Analía Concellón

Effect of short-term ozone treatments on tomato (Solanum lycopersicum L.) fruit quality and cell wall degradation.

We evaluated the effect of short-term gaseous ozone treatment (10 microL/L; 10 min) on tomato fruit quality and cell wall degradation. The treatments did not modify fruit color, sugar content, acidity, or antioxidant capacity but reduced fruit damage and weight loss and induced the accumulation of phenolic compounds. In addition, softening was delayed in ozone-treated fruit. Cell wall analysis showed that exposure to ozone decreased pectin but not hemicellulose solubilization. Polyuronide depolymerization was also reduced in ozone-treated fruit. While the treatments did not alter the activity of the pectin-degrading enzymes polygalacturonase (PG) and beta-Galactosidase (beta-Gal), a clear decrease in pectin methyl esterase (PME) was found. Results show that short-term ozone treatments might be useful to reduce fruit damage and excessive softening, two of the main factors limiting tomato postharvest life, without negatively affecting other quality attributes. The impact of the treatments on fruit softening might be associated with reduced disassembly (solubilization and depolymerization) of pectic polysaccharides.

Use of UV-C Treatments to Maintain Quality and Extend the Shelf Life of Green Fresh-cut Bell Pepper (Capsicum annuum L.)

UNLABELLEDnThe objective of this work was to select a Ultraviolet-C (UV-C) treatment for fresh-cut mature green bell pepper, and to evaluate the effect of its combination with refrigeration on quality maintenance. Bell pepper sticks were treated with 0, 3, 10, or 20 kJ/m² UV-C in the outer (O), inner (I), or both sides of the pericarp (I/O) and stored for 8 d at 10 °C. During the first 5 d of storage, all UV-C treatments reduced deterioration as compared to the control. The treatment with 20 kJ/m² I/O was the most effective to reduce deterioration, and was used for further evaluations. In a second group of experiments, mature green bell pepper sticks were treated with 20 kJ/m² I/O, stored at 5 °C for 7 or 12 d and assessed for physical and chemical analysis, and microbiological quality. UV-C-treated fruit showed lower exudates and shriveling than the control. UV exposure also reduced decay, tissue damage, and electrolyte leakage. After 12 d at 5 °C, UV-C irradiated peppers remained firmer and had higher resistance to deformation than the control. The UV-C treatments also reduced weight loss and pectin solubilization. UV-C exposure decreased the counts of mesophile bacteria and molds, and did not affect acidity or sugars. UV-C-treated fruit stored for 0 or 7 d at 5 °C did not show major differences in antioxidants from the control as measured against DPPH(•) or ABTS(•)⁺ radicals. Results suggest that UV-C exposure is useful to maintain quality of refrigerated fresh-cut green pepper.nnnPRACTICAL APPLICATIONnExposure to UV-C radiation before packing and refrigeration could be a useful nonchemical alternative to maintain quality and reduce postharvest losses in the fresh-cut industry.

Use of 1-methylcyclopropene to complement refrigeration and ameliorate chilling injury symptoms in summer squash

To elucidate the role of ethylene in summer squash [Cucurbita maxima var. Zapallito (Carr.) Millan] postharvest responses, harvested fruit was treated with the inhibitor of ethylene action 1-methylcyclopropene (1-MCP, 1 μL L−1) and stored at 10 or 0 °C for 14 or 19 days, respectively. Deterioration, chilling injury (CI), weight loss, surface color, firmness, respiration rate, acidity, sugars, and antioxidants were determined. At 10 °C 1-MCP treated fruit showed lower deterioration and weight loss. The inhibition of ethylene action delayed yellowing, softening, and respiration, and prevented the increase of acidity. Chilling injury, manifested as shrunken areas and surface depressions, yellowing and softening were reduced in 1-MCP-treated fruit stored at 0 °C. Sugars and antioxidants were not affected. Results suggest that ethylene is involved in senescence and CI development in summer squash. Inhibition of its action by 1-MCP could be useful to prevent deterioration and maintain quality.

Short UV-C Treatment Prevents Browning and Extends the Shelf-Life of Fresh-Cut Carambola

In this work, we selected a short UV-C treatment for fresh-cut carambola and assessed its efficacy in supplementing the benefits of low temperature storage. UV-C treated (6.0, 10.0, and 12.5u2009kJu2009m−2) carambola slices showed reduced deterioration compared to control fruit. Treatment with a dose of 12.5u2009kJu2009m−2 UV-C was more effective in maintaining quality and was selected for subsequent experiments evaluating the combination of UV-C and refrigeration on fruit storability and physical, chemical, and microbiological properties. Short UV-C exposure reduced weight loss and electrolyte leakage. UV-C treated carambola slices presented higher phenolic antioxidants than control after 21u2009d at 4°C and showed no alterations in soluble solids or titratable acidity. UV-C exposure also reduced the counts of molds, yeast, and aerobic mesophilic bacteria. UV-C treated fruit showed a fresh-like appearance even after 21u2009d as opposed to control carambola which presented spoilage and extensive browning symptoms. The reduction of fruit browning in UV-C treated fruit was not due to reduction in phenylalanine-ammonia lyase (PAL) and/or peroxidase (POD), but rather through polyphenol oxidase (PPO) inhibition and improved maintenance of tissue integrity.

Improvement of the Antioxidant Properties and Postharvest Life of Three Exotic Andean Fruits by UV-C Treatment

Three Andean fruits naranjilla (Solanum quitoense Lam.), uvilla (Physalis peruviana L.), and mortino (Vaccinium floribundum Kunth) were subjected to prestorage UV-C treatments (0, 8, or 12.5u2009kJu2009m−2) and evaluated weekly to select the most suitable dose for fruit quality maintenance during storage (21 days at 6°C). The highest dose retains quality through lower deterioration index for all three fruits and was selected to further analyze the effects on physicochemical and antioxidant properties during storage. UV-C exposure delayed softening in naranjilla and increased soluble solid content in uvilla. UV-C also improved the maintenance of antioxidant capacity (AC) in mortino and uvilla. Overall, results indicate that short prestorage UV-C exposure may be an effective nonchemical approach to supplement low temperature storage, maintain quality, and extend the postharvest life of Andean naranjilla, uvilla, and mortino fruit.

Anti-tubercular and antioxidant activities of C-glycosyl carbonic anhydrase inhibitors: towards the development of novel chemotherapeutic agents against Mycobacterium tuberculosis.

Abstract During the treatment of tuberculosis infection, oxidative stress due to anti-tubercular drugs may result in tissue inflammation. It was suggested that treatment with antioxidant drugs could be beneficial as an adjunct to anti-tuberculosis drug therapy. Recently our group has shown that several C-glycosides are inhibitors of Mycobacterium tuberculosis β-carbonic anhydrases (CAs, EC 4.2.1.1). In an effort to develop novel chemotherapeutic agents against tuberculosis, the anti-tubercular and antioxidant activities of a series of C-glycosides containing the phenol or the methoxyaryl moiety were studied. Many compounds showed inhibition of growth of M. tuberculosis H37Rv strain and good antioxidant ability. A glycomimetic incorporating the 3-hydroxyphenyl moiety showed the best activity profile and therefore this functionality represents lead for the development of novel anti-tubercular agents with dual mechanisms of action.