{"id":66295,"date":"2026-05-25T06:00:00","date_gmt":"2026-05-25T04:00:00","guid":{"rendered":"https:\/\/www.thegreenlist.nl\/?p=66295"},"modified":"2026-05-29T08:09:33","modified_gmt":"2026-05-29T06:09:33","slug":"koso-is-a-japanese-fermented-syrup-made-from-summer-fruit","status":"publish","type":"post","link":"https:\/\/www.thegreenlist.nl\/en\/koso-een-japanse-gefermenteerde-siroop-van-gered-zomerfruit\/","title":{"rendered":"Koso: a Japanese fermented syrup made from reduced summer fruit"},"content":{"rendered":"
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Summer fruits are delicious, but sometimes you buy a little too much. Before you know it, you have strawberries, berries, or peaches in the fruit bowl that really need to be eaten today. It's a shame to throw them away. Fortunately, there's a simple trick to transform that fruit into something very special: koso. This Japanese fermented syrup is made with nothing more than fruit and sugar. We learned this new cooking skill during a workshop at Diane's from Atelier de Cl\u00e9mentine!<\/strong><\/strong><\/p>\n\n\n\n\n\n\n\n

Fermentation: an old technique that's back in vogue<\/h2>\n\n\n\n

During a workshop on a beautiful summer's day at day caf\u00e9 and tea garden Opmaarhuizen<\/a> doken we samen met Diane van Cl\u00e9mentine's Workshop<\/a> in the world of fermentation. Diane, together with her mother Maryl\u00e8ne, gives workshops on fermentation and special drinks. During this workshop, two recipes were on the programme: koso (we'll get to that shortly) fermented vegetables<\/a>.<\/p>\n\n\n\n

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ALSO INTERESTING:<\/strong> Weekend get-away guide to Groningen.<\/a><\/p>\n<\/div>\n<\/div>\n\n\n\n

Before we started chopping, stirring, and filling jars, Diane first took us through the story behind fermentation. It's an ancient technique where microorganisms, such as bacteria and yeasts, convert sugars. This causes food to slowly change in taste, smell, and texture. The beauty of it is that this process starts by itself, as these microorganisms are already present on fruit and vegetables, in the air, and in the soil. People have used fermentation for centuries to preserve food longer, but also to develop new flavours. Think of bread, cheese, yoghurt, or sauerkraut. And therefore also koso.<\/p>\n\n\n\n

What is koso?<\/h3>\n\n\n\n

Koso is a fermented raw syrup from Japan made from fruit and sugar. By layering fruit and sugar and letting the mixture stand for a while, fermentation starts naturally. The sugar draws the juice out of the fruit, and the natural micro-organisms do the rest. The result is a fragrant syrup with a fresh, slightly sour taste and a deep fruitiness. Very different from a cooked syrup, where flavours often become a little flatter. With koso, the opposite happens: the flavours become more intense and complex.<\/p>\n\n\n\n

And perhaps the most enjoyable part: koso is a perfect way to save summer fruit. A punnet of strawberries that's becoming too soft, a few overripe peaches, or a handful of berries neglected at the back of the fridge: it can all go in the jar. This way, you can turn fruit that might otherwise go to waste into something new and surprisingly delicious.<\/p>\n\n\n\n

\"Fermented<\/figure><\/div>
\"Koso,<\/figure><\/div>
\"Koso:<\/figure><\/div><\/div><\/div><\/div><\/div>\n\n\n\n

Making your own syrup might sound complicated, but with summer fruits and a bit of patience, you can create a delicious Japanese fermented syrup.<\/em><\/p>\n\n\n

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\"Fruit<\/div>\n<\/div>\n

Making Koso: fermented syrup from 'saved' summer fruit.<\/h2>\n
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Koso is a Japanese fermented syrup made from fruit and sugar. During fermentation, the sugar draws the juice and aromas from the fruit while natural micro-organisms do their work. This creates a fresh, slightly sour syrup with a deep fruit flavour. It's also a perfect way to rescue summer fruit that needs to be used today or tomorrow.<\/strong><\/span><\/div>\n
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