Effect of Ozone and Calcium Lactate Treaments on Browning and Textured Properties of Fresh-Cut Lettuce

The effects of three treatments, 1 mg L−1 ozone at 18–20 °C, 15 g L−1 calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh-cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P \u3c 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (∼9%) than ozone samples (∼6%). Enzymatic activity decreased significantly (P \u3c 0.05) in ozone samples. Polyphenol oxidase activity in fresh-cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (−1) and at the end of storage (g−1) than CLac samples (4000–4800 units g−1). Ozone also reduced peroxidase activity to ∼300 units g−1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storag

Combined effect of water loss and wounding stress on gene activation of metabolic pathways associated with phenolic biosynthesis in carrot

Abstract: The application of postharvest abiotic stresses is an effective strategy to activate the primary and secondary metabolism of plants inducing the accumulation of antioxidant phenolic compounds. In the present study, the effect of water stress applied alone and in combination with wounding stress on the activation of primary (shikimic acid) and secondary (phenylpropanoid) metabolic pathways related with the accumulation of phenolic compound in plants was evaluated. Carrot (Daucus carota) was used as model system for this study, and the effect of abiotic stresses was evaluated at the gene expression level and on the accumulation of metabolites. As control of the study, whole carrots were stored under the same conditions. Results demonstrated that water stress activated the primary and secondary metabolism of carrots, favoring the lignification process. Likewise, wounding stress induced higher activation of the primary and secondary metabolism of carrots as compared to water stress alone, leading to higher accumulation of shikimic acid, phenolic compounds and lignin. Additional water stress applied on wounded carrots exerted a synergistic effect on the wound-response at the gene expression level. For instance, when wounded carrots were treated with water stress, the tissue showed 20- and 14-fold increases in the relative expression of 3-deoxy-D-arabino-heptulosanate synthase and phenylalanine ammonia-lyase genes, respectively. However, since lignification was increased, lower accumulation of phenolic compounds was detected. Indicatively, at 48 h of storage, wounded carrots treated with water stress showed ~31% lower levels of phenolic compounds and ~23% higher lignin content as compared with wounded controls. In the present study, it was demonstrated that water stress is one of the pivotal mechanism of the wound-response in carrot. Results allowed the elucidation of strategies to induce the accumulation of specific primary or secondary metabolites when plants are treated with water stress alone or when additional water stress is applied on wounded tissue. If the accumulation of a specific primary or secondary metabolite were desirable, it would be recommended to apply both stresses to accelerate their biosynthesis. However, strategies such as the use of enzymatic inhibitors to block the carbon flux and enhance the accumulation of specific compounds should be designed

Effects of tunnelling on a single pile: three-dimensional design tool

In most tunnelling projects in urban areas, a preliminary assessment is often required of the impact of a tunnel excavation on foundations adjacent to the tunnel. Despite the significant recent advances in computer hardware and commercial software, a full 3-D analysis is still relatively costly, especially if it is to be employed as a preliminary assessment tool to ascertain the impact of tunnel excavation on existing foundations. This paper provides a convenient and cost-effective design tool, in the form of design charts, that will allow an economical preliminary assessment of the 3-D effects of tunnelling on a single pile. The method adopted to develop these design charts will be briefly described and their use in practice will be illustrated by application of the design charts to several published case histories

Effects of tunnelling on a single pile : three-dimensional design tool

In most tunnelling projects in urban areas, a preliminary assessment is often required of the impact of a tunnel excavation on foundations adjacent to the tunnel. Despite the significant recent advances in computer hardware and commercial software, a full 3-D analysis is still relatively costly, especially if it is to be employed as a preliminary assessment tool to ascertain the impact of tunnel excavation on existing foundations. This paper provides a convenient and cost-effective design tool, in the form of design charts, that will allow an economical preliminary assessment of the 3-D effects of tunnelling on a single pile. The method adopted to develop these design charts will be briefly described and their use in practice will be illustrated by application of the design charts to several published case histories

UVA, UVB and UVC Light Enhances the Biosynthesis of Phenolic Antioxidants in Fresh-Cut Carrot through a Synergistic Effect with Wounding

Previously, we found that phenolic content and antioxidant capacity (AOX) in carrots increased with wounding intensity. It was also reported that UV radiation may trigger the phenylpropanoid metabolism in plant tissues. Here, we determined the combined effect of wounding intensity and UV radiation on phenolic compounds, AOX, and the phenylalanine ammonia-lyase (PAL) activity of carrots. Accordingly, phenolic content, AOX, and PAL activity increased in cut carrots with the duration of UVC radiation, whereas whole carrots showed no increase. Carrot pies showed a higher increase compared to slices and shreds. Phenolics, AOX, and PAL activity also increased in cut carrots exposed to UVA or UVB. The major phenolics were chlorogenic acid and its isomers, ferulic acid, and isocoumarin. The type of UV radiation affected phenolic profiles. Chlorogenic acid was induced by all UV radiations but mostly by UVB and UVC, ferulic acid was induced by all UV lights to comparable levels, while isocoumarin and 4,5-diCQA was induced mainly by UVB and UVC compared to UVA. In general, total phenolics correlated linearly with AOX for all treatments. A reactive oxygen species (ROS) mediated hypothetical mechanism explaining the synergistic effect of wounding and different UV radiation stresses on phenolics accumulation in plants is herein proposed