Screening of lactic acid bacteria from vacuum packaged beef for antimicrobial activity.

The objective of this study was to isolate lactic acid bacteria (LAB) from vacuum packaged beef and to investigate their antagonist activity. LAB mean counts of 5.19 log cfu/cm(2) were obtained from five samples of vacuum packaged beef. Two hundred isolates were selected and screened for the inhibitory effect on five ATCC reference Lactobacillus strains. Thirty six isolates showed activity in the agar spot test against at least two of the indicator strains. However, only six cell free supernatants (CFS) from these isolates exhibited activity against the indicator strains using the well-diffusion test and conditions that eliminated the effects of organic acids and hydrogen peroxide. L. acidophilus was the most sensitive indicator tested, whereas L. plantarum and L. fermentum were the most resistant ones. Identification by MIDI system indicated that these LAB isolates were Lactococcus lactis subsp. cremoris, Pediococcus acidilactici, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus casei GC subgroup A. The antagonistic factors produced by most of these LAB against L. acidophilus were resistant to heat treatment (100°C for 10 min) and stable over a wide pH range (4.0 to 9.0). These data suggest that these isolates could be used as promising hurdles aiming increased safety and extended shelf life of meat products.

Mercury in fish from the Madeira River and health risk to Amazonian and riverine populations.

The objective of this study was to quantify total mercury in highly popular Amazonian fish pacu, curimatã, jaraqui, and sardinha from the Madeira River and to estimate the exposure to methylmercury from fish consumption. The samples were obtained from two locations - Puruzinho Igarapé and Santa Rosa - near Humaitá, Amazonia, Brazil in two seasons of 2015 (high and low waters). The fish were identified, weighed and measured, and lipids were quantified. Total mercury was determined by gold amalgamation-atomic absorption spectrometry. Mean levels were used to calculate exposure of Amazonian and riverine populations. There was significant correlation (p < 0.05) between length × weight for all fish; length × lipid and weight × lipid were significant only for pacu. Total mercury levels varied along muscle tissue for the fish, except for sardinha; therefore muscle from the dorsal area along the fish were sampled, homogenized and used for analysis. The levels of total mercury varied from 0.01 to 0.46 mg/kg, with higher median levels in sardinha (0.24 mg/kg), followed by curimatã (0.16 mg/kg), jaraqui (0.13 mg/kg) and pacu (0.04 mg/kg), corresponding with the respective feeding habits along the trophic chain. Total mercury levels were not affected by the location of fish capture and by high and low waters seasons. Total mercury correlated significantly with length and weight for jaraqui and with length for sardinha (negative correlation). Total mercury levels in fish complied with legislation; however, exposures to methylmercury from fish consumption overpassed the safe intake reference dose for sardinha for Amazonians; however, for the riverine communities, all of the fish would cause potential health risk, mainly for children and women of childbearing age.

Antibacterial activity of coffee extracts and selected coffee chemical compounds against enterobacteria.

The in vitro antimicrobial activity of commercial coffee extracts and chemical compounds was investigated on nine strains of enterobacteria. The antimicrobial activity investigated by the disc diffusion method was observed in both the extracts and tested chemical compounds. Even though pH, color, and the contents of trigonelline, caffeine, and chlorogenic acids differed significantly among the coffee extracts, no significant differences were observed in their antimicrobial activity. Caffeic acid and trigonelline showed similar inhibitory effect against the growth of the microorganisms. Caffeine, chlorogenic acid, and protocatechuic acid showed particularly strong effect against Serratia marcescens and Enterobacter cloacae. The IC(50) and IC(90) for the compounds determined by the microtiter plate method indicated that trigonelline, caffeine, and protocatechuic acids are potential natural antimicrobial agents against Salmonella enterica. The concentrations of caffeine found in coffee extracts are enough to warrant 50% of the antimicrobial effect against S. enterica, which is relevant to human safety.

Influence of cultivar and germination on bioactive amines in soybeans (Glycine max L. Merril).

The levels of amines in soybeans as affected by cultivar in two consecutive years and by germination were investigated. Spermidine, spermine, putrescine, agmatine, and cadaverine were detected, whereas tyramine, histamine, tryptamine, serotonine, and phenylethylamine were not. Spermidine was the predominant amine followed by spermine. High concentrations of these amines confirmed soybean as a rich source. Cadaverine was confirmed to be inherent to soybean. The percent contribution of spermidine and spermine to total levels was not affected by cultivar in either years. However, amine levels were affected by cultivars in different ways in the consecutive years. Cadaverine was affected more by the cultivar, whereas spermidine, spermine, and agmatine were affected by harvest year. During germination the levels of amines from soybean increased significantly, except for agmatine. Spermidine and spermine accumulated in the cotyledon, whereas cadaverine and putrescine accumulated in the radicle and hypocotyl.

Effects of eggplant (Solanum melongena) on the atherogenesis and oxidative stress in LDL receptor knock out mice (LDLR(-/-)).

Eggplant (Solanum melongena) has been used as hypocholesterolemic agent in many countries. However, few controlled studies were addressed to this subject and atherogenesis. We have evaluated the effect of eggplant on cholesterol metabolism and atherogenesis in LDLR(-/-) mice. Animals were fed on chow (n=17) or atherogenic (n=21) diet during 12 weeks receiving water (control) or eggplant extract. Liver, serum and fecal lipids, together with serum lipoproteins were measured. Oxidative stress was evaluated through conjugate diene formation and ox-LDL antibodies by enzyme immunoassay. Atherosclerotic lesions were measured in different sites of aorta. Total cholesterol and atherogenic lipoproteins did not decrease after eggplant intake. Animals receiving eggplant and chow diet showed increased anti-ox-LDL antibodies and a decreased lag phase of conjugated diene formation, indicating a higher oxidative stress than controls. No differences were seen in lesion area of aortic valve. Eggplant extract had high histamine and other amine levels that could enhance LDL oxidation and its endocytosis. Eggplant did not decrease plasma cholesterol nor prevent the development of atherosclerosis in LDLR(-/-) mice. Surprisingly, eggplant increased oxidative stress, representing a risk factor for atherosclerosis. These results did not support the use of eggplant extract as hypocholesterolemic agent.

Spectrophotometric determination of urea in sugar cane distilled spirits.

Urea is an important precursor in the formation of ethyl carbamate, a known carcinogen in alcoholic beverages. Ethyl carbamate has recently been detected at high concentrations in sugar cane distilled spirits, but little is known about the concentration of urea in these beverages. The objectives of this study were to validate methodology for the determination of urea in sugar cane distilled spirits, to determine the levels in 68 samples from different regions within the state of Minas Gerais, Brazil, and to examine the relationship between the concentrations of urea and ethyl carbamate. The method, based on the reaction of urea with 1-phenyl-1,2-propanodione-2-oxime and spectrophotometric quantification at 540 nm, provided linear response from 0.5 to 15.0 mg/L. No purification of the sample was required. The limits of detection and quantification were 0.1 and 0.5 mg/L, respectively. Urea was detected in 69% of the samples at levels varying from 0.50 to 5.10 mg/L. There was no significant difference on the levels of urea in samples from different regions of the state. No significant correlation between the levels of urea and ethyl carbamate was observed for the samples analyzed.

Screening of lactic acid bacteria from vacuum packaged beef for antimicrobial activity / Avaliação de bactérias láticas de carne bovina embalada a vácuo quanto à atividade antimicrobiana

The objective of this study was to isolate lactic acid bacteria (LAB) from vacuum packaged beef and to investigate their antagonist activity. LAB mean counts of 5.19 log cfu/cm² were obtained from five samples of vacuum packaged beef. Two hundred isolates were selected and screened for the inhibitory effect on five ATCC reference Lactobacillus strains. Thirty six isolates showed activity in the agar spot test against at least two of the indicator strains. However, only six cell free supernatants (CFS) from these isolates exhibited activity against the indicator strains using the well-diffusion test and conditions that eliminated the effects of organic acids and hydrogen peroxide. L. acidophilus was the most sensitive indicator tested, whereas L. plantarum and L. fermentum were the most resistant ones. Identification by MIDI system indicated that these LAB isolates were Lactococcus lactis subsp. cremoris, Pediococcus acidilactici, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus casei GC subgroup A. The antagonistic factors produced by most of these LAB against L. acidophilus were resistant to heat treatment (100ºC for 10 min) and stable over a wide pH range (4.0 to 9.0). These data suggest that these isolates could be used as promising hurdles aiming increased safety and extended shelf life of meat products.

Este trabalho teve como objetivo isolar bactérias ácido láticas (BAL) de carne bovina embalada a vácuo e investigar sua atividade antimicrobiana. Uma média de 5,19 log ufc/cm² BAL foi obtida de cinco amostras. Duzentos isolados foram selecionados e o efeito inibitório sobre cinco cepas ATCC referência de Lactobacillus foi pesquisado. Trinta e seis isolados apresentaram atividade inibitória pelo teste 'agar spot' de pelo menos duas das cepas indicadoras. Sobrenadantes isentos de células (SIC) destes isolados foram obtidos. Apenas seis SIC apresentaram atividade contra as cepas indicadoras usando o método de difusão em poços e condições que eliminaram a influência do peróxido de hidrogênio e de ácidos orgânicos. L. acidophilus foi a cepa indicadora mais sensível, enquanto L. plantarum e L. fermentum foram as mais resistentes. Identificação pelo sistema MIDI indicaram que as BAL isoladas eram Lactococcus lactis subsp. cremoris, Pediococcus acidilactici, Lactobacillus delbrueckii subsp. bulgaricus e Lactobacillus casei GC subgrupo A. O efeito antagonista ao L. acidophilus dos SIC destas BAL foi resistente ao tratamento térmico (100ºC/10 min) e estável em ampla faixa de pH (4,0 a 9,0). Estes dados sugerem que os isolados obtidos poderiam ser utilizados como barreiras promissoras no aumento da segurança e na extensão da vida útil de produtos cárneos.

Starch levels in refrigerated and frozen chiken based meat products

Os teores de amido foram determinados em produtos a base de frango comercializados em Belo Horizonte , MG, no período de dezembro de 1996 a março de 1997. As amostras foram analisadas quanto aos teores de umidade e amido. O amido foi submetido a hidrolise ácida e a glicose resultante foi determinada a 620nm após reaçäo com antrona. O método apresentou exatidäo (92,7 por cento de recuperaçä), precisäo (CV=3,0 por cento), sensibilidade (limite de quantificaçäo-1,25G/100) e simplicidade na determinaçäo de amido em produtos cárneos. Dentre os produtos analisados, amido foi detectado em 100 por cento das amostras de almôndega e empanado, 60 por cento de linguiça, 50 por cento das de mortadela e 30 por cento de salsicha. Amido näo foi detectado nas amostras de hambúrguer analisadas. Teores médios mais elevados de amido foram encontrados em empanado (14,85 g/100g) seguido de almôndegas (4,45 g/100g), linguiça (1,73 g/100g), mortadela (1,14 g/100g) e salsicha (0,57 g/100g). O teor médio de umidade variou de 35,68 em linguiça a 46,24g/100 g em empanado. Todas as amostras de mortadela e 90 por cento das de salsicha atenderam a legislaçäo vigente quanto aos teores de amido. Foi observada variaçäo nos teores de amido entre produtos de diferentes marcas e de uma mesma marca