Mastering Cold Brew: A Practical Guide for Small Roasteries and Coffee Shops

Cold brew coffee has rapidly evolved from a niche product into a staple offering in coffee shops across
the globe. Its popularity is largely due to its smooth, refreshing profile, which appeals to a wide
range of coffee enthusiasts. For coffee shop or small roastery owners, mastering the art of cold brew
preparation is essential — not only to meet customer demand but also to differentiate your product
in a highly competitive market. By Dr Steffen Schwarz

Although cold brew coffee is often viewed as a contemporary trend, its origins can be traced back several centuries. The earliest known use of cold-brewing methods is believed to have originated in Japan during the 17th century. Dutch traders are credited with introducing the concept to Japan, where it
became known as ‘Kyoto-style’ coffee, named after the city where it gained popularity. This slow-drip method, now referred to as cold drip, became a staple in Japanese coffee culture, producing a delicate, aromatic coffee, distinct from the hot brews popular in Europe. In the United States, cold brew found its first significant commercial application in the 1960s with the introduction of the Toddy cold brew system, developed by Todd Simpson. This method, involving the steeping of coarse coffee grounds in cold water over extended periods, laid the foundation for the cold leach technique commonly used today. However, it was not until the early 21st century that cold brew truly surged in popularity, driven by a growing consumer interest in specialty coffee and innovative brewing methods.

Global Market Development

The global rise of cold brew coffee has been nothing short of remarkable, particularly over the last decade. In the United States, the cold brew market experienced explosive growth between 2011 and 2016, with sales increasing by over 580 percent. This surge was fuelled by factors such as the burgeoning specialty coffee movement, a shift towards healthier, less acidic coffee options, and the appeal of cold brew as a refreshing alternative to traditional hot coffee. In Europe, cold brew began gaining traction in the mid-2010s, particularly in the United Kingdom and Germany. Initially driven by
specialty coffee shops and roasteries, the trend gradually spread to larger chains and supermarkets. The European market has seen a steady increase in cold brew offerings, with consumers attracted by its unique flavour profile and versatility. In Germany, for example, cold brew is increasingly available in bottled form, catering to a growing demand for convenience. Asia has also embraced cold brew, albeit at a slightly slower pace. In countries like Japan, where cold brewing methods have a long history, the modern cold brew trend has been seamlessly integrated into the existing coffee culture. In South Korea and China, cold brew has become particularly popular among younger consumers who appreciate its smooth taste and lower acidity. The market in these regions has seen significant growth, with both
local cafés and international chains offering cold brew options.

Cold Brew: Beyond a Beverage

Cold brew is often mistakenly seen merely as a chilled coffee beverage, but in essence, it is a sophisticated extraction technique. Unlike hot brewing methods that rely on heat to quickly extract flavours and compounds from coffee grounds, cold brew relies on time and lower temperatures. This process results in a coffee that is noticeably smoother, sweeter, and less bitter, due to the reduced solubility of certain acidic compounds at lower temperatures. Cold brew can be categorised into three
primary extraction methods, each offering unique operational advantages and flavour profiles:

• Cold Leach (Maceration): This method involves steeping coarsely ground coffee in cold water for an extended period, typically between 14 and 26 hours.
• Cold Drip: This technique slowly drips cold water through coffee grounds using gravity,
with the entire process typically taking 3 to 12 hours.
• Cold Press: This method uses pressure, either positive or negative, to enhance the extraction
process, often reducing the required time significantly.
Cold Leach: The Art of Patience and Depth Cold leach, or maceration, is the most widely used
cold brew method. It involves immersing coarse coffee grounds in cold water and allowing them to
steep for a period ranging from 14 to 26 hours. This extended extraction time enables a thorough
dissolution of coffee solubles, resulting in a rich, full-bodied coffee with minimal acidity and bitterness.

Practical Tips for Cold Leach
• Coffee-to-Water Ratio: The standard ratio suggested by the study is 50-100 g/L. Adjust the ratio based on your desired strength and the specific characteristics of the beans.
• Grinding: Use a coarse grind to prevent overextraction. The particle size is crucial in the extraction process; too fine a grind can lead to an overly intense brew.
• Temperature: Extraction should ideally occur at refrigerator temperatures (around 8°C) to inhibit microbial growth while allowing sufficient extraction of flavours. Room temperature extraction (20°
C) is also common but may require stricter controls on extraction time and storage.
• Extraction Time: The study indicates that most extraction occurs within 7 hours but extending
the time to 14 -26 hours can enhance flavour without significantly increasing bitterness.
Exceeding 26 hours may lead to over-extraction, where unwanted bitter compounds become
more prominent.

Taste Profile

Cold leach typically yields a coffee with a fullbodied, smooth taste and lower acidity. The prolonged steeping time extracts a higher quantity of lipids and oils, contributing to a rounder, more velvety mouthfeel.

Cold Drip: Precision and Clarity

Cold drip, also known as Kyoto-style coffee, is more labour-intensive than cold leach but offers a unique flavour profile characterised by clarity and brightness. This method involves slowly dripping cold water over coffee grounds, with gravity driving the extraction. The drip rate is critical, as it directly influences the extraction process. The entire process can take anywhere from 3 to 12 hours, depending on the setup and desired flavour intensity.

Practical Tips for Cold Drip:

• Equipment: Invest in a reliable cold drip tower or system that allows precise control over the drip rate. This equipment can also serve as an attractive focal point in your coffee shop.
• Drip Rate: Aim for a drip rate of about one drop per second. Faster rates may result in under-extraction, while slower rates could lead to over-extraction and a more bitter flavour.
• Coffee-to-Water Ratio: Start with a 1:10 ratio, adjusting based on the desired strength. Cold drip tends to highlight the more delicate and nuanced flavours of the coffee, so using high quality beans is advisable.
• Monitoring: Regularly check the drip rate and water temperature to ensure consistency throughout the extraction process.

Taste Profile

Cold drip coffee is known for its clarity and pronounced acidity. It has a lighter body compared to cold leach and often exhibits more complex and subtle flavours, making it an excellent method for highlighting the unique characteristics of single-origin beans.

Cold Press: Speed and Intensity

Cold press extraction methods, such as using a French press or an AeroPress with cold water, employ pressure to speed up the extraction process. This method can reduce the time required to make cold brew to as little as two to four hours. The use of pressure enables the extraction of more intense flavours and higher caffeine content, making it a popular choice for those who prefer a stronger brew.

Practical Tips for Cold Press

• Pressure Settings: Whether using a French press or more advanced equipment, ensure even and consistent pressure throughout the extraction. This helps avoid over-extraction, which can lead to bitterness.
• Coffee-to-Water Ratio: Start with a ratio of 1:7 to 1:9. Cold press methods often produce a more concentrated brew, which can be diluted to taste or used as a base for other coffee beverages.
• Grind Size: A grind size slightly finer than that used for cold leach but still coarser than espresso is recommended to facilitate better extraction under pressure.
• Temperature: Cold or room-temperature water can be used. Cold water is generally preferable as it results in a more balanced extraction, while room-temperature water may introduce more acidity.

Taste Profile

Cold press produces a concentrated brew that is bold and intense, with a rich and syrupy body.
The use of pressure can extract more robust flavours and higher levels of caffeine, resulting in a brew that is strong yet smooth. This method is ideal for creating coffee concentrate that can be served as-is or used in various creative beverage applications.

Understanding Extraction and Time: Key Compounds

The extraction time significantly impacts the concentration of key compounds in cold brew coffee. In one of our studies, we provide detailed insights into how these compounds behave over time:
• Chlorogenic Acid: This compound, which contributes to bitterness and astringency, continues to increase up to about 120 minutes. However, its extraction largely stabilises after this point.
• Caffeine: The caffeine content increases steadily during the first 140 minutes of extraction but remains relatively stable thereafter.
• Acetic Acid: Acetic acid, which adds to the acidity of the coffee, shows minimal changes after 40 minutes of extraction.
• Lactic Acid: Lactic acid stabilises quite early, within just 40 minutes, contributing to the coffee’s acidity and smoothness.
• Trigonelline: This compound, known for its role in the formation of flavour and aroma, ceases to increase significantly after around 40 minutes.
• 5-Hydroxymethylfurfural (HMF): The presence of HMF remains relatively constant throughout the extraction process, indicating its stability. These findings suggest that, while the majority of extraction occurs within the first few hours, extending the time allows for the complete dissolution of specific compounds, which can enhance the overall flavour profile.

Ensuring Quality and Safety: Shelf Life Considerations

One of the key challenges in cold brew production is ensuring the product’s safety and shelf life. Unlike hot brewed coffee, which is typically consumed immediately after preparation, cold brew is often stored for later use, making it susceptible to microbial contamination.

Our studies found that improper handling and extended storage times can lead to the growth of spoilage organisms, including Bacillus cereus, which can pose health risks.

Best Practices for Shelf Life & Safety:

• Sanitisation: Thoroughly clean and sanitise all equipment before each use, including storage containers, grinders, and utensils. Cold brew’s long extraction time and lack of a heating step make it particularly vulnerable to contamination.
• Water Quality: Use filtered or bottled water to minimise the risk of contamination. Soft water is often preferred for cold brew as it prevents mineral build-up that can affect the flavour.
• Storage Conditions: Store cold brew in airtight containers and keep it refrigerated at all times.
The study indicates that cold brew should ideally be consumed within 24 to 48 hours.
Beyond this period, the risk of spoilage increases, and the flavour may degrade.
• Batch Testing: Regularly test batches for pH and microbial activity. A pH below 4.6 can inhibit the growth of many pathogens, making it a good benchmark for ensuring safety.
• Shelf Life: While some commercial products may claim longer shelf lives through pasteurisation or other preservation methods, for freshly prepared cold brew, limiting storage to a maximum of three days under refrigeration is advisable. Any signs of off-flavours or changes in aroma should prompt immediate disposal of the product.

Enhancing the Customer Experience

In addition to perfecting your cold brew techniques, consider how you can enhance the overall customer experience:
• Education: Educate your customers about the differences between cold brew methods. This can create a more engaging and informative purchasing experience, fostering customer loyalty.
• Tasting Flights: Offer cold brew tasting flights, allowing customers to compare different methods or single-origin cold brews side by side. This not only showcases the versatility of cold brew but also highlights the distinct characteristics of your offerings.
• Seasonal Variations: Experiment with seasonal cold brew variations, such as adding spices in
winter or citrus in summer. Nitro cold brew, with its creamy texture and visual appeal, is another excellent option that can attract attention and set your product apart.
• Sustainability: Incorporate sustainability into your cold brew offerings by using lower-grade beans or leftover coffee grounds for certain methods, thus reducing waste. Offering refillable bottles for regular customers can also align with the growing demand for eco-friendly practices.

Elevating Your Cold Brew Craft

Cold brew is more than a trend: it is a sophisticated coffee extraction technique which, when executed well, can elevate your coffee shop’s offerings and help you stand out in a crowded market. By understanding the nuances of cold leach, cold drip, and cold press methods, and by implementing rigorous quality control and safety practices, you can create a cold brew coffee that not only meets but exceeds customer expectations. Whether you are perfecting a traditional cold brew, introducing the precision of cold drip, or exploring the intensity of cold press, success lies in the details — from grind size and water quality to extraction time and storage conditions. By focusing on these elements and continuously refining your process, your cold brew can become a signature offering that sets your business apart and keeps customers coming back for more.

Dr Steffen Schwarz is the director of the Mannheim, Germany-based Coffee Consulate, which he founded in 2005 to meet the increasing demand for training. In addition to extensive workshop programmes, the company is engaged in research and product development, and manufactures
barista tools, teaching and analytical materials.

  • Dr Steffen Schwarz is the director of the Mannheim, Germany-based Coffee Consulate, which he founded in 2005 to meet the increasing demand for training. In addition to
    extensive workshop programmes, the company is engaged in research and product development, and manufactures barista tools, teaching, and analytical materials.

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