Abstract The objective of this study was to evaluate the influence of salt concentration on action of natamycin on important microorganisms in food manufacturing as this preservative has been used in immersion baths in several dairy products in the country. Strains of Candida albicans, Escherichia coli and Staphylococcus aureus were inoculated at different saline and peptone water concentrations and received natamycin treatments. These solutions were maintained at 12 °C and the behavior of the microorganisms evaluated at 0, 24 and 48 hours (T0, T1 and T2). Each microorganism was assessed in isolation as well as the association of C. albicans and E. coli. Under the conditions proposed by the research, it was possible to conclude that 0.025% natamycin has no efficacy on C. albicans inoculated at saline concentrations below 5%. The results obtained in E. coli counts suggest that natamycin may interfere with its development even at concentrations that may be considered low (0.1%) and at salinity conditions of 7.5% to 10%. The association of natamycin with sodium chloride potentiates its antimicrobial action, which can represent an economy and its use is amplified by the industries.

Resumo O objetivo desse trabalho foi avaliar a qualidade físico-química e microbiológica do leite de cabra produzido no Distrito Federal, Brasil. As amostras foram coletadas diretamente dos tetos e em pool de cada três animais (n=40) e de leite de conjunto (n=10). Nas análises físico-químicas, os resultados médios foram: gordura (animais: 3,01% ± 0,679, conjunto: 4,45% ± 1,223); sólidos não gordurosos (animais: 9,24% ± 0,651, conjunto: 9,2% ± 0,615); densidade (animais: 1,033g/mL ± 0,002, conjunto: 1,032g/mL± 0,002); proteínas (animais: 3,5% ±0,551, conjunto: 3,67% ±0,778); lactose (animais: 5,0% ± 0,035, conjunto: 4,94% ± 0,015); acidez Dornic (animais: 18,47ºD ±0,552, conjunto: 18,5ºD ± 0,5); pH (animais e conjunto: 6,9 ±0,098); crioscopia (animais: -0,560ºH ±0,010, conjunto: -0,558ºH ± 0,005). Nenhuma amostra apresentou resíduos de antibióticos. As contagens médias microbiológicas foram: aeróbios mesófilos 1,2x103 UFC/mL (animais) e 7,6x103 UFC/mL (conjunto); coliformes totais 1,0 UFC/mL (animais) e 1,2x104 UFC/mL (conjunto); Escherichia coli 2,0 UFC/mL (conjunto); psicrotróficos 1,0x104 UFC/mL (conjunto); bactérias ácido-láticas 4,7x102 UFC/mL (animais) e 7,8x103 UFC/mL (conjunto); bolores e leveduras 1,0 UFC/mL (animais) e 4,9x103 UFC/mL (conjunto) e Staphylococcus aureus 2,1x102 UFC/mL (animais) e 2,8x102 UFC/mL (conjunto). Listeria monocytogenes e Salmonella spp. não foram detectadas nas amostras analisadas. Os resultados obtidos permitem concluir que o leite de cabra produzido no Distrito Federal apresenta qualidade satisfatória e esses dados podem contribuir para o estímulo da produção na região.

Abstract The goals of this study were to evaluate the physicochemical and microbiological quality of goat milk produced in Distrito Federal, Brazil. The samples were collected as pool (n=40) and whole milk samples (n=10). The physicochemical means observed were: Fat (animals: 3.01% ± 0.679, whole milk: 4.45% ± 1.223); nonfat solids (animals: 9.24% ± 0.651, whole milk: 9.2% ± 0.615); density (animals: 1.033g/mL ± 0.002, whole milk: 1.032g/mL ± 0.002); protein (animals: 3.5% ± 0.551, whole milk: 3.67% ± 0.778); lactose (animals: 5.0% ± 0.035, whole milk: 4.94% ± 0.015); acidity (animals: 18.47°D ± 0.552, whole milk: 18.5°D ± 0.5); pH (animals and whole milk: 6.9 ± 0.098); cryoscopic index (animals:-0,560°H ± 0.010, whole milk -0.558°H ± 0.005). There were no positive samples for antibiotic residues. The mean scores microbiological counts were: aerobic mesophilic 1.2x103 CFU/mL (animals), 7.6x103 CFU/mL (whole milk); total coliforms 1.0 CFU/mL (animals), 1.2x104 CFU/mL (whole milk); Escherichia coli 2.0 CFU/mL (animals); psychrotrophics 1.0x104 CFU/mL (whole milk); acid lactic bacteria 4.7x102 CFU/mL (animals), 7.8x103 CFU/mL (whole milk); yeast and moulds, 1.0 CFU/mL (animals), 4.9x103 CFU/mL (whole milk); Staphylococcus aureus 2.1x102 CFU/mL (animals), 2.8x102 CFU/mL (whole milk). Listeria monocytogenes and Salmonella spp. were not detected in any sample. The results indicate that the goat milk produced in Distrito Federal offers quality and microbiological safety and may be an incentive for the further development of dairy goat.

The objective of this study was to evaluate the applicability of the Petrifilm™ plates to enumerate microbial groups in sheep milk. Samples of sheep milk (n = 30) were plated simultaneously, to enumerate mesophilic aerobes, total coliforms, lactic acid bacteria, Staphylococcus aureus and Escherichia coli, using convencional reference protocols and Petrifilm™ plates. The results were compared using McNemar's test, linear regression and ANOVA (p < 0,05). The results demonstrated good significant between conventional methodologies and Petrifilm™ plates. Further, the Petrifim™ STX for counting S. aureus had higher recoverability of bacteria compared with the conventional methodology. Based on the results obtained and in view of the ease and rapidity procedures results, Petrifim ™ plates may be considered as alternatives for microbiological testing in sheep milk.