Morphological and structural characterization of WO3 and Cr-WO3 thin films synthesized by sol-gel process

WO₃ thin films were prepared by spin-coating methanol solutions of a tungsten chloromethoxide, and easily modified with Cr by the addition of Cr 2-ethylhexanoate. The films were heat-treated up to 700 °C, and characterized by X-ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and Electron Energy Loss spectroscopy. The film morphology was rough and porous, not depending on Cr presence, while their structure was constituted by packed spheroidal or elongated dense structures, giving rise to the peculiar film surface morphology. Cr was distributed in the film structure without phase separations, up to as high as 5% Cr atomic concentration.     

Diversity,competition, extinction: the ecophysics of language change

As indicated early by Charles Darwin, languages behave and change very much like living species. They display high diversity, differentiate in space and time, emerge and disappear. A large body of literature has explored the role of information exchanges and communicative constraints in groups of agents under selective scenarios. These models have been very helpful in providing a rationale on how complex forms of communication emerge under evolutionary pressures. However, other patterns of large-scale organization can be described using mathematical methods ignoring communicative traits. These approaches consider shorter time scales and have been developed by exploiting both theoretical ecology and statistical physics methods. The models are reviewed here and include extinction, invasion, origination, spatial organization, coexistence and diversity as key concepts and are very simple in their defining rules. Such simplicity is used in order to catch the most fundamental laws of organization and those universal ingredients responsible for qualitative traits. The similarities between observed and predicted patterns indicate that an ecological theory of language is emerging, supporting (on a quantitative basis) its ecological nature, although key differences are also present. Here, we critically review some recent advances and outline their implications and limitations as well as highlight problems for future research.     

The effect of sugar concentration and starter culture on instrumental and sensory textural properties of chorizo-Spanish dry-cured sausage

In this study, instrumental and sensory textural properties of chorizo with different levels of glucose (0.1%, 0.5% and 1.0%) and with different starter cultures (Lactobacillus sakei K29, Pediococcus sp. P22 and Pediococcus sp. P208) were studied as well as the relationship between them. The ripening process was followed by physico-chemical and microbiological analysis. Starter culture and concentration of glucose had a highly significant effect on pH, moreover an interactive effect of both factors was found; and also of day of ripening and both starter culture and concentration of glucose. In general terms, changes of pH over time are influenced by the presence of sugar and starter culture even if all chorizos showed at first a rapid decrease, a stay or slow decrease, and a final rise. Texture profile analysis (TPA) proved that hardness and chewiness differ significantly among chorizos with or without starter cultures, except in the batch with 0.1% sugar. Furthermore, the highest values in both textural parameters were found in batches with 0.5% and 1% sugar. The texture differences between chorizos just described were also noticeable in the sensorial evaluation. Likewise, instrumental textural attributes showed significant correlations with sensorial analysis.     

Volatile ester-synthesising capacity in ‘Tardibelle’ peach fruit in response to controlled atmosphere and 1-MCP treatment

Peach fruit is highly perishable, which drastically restricts storage potential and marketing possibilities. Although aroma is a very important attribute for sensory quality of peach, post-harvest procedures, aimed at extending commercial availability of fruit, have focused preferentially on other quality aspects. In this work, we were interested in assessing the effect of 1-methylcyclopropene (1-MCP) treatment and controlled atmosphere storage on the post-storage production of volatile esters, important aroma-contributing compounds, by fruit of the late season cultivar ‘Tardibelle’. Results indicate that the supply of alcohol and acyl-CoA precursors was altered as a consequence of treatments considered, leading to significant changes in the emission of some volatile esters, particularly of the straight-chain type. Some enzyme activities involved in the production of volatile esters from fatty acids were partially inhibited in 1-MCP-treated fruit, suggesting that they are under ethylene regulation, although tissue-specific differences were also observed. Lipoxygenase and hydroperoxide lyase activities were particularly relevant for these modifications.     

Environmental analysis of the logistics of agricultural products from roof top greenhouses in Mediterranean urban areas

BACKGROUND: As urban populations increase so does the amount of food transported to cities worldwide, and innovative agro‐urban systems are being developed to integrate agricultural production into buildings; for example, by using roof top greenhouses (RTGs). This paper aims to quantify and compare, through a life cycle assessment, the environmental impact of the current linear supply system with a RTG system by using a case study for the production of tomatoes. RESULTS: The main results indicate that a change from the current linear system to the RTG system could result in a reduction, per kilogram of tomatoes (the functional unit), in the range of 44.4–75.5% for the different impact categories analysed, and savings of up to 73.5% in energy requirements. These savings are associated with re‐utilisation of packaging systems (55.4–85.2%), minimisation of transport requirements (7.6–15.6%) and reduction of the loss of product during transportation and retail stages (7.3–37%). CONCLUSIONS: The RTG may become a strategic factor in the design of low‐carbon cities in Mediterranean areas. Short‐term implementation in the city of Barcelona could result in savings of 66.1 tonnes of CO₂ eq. ha^?1 when considering the global warming potential, and of 71.03 t ha^?1 when considering that the transformation from woodland to agricultural land is avoided. Copyright © 2012 Society of Chemical Industry     

Enzymatic hydrolysis kinetics and nitrogen recovery in the protein hydrolysate production from pig bones

Hydrolysis of the protein contained in the pig bone residue from ham production was performed using the commercial enzymatic preparation Neutrase®. Enzymatic hydrolysis was carried out in a 2-litre bio-reactor at 55 °C and a pH of 7.0. The influence of the process variables on the degree of hydrolysis (DH), nitrogen recovery (NR) and the peptides molecular weight distribution was studied. The highest DH (12.4%) was obtained after 120 min hydrolysis with a 2.5% enzyme/substrate relation. The hydrolysis reaction mechanism is developed in two stages, as the nitrogen recovery does. The existence of a linear correlation between the degree of hydrolysis and the nitrogen recovery was proved. The commercial enzymatic preparation Neutrase® showed good efficiency in the hydrolysis and extraction of the protein present in the pig bone.     

The use of carbon dioxide at high pressure to control nine stored-product pests

The development of alternative treatments for pest control in food commodities is an increasing demand from the food industry, which should meet consumer demands for the reduced use or elimination of pesticides. The use of carbon dioxide (CO₂) at high pressure is one of the most rapid options for arthropod pest control among current commercial treatments, offering complete control within hours. The present study aimed to establish the efficacy of the technique against different stages of several insect and mite pests that affect stored-food products. Standard food diets containing eggs, larvae, pupae and adults of Oryzaephilus surinamensis, Cryptolestes ferrugineus, Lasioderma serricorne, Sitophilus oryzae, Rhyzopertha dominica, Acanthoscelides obtectus, Ephestia kuehniella, Liposcelis bostrychophila and Tyrophagus putrescentiae were treated with CO₂ for different times at two high pressures, 15 and 20 bar. A high level of control was achieved for most species and development stages when they were treated with CO₂ at 20 bar for 60 min. However, the efficacy at 15 bar was much lower. The eggs of L. bostrychophila and L. serricorne showed the highest tolerance of all species/stages and survived the most extreme conditions tested. The beetle O. surinamensis, the moth E. kuehniella, and the mite T. putrescentiae were easier to kill than the other species tested. Our results confirmed that the use of high-pressure CO₂ offers an effective and fast way to control most stored-product pests that affect food commodities.     

Effect of high carbon dioxide atmosphere packaging and soluble gas stabilization pre-treatment on the shelf-life and quality of chicken drumsticks

The effects of an aerobic modified atmosphere packaging (MAP) (70% CO₂, 15% O₂ and 15% N₂) with and without a CO₂ 3-h soluble gas stabilization (SGS) pre-treatment of chicken drumsticks were determined for various package and product quality characteristics. The CO₂ dissolved into drumsticks was determined. The equilibrium between CO₂ dissolved in drumsticks and CO₂ in head space was reached within 48 h after packaging, showing highest values of CO₂ in SGS pre-treated samples. This greater availability of CO₂ resulted in lower counts of TAB and Pseudomonas in SGS than in MAP drumsticks. Package collapse was significantly reduced in SGS samples. The average of CO₂ dissolved in the MAP treatment was 567 mg CO₂ kg^− 1 of chicken and, 361 mg CO₂ kg^− 1 of chicken during the MAP treatment, in SGS pre-treated samples. This difference could be the quantity of CO₂ dissolved during SGS pre-treatment.