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Aspergillus flavus and Aspergillus niger are fungi which can contaminate dried figs before and after harvest and consequently produce aflatoxins (AFs) and ochratoxin A (OTA). Many approaches have been applied to minimise the growth of these filamentous fungi, mainly involving the use of synthetic fungicides which are limited due to their negative impact on human health and the environment. In this context, biocontrol is a recent approach that needs to be explored. This study evaluated the potential of three volatile organic compounds (VOCs), octanoic acid (OA), 2-phenylethyl acetate (2PEA) and furfuryl acetate (FA), produced by Hanseniaspora uvarum and Hanseniaspora opuntiae yeasts on the growth, germination, gene expression and production of AFs and OTA by A. flavus M144 and A. niger M185 on dried fig-based agar and the incidence rates in dried figs. Two of the three VOCs evaluated (2PEA and FA) effectively controlled A. flavus M144 and A. niger M185 by using at least amounts of 50 μL (715 μL/L in the headspace) for FA and 100 μL (1430 μL/L in the headspace) for 2PEA in dried figs. One of the mode of actions of both compounds consists in early repressing the expression of genes involved in the biosynthesis of AFs (aflR) and OTA (pks) of A. flavus and A. niger, respectively. The results of this study support the application of 2PEA and FA at the early post-harvest stages of dried figs to control mycotoxin accumulation., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Aspergillus flavus is a toxigenic fungal colonizer of fruits and cereals and may produce one of the most important mycotoxins from a food safety perspective, aflatoxins. Therefore, its growth and mycotoxin production should be effectively avoided to protect consumers' health. Among the safe and green antifungal strategies that can be applied in the field, biocontrol is a recent and emerging strategy that needs to be explored. Yeasts are normally good biocontrol candidates to minimize mold-related hazards and their modes of action are numerous, one of them being the production of volatile organic compounds (VOCs). To this end, the influence of VOCs produced by Hanseniaspora opuntiae L479 and Hanseniaspora uvarum L793 on growth, expression of the regulatory gene of the aflatoxin pathway ( aflR) and mycotoxin production by A. flavus for 21 days was assessed. The results showed that both yeasts, despite producing different kinds of VOCs, had a similar effect on inhibiting growth, mycotoxin biosynthetic gene expression and phenotypic toxin production overall at the mid-incubation period when their synthesis was the greatest. Based on the results, both yeast strains, H. opuntiae L479 and H. uvarum L793, are potentially suitable as a biopreservative agents for inhibiting the growth of A. flavus and reducing aflatoxin accumulation.

Rotting caused by grey mould (Botrytis cinerea) is a concerning disease for numerous crops both pre- and postharvest stages. Application of antagonistic yeasts is a promising strategy for controlling grey mould incidence which could mitigate undesirable consequences of using synthetic fungicides. In this work, a screening for detection of yeasts isolated from figs producers of antifungal volatile organic compounds (VOCs) were performed by confrontation in double dishes systems. Eleven out of 34 yeasts confronted reduced B. cinerea growth parameter in vitro. This reduction was correlated (p ≤ 0.050) with the production of 10 volatile compounds: two acids (acetic acid and octanoic acid), 7 esters (Ethyl propionate, n-Propyl acetate, Isobutyl acetate, 2-methylbutyl acetate, furfuryl acetate, phenylmethyl acetate, 2-phenylethyl acetate) and one ketone (Heptan-2-one). In bases on in vitro assay, Hanseniaspora uvarum 793 was applied to in vivo assays with strawberries and cherries. The reduction of incidence of B. cinerea in strawberries at 7 °C and 25 °C was 54.9 and 72.1% after 6 and 3 days, respectively. The reduction of incidence of B. cinerea in cherries at 7 °C and 25 °C was 48.9 and 45.6% after 5 and 4 days, respectively. These results showed that VOCs produced by Hanseniaspora uvarum 793 are effective in the control of incidence of Botrytis cinerea in fruits, being a potential alternative to chemical fungicide., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The photocatalytic efficiency of TiO(2)-SiMgO(x) plates to oxidize H(2)S was first evaluated in a flat laboratory reactor with 50 mL min(-1) synthetic air containing 100 ppm H(2)S in the presence of humidity. The use of the photocatalyst-adsorbent hybrid material enhanced the photocatalytic activity in terms of pollutant conversion, selectivity, and catalyst lifetime compared to previous H(2)S tests with pure TiO(2) because total H(2)S elimination was maintained for more than 30 operating hours with SO(2) appearing in the outlet as reaction product only after 18 h. Subsequently, the hybrid material was successfully tested in a photoreactor prototype to treat real polluted air in a wastewater treatment plant. For this purpose, a new tubular photocatalytic reactor that may use solar radiation in combination with artificial radiation was designed; the lamp was turned on when solar UV-A irradiance was below 20 W m(-2), which was observed to be the minimum value to ensure 100% conversion. The efficient distribution of the opaque photocatalyst inside the tubular reactor was achieved by using especially designed star-shaped structures. These structures were employed for the arrangement of groups of eight TiO(2)-SiMgO(x) plates in easy-to-handle channelled units obtaining an adequate flow regime without shading. The prototype continuously removed during one month and under real conditions the H(2)S contained in a 1 L min(-1) air current with a variable inlet concentration in the range of tens of ppmv without release of SO(2)., (© 2012 American Chemical Society)

In this study, photoactive titanium dioxide films deposited on aluminium substrates using Radio-Frecquency (RF) magnetron sputtering have been developed, with the goal of advancing this technology for indoor air treatment. With this goal in mind, the influence of deposition parameters, namely post annealed heat treatment, working pressure and deposition time, on the physico-chemical properties of the layers has been studied. Photocatalytic efficiency for trichloroethylene degradation in gas phase, and self-cleaning performance of the developed materials have been evaluated. Samples have been thoroughly examined using different techniques (SAXRD, UV-Vis, SEM-EDX, contact angle, profilometry, hardness, among others) in order to determine the structural-photocatalytic relationship. The findings indicate that high-temperature annealing promotes the diffusion of alumina, copper and iron ions towards the surface of the samples resulting in the formation of aluminium alloys. These alloyed species can act as recombination centres adversely affecting the photocatalytic activity. The sputtering pressure also affects the nature of the titanium phases formed during the sputtering. Increasing the thickness of the TiO 2 layer leads to rougher surfaces with TiO 2 -anatase as the predominant crystal phase. Annealing temperatures of 350 °C, argon pressures between 0.8 and 1.0 Pa, and TiO 2 layer thickness of ca. 110 nm are the optimal conditions to prepare well-adhered TiO 2 layers with high photocatalytic performance. UV-A photoinduced superhydrophilicity phenomena was observed for all TiO 2 /Al materials. [Display omitted] • Highly photoactive TiO 2 coatings on aluminum substrate by RF magnetron sputtering were developed. • Calcination temperature, working pressure and sputtering deposition time define the photocatalytic performance. • Titania coatings with high homogeneity and mechanical resistance. • Aluminum alloys with iron, copper and titanium phases are detected on the surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of highly photoactive materials based on titania on polymeric surfaces. • Roll-coating technique is an easily scale-up method for deposition of coatings. • Robust and stable photoactive composites with self-cleaning properties. • In-situ measurements allow the analysis of superhydrophilic properties. • Correlation between the removal of pollutants in gas phase and self-cleaning ability. In this work we have studied the photocatalytic and self-cleaning properties of TiO 2 layers immobilized on polymeric panels, as passive elements for air treatment. In order to achieve easy scale-up technologies for the preparation of coatings, roller-coating technique was selected, comparing the results with those prepared by dip-coating. Composites were characterized by SAXRD, UV–Vis DRS spectroscopy, profilometry, N 2 adsorption–desorption, SEM and AFM microscopy. The adherence of the coating was evaluated according the ASTM D3359 standard adhesive tape test. The photocatalytic properties of the materials were evaluated by the photodegradation of trichloroethylene or formaldehyde, as model volatile organic compounds, in the gas phase. The hydrophilic-hydrophobic properties were measured by studying the in-situ variation of the water contact angle with time and UV-A irradiation. Moreover, the self-cleaning properties were analyzed according to ISO 27448:2009 for oleic acid removal. Although coatings of approximately ca. 250 nm layer thickness can be prepared by both techniques, roller-coating allows the material deposition with a coral-like structure in a single and simple step. Surface roughness was promoted by roller process. The developed materials present high photocatalytic performance for the elimination of both model pollutants in the gas phase. Aging tests under outdoor conditions and Scotch tape test show the stability and resistance of the coatings. In-situ irradiation measurements show the superhydrophilic character of the coatings. Water contact angle lower than 10 ° after 300 min of UV-A irradiation was achieved for oleic acid removal. The combination of TiO 2 nanoparticles with different crystal structures and sizes improves the photocatalytic performance. A correlation between the ability for pollutants degradation in gas phase and the self-cleaning properties (in-situ or oleic acid measurements) was determined. [ABSTRACT FROM AUTHOR]

Decahedral anatase titania particles (DAPs) immobilized on zeolites (zeolite/DAP hybrids), have been prepared by the first time. DAPs have been synthesized from titanium chloride (TiCl4) through a gas-phase reaction process by rapid heating and quenching. DAPs with well-defined {101} and {001} facets were synthetized and dispersed onto the zeolites. The incorporation of an 8wt% of DAPs into the zeolites has been achieved by means of the freezing-drying technique. Two types of zeolites (ZSM-5 and zeolite Y) with different SiO2/Al2O3 contents have been selected as adsorbents. The photocatalytic properties for the degradation of representative volatile organic compounds (VOC), i.e. acetaldehyde, formaldehyde or trichloroethylene were analyzed under batch and continuous flow reactors. Raw materials and composites were characterized by SEM, N2 adsorption-desorption, UV-vis spectroscopy, XRD, zeta potential and the amount of VOC adsorbed was measured at dynamic conditions. Zeolite/DAP hybrids combine the textural and crystalline properties of zeolite and DAPs phases. The zeolite type (crystal structure, SiO2/Al2O3 ratio and surface net charge) play a relevant role in the dispersion of DAPs. Zeolite/DAP composites show better photocatalytic performance than those prepared with commercial TiO2 due to the presence of {001} facets in the former. The composites prepared with hydrophobic ZSM-5 and DAPs, are the most versatile materials for photooxidation of aldehydes and organochloride compounds, with substantially less formation of non-desirable reaction products respect to those based on benchmark TiO2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mesoporous carbon/TiO 2 hybrids for VOCs depollution of air streams. • Optimising the TiO 2 particles incorporation on mesoporous carbon is a key parameter. • Hydrophobic carbon/TiO 2 hybrid increase ca. 15–20 % the photoactivity of bare TiO 2. • The photocatalytic system developed allows the treatment of polluted air streams at demanding operating conditions. The performance of a series of Adsorbent-Photocatalyst Hybrids (APHs) based on graphitized mesoporous carbons and TiO 2 , for the photooxidation of formaldehyde and trichloroethylene in gas phase has been studied. TiO 2 was incorporated to different carbonaceous materials including a commercial mesoporous carbon, Starbons with different hydrophobicity and micro-mesoporosity and activated carbon. However, the actual performance of the APHs is strongly affected by the nature of the carbonaceous material and the synthesis route selected to prepare the carbon/TiO 2 hybrids. The results obtained show the importance of the preparation route for the optimum distribution of the TiO 2 nanoparticles on the porous carbon and the influence on its photocatalytic properties. The photocatalysts prepared via mechanical mixing exhibit higher activity than those synthetized by incipient wet impregnation. The hybrid based on the hydrophobic Starbon ST-800 and TiO 2 achieved total removal of formaldehyde at high gas flow, improving by a 15 % the degradation rate of bare TiO 2 , without formation of undesired by-products. Moreover, in the case of the organochloride compound, both the reaction rate and the selectivity to CO 2 were promoted over ST-800/TiO 2 , being the most photoactive material of the series with a great stability over reaction time. [ABSTRACT FROM AUTHOR]