Coffee roasting is a complex process which can be affected by many variables that lead to a wide range of taste spectrum.
This is why consistency is key to coffee roasting. The ability to produce a quality cup of coffee that’s full of flavour and aroma is important for coffee roasters to keep customers happy and to ensure success and growth.
One way you can maintain consistency is through quality control. Essentially, quality control refers to the process through which a business seeks to ensure product quality is maintained or improved.
In the second part of our Quality Control series, we speak to Arran Stein, the coffee programme manager at Grumpy Mule Coffee.
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What does quality control mean for Grumpy Mule?
Based in Meltham, Yorkshire, in the UK, Grumpy Mule has a large scale of production that includes an extensive portfolio of large white-label clients.
Additionally, Grumpy Mule coffee features on supermarket shelves across the UK. The roastery purchases large amounts of green coffee on contract and depends on strict quality control for brand reputation and maintaining trusting relationships with clients.
“Quality control ensures the hard work by producers at origin, importers, and roasters is respected” explains Arran, who is also AST certified.
The wall of the roastery features five core values, which Arran says he lives by. One of the values reminds the team to “never forget where it came from”.
Aaron says this value can refer to both people and products, whether it be the roasting equipment or the green coffee.
“We need to ensure everything receives the respect it deserves,” he explains. “This is a core value of our daily quality control. We respect the producers’ work and the coffee itself by doing our utmost to ensure it is of the quality it deserves to be.
“If we aren’t doing this, I honestly believe we would be in the wrong line of work,” Arran says.
The team at Grumpy Mule performs quality control checks at various points, such as when they receive a sample, pre-shipment of the green coffee, for every call of arrival into the roastery, during new product development, and throughout every production run.
“Every Monday through Friday, we ‘production’ cup and highlight any slight problem on a spreadsheet for future reference,” Arran explains.
“It is time-consuming but vital to ensure consistency,” he adds. “Every roast that is done is captured, so we can refer back to it if needed.”
All the green coffee that arrives at the roastery undergoes the same checks. The beans are inspected for any defects and then moisture content and density are checked.
Then a sample roast is done, and the coffee is cupped. Arran explains the results of the cupping are logged into an online spreadsheet for future reference.
He adds they test several bowls of each green coffee to ensure consistency, even if the coffee is guaranteed specialty grade and has gone through rigorous checks with producers and importers.
“We spend a long time on quality control for new product development. We test numerous roast profiles for each coffee to ensure we are highlighting it at its natural best,” Aaron says.

Quality control for white-label coffees
When it comes to roasting white-labels coffees or those destined for sale at a local supermarket, Arran reveals the quality control standards are the same.
“Everything we do goes through the same rigorous process to ensure the final quality of the product,” he says. “Any slight issue can damage a brand, so we need to ensure consistency, especially when reaching such a wide audience.”
When roasting for white-label customers, Arran says they create various profiles. “They select one and trust us to ensure it is repeated accurately. This is why we log every single roast, from colour to end temperatures and end time.
“Even the slightest variance from the target is brought to our attention and cupped as a priority to ensure it is right for the customer,” he adds.
Should a customer ever have a complaint about a product, Grumpy Mule is able to refer back to the roast using the spreadsheets. This way, the team can ensure no minor issues were found.
“Then we get the order number, as one is printed on every bag, so we can find the batch and test it ourselves,” Arran explains.
Arran adds that any complaints are usually due to a misunderstanding around the recipe or “strength” of a coffee. “We work directly with our customers to help them and ensure they are happy with any future purchases,” Arran says.
Furthermore, any complaint Grumpy Mule receives is logged by their Quality Assurance team and discussed during the year-end meeting to ensure there are no recurring themes.

“Quality control is a sign of respect towards coffee.”
As Grumpy Mule Coffee has collected 31 Great Taste Awards over the past five years, it is clear the system of quality control the team has implemented works.
“To us, quality control is a sign of respect towards coffee and the people behind it,” Arran explains.
As a large part of quality control within the roastery is cupping skill and consistent training, the team regularly tests themselves to ensure they are doing their best.
For instance, Grumpy Mule has had four team members compete at the SCA UK Cup Tasters Competition. These team members all came from different departments, such as buying, training, quality assurance, and sales.
“We continually get other departments involved in cuppings. Often, we will call on others to taste a coffee to see if anyone detects any issues or defects. We aim to build up that knowledge and reference that is vital for consistent quality control,” Arran adds.
Grumpy Mule is certainly inspiring with its drive to develop the team’s skills and better its products.
Having standardised methods in place and a passionate team, alongside procedures to record findings, can give roasters a foundation for building longevity with customers and improving the quality of the product.

A final consideration when it comes to quality control is packaging materials. They should be of the highest quality to ensure the coffee is kept fresh and retains flavour.
At MTPak Coffee, our range of sustainable coffee packaging options is made from renewable materials such as kraft paper, rice paper, or multilayer LDPE packaging that comes with an environmentally friendly PLA lining.
We also give our clients complete control over the design process by allowing them to build their own coffee bags. Our design team is available to help create the ideal look for any type of coffee packaging. Plus, we offer a quick turnaround time of 40-hours and 24-hour shipping time.
Read the first article in our Quality Control Series, or dive into interviews with our coffee community.
Photo credits: Grumpy Mule Coffee