Effect of pre-harvest sanitizer treatments on Listeria survival, sensory quality and bacterial community dynamics on leafy green vegetables grown under commercial conditions.

Leafy green vegetables (LGVs) have large surface areas and can be colonized by various microorganisms including pathogens. In this study, we investigated the effect of pre-harvest sanitizer treatments on the survival of inoculated proxy pathogen Listeria innocua ATCC 33090 and the natural microbial community of mizuna, rocket (arugula), red chard and spinach grown under commercial conditions. Electrolyzed water (e-water), peracetic acid (PAA), and 1-bromo-3-chloro-5-dimethylhydantoin (BCDMH) were tested against water controls. We also observed the subsequent sensorial changes of harvested, bagged LGV leaves over a period of 12 days within chill storage alongside the growth, diversity and structure of bacterial populations determined using 16S rRNA gene amplicon sequencing and total viable counts (TVC). Treatment with PAA resulted in the highest reductions of L. innocua (2.4-5.5 log units) compared to the other treatments (0.25-2.5 log units). On day 0 (24 h after sanitizer application), the TVC on sanitizer treated LGVs were significantly reduced compared to water controls, except for rocket. During storage at 4.5 (±0.5)°C sanitisers only hindered microbial growth on LGVs initially and did not influence final bacterial population levels, growth rates or changes in LGV sample colour, decay, odour and texture compared to water controls. Shelf-life was not extended nor was it reduced. The community structure on LGV types differed though a core set of bacterial amplicon sequence variants (ASV) were present across all samples. No significant differences were observed in bacterial diversity between sanitizer treatments, however sanitizer treated LGV samples had initially reduced diversity compared to water treated samples. The bacterial compositions observed at the end point of storage considerably differed from what was observed at initial point owing to the increase in abundance of specific bacterial taxa, mainly Pseudomonas spp., the abundance and growth responses differing between LGV types studied. This study provides a better understanding on the microbiology and sensory impact of pre-harvest applied sanitiser treatments on different LGVs destined for commercial food use.

Culture-dependent and culture-independent assessment of spoilage community growth on VP lamb meat from packaging to past end of shelf-life.

Packaging and storage temperature are important factors that influence the shelf-life of vacuum packed (VP) meat. In this study the shelf-life of VP bone-in lamb hind shanks stored at 8 °C and -1.2 °C was determined in parallel to analyses of starting and eventual spoilage bacterial communities via Illumina MiSeq based 16S rRNA amplicon sequencing. The mean total viable counts (TVC) and lactic acid bacterial viable counts (LAB) were observed to increase to log 7.5 CFU/cm2 and 7 CFU/cm2 after 6 and 42 days at 8 °C and -1.2 °C and stayed stable until shelf-life termination after 13 and 124 days, respectively. The sequence data showed initial communities were patchily distributed and were mainly derived from skin microbiome taxa likely prevalent within the abattoir. A broad diversity of VP meat associated specific spoilage organisms (SSO) were comparatively abundant in this initial population. Overtime meat spoilage communities developed a distinctive and stable microbiome. At -1.2 °C SSO included mainly Carnobacterium, Yersinia and Clostridium spp. while at 8 °C SSO expanded to include Hafnia, Lactococcus, Providencia spp. Growth curves inferred from the sequence data after taking into account rRNA copy number suggested that SSO growth rates were consistent with overall growth rates determined from TVC and LAB data and are predictable.

[Simultaneous determination of germanium and some major ash forming elements in lignites using a dual-view ICP-OES].

In this article, an ICP-OES method of simultaneous determination germanium and some major ash forming elements especially for Fe, Al, Ca, Mg, K, Na, Ti in lignites is described. An ICP-OES instrument equipped with a dual-view plasma torch and a simultaneous detector was used. This technology allows the simultaneous determination of trace elements and major components in the axial view along with in the radial view. The moderate operation condition of the instrument and analytical wavelength lack of interference from elements in the sample matrix was selected, the spectral background was automaticly eliminated. The obtained coal ashes were dissolved in mixtures of nitric acid, hydrofluoric acid and perchloric acid after coal samples were cinerated. The analytical results were in good agreement with those provided by national standard methods. The detection limit of the instrument is ranged between 0.00039-0.10 microg. x mL(-1), the precision of the method is in the range of 0.79%-2.84%, the average recovery of samples is 92.38%, the proposed method is well suitable for the determination germanium and some major ash forming elements in lignites.

A biomass-supported Na2CO3 sorbent for flue gas desulfurization.

A novel sorbent for SO2 removal has been investigated. The sorbent is obtained by conventional incipient wetness impregnation of abandoned biomaterials (straw or dried leaves) with an aqueous solution of Na2CO3. A material with the composition 80 wt % Na2CO3/straw shows a desulfurization activity which is both higher and faster than that of the reference sample Na2CO3/gamma-Al2O3. The breakthrough and stoichiometric SO2 adsorption efficiencies for 80 wt % Na2CO3/straw reach 48.9% and 80.6%, respectively, at a temperature of 80 degrees C. The adsorption efficiencies are almost constant in the temperature range 70 to 300 degrees C. According to IR and XPS analysis the main products observed on the spent sorbent are sulfite below 150 degrees C and sulfate at 300 degrees C. The Na2CO3 in 80 wt % Na2CO3/straw can potentially be recycled by the oxidation of the straw with concomitant reduction of the sulfite species to elemental sulfur, making the proposed process CO2 neutral.

[Reparation and desulfurization of Na2CO3/straw sorbents for removing SO2 from flue gas].

A series of SO2 sorbents 5%-90% (mass percent) Na2CO3/straw were prepared by conventional incipient wetness impregnation of straw with an aqueous solution of Na2CO3. It was showed that small particle size (< or = 0.28 mm) of the straw and low flow rate (40 mL/min) of the feed gas favor the removal of SO2, while temperature (70 degrees C-300 degrees C) has little effect on the desulfurization efficiency. Based on XRD, SEM and ATR-IR analysis it can be concluded that the Na2CO3 on the surface of the straw is mainly in an amorphous state. The unique structural features of the straw and its interaction with Na2CO3 lead to the amorphous structure having greater surface area (12.14 m2/g) and pore volume (0.093 cm3/g) with a high loading of Na2CO3.