Influence of bacteriocins produced by Lactobacillus Plantarum BN in the shelf-life of refrigerated bovine meat

Sugar cane molasses is a cheap by-product of the sugar cane industry. This product was used for growth and production of bacteriocins by Lactobacillus plantarum BN and evaluated for its potential application in the extension of the shelf-life of raw meat. Bovine meat cubes were dipped in the filtered and neutralized supernatant of the fermented broth (Treatment A) and stored at 5(o)C. Counts of psychrotrophic and mesophilic aerobic microorganisms, pH determination and total acidity were performed on meat cubes after 0, 3, 6, 9, 12 and 15 days. These determinations were also done in cubes dipped in a 6 per cente lactic acid solution (treatment B) and distilled water (treatment C). After 3 days, the counts of psychrotrophic microorganisms in cubes submitted to treatment A, B and C increased 0.38, 1.42 and 2.04 log cycles, respectively. The same happened with mesophilic microorganisms (0.31, 0.33 and 1.04 log cycles increases, respectively). On the sixth day, the psychrotrophic population in samples submitted to treatments A and B were 2.07 and 0.64 log cycles, respectively, lower than in the control samples (treatment C). Mesophilic microorganisms in these samples were 1.58 and 1.12 log cycles, respectively, lower than the controls. On the sixth day, only samples submitted to treatment A presented lower counts than those recommended by ICMSF as quality standards for raw meat (<10(7) CFU/g). After nine days of storage under refrigeration, samples submitted to treatment A still maintained acceptable quality. From the twelfth day on, all samples exceeded the microbial quality limits. These results indicate that dipping of raw meat in filtered sugar cane molasses containing bacteriocins produced by L. plantarum BN may be an interesting technological option to extend the shelf life of refrigerated bovine meat.

Produçäo de Lactobacillus plantarum em Melaço de cana-de-açúcar / Production of Lactobacillus plantarum in sugar cane syrup

Comparative studies of Lactobacillus plantarum were carried out in MRS broth (CONTROL) nd in 3 per cent (w/v) sugar cane blackstrap molasses enriched as follows: 0,5 per cent yeast extract, 0,5 per cent amnonium citrate and 0,5 per cent sodium acetate (Medium 1) and 0,5 per cent yeast extract, 0,5 per cent amnonium citrate, 0,5 per cent sodium acetate, 0,5 per cent amnonium phosphate, 0,2 per cent amnonium citrate, 0,1 per cent Tween 80 and 0,005 per cent manganese sulphate (Medium 2). The experiment was carried out at a 5L fermentor, with 3.5 L as working volume. At the end of the fermentation period MRS presented the highest viable cells production (28.68 per cent log CFU?mL) while in Medium 2 it was 25,80 and in Medium 1 19.36 logCFU/mL., Biomass productivity was 0.0865 g. L elevado a menos 1(control), 0,0768 and 0,0507 g.L elevado a menos 1. h for Medium 2 and Medium 1, respectively. In Medium i total avaiable sugar consume was only 60.11 per cent while in MRS and Medium 2 it was 87,21 per cent and 83,80 per cent, respectively

The growth of micrococcus varians by utilizing sugar cane blackstrap molasses as susbstrate

Comparative studies on the growth of Micrococcus varians were carried out in BHI culture medium (control) as well as in a culture medium with 2(per cent) diluted sugar cane blackstrap molasses, enriched with 0.1 (per cent) yeast extract. The experiment was conducted with three samples of the experimental and control media in a 5 liter fermentor with working volume of 3.5 liters, continuous agitation (150 rpm), 35ñ0.1oC temperature, 0.7 L air. 1-1 medium.min-1, initial pH 7.0ñ 0.2, 24 hour fermentation period, and approximate inoculum of 6.0 log10 CFU/ml. Samples were collected at 2-hour intervals. Micrococcus varians grew in the two culture media studied, which confirms the experimental medium viability for the growth of this species. The final average concentration of biomass was higher in the control medium than in the experimental medium: 0.99 g.1-1 and 0.78 g.1-1, respectively. The final number of viable cells at the end of fermentation was 20.65 log10 CFU/ml for the control medium (BHI), while in the experimental medium the number of viable cells was 19.43 log10 CFU/ml. The consumption of total sugars was higher for the biomass in the control medium (79,78 per cent), while only 50.53(per cent) was consumed for the experimental medium.