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 and the presence of biosynthetic precursors. In previous works, a starter culture 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 this starter culture (FTQ) (24%) in bread dough combined with 0.2% calcium propionate (PCa), a chemical preservative, allowed to extend the shelf life of packaged bread for 15 days. In contrast, the use of PCa alone at the maximum concentration (0.4%) allowed by the Argentina Alimentary Code could not extend the shelf life of bread for more than 10 days. The greater effectiveness of FTQ together with CaP was attributed to an increased synthesis of anti-fungal compounds [acetic acid, phenyllactic (PLA) and hidroxifenylláctico (HO-PLA)] by the strain CRL778, as well as fermentative activity. Despite it 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), a buffer system (BS), the addition of citrate (C) and skimmed milk (SM) were evaluated on different parameters: the final cell counts of L. plantarum CRL 778 and final pH (24 h), fermentative activity and antifungal compounds production. A 2k factorial design with center point and response surface plots were used. Results demonstrated that C and SM were important effectors able to improve significantly (p

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