Lacto-fermentation, the “zero carbon” method of preserving vegetables

“Here, for 90 years, lacto-fermentation has been used to produce sauerkraut from white cabbage. This is our know-how », tastes Clémence Gourden, marketing director of Charles Christ, a cannery established in Connerré, east of Le Mans, in the Sarthe. Known for around 10,000 years, this ancestral know-how remains widely used in Asia and Eastern Europe, but has so far been relatively little used in France.

In the past five years, however, fermented vegetables and the lacto-fermentation process have experienced renewed interest. This is evident from the study launched three years ago by the Végépolys Valley competitiveness cluster, the International Center for Microbial Resources on Bacteria of Food Interest (CIRM-BIA) and the Joint Research Unit for Science and Technology of milk and eggs (UMR-STLO ). Solen Leherissey, project engineer and study coordinator, explains the beginnings and challenges of this study:

“It has become trendy. Now, with the exception of sauerkraut, nothing was known. We knew nothing about bacterial ecosystems. TAll scientists agreed to recognize that things were happening and that this trend, driven by the pandemic and the confinements, the search for new tastes and the development of short circuits, raised many questions. »

Collection of samples in the kitchen of Mrs. or Mr. Alle

As for the modus operandi, one of the special characteristics of this study is to have immediately associated 28 structures from the economic world (chambers of agriculture, gardeners, agri-food companies, research organizations, universities, colleges, etc.) and 250 citizens, amateurs or enthusiasts.

This allowed the researchers to collect 80 samples prepared in Madame or Monsieur Tout-le-Monde’s kitchen. With this time not just cabbage, but carrots, beets, fennel, swiss chard, leeks, turnips, cucumbers, aubergines… with or without spices and herbs… And a question center for researchers: are consumers putting themselves at risk with this homemade product?

Risk-free, energy-free storage

If simple to implement, lacto-fermentation requires some vigilance and the adoption of basic rules of sanitary hygiene (cleaning of containers, “stepping forward”, etc.) to guarantee storage without risk – and without energy consumption.

It’s the bacteria that do the work.”emphasizes Charles Christ’s marketing director.

The principle is to put in glasses, tubs or glasses with vegetables at just ripeness, previously washed and cut, by adding a precise amount of salt, even water, under anaerobic conditions (without air, by packing products) and let it ferment for two to three weeks at room temperature.

The microorganisms feed on sugar and produce lactic acid. Ph control (< 3.8) will guarantee the safety of products, which can then be stored between 4°C and 0°C.

“The advantage is that you get a product that is more digestible, much less sweet, which according to our studies would allow better absorption of nutrients in the human body and a possible increase in certain vitamins. The product retains its crunch and has a more acidic note »she explains.

Gardeners appreciate the safety and durability of the preparations

The other advantage of this process is being able to respond to production peaks in certain gardeners.

“This extends the life of the vegetables and makes it possible to spread the sales”adds Solen Leherissey, who is in high demand during the course. “There is real interest from micro-enterprises and gardeners for this reason. Everyone was waiting for assurance of the harmlessness of their preparation, because so far there are no rules regulating these productions”, she states.

Passed through the clutches of Inrae laboratories, none of the 80 jars analyzed revealed any pathogen.

To go further, the researchers tightened their investigations with special preparation of two vegetables: cabbage and carrots. Aiming to document the impact of different manufacturing parameters (salinity, carving, etc.) on microbial communities and on the nutritional quality of the produce.

“Then we looked samples from Moldova where the traditional fermentation culture is widespread. Which allowed us compare with French productions. For these three collections we worked on the exploration of microbial communities, micronutrients of nutritional interest and the study of culinary uses and consumer perception »says Florence Valence, head of CIRM-BIA at Inrae.

Changing tastes and consumption patterns

Above all, the study on fermented vegetables will have reassured players in an economic niche where major players in the French agri-food industry have been on standby, without being involved.

Convinced before the others, Charles Christ Cannery was the first brand to take a proactive approach. In 1992, it created the Nutriform organic range to offer the network of cooperatives and organic shops carrots, beets, red cabbage, black radishes, Korean kimchi, Kefir or Kombucha… marketed in the form of juice. , spreads, preparations for mixing in dishes…

The company, which in 2020 invested in two new buildings, one of which is dedicated to fermented vegetables, achieves a turnover of 20 million euros, including 20% ​​on organic, where lacto-fermented products count for a third. A niche market that is growing, where Charles Christ and new players such as Cototerra, JiBio, l’Atelier du Ferment, Cru’c… tend to change the palate of the French.

“These are products that bring new flavors, that replace, for example, vinaigrette or mayonnaise, and that respond to new uses and changing consumption patterns”, notes Clémence Gourden.

Pedagogy to gain acceptance of a still little-known approach

Acceptance and generalization will require pedagogy. “The approach is still unknown. The name of lacto-fermentation alone is often scary”, observes Solen Leherissey, on the occasion of the “Festival of plant fermentation: from science to jars”. Which festival, organized on October 27 in Rennes by Végépolys Valley and Inrae to close the Phlegm project, encouraged meetings between scientists, actors of this network and the general public.

Shared with the Chambers of Agriculture, the City of Taste and Taste in Nantes and the Chamber of Commerce and Crafts of the Pays de la Loire, the study’s work has made it possible to produce new recipes for these new ingredients, neither raw nor cooked .

A practical guide has been published to support teachers in agricultural schools and a work available online “The ABC of fermented greens” for acculturated artisans who want to enter this market and remove the brakes.

The issues of DLC and DDM remain to be decided

“Which should make it possible to speed up business formation in Brittany and the Pays de la Loire, where vegetable production is very important”believes Solen Leherissey, for whom the Phlegm project has opened up a wide range of questions, including those about expiration date (DLC) and date of minimum durability (DDM), which are discussed and remain to be decided.

In the meantime, specify the authors of the Phlegme study, fermented vegetables that have not received heat treatment must be stored between 0°C and 4°C to stabilize the product and avoid the spread of microorganisms and possible secondary fermentations due to yeast.

Conversely, preparations that have undergone heat treatment can be stored in the surrounding air for several years. “From one to four years if we add ascorbic acid”, says the study.

In all cases, each manufacturer must carry out aging tests with approved organizations to define the shelf life and be able to put a precise use-by date on the jar.