Water reconditioning by high power ultrasound combined with residual chemical sanitizers to inactivate foodborne pathogens associated with fresh-cut products

The suitability of high power ultrasound (HPU, 20 kHz, 0.28 kW/l) combined with residual chemical sanitizers for water reconditioning was studied. A synergetic disinfection effect was observed when HPU was combined with peroxyacetic acid (PAA) or a commercial mix of organic acids and phenolic compounds (OA/PC). In recycled water (RW) with a chemical oxygen demand (COD) of 500 mg O2/l, PAA inactivated 2 log units of Escherichia coli O157:H7 at concentrations of 3.2, 6.4, 16 mg/l after 7 min, 2 min, 29 s, respectively. The OA/PC or HPU treatments alone needed 26 min treatments to achieve the same reduction. The addition of TiO2 (5 g/l) to HPU (sonocatalysis) did not improve E. coli O157:H7 inactivation. However, when HPU was combined with a residual concentration of PAA (3.2 mg/l), the total inactivation of E. coli O157:H7 and Salmonella (6 log unit reductions) occurred after 11 min, but for Listeria monocytogenes only 1.7 log reductions were detected after 20 min. When HPU was combined with OA/PC, a synergistic effect for the inactivation of E. coli O157:H7 was also observed, but this sanitizer significantly modified the physical-chemical quality characteristics of the RW. These results show that the residual PAA concentration that can be found in the wash water combined with HPU could result in an environmentally friendlier and toxicologically safer strategy for water reconditioning of the fresh-cut industry. The use of the sanitizer alone requires higher concentrations and/or longer contacts times. Even though the residual PAA in combination with HPU was adequate for water reconditioning, it is not appropriate for the process wash water because this wash water must be instantaneously disinfected.Ciencias de la Alimentació

Disinfection Capacity of High-Power Ultrasound Against E. coli O157:H7 in Process Water of the Fresh-Cut Industry

The fresh-cut industry must treat process water to guarantee its microbial quality before reuse or recirculation back into the processing line. In the present study, the suitability of high-power ultrasound (HPU) for disinfecting and recycling process water was evaluated. An ultrasonic horn (20 kHz) was used to inactivate Escherichia coli O157:H7 inoculated in five types of process water which showed different physical and chemical characteristics. Differences in the inactivation level of E. coli O157:H7 at different HPU densities (0.14, 0.28, 0.56, and 1.12 kW/L) with controlled (20– 25 °C) and uncontrolled (15–72 °C, 3.6 °C/min) temperature increase were studied. Results showed that the higher the power density and temperature, the higher the efficiency, reaching up to 6 log reductions of E. coli O157:H7. Alkalinity (between 0 and 253 mg HCO3 − /L) and organic matter concentration (between 9 and 3,525 mg O2/L) in water did not reduce ultrasonic efficacy against E. coli O157:H7. Agglomerates >90 μm, which represented 34 % of those present in the process water, were reduced to only 11 % by HPU. Results indicate that HPU can be successfully applied to treat process water of the fresh produce industry because the antimicrobial efficacy was not affected by the continuous variation of the process water quality. HPU can be a suitable technology for the fresh produce industry to be able to reduce consumption of water and decrease wastewater and the generation of disinfection by-products.Ciencias de la Alimentació

Assessing the Real-Time Impact of COVID-19 on TB and HIV Services: The Experience and Response from Selected Health Facilities in Nairobi, Kenya

There was concern that the COVID-19 pandemic would adversely affect TB and HIV programme services in Kenya. We set up real-time monthly surveillance of TB and HIV activities in 18 health facilities in Nairobi so that interventions could be implemented to counteract anticipated declining trends. Aggregate data were collected and reported monthly to programme heads during the COVID-19 period (March 2020–February 2021) using EpiCollect5 and compared with monthly data collected during the pre-COVID period (March 2019–February 2020). During the COVID-19 period, there was an overall decrease in people with presumptive pulmonary TB (31.2%), diagnosed and registered with TB (28.0%) and in those tested for HIV (50.5%). Interventions to improve TB case detection and HIV testing were implemented from August 2020 and were associated with improvements in all parameters during the second six months of the COVID-19 period. During the COVID-19 period, there were small increases in TB treatment success (65.0% to 67.0%) and referral of HIV-positive persons to antiretroviral therapy (91.2% to 92.9%): this was more apparent in the second six months after interventions were implemented. Programmatic interventions were associated with improved case detection and treatment outcomes during the COVID-19 period, suggesting that monthly real-time surveillance is useful during unprecedented events

Isolation of human intestinal bacteria capable of producing the bioactive metabolite isourolithin A from ellagic acid.

Peer reviewe

Decomposition kinetics of gaseous ozone in peanuts Cinética da decomposição do gás ozônio em amendoim

This study was conducted to evaluate the decomposition kinetics of gaseous ozone in peanut grains. This evaluation was made with 1-kg peanut samples, moisture contents being 7.1 and 10.5% wet basis (w.b.), placed in 3-liter glass containers. The peanut grains were ozonated at the concentration of 450 µg L-1, at 25 and 35 ºC, with gas flow rates of 1.0 and 3.0 L min-1. Time of saturation was determined by quantifying the residual concentration of ozone after the gas passed through the grains to constant mass. The decomposition kinetics of ozone was evaluated after the grain mass was ozone-saturated. For the peanut grains whose moisture content was 7.1% (w.b.), at 25 and 35ºC and with flow rates of 1.0 and 3.0 L min-1, the values obtained for time of saturation of gaseous ozone ranged between 173 and 192 min; the concentration of saturation was approximately 260 µg L-1. For the grains whose moisture content was 10.5% (w.b.), a higher residual concentration of gaseous ozone was obtained at 25 ºC, that of 190 µg L-1. As regards the half-life of ozone, the highest value obtained was equivalent to 7.7 min for grains ozonated at 25 ºC, while for those with moisture content of 10.5% at 35 ºC, half-life was 3.2 min. In the process of ozone decomposition in peanut grains, temperature was concluded to be the key factor. An increase of 10 ºC in the temperature of the grains results in a decrease of at least 43% in the half-life of ozone.<br>Este trabalho foi desenvolvido com o objetivo de avaliar a cinética de decomposição do ozônio em grãos de amendoim. Para avaliar a cinética de decomposição do gás, utilizaram-se amostras de 1 kg de amendoim, com teores de água de 7,1 e 10,5% base úmida (b.u.), acondicionadas em recipientes de vidro com capacidade de 3 L. Os grãos de amendoim foram ozonizados na concentração de 450 µg L-1, nas temperaturas de 25 e 35 ºC, e vazões do gás de 1,0 e 3,0 L min-1. Determinou-se o tempo de saturação, quantificando-se a concentração residual do ozônio após a passagem do gás pela massa de grãos, até que a mesma se mantivesse constante. A cinética de decomposição foi avaliada depois da saturação da massa de grãos com o gás. Nessa etapa, obteve-se a concentração residual do ozônio, depois de períodos de repouso, durante os quais o gás reagia no meio poroso, e dessa forma, era decomposto. Um modelo cinético de primeira ordem foi ajustado aos dados da concentração residual em função do tempo, após linearização. A partir dos valores da constante da taxa de decomposição, definida como a inclinação da reta referente ao modelo cinético de primeira ordem linearizado, foi possível obter a meia-vida do ozônio em grãos de amendoim. Para os grãos de amendoim com teor de água de 7,1% (b.u.), nas temperaturas de 25 e 35 °C, e vazões de 1,0 e 3,0 L min-1, os valores obtidos de tempo de saturação do gás permaneceram na faixa entre 173 e 192 min, com concentração de saturação de aproximadamente 260 µg. L-1. Para os grãos com teor de água de 10,5% b.u., obteve-se maior concentração residual do gás na temperatura de 25 ºC, sendo igual a 190 µg. L-1. No que se refere ao tempo de meia-vida do ozônio, o maior valor obtido foi equivalente a 7,7 min para os grãos ozonizados na temperatura de 25 ºC, enquanto para aqueles com 10,5% de teor de água, na temperatura de 35 ºC, foi de 3,2 min. Concluiu-se que, no processo de decomposição do ozônio em grãos de amendoim, o fator determinante é a temperatura. Observou-se que o aumento de 10 ºC na temperatura dos grãos implica decréscimo de, pelo menos, 43% no tempo de meia-vida do gás

The XXL Survey: XL. Obscuration properties of red AGNs in XXL-N

The combination of optical and mid-infrared (MIR) photometry has been extensively used to select red active galactic nuclei (AGNs). Our aim is to explore the obscuration properties of these red AGNs with both X-ray spectroscopy and spectral energy distributions (SEDs). In this study, we re-visit the relation between optical/MIR extinction and X-ray absorption. We use IR selection criteria, specifically the W1 and W2 WISE bands, to identify 4798 AGNs in the XMM-XXL area (∼25 deg2). Application of optical/MIR colours (r−W2 >  6) reveals 561 red AGNs (14%). Of these, 47 have available X-ray spectra with at least 50 net (background-subtracted) counts per detector. For these sources, we construct SEDs from the optical to the MIR using the CIGALE code. The SED fitting shows that 44 of these latter 47 sources present clear signs of obscuration based on the AGN emission and the estimated inclination angle. Fitting the SED also reveals ten systems (∼20%) which are dominated by the galaxy. In these cases, the red colours are attributed to the host galaxy rather than AGN absorption. Excluding these ten systems from our sample and applying X-ray spectral fitting analysis shows that up to 76% (28/37) of the IR red AGNs present signs of X-ray absorption. Thus, there are nine sources (∼20% of the sample) that although optically red, are not substantially X-ray absorbed. Approximately 50% of these sources present broad emission lines in their optical spectra. We suggest that the reason for this apparent discrepancy is that the r−W2 criterion is sensitive to smaller amounts of obscuration relative to the X-ray spectroscopy. In conclusion, it appears that the majority of red AGNs present considerable obscuration levels as shown by their SEDs. Their X-ray absorption is moderate with a mean of NH ∼ 1022 cm−2