Browsing by Author "Fundo, Joana"
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- Antimicrobial potential of formulations, incorporating spent yeast derived from synthetic biotechnology, against Pseudomonas spp.Publication . Deuchande, Teresa; Fundo, Joana; Rodrigues, Daniela; Souza, Carla; Pintado, Manuela; Amaro, Ana L.Yeasts are currently used as cell factories for the sustainable production of high value biomolecules for applications in the pharmaceutical and cosmetic sectors. However, the production of such molecules through fermentation, conducted in bioreactors and making use of genetically engineered yeast strains, generates a number of waste-streams, with spent yeast as the second main by-product of fermentation processes, representing more than 20% of the total waste produced. Since this by-product is rich in several molecules including proteins, vitamins and several minerals, being also a natural source of glucans and mannoproteins with known bioactivities, it is of interest to develop valorization strategies for these residues. In this work, spent yeast was autolysed and a set of formulations, incorporating the resulting supernatant and pellet at different concentrations, were tested as potential antimicrobial solutions to prevent diseases in plants and fungi caused by Pseudomonas spp. The formulations were initially tested against P. aeruginosa and then against strains affecting cultivated mushrooms (Agaricus bisporus), P. tolaasi, and P. agarici; and a number of P. syringae strains responsible for plant diseases including the pathovars actinidifoliorium, tomato, pisi, syringae and atrofaciens. It has been recently shown that spent yeast hydrolysates possess antimicrobial activity against Salmonella enterica, Aeromonas salmonicida, Bacillus cereus and Bacillus subtilis (Martin et al. 2021), suggesting that spent yeast extracts may have potential antimicrobial effect against a range of microorganisms. To date, there are no studies showing the potential of spent yeast extracts against Pseudomonas strains. The results showed that the supernatant of the autolyzed yeast at 0.1% inhibited the growth of P. aeruginosa by about 20% and P. tolaasii by 10% but increased the growth of P. agarici by up to 34%. The combination of supernatant with lactose also slightly increased P. tolaasii growth inhibition (12%) but it reduced the inhibitory effect of supernatant against P. aeruginosa. With regard to plant pathogens, the formulations containing 0.1% and 0.3% of pellet inhibited by 25% the growth P. syringae pv. actinidifoliorium, the bacterium responsible for kiwi canker, but for all the other pathovars, the inclusion of spent yeast extracts in the formulation induced bacterial growth. Among all the tested formulations, the ones including supernatant and pellet at low concentrations were the most promising leading to slight growth inhibition of some environmental Pseudomonas spp.
- Effect of non-thermal methods on the safety of strawberries (Fragaria anannassa) and watercress (Nasturtium officinale)Publication . Alexandre, Elisabete M. C.; Santos, Dora M.; Fundo, Joana; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Effect of ozone on Listeria innocua in bell peppers (Capsicum annuum L.) and in contaminated waterPublication . Alexandre, Elisabete M. C.; Fundo, Joana; Santos, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Effect of ozone on the quality of fresh-cut green beans (Phaseolus vulgaris L.) and bell peppers (Capsicum annuum L.)Publication . Alexandre, Elisabete M. C.; Fundo, Joana; Santos, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.Ozone is a potent oxidant and disinfectant agent with multiple industrial applications. The efficacy of ozone treatments has been recognised in the sanitation of equipments and water disinfections. Recently, ozone started to be used as an innovative food processing technology that guarantees product safety. The objective of this work was to study the effect of ozone on the quality of fresh-cut green beans (Phaseolus vulgaris, L.) and green and red bell peppers (Capsicum annuum, L.). The quality factors analysed were enzyme (peroxidase) activity, colour and texture for green beans, and colour, texture and pH for bell peppers. Experiments were carried out in pilot equipment. An ozone generator was interconnected to a container filled with tap water. Ozone was continuously incorporated in water and its content was indirectly measured by potential difference. Green beans and bell peppers were cut in small portions. Samples were immersed in ozonated and non-ozonated water baths and removed after different times till a maximum of 180 minutes. Data from both treatments were compared by analysis of variance. For green beans, results showed that ozone treatment did not affect the colour, but significantly influenced texture (firmness) and peroxidase inactivation (at 7% significance level). After 40 minutes enzyme activity was reduced approximately 20%. This inactivation was verified for the rest of the sampling times. Ozone treatment affected pH and texture (fracturability) of red bell peppers (at 1% significance level). The other quality factors were not significantly influenced by ozone.
- Effect of ozone on the quality of fresh-cut green beans (Phaseolus vulgaris L.) and bell peppers (Capsicum annuum L.)Publication . Alexandre, Elisabete M. C.; Fundo, Joana; Santos, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Effect of ozone on the quality of fresh-cut green beans (Phaseolus vulgaris L.) and bell peppers (Capsicum annuum L.)Publication . Alexandre, Elisabete M. C.; Fundo, Joana; Santos, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Freeze-drying processes applied to melon rinds to attain a value-added food ingredientPublication . Brandão, Teresa; Sroy, Sengly; Fundo, Joana; Silva, Cristina; Miller, FátimaAim: Several studies pointed out melon rinds as rich sources of bioactive compounds with relevant antioxidant activity. Being considered a non-edible part with no economic value, fruit industries discharge large amounts of these residues to the environment. If these wastes are conveniently processed and transformed, novel food ingredients with potential health benefits may arise.The objective was to transform melon rinds by freeze-drying to attain dried small bits that can be used as additives to enrich diverse food matrixes. An ozone pre-treatment was applied seeking decontamination and retention of quality characteristics. The impact of these processes was assessed in bioactive compounds (vitamin C, total phenolics and chlorophylls), antioxidant activity, and melon peel microflora (mesophylls, yeasts and moulds) during 7 weeks of storage of the dried materials at room temperature. Method: Melon rinds (Cucumis melo L. var. reticulatus) were cut in small cubes. Before freeze-drying (-50 °C, 1.5-2 bar, 80-90 h) and storage (7 weeks in the dark at room temperature), part of the samples was exposed to a gaseous ozone pre-treatment (15 °C, 152±71 ppm, 30 min). Vitamin C, total phenolics, chlorophylls and antioxidant activity were analysed by HPLC and spectrophotometric methods in raw peel and throughout storage. Mesophylls, yeasts and moulds were also enumerated. Results: Vitamin C, total phenolics, chlorophylls, and antioxidant activity decreased during storage in both non-ozonized and ozonized dried samples. However, pre-ozonized samples retained better the bioactive compounds analyzed throughout the storage: almost 85% of total phenolics and chlorophylls were preserved, and 66% of vitamin C. In terms of microflora inactivation, the effects of ozone and freeze-drying were not significant. However, a decrease of ~1 log-cycle was observed at the end of storage for the groups of microorganisms considered. Studies with undesirable target microorganisms are required to attain a safe product. Conclusion: Freeze-drying with an ozone pre-treatment can be considered a potential process to transform melon peel into an edible form. When the small cubes of melon rinds were freeze-dried, they became lighter and softer. They can be incorporated into different products (e.g., cakes, breads, yogurts), enriching their nutritional profile and creating a value-added food ingredient.
- Fresh-cut pear quality during storage: a NMR study of water transverse relaxation timePublication . Fundo, Joana; Carvalho, Alexandra; Feio, Gabriel; Silva, Cristina L.M.; Quintas, Mafalda A. C.Fresh-cut fruits have become an important food market segment due to increasing demand for fresh, healthy and convenient foods. However, processing fruits promotes a decrease in its stability with a faster physiological deterioration, biochemical changes and microbial degradation. Recently, food stability is strongly attributed to molecular dynamics and “water availability”. Understanding cooperatively changes in location and mobility of water is particularly important, considering that water dynamics profoundly influences physicochemical and microbiological quality of foods. The aim of this study was to use nuclear magnetic resonance spectroscopy (NMR) as a tool to evaluate storage fresh-cut fruit quality. Recently, NMR has evolved to become a powerful methodology to probe the molecular dynamics of food constituents, which in turns is a fundamental parameter to determine the dynamic properties of food components and contributes to food degradation reactions comprehension. In this work fresh-cut pear transverse relaxation time (T2) was measured for a period of 7 days of storage at 5 °C. The relationship between the obtained values, microstructure and quality parameters was investigated. In general, results show the existence of one class of water fluidity in the system, the one present in cells after processing. T2, a measure of this fluidity, is affected by the processing and storage time. Also, it is possible to find a relationships between T2 and the quality parameters: total colour difference (TCD), firmness and aw. T2 increases with aw, while it decreases with TCD and firmness. These results highlight the usefulness of NMR methodology application in food science
- Fresh-cut pear quality during storage; a NMR study of water transverse relaxation timePublication . Fundo, Joana; Carvalho, Alexandra; Feio, Gabriel; Silva, Cristina L. M.; Quintas, Mafalda
- Impact of ozonisation on quality parameters, nutritional aspects and inactivation of Listeria innocua in beansPublication . Alexandre, Allana Patrícia Santos; Fundo, Joana; Miller, Fátima; Brandão, Teresa; Calori-Domingues, Maria Antónia; Silva, Cristina L.; Augusto, Pedro Esteves Duarte
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