Cyclodextrin polymers and salts: An Eco-Friendly combination to modulate the removal of sulfamethoxazole from water and its release.

This study is aimed to validate water-insoluble cyclodextrin-epichlorohydrin polymer (ß-EPI) use to remove, by adsorption, sulfamethoxazole (SMX) from water and then release it via an environmentally friendly treatment so that the adsorbent can be recycled according to one of the objectives of the European Project Life "Clean up" (LIFE 16 ENV/ES/000169). SMX adsorption experiments on ß-EPI polymer in-batch were performed, varying different experimental parameters of the process, such as contact time, pH values, and so on. The adsorption process, exothermic and driven by enthalpy, occurs both through the formation of inclusion and association complexes, involves mainly hydrophobic and hydrogen bonds, has a rate-controlling step depending on both pollutant concentration and adsorbent dose and can be described by the Freundlich and Dubinin-Radushkevich models which confirm the polymer surface heterogeneity and the physical nature of the adsorption. The presence of salts gives rise to a general decrease in the SMX sorption, mainly in the case of bromide, which was used to promote the SMX desorption and regenerate the adsorbent. The overall results indicate that ß-EPI polymer is not only capable of removing SMX by adsorption with short contact times and a qmax = 10 mg/g but it is also easily regenerated using a 0.5 M solution of sodium bromide without any loss in the adsorption performance and with obvious economic and environmental advantages. The polymer as synthesized, with SMX adsorbed and regenerated was characterized by FT-IR, SEM and DSC.

Removal and toxicity evaluation of a diverse group of drugs from water by a cyclodextrin polymer/pulsed light system.

The presence of pharmaceutical compounds (PhCs) in the effluents of wastewater treatment plants (WWTPs) is an ecological concern. The issue could be alleviated by trapping those substances by cyclodextrin (CD) polymers or photolyzing them by pulsed light (PL). Consequently, a sequential CD polymer/PL system was tested for the removal of PhCs. Firstly, a survey detected the presence of recurrent PhCs in the effluents of local WWTPs. Then, pure water was spiked with 21 PhCs, 100 µg/L each one. The three-dimensional network provides amphiphilic features to the CD polymer that reduced the pollutant concentration by 77 %. Sorption involves a plead of physical and chemical mechanisms hindering the establishment of a general removal model for all compounds. The performed simulations hint that the retention capacity mainly correlates with the computed binding energies, so that theoretical models are revealed as valuable tools for further improvements. The complementary action of PL rose the elimination to 91 %. The polymer can be reused at least 10 times for ibuprofen (model compound) removal, and was able to eliminate the ecotoxicity of an ibuprofen solution. Therefore, this novel sequential CD polymer/PL process seems to be an efficient alternative to eliminate PhCs from wastewater.

Application of mathematical models for bacterial inactivation curves using Hypericin-based photosensitization.

AIMS: The aim of this study was to evaluate which of the three mathematical models (Weibull, Geeraerd and Logistic) makes the best approximation for Hypericin-based photosensitization bacterial inactivation. METHODS AND RESULTS: The inactivation of common food-borne pathogens Listeria monocytogenes and Bacillus cereus has been analysed. Three models, Weibull, Logistic and Geeraerd, have been used for different treatment conditions (10(-7 ) mol l(-1) and 10(-8)  mol l(-1) Hypericin concentrations and 2 and 60 min incubation time). The Logistic method showed better correspondence (estimated R(2)  ≥ 0·98, RMSE ≤ 0·41), than the Weibull (estimated R(2)  ≥ 0·91, RMSE ≤ 0·90) and the Geeraerd model (R(2)  ≥ 0·83, RMSE ≤ 1·27). After evaluation of best fitting model for the dependence of bacterial population reduction on irradiation time, the parameters describing treatment efficiency have been calculated. CONCLUSIONS: Our results indicate that the Logistic model described in the best way the inactivation of B. cereus and L. monocytogenes by Hypericin-based photosensitization. SIGNIFICANCE AND IMPACT OF THE STUDY: This study identified a best model for describing bacterial inactivation by hypericin-based photosensitization, which provides a way to evaluate the efficacy of different treatment conditions for this novel decontamination technique.

Methodology for modeling the disinfection efficiency of fresh-cut leafy vegetables wash water applied on peracetic acid combined with lactic acid.

A methodology to i) assess the feasibility of water disinfection in fresh-cut leafy greens wash water and ii) to compare the disinfectant efficiency of water disinfectants was defined and applied for a combination of peracetic acid (PAA) and lactic acid (LA) and comparison with free chlorine was made. Standardized process water, a watery suspension of iceberg lettuce, was used for the experiments. First, the combination of PAA+LA was evaluated for water recycling. In this case disinfectant was added to standardized process water inoculated with Escherichia coli (E. coli) O157 (6logCFU/mL). Regression models were constructed based on the batch inactivation data and validated in industrial process water obtained from fresh-cut leafy green processing plants. The UV254(F) was the best indicator for PAA decay and as such for the E. coli O157 inactivation with PAA+LA. The disinfection efficiency of PAA+LA increased with decreasing pH. Furthermore, PAA+LA efficacy was assessed as a process water disinfectant to be used within the washing tank, using a dynamic washing process with continuous influx of E. coli O157 and organic matter in the washing tank. The process water contamination in the dynamic process was adequately estimated by the developed model that assumed that knowledge of the disinfectant residual was sufficient to estimate the microbial contamination, regardless the physicochemical load. Based on the obtained results, PAA+LA seems to be better suited than chlorine for disinfecting process wash water with a high organic load but a higher disinfectant residual is necessary due to the slower E. coli O157 inactivation kinetics when compared to chlorine.

Belgian and Spanish consumption data and consumer handling practices for fresh fruits and vegetables useful for further microbiological and chemical exposure assessment.

A consumer survey was organized in Spain and Belgium to obtain consumption data and to gain insight into consumer handling practices for fresh vegetables consumed raw or minimally processed (i.e., heads of leafy greens, bell peppers, tomatoes, fresh herbs, and precut and packed leafy greens) and fruits to be consumed without peeling (i.e., apples, grapes, strawberries, raspberries, other berries, fresh juices, and precut mixed fruit). This information can be used for microbiological and/or chemical food safety research. After extensive cleanup of rough databases for missing and extreme values and age correction, information from 583 respondents from Spain and 1,605 respondents from Belgium (18 to 65 years of age) was retained. Daily intake (grams per day) was calculated taking into account frequency and seasonality of consumption, and distributions were obtained that can be used in quantitative risk assessment for chemical hazards with chronic effects on human health. Data also were recalculated to obtain discrete distributions of consumption per portion and the corresponding frequency of consumption, which can be used in acute microbiological risk assessment or outbreak investigations. The ranked median daily consumption of fruits and vegetables was similar in Spain and Belgium: apple > strawberry > grapes > strawberries and raspberries; and tomatoes > leafy greens > bell peppers > fresh herbs. However, vegetable consumption was higher (in terms of both portion and frequency of consumption) in Spain than in Belgium, whereas the opposite was found for fruit consumption. Regarding consumer handling practices related to storage time and method, Belgian consumers less frequently stored their fresh produce in a refrigerator and did so for shorter times compared with Spanish consumers. Washing practices for lettuce heads and packed leafy greens also were different. The survey revealed differences between these two countries in consumption and consumer handling practices, which can have an impact on outcomes of future microbiological or chemical risk assessment studies.

Shelf-life extension of minimally processed carrots by gaseous chlorine dioxide.

Chlorine dioxide (ClO(2)) gas is a strong oxidizing and sanitizing agent that has a broad and high biocidal effectiveness and big penetration ability; its efficacy to prolong the shelf-life of a minimally processed (MP) vegetable, grated carrots (Daucus carota L.), was tested in this study. Carrots were sorted, their ends removed, hand peeled, cut, washed, spin dried and separated in 2 portions, one to be treated with ClO(2) gas and the other to remain untreated for comparisons. MP carrots were decontaminated in a cabinet at 91% relative humidity and 28 degrees C for up to 6 min, including 30 s of ClO(2) injection to the cabinet, then stored under equilibrium modified atmosphere (4.5% O(2), 8.9% CO(2), 86.6% N(2)) at 7 degrees C for shelf-life studies. ClO(2) concentration in the cabinet rose to 1.33 mg/l after 30 s of treatment, and then fell to nil before 6 min. The shelf-life study included: O(2) and CO(2) headspace concentrations, microbiological quality (mesophilic aerobic bacteria, psychrotrophs, lactic acid bacteria, and yeasts), sensory quality (odour, flavour, texture, overall visual quality, and white blushing), and pH. ClO(2) did not affect respiration rate of MP carrots significantly (alpha< or =0.05), and lowered the pH significantly (alpha< or =0.05). The applied packaging configuration kept O(2) headspace concentrations in treated samples in equilibrium and prevented CO(2) accumulation. After ClO(2) treatment, the decontamination levels (log CFU/g) achieved were 1.88, 1.71, 2.60, and 0.66 for mesophilic aerobic bacteria, psychrotrophs, and yeasts respectively. The initial sensory quality of MP carrots was not impaired significantly (alpha< or =0.05). A lag phase of at least 2 days was observed for mesophilic aerobic bacteria, psychrotrophs, and lactic acid bacteria in treated samples, while mesophilic aerobic bacteria and psychrotrophs increased parallelly. Odour was the only important attribute in sensory deterioration, but it reached an unacceptable score when samples were already rejected from the microbiological point of view. The shelf-life extension was limited to one day due to the restricted effect of the ClO(2) treatment on yeast counts. Nevertheless, ClO(2) seems to be a promising alternative to prolong the shelf-life of grated carrots.

Factors affecting the inactivation of micro-organisms by intense light pulses.

AIM: To determine the influence of several factors on the inactivation of micro-organisms by intense light pulses (ILP). METHODS AND RESULTS: Micro-organisms on agar media were flashed 50 times under different conditions and their inactivation measured. Micro-organisms differed in sensitivity to ILP but no pattern was observed among different groups. Several enumeration methods to quantify the effect of ILP were investigated and showed relevant differences, shading effect and photoreactivation accounted for them, the strike method yielded the most reliable results. Higher decontamination efficiencies were obtained for Petri dishes located close to the strobe and inside the illumination cone. Decontamination efficacy decreased significantly at contamination levels >6.85 log(10). After 13 successive treatments, no resistance to ILP could be demonstrated. Media warming up depended on the distance from the strobe and the number of flashes. CONCLUSIONS: For an industrial implementation: the position and orientation of strobes in an unit will determine the lethality, products should be flashed as soon as possible after contamination occurs, a cooling system should be used for heat-sensitive products and flashed products should be light protected. No resistant flora is expected to develop. SIGNIFICANCE AND IMPACT OF THE STUDY: Conclusions derived from this work will allow a better implementation of this decontamination technique at industrial level.

Intense light pulses decontamination of minimally processed vegetables and their shelf-life.

Intense light pulses (ILP) is a new method intended for decontamination of food surfaces by killing microorganisms using short time high frequency pulses of an intense broad spectrum, rich in UV-C light. This work studied in a first step the effect of food components on the killing efficiency of ILP. In a second step, the decontamination of eight minimally processed (MP) vegetables by ILP was evaluated, and thirdly, the effect of this treatment on the shelf-life of MP cabbage and lettuce stored at 7 degrees C in equilibrium modified atmosphere packages was assessed by monitoring headspace gas concentrations, microbial populations and sensory attributes. Proteins and oil decreased the decontamination effect of ILP, whilst carbohydrates and water showed variable results depending on the microorganism. For this reason, high protein and fat containing food products have little potential to be efficiently treated by ILP. Vegetables, on the other hand, do not contain high concentrations of both compounds and could therefore be suitable for ILP treatment. For the eight tested MP vegetables, log reductions up to 2.04 were achieved on aerobic mesophilic counts. For the shelf-life studies, respiration rates at 3% O2 and 7 degrees C were 14.63, 17.89, 9.17 and 16.83 ml O2/h kg produce for control and treated cabbage, and control and treated lettuce respectively; used packaging configurations prevented anoxic conditions during the storage times. Log reductions of 0.54 and 0.46 for aerobic psychrothrophic count (APC) were achieved after flashing MP cabbage and lettuce respectively. APC of treated cabbage became equal than that from control at day 2, and higher at day 7, when the tolerance limit (8 log) was reached and the panel detected the presence of unacceptable levels of off-odours. Control never reached 8 log in APC and were sensory acceptable until the end of the experiment (9 days). In MP lettuce, APC of controls reached rejectable levels at day 2, whilst that of treated samples did after 3 days. Both samples were sensory unacceptable at day 3, controls because of bad overall visual quality (OVQ), off-odour and leaf edge browning and treated samples due to bad OVQ; browning inhibitors might be proposed to preserve OVQ. Yeasts and lactic acid bacteria counts were low in all the samples. It seems that ILP treatment alone under the conditions used in this work does not increase MP vegetables shelf-life in spite of the reduction in the initial microbial load.

Characterization of avocado (Persea americana mill.) varieties of low oil content.

Several avocado varieties of low oil content (6.73-8.07%) from Venezuela (Booth 1, Booth 7, Ceniap 2, Figueroa, Guacara Morado, Luiz de Queiroz, Princesa, Quebrada Seca, Santa Clara, Santa Cruz, Taylor, and Tonnage) were characterized for pulp oil and moisture; weight (whole fruit, seed, pulp, and peel); length, width, and fruit shape; peel characteristics (roughness, color, and hand peeling); and ripeness time. Oil plus moisture percentages were between 87.62 and 93.71. Pulp percentage of Quebrada Seca was the lowest of the 49 varieties studied, and its seed percentage the highest. Princesa had the highest pulp percentage (76%). Seven varieties were pyriform and five ovate, seven had rough peel and five smooth peel, and four of them had purple peel and the others green. Five varieties were easy to hand peel. Peak ripening of some varieties was at 4-9 days. Princesa is the variety with the highest potential yield with 67944 kg of fruit/ha, 51675 kg of pulp/ha, 3679 kg of oil/ha, and 3016 kg of starch/ha.