CONICET | Buscador de Institutos y Recursos Humanos

The bio‐preservative capacity of lactic starter cultures in bakery products depends on antifungal metabolite production which is closely linked to the culture medium components and the presence of biosynthetic precursors. In previous works, a starter culture (FTQ) containing the antifungal strain Lactobacillus plantarum CRL778, wheat flour (70%), quinoa flour (30%), glucose (2%) and water (200%) was developed. The addition of quinoa flour stimulated the fermentative activity and the synthesis of antimicrobial compounds by the strain. The use of FTQ (24%) in bread dough combined with 0.2% of the chemical preservative calcium propionate (PCa) allowed extending the shelf life of packaged bread up to 15 days. In contrast, the use of PCa alone, at the maximum concentration (0.4%) allowed by the Argentinean Alimentary Code, could not extend the bread shelf life beyond 10 days. The great effectiveness of FTQ together with PCa was attributed to an increased synthesis of anti‐fungal compounds [acetic acid, phenyllactic (PLA) and hydroxyfenyllactic (HO‐PLA) acids] by the strain CRL778. Despite its efficacy, the use of FTQ at industrial level is limited due to the high cost of quinoa. The aim of this work was to optimize the antifungal effect of FTQ to reduce the quinoa concentration in baking. To achieve this, the effect of the initial pH of the starter culture (pHi), the addition of citrate (C) (0‐0.4%) and skimmed milk (SM) (0‐5%) were evaluated in a buffer system. The following parameters were determined at 24 h: cell counts of L. plantarum CRL 778, pH, fermentative activity and antifungal compound production. A 2k factorial design with center point and response surface plots were used for statistical analyses. Results demonstrated that C and SM were important effectors to improve (p