Quinoa flour as substrate to production of antifungal organic acids by Lactobacillus plantarum CRL 778

DALLAGNOL A. M; ROLLÁN G; TORINO M.I; FONT G.

San Salvador de Bahía

Congreso; XXII Congreso Brasilero de Ciencia y Tecnologia de Alimentos; 2010

The development of starter for bakery containing selected antifungal lactic acid bacteria (LAB), may limit the most frequent cause of spoilage in baked goods: fungi growth. In this way, dough fermentation by antifungal LAB increases the shelf-life but also the healthy and hygienic state of the final products. Lactobacillus plantarum CRL 778 was previously screened in our laboratory due to its ability to synthesize phenyllactic (PLA) and hydroxyphenyllactic (OH-PLA) acids, reported as anti-mould metabolites. The concentration of these acids detected in culture medium was rather low; therefore, different strategies for improving antifungal production are being evaluated. The aim of this work was to assess the efficacy of quinoa (Chenopodium quinoa) flour as phenylalanine and tyrosine source for the PLA and OH-PLA production by L. plantarum CRL 778, in order to formulate ready-to-use bio-preserving starters for bread manufacture. The quinoa content of the starters was established inoculating an active culture of L. plantarum CRL 778 in media (slurries) containing: different wheat/quinoa flour ratio (%): 100/0, 90/10, 80/20, 70/30, 60/40, 50/50 and 0/100; cerelose (glucose monohydrate) and tap water. Slurries were fermented 24 h at 30 °C under stirring, and analyzed to determine: pH, acidity (°D), growth on MRS agar (Log CFU/mL) and organic acid (mM, by HPLC). Results showed that quinoa flour widely stimulated both growth (from 8.6 to 9.7 log CFU/mL) and organic acid production (2, 3, 5 and 9-folds for lactic, PLA, OH-PLA and acetic acid, respectively) when quinoa ratio was increased from 0 to 100 %. To evaluate the bio-preservative effect of the quinoa containing starters, bread loaves were beaked with the 70/30 wheat/quinoa slurry added at different ratio (40, 20, 10 and 0% v/v respect to the water content for making bread dough) and their shelf-life was compared to that reach with calcium propionate (CP, from 0% to 0.3%.), a chemical additive usually employed in bakery for bread conservation. A 100 % (10 loaves) of the experimental breads attained the expected shelf-life of 15-days when contained 40/0.3%, 40/0.2% or 20/03% of slurry and CP, respectively. When 0.3 % of CP was used without slurry addition, only a 50% of bread was conserved. On the basis of these preliminary results, we conclude that Chenopodium quinoa might be used for the development of bio-preservative starter for bread manufacture.