RESUMO

Aspergillus flavus (A. flavus), a frequent contaminant in silage, is a significant producer of aflatoxins, notably the potent carcinogen aflatoxin B1. This contaminant poses a potential risk during the initial aerobic phase of ensiling. The present work studied the impact of temperature on A. flavus growth and aflatoxin B1 production in laboratory-scale sorghum silos during the initial aerobic phase. Growth curves of A. flavus were generated at various temperatures and modeled with the Gompertz model. Results indicated that the optimal temperature range for the maximum growth rate in sorghum mini-silos is between 25 and 30°C. Mold biomass and aflatoxin B1 levels were quantified using qPCR and HPLC, respectively. A predictive model for aflatoxin B1 synthesis in the initial ensiling phase was established, in function of grain moisture, external temperature, and time. Within the studied range, A. flavus's initial concentration did not significantly influence aflatoxin B1 production. According to the model maximum aflatoxin production is expected at 30% moisture and 25°C temperature, after 6 days in the aerobic phase. Aflatoxin B1 production in such conditions was corroborated experimentally. Growth curves and aflatoxin B1 production highlighted that at 48 h of incubation under optimal conditions, aflatoxin B1 concentrations in mini-silos exceeded national legislation limits, reaching values close to 100 ppb. These results underscore the risk associated with A. flavus presence in ensiling material, emphasizing the importance of controlling its development in sorghum silos.

RESUMO

BACKGROUND: The global beef market demands the meat industry to ensure product quality and safety in markets that are often very distant. The present study aimed to evaluate the effects of chilled (CH, 120 d) and chilled-then-frozen (CHF, 28 d + 92 d) storage conditions of beef vacuum packaged (VP) and vacuum packaged with antimicrobial (VPAM) on meat quality, oxidative status and microbial loads. Treatments resulted from the combination of storage condition and packaging type: VP + CH, VP + CHF, VPAM + CH and VPAM + CHF. RESULTS: Warner-Bratzler shear force values decreased in all treatments after 28 d of chilling. Except for VP + CH, L* values (lightness) of meat color did not differ in each treatment as the storage time increased. Meat from VP + CH had greater a* values than CHF treatments on day 120 of storage. A consumer panel did not detect differences in tenderness, flavor and overall liking between VP and VPAM beef, but they preferred CHF steaks rather than CH beef. TBARS values did not differ between VP and VPAM and between CH and CHF at any time during the storage period. At the end of storage time, all treatments except VP + CHF presented a greater concentration of thiols than at 48 h post-mortem. On day 120 of storage, VP + CH had greater catalase enzyme activity than CHF treatments while VP + CH and VP + CHF showed a greater superoxide dismutase activity than VPAM + CHF. Storage condition (CH or CHF) had a greater impact on microbial counts than the type of packaging. CONCLUSION: Freezing meat after an ageing period represents a suitable strategy to extend beef storage life without a detrimental impact on its quality. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Assuntos

RESUMO

SARS-CoV-2 surveillance of viral populations in wastewater samples is recognized as a useful tool for monitoring epidemic waves and boosting health preparedness. Next generation sequencing of viral RNA isolated from wastewater is a convenient and cost-effective strategy to understand the molecular epidemiology of SARS-CoV-2 and provide insights on the population dynamics of viral variants at the community level. However, in low- and middle-income countries, isolated groups have performed wastewater monitoring and data has not been extensively shared in the scientific community. Here we report the results of monitoring the co-circulation and abundance of variants of concern (VOCs) of SARS-CoV-2 in Uruguay, a small country in Latin America, between November 2020-July 2021 using wastewater surveillance. RNA isolated from wastewater was characterized by targeted sequencing of the Receptor Binding Domain region within the spike gene. Two computational approaches were used to track the viral variants. The results of the wastewater analysis showed the transition in the overall predominance of viral variants in wastewater from No-VOCs to successive VOCs, in agreement with clinical surveillance from sequencing of nasal swabs. The mutations K417T, E484K and N501Y, that characterize the Gamma VOC, were detected as early as December 2020, several weeks before the first clinical case was reported. Interestingly, a non-synonymous mutation described in the Delta VOC, L452R, was detected at a very low frequency since April 2021 when using a recently described sequence analysis tool (SAM Refiner). Wastewater NGS-based surveillance of SARS-CoV-2 is a reliable and complementary tool for monitoring the introduction and prevalence of VOCs at a community level allowing early public health decisions. This approach allows the tracking of symptomatic and asymptomatic individuals, who are generally under-reported in countries with limited clinical testing capacity. Our results suggests that wastewater-based epidemiology can contribute to improving public health responses in low- and middle-income countries.

Assuntos

RESUMO

We evaluated a combination of two temperatures and two packaging materials for long-term storage of vacuum-packaged (VP) beef striploins. Microbial populations and microbiome composition were monitored during refrigerated storage (120 days between 0-1.5 °C) and refrigerated-then-frozen storage (28 days between 0-1.5 °C then 92 days at -20 °C) under low-O2 permeability VP and high-O2 permeability VP with an antimicrobial (VPAM). Pseudomonas (PSE) and Enterobacteriaceae (EB) counts in VPAM samples were significantly higher (p < 0.05) than in VP samples at 28, 45, 90, and 120 days of storage. Microbiome data showed that bacteria of the genera Serratia and Brochothrix were more abundant in VPAM samples at 120 days, while lactic acid bacteria (LAB) dominated in VP samples. Frozen temperatures inhibited microbial growth and maintained a relatively stable microbiome. Refrigerated and frozen VPAM samples showed the greatest difference in the predicted metabolic functions at the end of storage driven by the microbiome composition, dominated by PSE and LAB, respectively. Although no signs of visible meat deterioration were observed in any sample, this study suggests that VP meat refrigerated and then frozen achieved better microbiological indicators at the end of the storage period.

RESUMO

Biodiesel generated by transesterification of triglycerides from renewable sources is a clean form of energy that is currently used in many countries in blends with petrodiesel. It is mainly produced from food-grade vegetable oils obtained from oleaginous crops. High prices of these oils have made the sustainability of biodiesel production questionable. The use of nonedible feedstocks, such as intracellular triglycerides accumulated by oleaginous yeasts, appears as a feasible alternative. However, it has been demonstrated that an economically sustainable production of yeast oil could only be possible if low-cost media based on industrial subproducts, or wastes are used. In this work, we propose intracellular lipids production by a previously selected oleaginous yeast strain in a medium composed only by sugar cane vinasse and crude glycerol. Different culture strategies were studied. The highest biomass and lipid yields were obtained when the yeast R. graminis S1/2R was cultivated in batch without control of dissolved oxygen. The fatty acid methyl esters obtained under these conditions met the specification of international biodiesel standards.

Assuntos

RESUMO

The objective of this study was to test the effect of the combined application of lactic acid (0-5%) (LA) and UV-C light (0-330 mJ/cm2) to reduce Listeria monocytogenes and lactic acid bacteria (LAB) on beef without major meat color (L *, a *, b *) change and its impact over time. A two-factor central composite design with five central points and response surface methodology (RSM) were used to optimize LA concentration and UV-C dose using 21 meat pieces (10 g) inoculated with L. monocytogenes (LM100A1). The optimal conditions were analyzed over 8 weeks. A quadratic model was obtained that predicted the L. monocytogenes log reduction in vacuum-packed beef treated with LA and UV-C. The maximum log reduction for L. monocytogenes (1.55 ± 0.41 log CFU/g) and LAB (1.55 ± 1.15 log CFU/g) with minimal impact on meat color was achieved with 2.6% LA and 330 mJ/cm2 UV-C. These conditions impaired L. monocytogenes growth and delayed LAB growth by 2 weeks in vacuum-packed meat samples throughout 8 weeks at 4 °C. This strategy might contribute to improving the safety and shelf life of vacuum-packed beef with a low impact on meat color.

RESUMO

The aim of this study was to assess the risk of exposure to polycyclic aromatic hydrocarbons (PAH) from yerba mate infusions in Uruguay using the margin of exposure approach (MOE) and a probabilistic method (Monte Carlo simulation). Servings/day, portion size, weekly frequency of mate consumption and body weight were the factors considered. The amount in infusions of benz[a]pyrene (B[a]P), PAH2 (sum of chrysene and B[a]P), and PAH4 (sum of benz[a]anthracene, chrysene, benz[b]fluoranthene and B[a]P) were used as markers of PAH exposure. Total content of PAH in infusions had large inter-brand variability (48-54 %) with significant differences among brands. PAH content in infusions prepared as habitually consumed was about 40 % of total content. The probability of occurrence of MOE < 10,000 varied according to the infusion preparation and the marker of exposure used, being higher for infusions prepared for total content and when B[a]P was used as marker of exposure. When the average B[a]P amount in infusion as habitually consumed was used in the simulation model, the probability of MOE < 10,000 was 9 %. The main factors contributing to B[a]P MOE variance were B[a]P amount (28.4 %), servings/day (17.3 %), and portion size (9.6 %). Heavy drinkers of yerba mate with high B[a]P content are those at risk to PAH exposure from mate infusions.

RESUMO

The capacity of microorganisms from water kefir (WK) to control Aspergillus flavus growth during the aerobic phase of ensiled sorghum grains was determined. Sorghum inoculated with A. flavus was treated with filter-sterilized and non-sterilized water kefir, ensiled, and incubated 7 days at 25 °C. A. flavus growth was quantified by qPCR after incubation. Mold growth was inhibited in the presence of water kefir while no inhibition was observed when filter-sterilized water kefir was applied, demonstrating the relevant role of the microorganisms in the kefir water in the biocontrol process. Fungal and bacterial diversity in treated sorghum mini-silos was analyzed by high-throughput sequencing. Firmicutes was the predominant bacterial phyla and Lactobacillus represented the most abundant genus, while Ascomycota was the predominant fungal phyla with Saccharomyces and Pichia as the major genera. Bacterial and yeast counts before and after incubation indicated that the microbial community obtained from WK was able to grow in the sorghum mini-silos in the presence of A. flavus. Results of the present work indicate that the use of a mixed inoculum of microorganisms present in WK may represent an alternative management practice to avoid the growth of A. flavus in ensiled sorghum grains and the concomitant contamination with aflatoxins.

RESUMO

The objective of this work was to investigate the effect of the addition of carboxymethyl chitosan on the structural properties and antilisterial activity of nisin-incorporated chitosan films. Chitosan and carboxymethyl chitosan solutions were prepared with different mass ratios and bacteriocin nisin was added (0, 1000 and 6000 IU/ml). Filmogenic solutions were cast, dried and their physico-chemical and antimicrobial properties were investigated. For the same chitosan/carboxymethyl chitosan mass ratio, the addition of NIS at 6000 IU/ml led to changes in the macro- and microstructure, as well as in physico-chemical properties of films. On the other hand, carboxymethyl chitosan had a plasticizing effect and enhanced the distribution of the bacteriocin within the biopolymer matrix. Moreover, nisin-incorporated blend films of chitosan and carboxymethyl chitosan were more effective against Listeria monocytogenes than their pure chitosan counterparts. This study showed that different formulations of nisin-incorporated composite films of chitosan and carboxymethyl chitosan may provide options for developing bioactive packaging to improve food safety.

Assuntos

RESUMO

BACKGROUND: Microbial oils produced by diverse microorganisms are being considered as alternative sources of triglycerides for biodiesel production. However, the standalone production of biodiesel from microorganisms is not currently economically feasible. In case of yeasts, the use of low-value nutrient sources in microbial production and the implementation of cost-efficient downstream processes could reduce costs and make microbial lipids competitive with other commodity-type oils in biodiesel production. Industrial biodiesel synthesis from oleaginous seeds is currently based on a multistep process. However, a simple process called in situ transesterification (ISTE), which takes place within the biomass without a previous lipid extraction step, is receiving increasing interest. In this work, the optimal conditions for an ISTE process to obtain biodiesel from previously selected oleaginous yeast (Rhodotorula graminis S1/S2) were defined using the response surface methodology (RSM). RESULTS: Using the RSM approach, the optimal conditions for the maximum yield with minimum reaction time included a methanol-to-biomass ratio of 60:1, 0.4 M H2SO4, and incubation at 70°C for 3 h. The optimized in situ process yield was significantly higher (123%) than that obtained with a two-step method in which fatty acids from saponifiable lipids were first extracted and then esterified with methanol. The composition of the fatty acid methyl ester mixture obtained from R. graminis S1/S2 by ISTE met Uruguayan standards for biodiesel. CONCLUSION: The characteristics achieved by the optimized method make microbial oil a potential alternative for biodiesel production from yeast at an industrial scale.

Assuntos

RESUMO

Introducción: el déficit de yodo en embarazadas puede perjudicar la salud de la madre y del recién nacido, está relacionado con diversas complicaciones obstétricas como abortos espontáneos, muertes fetales, anomalías congénitas, aumento de la mortalidad perinatal y el cretinismo. La Organización Mundial de la Salud (OMS) establece que el déficit de yodo sigue siendo la principal causa global evitable tanto de retraso mental como de parálisis cerebral, y afecta en grado variable el desarrollo y bienestar de millones de personas en el mundo. Las embarazadas constituyen una población vulnerable, con altos requerimientos de yodo. No se han realizado estudios en embarazadas en Uruguay luego de la yodación universal de la sal (1999). Objetivo principal: evaluar el estado nutricional de yodo en una población de embarazadas. Objetivo secundario: obtener una impresión cualitativa de las posibles fuentes de yodo nutricionales en esta población. Material y método: se realizó una encuesta nutricional específicamente confeccionada y se recolectaron muestras de la primera orina de la mañana para determinar yoduria en mujeres embarazadas independientemente del trimestre. Se consideró deficiencia de yodo para esta población una excreción urinaria media por debajo de 150 ?g/l (OMS, 2007). Resultados: se analizaron 96 muestras de orina. La mediana de la excreción urinaria media de yodo para esta población fue de 182 ?g/l, considerándose en rango de normalidad para las embarazadas valores entre 150 y 249 ?g/l. Conclusiones: este estudio ha confirmado que la excreción urinaria de yodo en la orina está en el rango adecuado a lo establecido por la OMS.

Abstract Introduction: iodine deficit in pregnant women may have a negative effect on the mother and the newborn, and it is associated to several obstetric complications such as spontaneous abortion, fetal death, congenital anomalies, increase of perinatal mortality and cretinism. The World Health Organization (WHO) establishes that iodine deficit is still the main global avoidable cause for mental retardation and brain palsy, and it affects the development and wellbeing of millions of people around the world at different levels. Pregnant women are a vulnerable population with high requirements. No studies in the pregnant women population have been conducted in Uruguay after the universal salt iodation in 1999. Main objective: assessment of iodine nutritional condition in a pregnant women population Secondary objective: to obtain a qualitative impression of the possible sources of nutritional iodine in this population. Methods: a specially prepared nutritional survey was conducted and first morning urine samples were collected to determine ioduria in pregnant women, regardless of the trimester. In this population, iodine deficiency was defined for this population when urine excretion was below 150 ?g/l (WHO, 2007). Results: ninety six urine samples were analysed. Median of the average urinary excretion for this population was 182 ?g/l, normal rates being between 150 and 249 ?g/l. Conclusions: the study confirmed iodine urinary excretion lies within the adequate range established by the WHO.

Resumo Introdução: a deficiência de iodo em gestantes pode prejudicar a saúde da mãe e do recém-nascido e está relacionado com diversas complicações obstétricas como abortos espontâneos, mortes fetais, anomalias congénitas, aumento da mortalidade perinatal e também com o cretinismo. A Organização Mundial da Saúde (OMS) declarou que a deficiência de iodo continua sendo a principal causa global evitável tanto de retraso mental como de paralisia cerebral, e que afeta, em diferentes graus, o desenvolvimento e o bem-estar de milhões de pessoas no mundo. As gestantes são uma população vulnerável com altos requerimentos. No Uruguay, desde 1999 quando começou a iodetação universal do sal, não são realizados estudos em gestantes. Objetivo principal: avaliar o estado nutricional de iodo em uma população de gestantes. Objetivo secundário: obter uma relação qualitativa das possíveis fontes nutricionais de iodo nesta população. Material e métodos: realizou-se um inquérito nutricional e foram coletadas amostras da primeira urina da manhã para determinar iodúria em gestantes em qualquer trimestre da gravidez. Nesta população considerou-se deficiência de iodo uma excreção urinaria média inferior a 150 ?g/l (OMS, 2007). Resultados: foram analisadas 96 amostras de urina. A mediana da excreção urinaria media de iodo nesta população foi de 182 ?g/l, considerando como normais valores entre 150 e 249 ?g/l. Conclusões: este estudo confirmou que a excreção urinaria de iodo está compreendida no intervalo considerado adequado de acordo com o estabelecido pela OMS.

Assuntos

RESUMO

Introducción: el déficit de yodo en embarazadas puede perjudicar la salud de la madre y del recién nacido, está relacionado con diversas complicaciones obstétricas como abortos espontáneos, muertes fetales, anomalías congénitas, aumento de la mortalidad perinatal y el cretinismo. La Organización Mundial de la Salud (OMS) establece que el déficit de yodo sigue siendo la principal causa global evitable tanto de retraso mental como de parálisis cerebral, y afecta en grado variable el desarrollo y bienestar de millones de personas en el mundo. Las embarazadas constituyen una población vulnerable, con altos requerimientos de yodo. No se han realizado estudios en embarazadas en Uruguay luego de la yodación universal de la sal (1999). Objetivo principal: evaluar el estado nutricional de yodo en una población de embarazadas. Objetivo secundario: obtener una impresión cualitativa de las posibles fuentes de yodo nutricionales en esta población. Material y método: se realizó una encuesta nutricional específicamente confeccionada y se recolectaron muestras de la primera orina de la mañana para determinar yoduria en mujeres embarazadas independientemente del trimestre. Se consideró deficiencia de yodo para esta población una excreción urinaria media por debajo de 150 ?g/l (OMS, 2007). Resultados: se analizaron 96 muestras de orina. La mediana de la excreción urinaria media de yodo para esta población fue de 182 ?g/l, considerándose en rango de normalidad para las embarazadas valores entre 150 y 249 ?g/l. Conclusiones: este estudio ha confirmado que la excreción urinaria de yodo en la orina está en el rango adecuado a lo establecido por la OMS.(AU)

Abstract Introduction: iodine deficit in pregnant women may have a negative effect on the mother and the newborn, and it is associated to several obstetric complications such as spontaneous abortion, fetal death, congenital anomalies, increase of perinatal mortality and cretinism. The World Health Organization (WHO) establishes that iodine deficit is still the main global avoidable cause for mental retardation and brain palsy, and it affects the development and wellbeing of millions of people around the world at different levels. Pregnant women are a vulnerable population with high requirements. No studies in the pregnant women population have been conducted in Uruguay after the universal salt iodation in 1999. Main objective: assessment of iodine nutritional condition in a pregnant women population Secondary objective: to obtain a qualitative impression of the possible sources of nutritional iodine in this population. Methods: a specially prepared nutritional survey was conducted and first morning urine samples were collected to determine ioduria in pregnant women, regardless of the trimester. In this population, iodine deficiency was defined for this population when urine excretion was below 150 ?g/l (WHO, 2007). Results: ninety six urine samples were analysed. Median of the average urinary excretion for this population was 182 ?g/l, normal rates being between 150 and 249 ?g/l. Conclusions: the study confirmed iodine urinary excretion lies within the adequate range established by the WHO.(AU)

Resumo Introdução: a deficiência de iodo em gestantes pode prejudicar a saúde da mãe e do recém-nascido e está relacionado com diversas complicações obstétricas como abortos espontâneos, mortes fetais, anomalias congénitas, aumento da mortalidade perinatal e também com o cretinismo. A Organização Mundial da Saúde (OMS) declarou que a deficiência de iodo continua sendo a principal causa global evitável tanto de retraso mental como de paralisia cerebral, e que afeta, em diferentes graus, o desenvolvimento e o bem-estar de milhões de pessoas no mundo. As gestantes são uma população vulnerável com altos requerimentos. No Uruguay, desde 1999 quando começou a iodetação universal do sal, não são realizados estudos em gestantes. Objetivo principal: avaliar o estado nutricional de iodo em uma população de gestantes. Objetivo secundário: obter uma relação qualitativa das possíveis fontes nutricionais de iodo nesta população. Material e métodos: realizou-se um inquérito nutricional e foram coletadas amostras da primeira urina da manhã para determinar iodúria em gestantes em qualquer trimestre da gravidez. Nesta população considerou-se deficiência de iodo uma excreção urinaria média inferior a 150 ?g/l (OMS, 2007). Resultados: foram analisadas 96 amostras de urina. A mediana da excreção urinaria media de iodo nesta população foi de 182 ?g/l, considerando como normais valores entre 150 e 249 ?g/l. Conclusões: este estudo confirmou que a excreção urinaria de iodo está compreendida no intervalo considerado adequado de acordo com o estabelecido pela OMS.(AU)

RESUMO

The traditional instrumental technology for pesticide residue analysis is too expensive and labor-intense to meet the regional needs concerning environmental monitoring. ELISA methodology was used for a pilot scale study of groundwater quality in an agricultural region a few kilometers southwest of Montevideo, the capital city of Uruguay. The study spanned 2 years and examined concentrations (detection limits are given in [ppb]) of two triazine herbicides (simazine [0.3] and atrazine [0.4]) and the carbamate insecticide carbaryl [10] and its major metabolite 1-naphthol [17]. In general, pesticide concentrations were below detection limits in the samples tested and in all cases were well below the maximum contaminant levels set by the U.S. EPA. 1-Naphthol was detected frequently by ELISA, but the assay may have tended to systematically overestimate this analyte. To our knowledge, this is the first study of its type in Uruguay and perhaps the first systematic approach to monitoring for organic pesticides in groundwater water sources in the temperate region of South America.

Assuntos

RESUMO

This paper reports on the generation of monoclonal antibodies and the development of a new enzyme-linked immunosorbent assay (ELISA) for the detection of molinate (S-ethyl hexahydroazepine-1-carbothioate). Hybridoma cells were generated using spleen and lymph node cells from a mouse immunized with S-2-carboxyethyl hexahydroazepine-1-carbothioate conjugated to keyhole limpet hemocyanin. After screening with a competitive ELISA, two monoclonal antibodies, mAbs 16C11 and 14D7, with IC(50) values of 82 +/- 2 and 173 +/- 8 ng/mL, respectively, were selected. MAb 16C11 can detect molinate concentrations of 1 ng/mL with no cross-reactivity to any other thiocarbamate pesticides; however, it was susceptible to the presence of organic solvents and to variation in buffer ionic strength. MAb 14D7 tolerated concentrations up to 5% of propylene glycol and 12.5% of acetonitrile in the assay buffer. The sensitivity of mAb 14D7 was further improved by decreasing the amount of coating antigen in the ELISA; the final inhibition assay showed an IC(50) of 69.2 +/- 1.4 ng/mL. In summary, mAb14D7 provided a more sensitive and robust assay, as compared with previous polyclonal antibody-based assays, with the additional advantage of being based upon a consistent and unlimited source of a defined reagent.

Assuntos