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Modern sours: smoothie and pastry sour

Sour beers have undergone a real revolution over the past decade. Alongside traditional lambics that mature for years and delicate goses, a completely new wave appeared: fast, intensely fruity, sometimes downright dessert-like beers, known as smoothie sour and pastry sour. These thick, hazy, fruit-loaded drinks divide the beer world: some adore them for their bold, juicy flavours, others criticise them as a departure from beer tradition. What actually are these modern sours, how are they made and where did their phenomenon come from? In this post we will explain the difference between traditional and modern sours, the role of quick souring, lactose and fruit puree, and why this style stirs so much emotion. It is a guide to one of the hottest and most controversial beer trends.

From traditional to modern

To understand modern sours, it is worth distinguishing them from traditional ones. Classic sour beers, like Belgian lambics, gose or Berliner Weisse, rest on bacteria and wild yeast, and their acidity develops slowly, often over months or years of spontaneous or long fermentation. It is a historical style, requiring patience and giving complex, dry profiles. Modern sours go a completely different way: they bet on speed, intense fruit and often a sweeter, dessert-like character. Instead of waiting years, breweries sour the beer in a few days, and then load it with fruit and adjuncts. It is a change not only technological but philosophical: from slow craft toward immediate, juicy pleasure. These two worlds of sour beers are linked by acidity, but divided by almost everything else, from the method, through time, to the final flavour and look. We write more about traditional sours in our post on sour beers.

Kettle sour - quick souring

The foundation of most modern sours is a technique called kettle sour, that is souring in the kettle. Instead of relying on slow, spontaneous fermentation, the brewery introduces lactic acid bacteria, most often Lactobacillus, into the wort and lets them sour the beer within just one to a few days, before boiling and the actual fermentation. Then the wort is boiled, which stops the work of the bacteria, and fermented normally with yeast. The result is a clean, one-dimensional, lactic acidity, obtained quickly and predictably, without wild yeast and the risk of long maturation. Kettle sour is the base on which most fruited, smoothie and pastry sours are built. It is a technique that democratised sour beers: it lets almost any brewery make a sour beer quickly and repeatably, without specialised infrastructure for spontaneous fermentation. It is what made this whole new wave possible.

Fruited sour

The natural development of kettle sour is the addition of fruit. Fruited sour beers combine the clean, lactic acidity of the base with the intense flavour of fruit, most often added as a puree after fermentation. The acidity goes superbly with the fruit, underlining its juiciness and creating a refreshing, vivid profile. It is precisely fruited sours that became the bridge between tradition and the modern craze: they are approachable, colourful and tasty, easy to love even for someone who does not care for dry lambics. Fruits like raspberries, blackberries, mango, passion fruit or cherries give the beers vivid colours and aromas. Fruited sours are often the point of entry into the world of modern sours, pleasant and uncomplicated. From there it is only a step to even more intense and thick variants, that is smoothie and pastry sours, which take fruitiness and adjuncts to the extreme, creating beers that resemble cocktails or desserts.

Smoothie sour - beer like a cocktail

Smoothie sour is one of the most characteristic and controversial modern styles. It is in essence a heavily fruited kettle sour, loaded with adjuncts so that it resembles a real fruit smoothie. Breweries add enormous amounts of fruit puree, often lactose for thickness and sweetness, and crucially, do not filter the beer, leaving the fruit pulp in the can. The result is a beer that is thick, hazy, intensely fruity, downright creamy, functioning more like a liquid smoothie than a classic drink. It is a deliberate imitation of the smoothie-drinking experience: thickness, fruit pulp and juicy flavour. Smoothie sour is the extreme of the modern trend, a beer that blurs the line between beer and a dessert fruit drink. For many it is a fascinating innovation, for others a step too far. Regardless of the assessment, smoothie sour became a symbol of the new wave of sours and one of the most recognisable, though divisive, styles of modern craft brewing.

Pastry sour - dessert in beer

Pastry sour goes even further, that is a sour beer designed to taste like a dessert or baked good. The name comes from the cakes and sweets these beers try to imitate in liquid form. Breweries reach for adjuncts such as vanilla, lactose, fruit, sometimes spices or cocoa, to recreate the flavour of cheesecake, ice cream, fruit tart or other desserts. Pastry sour combines the acidity of the base with clear sweetness and a dessert character, creating a beer that more resembles a cake than a classic drink. It is a category related to smoothie sour and equally controversial. Pastry sour is the apogee of the trend of combining beer with culinary imagination: beer as an edible dessert. For lovers of bold, sweet-sour flavours it is a treat, for purists proof that the trend has gone too far. Either way, pastry sour shows how flexible and capacious a category modern craft beer has become.

The role of lactose and puree

Two ingredients define the character of many modern sours: lactose and fruit puree. Lactose is a milk sugar that is not fermented by beer yeast, so it remains in the beer, lending it sweetness, thickness and a creamy texture. It is what balances the acidity and builds the dessert character of pastry and smoothie sours, although its use is sometimes a matter of dispute among brewers. Fruit puree in turn provides intense flavour, colour and, when not filtered, a thick texture with pulp. It is usually added after fermentation, to keep the fresh, juicy profile of the fruit, which the heat of boiling would not survive. The combination of lactose and abundant puree is a recipe for a thick, sweet-sour, hazy beer with the look and consistency of a cocktail. It is these two ingredients, more than anything else, that distinguish modern sours from their traditional, dry ancestors.

Haze, thickness and look

Modern sours stand out not only in flavour, but also in look. To fully recreate the smoothie-drinking experience, breweries deliberately do not filter the beer and leave in it the pulp and particles of fruit. The result is a beer that is thick, hazy, opaque, of an intense, often downright vivid colour coming from the fruit. Such a drink more resembles a fruit cocktail or mousse than a clear, classic beer. The thickness and creamy texture, boosted by lactose, complete this impression. Visually, modern sours are the opposite of traditional, clear beer: colourful, thick, full of suspension. For some it is an attractive, Instagram-worthy spectacle, for others a departure from what beer should be. The look here is an integral part of the concept: smoothie sour should not only taste but also look like a fruit cocktail, engaging the sense of sight on a par with taste. It is a deliberate, coherent aesthetic measure.

Where the trend came from

Modern sours did not come out of nowhere. The trend was born as a development of an arc that began about a decade ago, when gose and kettle sour gained popularity alongside beers with fruit. Over time breweries, such as the American Tired Hands or the Swedish Omnipollo, began experimenting with ever more intensely fruited, sweet beers, initially on a hazy NEIPA base, and then kettle sours. These breakthrough releases started a fashion that spread across the whole craft beer world. The trend was fuelled by the desire to create bold, culinary flavours and the growing appetite of consumers for novelty and intense experiences. Modern sours fit a wider tendency of adding kitchen ingredients to beer, to create drinks of as much flavour as texture. It is a natural evolution of brewers creativity, who keep pushing the boundaries of what beer can be, drawing inspiration from the world of desserts and cocktails.

Controversy and criticism

Modern sours are one of the most divisive trends in beer. Let us gather the main styles and points of contention:

Critics charge these beers with artificiality, an excess of sweetness and departing from the essence of beer, becoming rather fruit drinks. Supporters value their boldness, intensity and creativity. The table shows that the further toward smoothie and pastry, the greater the emotion and disputes about the boundaries of the definition of beer.

How to approach tasting

How to approach modern sours sensibly? Above all with an open mind and the right expectations. Do not judge a smoothie sour by the criteria of a classic lambic, because these are completely different beers with different aims. Pay attention to the balance between acidity and sweetness: in the best examples the fruit is juicy and natural, and the sweetness does not overwhelm but complements the sour backbone. Assess the quality and naturalness of the fruit flavour, whether it is not artificial or bland. Check the texture: whether the thickness is pleasant, or rather sticky. Drink these beers fresh, because intense fruit quickly loses its form. Treat them as a bold, dessert experiment, rather than a replacement for traditional beer. Note your impressions, to find breweries that do them well. We write more about the role of bacteria in sour beers in our post on bacteria in beer.

The key points in a nutshell

Modern sours are a new wave of beers that departed from slow, wild lambics toward fast, intensely fruity and dessert-like drinks. Their base is the kettle sour, that is quick souring with Lactobacillus bacteria in a few days. On this base are built fruited sours, thick and hazy smoothie sours imitating a cocktail and pastry sours tasting like a dessert. The key ingredients are lactose giving sweetness and thickness and fruit puree added after fermentation, left without filtration. The trend, started by breweries like Omnipollo, divides the beer world: some love it, others see in it a departure from tradition. Want to assess these beers and record your impressions? Keep notes in the GustoNote app. See also our posts on sour beers and bacteria in beer.