Fermentation of quinoa and wheat slurries by Lactobacillus plantarum CRL 778: proteolytic activity

Abstract

Quinoa fermentation by lactic acid bacteria (LAB) is an interesting alternative to produce new bakery products with high nutritional value; furthermore, they are suitable for celiac patients because this pseudo-cereal contains no gluten. Growth and lactic acid production during slurry fermentations by Lactobacillus plantarum CRL 778 were greater in quinoa (9.8 log cfu/mL, 23.1 g/L) than in wheat (8.9 log cfu/mL, 13.9 g/L). Lactic fermentation indirectly stimulated flour protein hydrolysis by endogenous proteases of both slurries. However, quinoa protein hydrolysis was faster, reaching 40-100% at 8 h of incubation, while wheat protein hydrolysis was only 0-20%. In addition, higher amounts of peptides (24) and free amino acids (5 g/L) were determined in quinoa compared to wheat. Consequently, greater concentrations (approx. 2.6-fold) of the antifungal compounds (phenyllactic and hydroxyphenyllactic acids) were synthesized from Phe and Tyr in quinoa by L. plantarum CRL 778, an antifungal strain. These promising results suggest that this LAB strain could be used in the formulation of quinoa sourdough to obtain baked goods with improved nutritional quality and shelf life, suitable for celiac patients.

Optimization of lactic ferment with quinoa flour as bio-preservative alternative for packed bread

“…For LAB cell counts, aliquots (0.1 mL) in serial 10-fold dilutions from each homogenate were spread on MRS agar with 0.01 g/L cycloheximide to inhibit yeast growth. To support the fact that the counted LAB cells corresponded to L. plantarum CRL 778, a naturally antibiotic [streptomycin (Sp), spectinomycin (St)]-resistant strain of L. plantarum CRL 778 R previously obtained (Dallagnol et al 2013) was grown in a slurry containing quinoa and wheat in a similar way than the wildtype strain. The resistant strain was used only for comparison and was corroborated that the obtained cell count after the fermentation was that of the obtained with the wild type.…”

“…Peptide assessing-Peptide profiles were evaluated by reverse-phase high-performance liquid chromatography (RP-HPLC) as previously reported (Dallagnol et al 2013). Peptide picks were expressed as arbitraries united (AU).…”

“…Citrate was added because of its capacity to improve the synthesis of PLA and OH-PLA (Dallagnol et al 2011), the maximum amount tested corresponding to that allowed by the Argentinean Food Code. Finally, milk was considered to stimulate L. plantarum CRL 778 growth (Gerez et al 2010).…”

“…plantarum CRL 778 has a good proteolytic activity on wheat protein (Gerez et al 2006;2012). Its ability to grow in quinoa's (Chenopodium quinoa) flour and to synthesize antifungal compounds was previously studied (Dallagnol et al 2013). The production of these antifungal was related to the proteolytic activity of the strain and the consequent release of Phe and tyrosine (Tyr), which are sources for the synthesis of PLA and OH-PLA, respectively (Valerio et al 2004).…”

“…It has been reported that the synthesis of PLA by L. plantarum CRL 778 in a chemically defined medium (CDM) could be improved with high amounts of phenylalanine (Phe) while the production of both, PLA and OH-PLA increased by cometabolism of glucose with citrate (Dallagnol et al 2011). Citrate would act as an external electron acceptor stimulating the glutamate dehydrogenase (GDH) activity.…”