This review includes an overview of the most important preventive measures along the farm to fork chain to prevent microbial contamination of leafy greens. It also includes the technological and ...managerial interventions related to primary production, postharvest handling, processing practices, distribution, and consumer handling to eliminate pathogens in leafy greens. When the microbiological risk is already present, preventive measures to limit actual contamination events or pathogen survival are considered intervention strategies. In codes of practice the focus is mainly put on explaining preventive measures. However, it is also important to establish more focused intervention strategies. This review is centered mainly on leafy vegetables as the commodity identified as the highest priority in terms of fresh produce microbial safety from a global perspective. There is no unique preventive measure or intervention strategy that could be applied at one point of the food chain. We should encourage growers of leafy greens to establish procedures based on the HACCP principles at the level of primary production. The traceability of leafy vegetables along the chain is an essential element in ensuring food safety. Thus, in dealing with the food safety issues associated with fresh produce it is clear that a multidisciplinary farm to fork strategy is required.
Increasing concerns about the possible formation of carcinogenic compounds and the emergence of new, more tolerant pathogens, have raised questions on the use of chlorine in fresh-cut produce. There ...is a growing need to investigate the efficacy of new commercial sanitizing and other alternative technologies. In the present study, the effectiveness of chlorine and other commercial sanitizer agents (Sanova, Sanoxol 20, Tsunami 100, Purac FCC 80, Citrox 14W and Catallix) was evaluated on epiphytic microorganisms and their influence on the sensory quality of fresh-cut escarole and lettuce. Different sanitizer concentrations (manufacturer's recommended dose and half of this dose) and application systems (submersion and spray) were also compared. The antimicrobial efficacy of the treatments was evaluated, initially after washing, and after 8 days of storage simulating a commercial shelf-life (3 days at 4
°C
+
5 days at 8
°C). All the tested washing solutions were more effective in reducing the microbial load than water washes, particularly in fresh-cut escarole. However, the microbial load of fresh-cut escarole and lettuce after 8 days of storage was very similar for most of the treatments despite the different application systems and concentrations of the sanitizers. Clearly epiphytic microorganisms of fresh-cut escarole and lettuce were able to grow rapidly during storage under low temperature, reaching similar or higher values than the unwashed fresh-cut produce at the day of production. The overall visual quality of fresh-cut salad leaves was scored as good or very good (≥6) after 8 days of storage, except for the product washed with Purac. Thus, despite the high number of mesophilic bacteria present in the product, between 6 and 8
log
cfu
g
−1, it was not associated with a detrimental quality. Therefore, the determination of the initial epiphytic reductions of fresh-cut products after washing with different sanitizing agents provides little information about the microbial or sensory quality of the product at the time of consumption.
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.
This study aimed to characterize an animal model of colorectal cancer (CRC) in the early stages of disease development. Twenty-nine male Wistar rats were divided into two control groups (CTRL1 and ...CTRL2), receiving EDTA-saline injections and two induced groups (CRC1 and CRC2), receiving 1,2-dimethylhydrazine (DMH) injections for seven consecutive weeks. CRC1 and CTRL1 were euthanized at the 11th week, while CRC2 and CTRL2 were euthanized at the 17th week. DMH treatment decreased microhematocrit values and IL-6, ghrelin, and myostatin serum levels. Histopathological analysis of intestinal sections showed that DMH-treated rats were characterized by moderate to severe epithelial dysplasia. An adenoma was observed in one animal (CRC2 group), and the presence of inflammatory infiltrate at the intestinal level was primarily observed in DMH-treated animals. DMH also induced Ki-67 immunoexpression. The gut microbiota analysis showed a higher abundance of Firmicutes, Clostridia, Clostridiales, Peptostreptococcaceae,
,
and
in CRC than CTRL rats, whereas Prevotellaceae,
,
and
levels were more prevalent in CTRL animals. Our results suggest that this model could be helpful to investigate chemoprevention in the early stages of CRC.
Chlorine dioxide (ClO
2) has been postulated as an alternative to sodium hypochlorite (NaClO) for fresh-cut produce sanitization to avoid risks associated with chlorination by-products. Experiments ...were performed to determine the prevention of cross-contamination of fresh-cut lettuce by
Escherichia coli using chlorine dioxide (3 mg/L) or sodium hypochlorite (100 mg/L) as sanitation agents. The efficacy of these sanitation solutions was evaluated simulating as much as possible the conditions of a fresh-cut processing line. Thus, to evaluate the potential risk of cross-contamination during pre-washing, inoculated fresh-cut lettuce was pre-washed and after that non-inoculated lettuce was then pre-washed in the same water. After this pre-washing, non-inoculated lettuce was cross-contaminated, changing from 0 to 3.4 log units of
E. coli cells. During washing with sanitizers, none of the tested sanitation agents significantly reduced
E. coli counts in both inoculated and cross-contaminated lettuce. These results suggest that when cross-contamination occurs, even if the event is recent, subsequent sanitation steps are inefficient for inactivating
E.
coli cells on the vegetable tissue. However, chlorine dioxide and sodium hypochlorite solutions were able to inactivate most
E. coli cells that passed from inoculated product to wash water. Therefore, they might be able to avoid cross-contamination between clean and contaminated product during the washing step. Scanning electron microscopy micrographs indicated that bacterial cells were mainly located in clusters or tissue stomata where they might be protected, which explains the low efficacy of sodium hypochlorite and chlorine dioxide solutions observed in this study.
HIV-1-associated neurocognitive disorders (HAND) in stable patients undergoing antiretroviral therapy (ART) may result from ongoing immune dysregulation and chronic inflammation. A contributing ...factor may result from the unstable HLA class I allele, HLA-C*07.
To assess the genetic profile of killer-cell immunoglobulin-like receptors (KIR), human leukocyte antigens (HLA), and immune activation or senescence markers and their association with HAND in stable HIV-1 patients receiving ART.
An observational cross-sectional study was carried out with 96 patients with asymptomatic or symptomatic HAND. HLA and KIR as well as immune activation/senescence biomarkers in peripheral blood cells were assessed by SSO-Luminex typing and flow cytometry, respectively.
HLA-C*07 is associated with symptomatic HAND. The frequency of two copies of HLA-C*07 was higher in patients with symptomatic than with asymptomatic HAND (12.0 vs. 2.2%,
< 0.001). The percentage of senescent CD8
CD28
T-cells was higher in patients with two copies of HLA-C*07 (
< 0.05). In patients with symptomatic HAND, the percentages of non-senescent CD8
CD28
T cells were inversely proportional to the number of copies of the HLA-C*07 (
< 0.05).
Patients with symptomatic HAND showed a higher frequency of the homozygotic unstable HLA-C*07 allotype, which could be associated with neurocognitive complications. Two copies of HLA-C*07 were associated with immune senescent T lymphocyte profiles characterized by the loss of CD28 expression.
The efficacy of an electrochemical treatment in water disinfection, using boron-doped diamond electrodes, was studied and its suitability for the fresh-cut produce industry analyzed. Tap water (TW), ...and tap water supplemented with NaCl (NaClW) containing different levels of organic matter (Chemical Oxygen Demand (COD) around 60, 300, 550 ± 50 and 750 ± 50 mg/L) obtained from lettuce, were inoculated with a cocktail of Escherichia coli O157:H7 at 105 cfu/mL. Changes in levels of E. coli O157:H7, free, combined and total chlorine, pH, oxidation–reduction potential, COD and temperature were monitored during the treatments. In NaClW, free chlorine was produced more rapidly than in TW and, as a consequence, reductions of 5 log units of E. coli O157:H7 were achieved faster (0.17, 4, 15 and 24 min for water with 60, 300, 500 and 750 mg/L of COD, respectively) than in TW alone (0.9, 25, 60 min and 90 min for water with 60, 300, 600 and 800 mg/L of COD, respectively). Nonetheless, the equipment showed potential for water disinfection and organic matter reduction even without adding NaCl. Additionally, different mathematical models were assessed to account for microbial inactivation curves obtained from the electrochemical treatments.
► Electrochemical disinfection was tested in process wash water from the fresh-cut lettuce. ► Escherichia coli O157:H7 has been used as a model, due to its relevance in the fresh-cut products. ► Electrochemical treatment with BDD electrodes eliminated pathogens and COD of process wash water. ► This technology is suitable for the fresh-cut industry to maintain quality of wash water.
The use of ozonated water as a sanitizer to extend the shelf life of fresh-cut lettuce and the effect on the antioxidant constituents (polyphenols and vitamin C) were investigated. Fresh-cut iceberg ...lettuce (Lactuca sativa L.) was washed at 4 °C using three different ozonated water dips 10, 20, and 10 activated by ultraviolet C (UV-C) light mg L-1 min total ozone dose, and the dips were compared with water and chlorine rinses. Treated lettuce was packaged in air or active modified atmosphere packaging (MAP) (4 kPa of O2 + 12 kPa of CO2 balanced with N2) and stored for 13 days at 4 °C. Despite its strong oxidizing activity, ozonated water did not stimulate the respiratory activity of fresh-cut lettuce. Moreover, ozonated water maintained the initial visual appearance of fresh-cut lettuce and controlled browning during storage in air. Initially, ozonated water and chlorine reduced the total mesophilic population by 1.6 and 2.1 log, respectively, when compared with water. Active MAP was effective in controlling total microbial growth, achieving 2.0 log reduction in relation to samples stored in air at the end of storage. On the other hand, active MAP caused a 2.0−3.5 reduction of coliforms on sanitized samples compared with water-washed samples. The most efficient treatments were ozone 20 and ozone 10 activated by UV-C, which were as effective as chlorine. Changes in individual phenolic compounds were independent of the washing treatments. In air, chlorogenic and isochlorogenic acid contents increased noticeably after 13 days while monocaffeoyltartaric and dicaffeoyltartaric acids remained unchanged. MAP effectively suppressed accumulation of caffeoylquinic derivatives, whereas caffeoyltartaric derivatives decreased during MAP storage to reach similar levels. The content of vitamin C (ascorbic acid and dehydroascorbic acid) decreased during storage, particularly under MAP. Ozonated water could be an alternative sanitizer to chlorine for fresh-cut lettuce due to good retention of sensorial quality and browning control with no detrimental reduction in the antioxidant constituents. Keywords: Lactuca sativa L.; browning; chlorine; microbial quality; minimal processing; modified atmosphere packaging; polyphenols; sanitizers; sensory quality; vitamin C
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.
•HPU and a residual PAA concentration were effective for water reconditioning.•HPU combined with PAA totally inactivated Escherichia coli O157:H7 and Salmonella.•Lower efficacy was observed for the inactivation of Listeria monocytogenes.•OA/PC modified adversely the physico-chemical characteristics of recycled water.
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