn’t be able to get the best out of their coffee.

Moreover, green coffee freshness can depend on a number of other factors. Some of these include:

• Origin country
• Harvest date
• Variety
• Processing method
• Bean density

In line with this, roasters need to ensure they store their green coffee in dry, cool conditions to best preserve freshness and quality.

Avoiding and mitigating contamination

Not only is preserving green coffee freshness vital for roasters, but maintaining the integrity of green coffee is equally important.

“It’s essential to prevent green coffee from becoming contaminated in the same way as any food product,” Giorgio says. “You need to store green coffee away from excessive humidity and extreme temperatures to avoid the formation of fungi or moulds, as well as to not attract any insects or pests.”

According to European Union regulations, the roasting process is considered a “kill step”. This is a term used in the food safety industry to describe the point where dangerous pathogens and microorganisms are removed from the product. However, it is still possible for green coffee to become contaminated in other ways, which can have a negative impact on quality. What’s more, it could have harmful effects on consumers.

Food safety regulations vary from country to country, so it’s important for roasters to check which ones apply to them. Water activity in green coffee should remain between 0.5% and 0.7% aw (a measurement of vapour pressure between the food product and the vapour pressure of distilled water) in line with food safety protocols.

It should be noted that many food safety laws and requirements fall within the responsibility of green coffee importers and exporters. However, roasters also have a duty to make sure their green coffee is free from contaminants before it arrives at their roastery using a set of quality control checks. Moreover, roasters are also responsible for food safety while the green coffee is in storage, and beyond.

What equipment do roasters need to preserve green coffee freshness & quality?

First and foremost, upon arriving at the roastery, specialty coffee roasters have to ensure their green coffee is fresh and of a certain quality. Checking for any primary and secondary defects is also important, which can include:

• Broken beans
• Black beans
• Signs of pest infestations
• Presence of mould
• Physical contaminants, such as stones or small sticks

“For roasters, it’s crucial that green coffee meets their desired quality standards, especially to maintain consistency throughout the roasting process and in the final product,” Giorgio explains.

Secondly, roasters need to make sure they store their green coffee in optimal environmental conditions. 

For example, to maintain a green coffee moisture level of 8% to 12.5%, a roastery’s storage space should have between 60% and 65% humidity level, with a temperature range of 15°C to 25°C (59°F to 77°F). In order to do this, roasters can invest in a well-designed ventilation system.

In terms of storage equipment, green coffee silos are a popular solution for many roasters. These are specially-designed storage containers which are available in different shapes and sizes. Some silos are polygonal-shaped, while others are circular.

“IMF’s silos help to preserve freshness and quality by preventing green coffee from coming into contact with moisture and oxygen,” Giorgio says. “This way, roasters can protect green coffee from excessive humidity to maintain its inherent organoleptic qualities.”

He also adds that alongside storage solutions, IMF also provides equipment for roasters to precisely measure a number of environmental factors, such as humidity and exposure to light.

How do specialty roasters manage their stock?

As well as investing in the right equipment, roasters also need to use proper techniques for green coffee inventory management.

Most roasters use a “first in, first out” (FIFO) system for storing and roasting green coffee. This involves roasting coffee in line with when it first arrived at the roastery, while also ensuring all orders stay on track and are fulfilled.

For instance, if a roaster receives a new batch of Colombian coffee from an exporter or importer, they first need to roast any Colombian beans which predate this new batch. As a result, roasters will minimise waste and make sure that the older batch of coffee doesn’t stale and taste flat.

Storing green coffee in silos can assist with the FIFO method, as they are typically designed to dispense coffee beans to be transported to the roaster.

However, prior to roasting, green coffee must be cleaned and sorted. These processes help to remove any defected beans or contaminants.

“IMF’s cleaning and sorting machines remove contaminants based on size or weight, such as twigs, stones, dust, and materials from green coffee packaging,” Giorgio explains. “We also provide optical sorting machines which use infrared refraction and multispectral cameras to recognise any foreign objects based on colour and shape which aren’t visible to the naked eye.”

Ultimately, cleaning and sorting systems ensure that green coffee – and thereby roasted coffee – are consistently free from contaminants and impurities.

What are the benefits of managing green coffee supplies effectively?

Firstly, it’s important to point out that roasters are obliged to follow food safety regulations, and should therefore always make sure their coffee is free from contaminants and debris.

However, alongside this, many specialty roasters pay high prices for green coffee, so they need to maintain and preserve the quality of their products as much as possible. That way, the end consumer will experience the full range of the coffee’s flavours and aromas – building trust and brand loyalty.

A large part of this lies with consistency. Let’s say a customer orders a bag of Kenyan coffee, and then orders the same coffee again three months later. The customer naturally expects the coffee to taste similar, so proper storage and inventory management is essential to this.

Moreover, if a roaster fails to store green coffee correctly, it can undo the hard work of producers and exporters who have helped to maintain coffee quality throughout the supply chain. Similarly, the coffee will lose its unique characteristics, and may even drop a few points on the Specialty Coffee Association’s 100-point quality scale.

Reducing waste and labour

Finally, proper green coffee inventory management helps roasters to minimise waste, and thereby costs – improving the efficiency of their business.

“IMF offers customisable solutions which help roasters manage their green coffee effectively,” Giorgio says. “We design storage and dosing systems which optimise both space and workflow.

“Our automated systems also help to minimise labour, while the centralised filtration system ensures a cleaner and safer workplace,” he adds.

For any roaster to be successful, proper green coffee inventory management systems are crucial. Without these methods in place, green coffee can quickly become old, stale, or even contaminated.

To ensure that they are always selling high-quality coffee, roasters need to invest in the right storage equipment and implement a set of reliable and consistent stock management techniques. 

Enjoyed this? Then read our article on how heat retention & recirculation can help specialty coffee roasters to improve efficiency.

Photo credits: IMF Roasters

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When it comes to machines, this is especially true – particularly those which include heat retention and recirculation technology. Not only can these systems help to reduce energy consumption, and thereby decrease costs, they can also help to cut emissions.

Moreover, given that demand for sustainable coffee is only growing, it’s vital that roasters pay closer attention to their environmental impact.

To learn more about how heat retention and recirculation in coffee roasting work, as well as the benefits of these systems, I spoke to Alessandro Garbin, the CEO of IMF Roasters. Read on for more of his insight.

You may also like our article on how you can reduce emissions during coffee roasting.

What are heat recirculation and retention in coffee roasting?

Before we discuss how heat recirculation and retention work, we first need to look at the types of heat transfer in coffee roasting.

There are two types of heat transfer when roasting coffee:

• Conductive heat transfer: this is when heat transfers between two objects that are in direct contact. For example, when a coffee bean touches the surface of the roaster drum or another bean.
• Convective heat transfer: this happens when heat transfers through liquid or gas. This type of heat transfer can be natural or intentional.
  • Natural: hot air will rise to the top of the roaster drum
  • Intentional: using a fan or pump to force cool air into the roaster drum

Radiation heat transfer is also used in coffee roasting. This is when heat is released as a result of the vibrational and rotational movements of molecules and atoms. This means it’s almost impossible for roasters to control this type of heat transfer.

Conductive heat transfer also isn’t as prominent in coffee roasting as convective heat transfer. As such, it’s key for roasters to efficiently control it.

As well as utilising some kind of heat source (usually either gas or electric), most roasters have an in-built fan or pump. When in operation, both of these systems work to continuously intake air and heat it to roast coffee. A roaster’s ventilation system will then remove the smoke and waste gases from the machine.

Heat recirculation systems

Alessandro explains what heat recirculation is in the context of coffee roasting.

“Machines reuse air which has already been used to roast coffee,” he says. “After the air is cleaned using high temperatures, it can be used again inside the drum or roasting chamber.”

A roaster’s heat source and ventilation system are constantly working in unison. This means that air is continuously heated and reheated throughout the roasting process.

However, for roasters which come with recirculation systems, they can reuse hot air. To achieve this, the recirculator removes waste products – such as exhaust gases, chaff, and smoke – before returning the hot air to the drum or roasting chamber.

Some roasters also come equipped with more than one heat recirculation system, which can provide a number of benefits.

IMF’s Vortex system works by mixing ambient air with hot recirculated air before it enters the drum or roasting chamber. 

“The temperature of the air which needs to be recycled and reused from the drum or roasting chamber can often become too high,” Alessandro says. “The Vortex system then mixes this hot air with fresh, cooler air so that it reaches the optimal temperature for the required roast profile.”

Meanwhile, the Equaliser system maintains the same volume of hot air both inside the drum and surrounding its surface. This helps to distribute heat more evenly.

“IMF’s Equaliser system ensures a more uniform heat transfer to every coffee bean so that roasters can achieve a more even and homogenous roast profile,” Alessandro explains.

Why is heat circulation so important for roasters?

To maximise profitability, there are many factors that roasters need to consider. Among these are cost management and retaining customers by ensuring your roasted coffee is consistently high in quality.

Heat circulation systems can allow roasters to effectively manage both of these factors.

Many older machines tend to include an afterburner, which purifies air by heating it up to very high temperatures. However, while afterburners do help to reduce emissions, they also require gas to run.

For many roasters, increasing gas usage to reduce emissions is not always cost-effective. However, heat recirculation systems don’t rely on gas – meaning roasters can lower both their environmental impact and energy costs.

“Heat recirculation technology can help to make sure that emissions from roasting fall within the limits imposed by current regulations, [although this depends on where you are located],” Alessandro says. “You also don’t need to integrate any additional abatement systems, such as thermal systems or catalytic converters.”

It’s an understatement to say that demand for more sustainable coffee is increasing – especially among younger generations. This statement rings true across the entire supply chain, including with roasting.

“IMF roasters include a double-function heating chamber which recycles used hot air and heats it to very high temperatures,” Alessandro explains. “This way, when some of the air is emitted into the atmosphere, it’s already clean, while the rest can be reused during the roasting process.

“Moreover, this means the volume of air emitted from IMF’s roasters is lower – [maximising heat recirculation and reducing gas consumption up to 47%],” he adds.

How does heat retention affect day-to-day operations?

First and foremost, as conduction and convection are the two main types of heat transfer, recirculation systems help to make sure that heat distributes more evenly in the drum or roasting chamber. 

If heat is distributed unevenly, this can lead to a number of issues for roasters. One of the biggest concerns would be uneven roast profiles. This is when some beans are underdeveloped and others are burned or scorched. Not only does this create an inconsistent product, it will also significantly impact the flavour and quality of coffee.

“Not all heat recirculation systems guarantee a constant air temperature during roasting,” Alessandro says. “High-quality roasters like IMF ensure a consistent temperature by incorporating fresh air into the drum or chamber, which allows for greater thermal stability.”

Improving consistency

Furthermore, as machines become progressively hotter throughout the day, some roasters find it difficult to maintain consistency between batches. With better heat retention systems, temperature variance between roasts will decrease, which inevitably improves roast profile consistency.

Alongside maintaining coffee quality, heat recirculation systems can help to reduce costs in the long term. When lower volumes of air are reheated, roasters are able to reduce their energy usage, thereby reducing energy costs and lowering their carbon footprint at the same time.

Finally, Alessandro offers advice on how to make sure heat recirculation and retention systems keep running efficiently in your roaster.

“As with any roaster, it is recommended to regularly clean and maintain your machine so that it lasts for a longer time,” he concludes.

For any roaster looking to become more energy-efficient, it’s clear that investing in a high-quality roaster is key. However, managing costs and keeping emissions down will become easier if roasters keep an eye on heat retention and recirculation technology.

In doing so, roasters will be able to manage their energy consumption much more effectively. In turn, they are likely to experience a decrease in their costs, as well as their environmental impact – both of which are more important than ever before.

Enjoyed this? Then read our article on how coffee roasters can design an appealing and efficient roasting space.

Photo credits: IMF Roasters, Better Days Coffee Company

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But alongside this, roasters also need to make sure all their coffee stays fresh – no matter how many they are selling at any given time. To do this, they need to carefully manage and rotate their stock of green coffee.

Although stock rotation can be challenging, there are several ways in which roasters can do this effectively, sustainably, and profitably. To find out more, I spoke to Richard Sandlin, Director of Business Development at Royal Coffee. Read on for more of his insight.

You may also like our article on whether you can freeze green coffee.

Why do specialty coffee roasters need to rotate their beans?

In simple terms, green coffee rotation is done in two ways:

• When roasters sell previous harvests of a particular coffee to customers and then purchase a new harvest of the same coffee.
• When roasters sell a previous harvest of a particular coffee to customers and then buy a new harvest which currently isn’t on their menu.

“It’s mainly about ‘first in, first out’,” Richard says. This is when coffees which were bought first need to be sold first to make sure that stock stays as fresh as possible, but it is often more complicated than this.

“Buying green coffee isn’t as simple as buying 60kg bags or lots,” he explains. “Coffee is a seasonal product – it’s harvested at different times around the world, it ships at different times, and arrives at different times. 

“Because of coffee’s inherent seasonality, I always encourage roasters to equally consider three key pillars: price, availability, and quality,” Richard adds. “When one of these three pillars moves in a more drastic direction, sourcing the right coffee for your needs can be more difficult, so rotating your coffee and thinking more strategically can be the perfect solution.”

Preserving freshness

In order for customers to experience the full spectrum of the flavours in coffee, it must be fresh, so it’s important to rotate them. This is because as coffee ages, it oxidises and becomes stale, thereby losing its flavours and aromas.

Roasted coffee is much more susceptible to staling than green coffee as the roasting process causes a number of irreversible changes in the beans’ cell structure. However, green coffee can still age and lose its freshness, so roasters need to also take this into consideration.

Generally speaking, green coffee stays fresh for six to 12 months, so roasters should purchase coffee with this in mind.

“In a perfect world, a roaster’s coffee will arrive in an importer’s warehouse about one to three months before they need it,” Richard says. “Moreover, roasters ideally contract or buy enough green coffee to last them between three and six months.

“Rotating your green coffee efficiently ensures that you always have access to the freshest coffee, without buying 12 months of coffee upfront,” he adds.

Inventory management

Whatever size a roaster may be, stock management is an essential part of operating a business as effectively as possible.

Ultimately, roasters need to understand how much storage space is available before purchasing larger volumes of coffee. Furthermore, roasters must also be aware of which green coffee needs to be roasted first so that they can sell it sooner rather than later.

Richard, meanwhile, tells me that managing stock is also about much more than storage space.

“You need to know how to look for core coffees that are dependable,” he says. “For example, you can buy coffees from Honduras, Guatemala, Peru, and Colombia almost year-round to create a consistent profile for your blends.

“It’s best to focus on flavour first and origin second,” he adds. “This allows roasters more room to manage not only their inventory, but also their cash flow.

“For this particular reason, Royal Coffee launched the Royal Gem collection – 50lb (around 22.6kg) boxes of green coffee curated by our expert traders,” he continues. “Our goal with this collection is to help streamline green coffee buying and logistics to make it easier for roasters to scale their businesses by offering reliable, affordable, and delicious coffees.”   

Variety

Maintaining coffee freshness and selling a variety of different lots at the same time can often be something of a balancing act. Today’s specialty coffee drinkers expect a range of origins, varieties, processing methods, and roast profiles.

While blends are an essential part of many roasters’ offerings, single origins are also popular.

“Single origins can allow roasters to be more flexible,” Richard says. “Your single origin range can be as broad as you want it to be.”

As part of this, some roasters choose to sell much smaller quantities of coffee – including micro and nano lots. These lots can often be unique selling points for roasters as they tend to have much more distinct and complex sensory profiles.

“Royal Coffee’s Crown Jewels are process and variety-specific, micro-milled lots which are chosen specifically to sell as top-shelf offerings,” Richard says. “Each Crown Jewel lot comes with a five-part analysis which explains the producer’s story, specifications about the coffee, and a range of optimal roast profiles and brew methods, as well as cupping notes from our team.”

Micro and nano lots are available in much smaller quantities than most coffees. In turn, roasters can sell them more quickly, which not only creates a more exclusive and limited-edition product, but means that roasters can manage their stock and rotate coffee more efficiently.

How should roasters rotate their specialty coffee?

When it comes to roastery management and green coffee rotation, there can be many challenges and risks. However, there are also several ways which roasters can overcome any potential issues.

Buy smaller volumes of coffee

Although larger roasters will still need to purchase significant volumes of coffee to keep up with demand, smaller lots can help them to stay flexible. This is because they will sell – and in turn can be rotated – more quickly.

“Roasters should develop their own monthly usage calculator to understand more about their menu slots,” Richard explains. “For example, at any one time, a roaster could have three single origins, two blends, a decaf option, and then a ‘roaster’s choice’ coffee.

“Once you have more of a grasp of how much of these coffees you need every month, you can then calculate the number of full-size bags that you have to buy for any given period, as well as any 22lb (around 10kg) Crown Jewel boxes or 50lb Royal Gem boxes,” he adds.

Balance costs

For any coffee business, knowing how to manage costs is vitally important. However, roasters also need to sell coffees which will be popular with a broad range of consumers, which also means offering a broad spectrum of quality.

“For most roasters, it’s far easier to build a business on buying US $3 to $6/lb coffees than US $8 to $12/lb coffees,” Richard tells me. “If you compare quality and cost, roasters typically sell much more mid-tier priced coffee than more expensive coffee.

“However, there are also times when roasters need to buy more top-quality coffee, like Geshas or experimental processed coffees, but this is typically the exception rather than the norm,” he adds.

Packaging

When it comes to green coffee rotation, Richard explains that another important factor which can often be missed is packaging. 

With the increasing need to stand out from competitors, packaging design has become more of a focus for roasters and consumers. However, roasters still need to be mindful of how much packaging they are ordering for particular coffees.

“The more flexibility you have with your packaging, the better your ability will be to rotate your coffee,” he says. “In turn, you can then sell the freshest possible coffees.”

Purchasing packaging with lower minimum order quantities and shorter lead times can help roasters to keep on top of their stock. Moreover, doing so can also make sure roasters are managing their costs more effectively.

What are the benefits of rotating coffee?

It’s clear that when roasters rotate their coffee on a regular basis, there are a number of advantages.

Menu curation

As part of remaining competitive, every roaster needs to develop their own unique menu, while also making sure they can balance costs and remain profitable.

Moreover, a roaster’s offerings need to cater to a wide range of consumers. These include preferences for more traditional flavour profiles to people who are interested in more complex-tasting coffees.

“Many roasters look to the higher-end coffees, such as Royal Coffee’s Crown Jewels, as marketing opportunities to push the boundaries of quality,” Richard tells me. “This can pay dividends because even though these coffees are less profitable per pound, they still gauge a lot of interest from customers and wholesalers.

“Conversely, however, the more flexibility you have with your menu, the easier it will be to move coffees which perhaps aren’t as fresh,” he adds. “Even if you predominantly focus on single origins, having one or two core blends is critical to selling older coffees.

“What might taste a little older to one roaster might be in the sweet spot for another, so there isn’t one general rule of thumb to follow,” Richard continues. “Understanding your quality control process is the best place to start – the more you know your coffee, the easier it will be to catch when it is starting to taste less fresh.”

Creating more consistency for customers

For some roasters, rotating coffees can pose some risk – especially when it comes to maintaining consistent sensory profiles. This can be particularly apparent with blends, which customers often rely on for more dependable flavours.

“Coffee rotation is about thinking more strategically, diversifying your needs, and finding coffees that can wear multiple hats on your menu,” Richard explains.

“For example, honey processed Honduran coffees aren’t available all year round,” he adds. “However, honey processed coffees – or coffees which have similar flavour profiles – from other Central American countries are.

“Basing some portion of your business around blends, in tandem with single origins, means you can have something for everyone,” Richard continues.

To run a successful and sustainable roastery, stock management is clearly an important factor. However, it’s also clear that rotating coffees in a regular, structured manner is a key part of this.

“There’s no need to reinvent your entire menu every month, but rotating new items in and out every few months keeps your offerings fresh and allows you to change with the seasons,” Richard concludes. “Source and contract coffee with the seasons, which guarantees freshness while keeping a healthier cash flow.”

Enjoyed this? Then read our article on how much green coffee you should order for your roastery.

Photo credits: Royal Coffee

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