Explore Beer's Alr, Lager Difference: A Quick Guide

Beer lovers, rejoice! The two main categories of beer are ales and lagers. While both are uniquely wonderful, the differences between them are stark. Ales are typically fermented at warmer temperatures, using yeast that ferments at higher temperatures, while lagers are fermented at cooler temperatures, using yeast that ferments at lower temperatures. Ales tend to be stronger and sweeter in flavour, while lagers tend to be more crisp and clean. Ales are the undisputed darlings of the craft beer world, while lagers are the workhorses, often found at ball games or in German beer halls.

Fermentation technique

The main difference between ales and lagers lies in their fermentation technique. Ales are fermented with top-fermenting yeast at warm temperatures (60–70°F), while lagers are fermented with bottom-fermenting yeast at cold temperatures (35–55°F).

Ales are fermented at room temperature, which falls between 60°F and 70°F (or 15.5°C and 21°C). The strain of yeast typically used for this process is called ale yeast or Saccharomyces cerevisiae. Top-fermenting yeast ferments the sugar into alcohol at the top of the fermentation tank, near the wort's surface. This allows brewers to skim the yeast from the wort and reuse it in other batches. Because top-fermenting yeasts work vigorously in warm temperatures, ales can have a relatively short fermentation time, usually between two and five weeks.

Lagers, on the other hand, are fermented at cooler temperatures, typically between 41°F and 50°F (5°C to 10°C). They use bottom-fermenting yeast, also known as lager yeasts or Saccharomyces pastorianus. Bottom-fermenting yeasts sink to the bottom of the fermentation tank once they have consumed all the sugars to form alcohol. Due to the cooler temperatures and the yeast's action, lagers take longer to ferment, typically between four and eight weeks.

The birth of the Pilsner style in the 1800s introduced lagers to much of the world. Before this, virtually all beer was ale since yeast was not known as an ingredient, and cold fermentation was challenging. The ability to view yeast strains under a microscope and the advent of refrigeration in the 19th century significantly impacted the beer landscape.

Today, technological advancements have made it possible to brew both ales and lagers with relative ease. However, ales are typically more common among craft brewers due to their shorter fermentation time, which can be as little as seven days. This makes it more convenient for small breweries that may not have the fermenter space to produce lagers regularly.

The fermentation technique is not only a distinguishing factor between ales and lagers but also plays a crucial role in the flavour profiles of these beers. Ales tend to be sweeter and fuller-bodied, while lagers are smoother with crisp notes resulting from cold, slow fermentation.

Yeast type

The type of yeast used in the fermentation process is the most significant difference between ales and lagers. Ales are fermented with top-fermenting yeast, Saccharomyces cerevisiae, which is also used in baking bread. Lager yeasts, on the other hand, are bottom-fermenting and are known as Saccharomyces pastorianus or Saccharomyces uvarum.

The distinction between top- and bottom-fermenting yeasts is based on the behaviour of the yeast during fermentation. Ale yeasts produce large, foamy heads during fermentation, leading to the "top-fermenting" label. Lager yeasts, on the other hand, do not produce these large heads and are thus called "bottom-fermenting". However, it's important to note that most yeast cells, regardless of type, will eventually flocculate and settle at the bottom of the fermentation vessel.

Ale yeasts perform best at warmer temperatures, typically in the range of 60°F to 75°F (16°C to 24°C), with some strains requiring temperatures as high as 95°F to 100°F (35°C to 38°C). These warmer temperatures increase the rate of fermentation and carbon dioxide production, contributing to the yeast rising to the top. Ale yeasts are also comfortable with shorter fermentation periods, typically taking 3 to 5 weeks, or even as little as 7 days.

Lager yeasts, in contrast, thrive at colder temperatures, usually in the range of 45°F to 55°F (7°C to 13°C), with some strains capable of fermenting as low as 32°F (0°C). The colder temperatures slow down the fermentation process, resulting in less foaming. Lagering, or cold conditioning, is an important step in lager production, where the beer is stored at cold temperatures for an extended period, which can be anywhere from three weeks to several months.

The choice of yeast and fermentation temperature has a significant impact on the flavour profile of the beer. Ale yeasts, with their warmer fermentation, produce more esters and phenols, resulting in fruity and spicy flavours that balance the malt and hops. Lager yeasts, on the other hand, produce clean, crisp, and rounded flavours, allowing the malt and hops to shine through.

Temperature

The fermentation process is the primary difference between ales and lagers, and temperature plays a key role in this process. Ales are fermented with top-fermenting yeast at warm temperatures of 60°F to 70°F (15.5°C to 21°C), while lagers use bottom-fermenting yeast and are fermented at cold temperatures of 41°F to 50°F (5°C to 10°C).

The warmer temperatures used for ales allow for faster fermentation and ageing, typically taking only 2 to 5 weeks. Ale yeast, or Saccharomyces cerevisiae, works vigorously in these warm temperatures, allowing for a shorter fermentation time.

Lagers, on the other hand, are fermented at cooler temperatures, which slows down the yeast activity. This is why lagers take longer to ferment, usually requiring 4 to 8 weeks. The cold temperatures also suppress many of the by-products of yeast fermentation, resulting in the clean, crisp character of a good lager.

It's worth noting that the ideal serving temperature for beer depends on the style, brewing process, and tradition. Lagers are generally served colder than ales, and stronger and darker beers are served warmer than lighter beers. For example, macro lagers are served very cold, around 33°F to 40°F, while darker lagers like Oktoberfest or amber lagers are served slightly warmer, in the range of 45°F to 50°F. Pale ales and IPAs benefit from being served at higher temperatures, with a range of 45°F to 55°F, to enhance their fruity, citrusy, and hoppy characteristics.

Flavour

The flavour of a beer is determined by a number of factors, including its level of carbonation, aroma, colour, and specific and unique flavours. However, the primary difference between ales and lagers is in their fermentation processes, which in turn influences their flavour profiles.

Ales are fermented with top-fermenting yeast at warm temperatures of 60˚–70˚F (15.5˚–21˚C). This warm fermentation process allows ales to ferment and age relatively quickly, in as little as 3-5 weeks. The ale yeast, or Saccharomyces cerevisiae, ferments the sugar into alcohol at the top of the fermentation tank, near the surface of the wort. This allows brewers to skim the yeast from the wort and reuse it in other batches. The warm temperatures also encourage the yeast to work vigorously, contributing to the shorter fermentation time.

Ales tend to be fuller-bodied and sweeter than lagers, with a bitter edge from the hops. They often present with flavours of fruit, herbs, or spices, which can be attributed to the hops, yeast strains, or malts used in the brewing process. Some common flavour notes found in ales include:

• Chocolate or coffee (especially in stouts and porters)
• Caramel
• Toast
• Nuts
• Banana (often found in German wheat beers)
• Coriander

Lagers, on the other hand, are fermented with bottom-fermenting yeast at cold temperatures of 35˚–50˚F (5˚–10˚C). This bottom-fermenting yeast, known as Saccharomyces pastorianus, gathers at the bottom of the fermentation tank as it ferments the sugar. Lagers typically take longer to ferment, usually between 4 to 8 weeks. The colder temperatures reduce the number of by-products produced during fermentation, resulting in a cleaner, crisper flavour profile.

Lagers are generally smoother and less bitter than ales, with crisp notes from the cold, slow fermentation. They are often characterised by a light, crisp taste that is mellow and refreshing. While lagers can vary in colour from pale to amber to dark, the most commonly produced and consumed lagers are pale lagers, which tend to have a mild flavour. Some common flavour notes found in lagers include:

• Nuts
• Bread
• Coffee
• Chocolate
• Malt
• Hops

While the fermentation process and yeast used are the primary determinants of whether a beer is an ale or a lager, it is important to note that there are many subcategories and variations within each type, resulting in a diverse range of flavour profiles.

Colour

The colour of beer is determined by a variety of factors, including the type of malt used, the brewing process, and any additional ingredients. The colour of beer can be measured using the Standard Reference Method (SRM) colour scale, which ranges from 1, representing very pale beers, to 40 or beyond for extremely dark beers.

Ales come in a wide range of colours, from pale straw hues to deep black. Amber ales, for example, range from light amber to deep reddish hues, while brown ales can be light amber-brown to dark brown, almost black. Pale ales are light golden, and Indian pale ales (IPAs) are golden wheat colour.

Lagers also vary in colour, from pale straw colours to black. Pilsners are pale and hoppy, with a light to medium gold straw colour, while Märzen, also called Oktoberfest, is a dark brown lager. Dunkel is a dark brown lager, and Schwarzbier is an even darker brown.

Frequently asked questions