Résumé : In the context of the agroecological transition of agri-food systems, the grain-to-breadsupply chain is reinventing itself. Alternative bread supply chains (ABSC) are leading totechnical and social innovations which have the potential to overcome the pitfalls of theproductivist agro-industrial system. ABSC mark an agroecological transition, from aproduction system based on the exploitation of nature to one paying more attention tothe living matter. They are often based on ancient varieties. Yet, Belgian grain-to-breadchains face particularly challenging lock-ins. The notion of “baking value” in the termsof the conventional bakery is one of these. Indeed, the ancient varieties of wheatgrown in Belgium cannot meet the standards required by the industry. Yet, artisanalbakers are well able to make bread with flour sourced from these varieties. Crossinglaboratory analyses with qualitative research, the findings of this study question thenotion of a lock-in due to industrial criteria of bread-making. Actors of ABSC haveoverall different notions of the “quality” (nutrition, flavour, etc.) of the flour, and verydifferent from the industrial interpretations. ABSC bakers also use their sensitivity to“feel” the quality of the flour. Their craft skills to work with flours deemed by the industryas unsuitable for bread-making as well as the attention to the raw material are pointedout by the bakers as a fundamental aspect of their profession. Working with what theysee as living matter is a part of the bakers’ artisanal know-how, a part of their identity.