Black garlic: the fermented bulb selling for 4 euros a jar

Black garlic: fermenting a bulb and multiplying its price

A small jar containing between 20 and 30 black garlic cloves costs around 4 euros at Mercadona. The product, which is nothing more than ordinary garlic subjected to a controlled fermentation process, has entered the supermarket wrapped in a superfood narrative and has peine a divide between those who see it as a nutritional find and those who dismiss it as a marketing operation on an ingredient that in Spain grows "like weeds" and sells dirt cheap.

The debate starts with a direct question: panacea or exaggeration? And judging by the arguments being traded, there is no middle ground for many of those taking part. Black garlic is simply fermented regular garlic, no mystery about it: the transformation requires keeping the bulb at a stable temperature for weeks, and out of it comes a dark, soft, sweetish clove that loses the characteristic pungency of raw garlic.

What black garlic really is and how much it costs to produce

The process is not necessarily Japanese. All it takes is for the garlic to ferment at a certain temperature for a few weeks, and the geographic origin is irrelevant. The fame and the high price arrived through marketing rather than technique: it was Asian producers who first packaged and sold the invention with a story of exclusivity.

The temperature range used in homemade descriptions hovers around 70 degrees with 85-90% humidity, and the timing is controlled "by eye". It is not a trivial process: getting it wrong ruins the product. That is why those who have tried it at home have opted for other routes, such as lacto-fermented garlic, which is not the same but shares the logic of fermentation.

The properties attributed to it and the allicin debate

The most contested point is the nutritional one. Fresh garlic releases allicin when crushed or cut and consumed immediately; black garlic, on the other hand, is low in allicin but rich in other antioxidants, including the sulfur compound SAC (s-allylcysteine), which is well absorbed and more stable. Some studies suggest the fermented version doubles antioxidant levels compared with fresh garlic, and there is even a Japanese study from 2009 that found it more effective at reducing tumor size in the lab.

Against that, the skeptical objection: if garlic owes its virtue to allicin and allicin requires freshness, the fermented version loses the main active compound. The debate stalls there, unresolved, because neither side offers a clinical comparison in humans.

Price as an argument: everyday garlic versus a gourmet product

The most repeated criticism is not nutritional but economic. Spain produces abundant, cheap garlic; paying 4 euros for a jar of 20-30 cloves of a fermented bulb reads as a markup of between 2,000% and 5,000% on the original product. The comparison with Las Pedroñeras appears as a byword for quality at a reasonable price.

The pattern repeats with other foods: quinoa, goji berries, avocado. Products that existed before the narrative and were relaunched with superfood packaging. The historical precedent is the potato, recommended in sixteenth-century Europe as an aphrodisiac and antidote in doses of "one finger" every night.

How to eat it and why it does not replace raw garlic

On its own it is unpleasant for many palates: it leaves a lingering aftertaste for hours. The formula that works is spreading it on bread, grating it into salads or using it as a base for mayonnaise to accompany potatoes or burgers. There is also a black garlic honey described as a delicacy.

Daily raw garlic, meanwhile, has radical defenders and one practical problem: it upsets the stomach and is socially off-putting. The middle-ground solution is taking it on butter at breakfast or in tiny pieces with a carbonated drink. And there is a real warning: some people with fructose intolerance or malabsorption do not tolerate garlic well, a claim that draws skepticism from those who consider it an excuse.

With all this on the table, the conclusion gets stuck right where it started: nobody disputes that garlic is good for you, but the markup on the fermented version still lacks a nutritional justification to back it up against the humble bulb of old.