Percorrer por autor "Nunes, Carla"
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- Biocontrol of postharvest decay using a new strain of Pseudomonas syringae CPA-5 in different cultivars of pome fruitsPublication . Nunes, Carla; Usall, Josep; Teixido, Neus; Abadias, Isabel; Asensio, Angels; Vinas, InmaculaEpiphytic micro-organisms isolated from fruits and leaves surfaces of apples from different orchards were screened for antagonistic activity against Penicillium expansum. From all micro-organisms tested the new strain CPA-5 of Pseudomonas syringae, isolated from organic orchard, was selected. This strain was very effective against Botrytis cinerea, P expansum and Rhizopus stolonifer at various antagonist and pathogen concentrations on 'Golden Delicious' apple, and 'Blanquilla', 'Rocha' and 'Conference' pear. Under cold storage conditions and in semi-commercial trials R syringae (CPA-5) significantly reduced development of P expansum and B. cinerea on 'Golden Delicious' apple, and 'Blanquilla' and 'Rocha' pears. Control of P expansum equal to the fungicide imazalil was obtained with CPA-5 at 10(8)cfu ml(-1) on 'Gold Delicious' apple and 'Rocha' pear. The populations of P syringae CPA-5 increased more than 100-fold during the first 50 days, and then remained stable on apple, and slightly decreased on pears. This indicates the high capacity of this antagonist to colonize wound surfaces of pome fruits under cold storage conditions.
- Carob pulp as raw material for production of the biocontrol agent P. agglomerans PBC-1Publication . Manso, Teresa; Nunes, Carla; Raposo, Sara; Lima-Costa, Maria EmíliaLarge-scale production has been the major obstacle to the success of many biopesticides. The spreading of microbial biocontrol agents against postharvest disease, as a safe and environmentally friendly alternative to synthetic fungicides, is quite dependent on their industrial mass production from low-cost raw materials. Considerable interest has been shown in using agricultural waste products and by-products from food industry as nitrogen and carbon sources. In this work, carob pulp aqueous extracts were used as carbon source in the production of the biocontrol agent Pantoea agglomerans PBC-1. Optimal sugar extraction was achieved at a solid/liquid ratio of 1:10 (w/v), at 25°C, for 1 h. Batch experiments were performed in shake flasks, at different concentrations and in stirred reactors at two initial inoculums concentrations, 106 and 107 cfu ml−1. The initial sugar concentration of 5 g l−1 allowed rapid growth (0.16 h−1) and high biomass productivity (0.28 g l−1 h−1) and was chosen as the value for use in stirred reactor experiments. After 22 and 32 h of fermentation the viable population reached was 3.2 × 109 and 6.2 × 109 cfu ml−1 in the fermenter inoculated at 106 cfu ml−1 and 2.7 × 109 and 6.7 × 109 cfu ml−1 in the bioreactor inoculated at 107 cfu ml−1. A 78% reduction of the pathogen incidence was achieved with PBC-1 at 1 × 108 cfu ml−1, grown in medium with carob extracts, on artificially wounded apples stored after 7 days at 25°C against P. expansum.
- Código de boas práticas de higiene no processamento de citrinos para comercialização em frescoPublication . Duarte, Amílcar; Marques, Carla; Nunes, Carla; Lopes, Luís; Salazar, MiguelA citricultura constitui um dos mais importantes sectores da fruticultura nacional, sendo o mais importante no Algarve, onde gera um valor superior a 30% do Produto Agrícola Bruto e é responsável por mais de 4.000 postos de trabalho. Quanto às outras regiões do país, observa-se um aumento de investimento neste sector no Alentejo.A implementação da Protecção Integrada e, mais recentemente, da Produção Integrada têm contribuído para a adopção de tecnologias de produção mais seguras e com menor impacte ambiental, as quais correspondem às novas exigências dos consumidores.
- Development and application of a SCAR marker to monitor and quantify populations of the postharvest biocontrol agent Pantoea agglomerans CPA-2Publication . Nunes, Carla; Bajji, Mohammed; Stepien, Valerie; Manso, Teresa; Torres, Rosario; Usall, Josep; Jijakli, M. HaissamPantoea agglomerans CPA-2 is an effective biocontrol agent of postharvest diseases of citrus and pome fruit. A monitoring technique was developed for its identification and to quantify its populations. The methodology used consisted of (i) searching for a semi-selective medium, (ii) identification of molecular markers and (iii) monitoring population dynamics in a commercial trial. As a semi-selective medium, Malonate Broth Agar supplemented with tetracycline hydroxychloricle and incubation at high temperature (max. of 40 degrees C) facilitated the selective recovery of P agglomerans CPA-2 colonies. The RAPD technique was applied to a collection of 13 strains of P. agglomerans, including CPA-2. Among the 12 primers tested, OPL-11 amplified a fragment (about 720 bp) specific to strain CPA-2. On the basis of this fragment, two SCAR markers were amplified using a primer pair derived from OPL-11 elongation. A first SCAR marker of 720 bp was specifically amplified for the strain CPA-2 and a second one of 270bp was obtained for all P. agglomerans strains tested, including CPA-2. Commercial trials demonstrated a significant reduction of decay with the treatment of formulated cells of R agglomerans CPA-2. Population dynamics of CPA-2 in commercial trials were determined on fruit surfaces and in the environment using both the classical plating technique and PCR with SCAR primers. In general, no significant differences were observed between results obtained from the two methods. On fruit surfaces, 1 day after CPA-2 applied its population by classical methods was 4.37 x 10(6) cfu wound(-1) and at the end of the experiment the population increased to 5.8 x 10(5) cfu wound(-1). The percentages of colonies identified as P agglomerans CPA-2 at these sampling times using SCAR primers were 90 and 95%, respectively. Population dynamics in the environment to evaluate the environmental fate of R agglomerans CPA-2 showed that it has a limited persistence and limited capacity for dispersion. (c) 2007 Published by Elsevier B.V.
- Effect of electrolyzed water as a disinfectant for fresh-cut fruitPublication . Graça, Ana; Salazar, Miguel; Quintas, Célia; Manso, Teresa; Nunes, Carla; Nunes, CarlaIn fresh-cut processing the disinfection is the most important step. This process can affect the quality and the safety of the end product as well as its shelf life. Chlorine is the most used disinfectant in fresh-cut industry but due to its association with environmental and health risks, the development of alternative sanitizers is emergent. Electrolyzed water (EW) may be an alternative to the use of chlorine sanitizers and both acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW) can be used with this purpose. In fact, several studies have shown that EW can be effective in reducing pathogenic bacteria on the surface of fruits and vegetables. This manuscript presents a review of electrolyzed water approaches, its antimicrobial activity in fresh-cut produce and the results of a study undertaken in our laboratory to evaluate the disinfection efficacy of AEW and NEW on fresh-cut apples and oranges. Fresh-cut apples and fresh cut oranges were inoculated with a suspension of Listeria innocua and fresh-cut oranges with Escherichia coli at a concentration of 107 cfu mL-1 and treated with the different solutions. Untreated freshcut fruits were used as control. The best sanitizing treatment for both pathogens and fruits was AEW at 200 ppm of free chlorine applied during 5 minutes.
- Growth of Escherichia coil, Salmonella enterica and Listeria spp., and their inactivation using ultraviolet energy and electrolyzed water, on 'Rocha' fresh-cut pearsPublication . Graça, Ana; Santo, David; Quintas, Célia; Nunes, CarlaThe present study aimed at evaluating the growth of Escherichia coil, Salmonella enterica, and Listeria spp. and studying the efficacy of Ultraviolet-C (UV-C) irradiation, acidic electrolyzed (AEW) and neutral electrolyzed (NEW) waters in the reduction of these bacteria on 'Rocha' pear. Fresh-cut pieces were inoculated and incubated at 4-20 degrees C for 8 days. Inoculated pears were treated with UV-C (2.5-10 kJ/m(2)), AEW, NEW and sodium hypochlorite (SH) and microbiological and quality parameters were evaluated. The three bacteria, inoculated at 6.1-6.2 log cfu/g, grew on the pear at high growth rates at 12 and 20 degrees C reaching populations of 8.1-8.6 log cfu/g, in 24 h. At 8 degrees C the microorganisms increased their populations by at least 1 log cfu/g in three days. At 4 degrees C adaptation phases of less than 24 h for Listeria spp. were measured before exponential growth occurred and the enterobacteria did not grow despite having survived for 8 days. AEW and NEW caused microbial reductions similar to SH, of approximately 1 log cfu/ g, while the best UV-C dose (7.5 kJ/m(2)) of at least 2.4 log cfu/g. Fresh-cut pears were a good substrate for foodborne bacteria emphasizing the importance of preventing contaminations and cross contaminations. The UV-C was more effective than the chemical decontaminations, as it provided superior microbial reductions without greatly affecting the quality of pears. (C) 2017 Elsevier Ltd. All rights reserved.
- Influence of cultivation salinity in the nutritional composition, antioxidant capacity and microbial quality of Salicornia ramosissima commercially produced in soilless systemsPublication . Lima, Alexandre R.; Castaneda-Loaiza, Viana; Salazar, Miguel; Nunes, Carla; Quintas, Celia; Gama, Florinda; Pestana, Maribela; Correia, Pedro J.; Santos, Tamara; Varela, João; Barreira, Luísathe consumption of halophytes as healthy gourmet food has increased considerably in the past few years. However, knowledge on the nutritional profile of domesticated halophytes is scarce and little is known on which cultivation conditions can produce plants with the best nutritional and functional properties. In this context, Salicornia ramosissima J. Woods was cultivated in six different salt concentrations, ranging from 35 to 465 mM of NaCl. Both the nutritional profile, the antioxidant capacity, and microbial quality of the produced plants were evaluated including minerals and vitamins. Salt has a marked effect on growth, which decreases for salinities higher than 110 mM. Nonetheless, plants cultivated with intermediate levels of salinity (110 and 200 mM) revealed better antioxidant status with higher amounts of phenolic compounds. Overall, results from this paper indicated that soilless culture systems using low-intermediate salinities produces S. ramosissima plants fit for commercialization and human consumption.
- Métodos eco-inovadores de desinfecção para fruta cortada de modo de produção biológicoPublication . Duarte, Amílcar; Graça, Ana; Salazar, Miguel; Nunes, CarlaO cloro é o desinfectante de uso habitual a indústria de fruta cortada mas apresenta problemas de eficácia, de saúde e ambientais, pelo que há uma tendência para ser eliminado do processo de desinfecção, não apenas para os alimentos de modo de produção biológico (MPB) mas também de alimentos convencionais. Neste trabalho foi testada em pêra 'Rocha'cortada a actividade biocida de três sistemas eco-inovadores de desinfecção (iluminação UV-C, água electrolisada e água ozonizada). Cubos de pêra foram inoculadas com uma suspensão de Escherichia coli, Listeria innocua ou Salmonella choleraesuis e tratados com os sistemas eco-inovadores. Para cada um testaram-se diferentes doses ou tempos de exposição (UV-C: 0-10 kJ.m-2 ; água electrolisada: 10-200 ppm cloro livre, 5 min; e água ozonizada: 0,4 ppm, 1-5 min). Como testemunha utilizou-se o tratamento com hipoclorito de sódio a 100 ppm. Os resultados demonstram que o sistema mais eficaz foi a iluminação UV-C, seguido de água electrolisada e de água ozonizada. A iluminação UV-C e a água electrolisada apresentaram, de um modo geral, eficácia superior à do hipoclorito de sódio e o ozono, eficácia similar. Dos métodos testados, o mais promissor para uso em alimentos MPB e numa agricultura sustentável é a iluminação UV-C, pois, além de elevada eficácia, apresenta a vantagem de não utilizar água nem produzir resíduos nem subprodutos nos frutos nem no ambiente.
- Microbial and sensory evaluation of Halophytes cultivated in a soilless system under different salinitiesPublication . Quintas, Célia; Ribeiro Lima, Alexandre; Gama, Florinda; Nunes, Carla; Salazar, Miguel; Barreira, LuísaThe increasing interest in halophytes as sustainable crops and their potential functional properties highlights the need to understand how cultivation conditions affect their quality for human consumption. The present study aimed to evaluate the influence of salinity on the microbial quality of the halophytes Disphyma crassifolium, Inula crithmoides, Mesembryanthemum nodiflorum, and Suaeda maritima, cultivated using a soilless system under different salinities. The sensorial quality of D. crassifolium and S. maritima was also assessed by an experienced panel of culinary chefs. The microbial quality was measured by counting aerobic microorganisms (30 °C and 6.5 °C), fungi, Escherichia coli, and coagulase-positive staphylococci. Salinity increase caused a concentration-dependent salt accumulation in the plants, triggering a rise in the microbial populations, namely aerobic and filamentous fungi on D. crassifolium and I. crithmoides and psychrotrophic microorganisms on S. maritima (p < 0.05). Except for M. nodiflorum, plants cultivated at the highest salinity (465 mM) had levels of filamentous fungi higher than 3 Log CFU/g. Concerning aerobes, plants presented a satisfactory microbiological quality (<6 Log CFU/g) even when cultivated at high salinity (465 mM), and yeasts, E. coli, and staphylococci were never detected. D. crassifolium and S. maritima cultivated at intermediate salinities were preferred by the sensory evaluation panel. In conclusion, soilless system cultivation produces plants adequate for consumption, considering their microbial and sensorial quality.
- Microbiological quality and safety of minimally processed fruits in the marketplace of southern PortugalPublication . Graça, Ana; Esteves, E.; Nunes, Carla; Abadias, Maribel; Quintas, CéliaThe availability of fresh-cut fruit (FCF) in the marketplace has been increasing in Portugal, although reports of its microbial quality are not known. Due to the growing concerns of these commodities over their microbial safety, the objectives of this work were to study the microbiological quality and prevalence of Salmonella and Listeria monocytogenes on fresh-cut fruits sold in southern Portugal. A study to examine the changes in pH and microbial counts, before and after the expiration dates, was also made. A total of 160 samples was purchased in the local grocery stores between September 2011 and August 2014, before their sell-by date. These samples were assayed for aerobic mesophilic (AM) and psychrotrophic (AP) microorganisms, yeasts and molds (YM), lactic-acid bacteria (LAB), coliforms (TC), Escherichia coli and coagulase positive staphylococci as well as L. monocytogenes and Salmonella. The microbiological counts ranged from 3.0-9.2 lg cfu/g (AM); 2.2–10.7 lg cfu/g (AP); 2.3–10.4 lg cfu/g (YM); 1.9–9.0 lg cfu/g (LAB) and less than 1–9.1 lg cfu/g (TC). The melons and watermelon presented the highest levels of the microbial quality parameters studied. However, no E. coli, staphylococci, Salmonella and L. monocytogenes were detected in any of the samples. After the sell-by date, an increase of the AM, AP, LAB and YM values was observed in all fruits. Conversely, the differences found in TC counts before and after the best-before date had no statistical significance. A decrease in pH was observed in all fruits except pineapple whose pH slightly increased after 14 days of storage. The results highlight the importance of preventing contamination and cross contamination, selecting adequate decontamination technologies and maintaining a strict temperature control during processing, distribution and selling of FCF.