INVESTIGADORES
VIGNOLO Graciela Margarita
congresos y reuniones científicas
Título:
Mixed starter cultures from autochthonous strains in fermented meat model systems
Autor/es:
PALAVECINO PRPICH, NOELIA; CASTRO, MARCELA; RIVAS, F; CAYRÉ MARÍA ELISA; GARRO, OSCAR; VIGNOLO, GRACIELA
Lugar:
San Miguel de Tucuman
Reunión:
Simposio; IV International Symposium on Lactic Acid Bacteria: Food, Health and Applications; 2013
Institución organizadora:
CERELA-CONICET
Resumen:
The introduction of starter cultures designed using autochthonous microflora can enhance safety of
fermented meat products while preserving their sensory qualities. The selection of potential starter
strains is based on their technological and safety characteristics. Each of the strains of a mixed
culture meant to be added to a meat product should be compatible. A first approach to this
situation can be simulated in model systems where assessments compiled in vitro can be checked.
Hence, the aim of this study was to evaluate the behavior of pre‐selected autochthonous strains, as
mixed cultures, in meat model systems. From a compatibility trial, carried out by means of the agar
well diffusion method, comprising seven strains of Lactobacillus sakei and three strains of
coagulase negative cocci (CNC) (Staphylococcus vitulus and two S. xylosus strains), two pairs of
strains were selected. Culture A: L. sakei 487 and S. vitulinus; culture B: L.sakei 442 and S xylosus
C8. The meat model contained: minced beef and pork meat (70:30), NaCl, milk powder, sugar,
spices and KNO3. The ingredients were thoroughly mixed and placed in a beaker. The meat matrix
was separated into three batches, which were then subdivided into six batches to create the
corresponding duplicates. Batches A and B corresponded to the aforementioned mixed cultures
and the third one corresponded to the control system, with the addition of sodium azide and no
added cultures. The batches were incubated at 20°C and samples were withdrawn at the
beginning of the trial, one and seven days after inoculation. Microbial counts were assessed on
MRS agar and mannitol salt agar (AMS). Total protein content on sarcoplasmic fraction was
determined by means of the bicinchoninic acid method and free aminoacid concentration was
determined by the OPA method. pH measurements were also registered. Both mixed cultures
adapted well to the meat environment; LAB final counts reached values of 8.6 and 8.8 log colony
forming units per gram (cfu/g) and CNC final counts were 7.4 and 8.3 log (cfu/g) in batch A and B,
respectively. Regarding pH values, they diminished from 5.54 (initial time) to 4.66 (A) and 4.68 (B)
at the end of the trial, while the control system did not show pH variations. Final pH values from
both batches are similar to those found in local dry sausages at the end of the ripening stage. Total
protein content reduction was 16% (control), 77.9% (A) and 78.4% (B) indicating a strong metabolic
activity of both mixed cultures. Besides, the release of soluble aminoacids started being 0.98 mMl,
showed a peak of 3.11 mM (A) and 2.43 mM (B) at 24 h, followed by a reduction (1.99 mM) in both
batches. Protein fraction released at 24 h may have contributed to aminoacid supply for bacterial
growth. The acidogenic capacity and the hydrolysis of meat proteins observed in batches A and B
highlight the potential contribution of both mixed cultures to meat fermentation.