? Study of the functionality of the bacteriocinogenic strain lactobacillus sakei/curvatus acu 1 on cooked beef surface

RIVAS F., PALAVECINO PRPICH N., CASTRO M., GARRO O., CAMPOS C.A.

Parana

Congreso; 16th World Congress of Food Science and Technology: ?Addressing Global Food Security and Wellness through Food Science and Technology; 2012

Antimicrobial peptides from lactic acid bacteria have become the joker of food biopreservation being its applicability in each food matrix a matter to elucidate. In this sense we studied the functionality of the bacteriocin produced, either in situ or ex situ, by Lactobacillus sakei/curvatus ACU 1 on cooked beef surface. Slices of beef were cooked/sterilized in autoclave, cooled at room temperature and then immersed in: a) cell suspension of the producer strain (1x103 UFC/ml); b) cell suspension + cell free supernatant (CFS) of the producer strain; c) CFS of the producer strain; d) freeze-dried CFS of the producer strain reconstituted in distilled water, for 5 minutes. Afterwards, Listeria innocua ATCC 33090 (1x104 UFC/ml) was poured onto the slices and they were packed in sterile polyethylene bags. Growth of the producer strain on slices was also checked. Slices were stored for 28 days at 4-5°C. Bacterial counts were taken on Palcam Agar and MRS agar every 7 days. In situ bacteriocin production (system a) reduced listerial counts 4 Log cycles but the joint presence of the producer cell and the bacteriocin (system b) exerted the most pronounced listericidal effect reducing the population 9 Log cycles. CFS (system c) and freeze-dried reconstituted CFS (system d) showed an inhibitory effect similar to that of the cell suspension. The combination of in situ and ex situ bacteriocin production seemed to be a highly promising way of bacteriocin supply being the most effective one against Listeria on beef surface