Susana Dias

Prof. Susana Dias

Coimbra Polytechnic Institute

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 March 2022 in Foods
Verified
Journal Article
Open access
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LCLara Campos
Lara Campos
LSLuana Seixas
Luana Seixas
SDSusana Dias
Susana Dias
António PeresAntónio Peres
António Peres
AVAna C.A. Veloso
Ana C.A. Veloso
Marta HenriquesMarta Henriques
Marta Henriques
Pomegranate by-products can be an asset to the food industry due to the richness in bioactive and antimicrobial compounds. This work studied the influence of conventional solvent and sonication-assisted extraction methods on the bioactive profile, antimicrobial properties, and phytotoxicity effect of the peels and seeds extracts from Acco, Big Full, and Wonderful pomegranate cultivars. The bioactive composition of the extracts was evaluated for the content of total phenolics, total flavonoids, and antioxidant activity (expressed as the half-maximal inhibitory concentration—IC50) by spectrophotometric methods, while the tannins were determined by titration and the anthocyanins were estimated by the pH-differential method. For the evaluation of the antimicrobial activity, the disk diffusion method of Kirby-Bauer was adapted through inhibition halos against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and Yarrowia lipolytica. The extracts’ phytotoxicity was evaluated in vitro on garden-cress seeds. Extracts from conventional extraction were richer in total phenolics, expressed as gallic acid equivalents (0.16–0.73 mg GAE/mg extract), while those from sonication-assisted extraction had higher contents of total flavonoids, expressed as catechin equivalents (0.019–0.068 mg CATE/mg extract); anthocyanins, expressed as cyanidin-3-glucoside (0.06–0.60 µg C3G/mg, dry basis); and antioxidant activity (IC50, 0.01–0.20 mg/mL). All extracts were more effective against Gram-positive bacteria and yeasts than Gram-negative bacteria. In general, the sonication-assisted extracts led to higher inhibition halos (8.7 to 11.4 mm). All extracts presented phytotoxicity against garden-cress seeds in the tested concentrations. Only the lowest concentration (0.003 mg/mL) enabled the germination of seeds and root growth, and the sonication-assisted extracts showed the highest Munoo-Liisa vitality index (51.3%). Overall, sonication-assisted extraction obtained extracts with greater bioactive and antimicrobial potential and less phytotoxicity.

12 August 2020 in Journal of Food Processing and Preservation
Verified
Journal Article
Closed access
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LFLaura Ferreira
Laura Ferreira
ABAna Borges
Ana Borges
DGDavid Gomes
David Gomes
SDSusana Dias
Susana Dias
Carlos PereiraCarlos Pereira
Carlos Pereira
Marta HenriquesMarta Henriques
Marta Henriques

10 January 2023 in Foods
Verified
Journal Article
Open access
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TSTânia Silva
Tânia Silva
APArona Pires
Arona Pires
DGDavid Gomes
David Gomes
JVJorge Viegas
Jorge Viegas
SDSusana Dias
Susana Dias
Carlos PereiraCarlos Pereira
Carlos Pereira
Small ruminant dairy products are common in some Mediterranean countries, in the Middle East and Africa, and can play a particular role in the development of rural areas. Butter has been the object of few research studies aimed at evaluating its potential as a vehicle for probiotic microorganisms. Moreover, the recovery of fermented buttermilk with functional properties can be considered an excellent opportunity to value this dairy byproduct. Therefore, the purpose of the present work was to develop different sheep butters and respective buttermilks after cream fermentation by: (1) a mesophilic aromatic starter (A); (2) a kefir culture (K); and (3) a mixture of probiotic bacteria (P). The butters and buttermilk produced with fermented cream were compared with non-fermented sweet cream (S) butter or buttermilk, respectively, regarding their physicochemical, microbiological and sensory characteristics. The adjusted production (%, w/v) obtained for butter were: S (44.48%), A (36.82%), K (41.23%) and P (43.36%). S, A and K butters had higher solids, fat and ashes contents than P butter. The probiotic butter had a total fat of ca. 75% (w/w), below the legal limits, while all others had fat levels above 81.5%. In all samples, the pH decreased and the acidity increased over 90 days of refrigerated storage. These variations were more evident in the P butter, which agrees with the highest lactic acid bacteria counts found in this sample. Differences in color between samples and due to storage time were also observed. In general, the butter samples tended to become darker and yellower after the 60th day of storage. Texture analysis showed comparable results between samples and greater hardness was observed for the P butter, most probably due to its higher relative saturated fatty acids content (66.46% compared to 62–64% in S, A and K butters). Regarding rheological properties, all butters showed pseudoplastic behavior, but butter P had the lowest consistency index (249 kPa.sn−1). The probiotic butter and the corresponding buttermilk had viable cell counts greater than 7 Log CFU/g, indicating their suitability as probiotic carriers. All products were well accepted by consumers and small, but non-significant, differences (p > 0.05) were observed in relation to the sensory parameters evaluated. In general, it can be concluded that the use of adequate starter cultures can allow the production of innovative and potentially healthier products, alongside the valorization of dairy byproducts, improving the income of small-scale producers.

22 October 2024 in Dairy
Verified
Journal Article
Open access
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Carlos PereiraCarlos Pereira
Carlos Pereira
DGDavid Gomes
David Gomes
SDSusana Dias
Susana Dias
SSSandra Santos
Sandra Santos
APArona Pires
Arona Pires
JVJorge Viegas
Jorge Viegas
In this study, butter and the corresponding buttermilk samples were produced with cream fermented by aromatic (A) or probiotic (P) cultures with or without complementary bioprotective culture (BC). The samples were characterised for their composition and colour parameters. Texture and rheological properties were evaluated at 10 and 20 °C. Microbiological (lactobacilli, lactococci, and yeast and mould counts) and sensory (aroma, taste, texture, and global evaluation) analyses were also performed. All butter sample characteristics were in accordance with the Portuguese standard. Regarding colour, the sample obtained with cream fermented by probiotics plus bioprotective culture (PBC) presented higher L* and b* values, indicating a slightly higher yellow chroma. However, colour differences (ΔEab*) in the butter samples were, in most cases, not detectable by a common observer. Butter samples P and PBC presented a significantly higher viscous modulus and consequently higher dynamic viscosity values (ca. log 6.5 Pa.s at 10 °C and log 5 Pa.s at 20 °C). Butter samples presented a pseudoplastic behaviour, and rheological parameters showed a high dependence on temperature. The counts of lactobacilli and lactococci in the butter samples were of the order of log 7–8 CFU/g, while yeast and mould counts were lower than log 2 CFU/g until the 30th day of storage, after which they showed a sharp increase to ca. log 5 CFU/g between the 30th and the 60th days of storage. Regarding sensory attributes of butter, sample P received the highest overall liking, followed by samples ABC and PBC. Sample A was the least appreciated. Buttermilk samples presented significant differences regarding their composition, viscosity, and colour parameters. In all cases, lactobacilli and lactococci counts exceeded log 7 CFU/mL after 30 days of storage, but yeast and mould counts were of the order of log 5–6 CFU/mL at the 15th day of storage. Samples P and PBC presented yeast and mould counts ca. 1–2 log cycles lower than samples A and ABC, indicating the potential of probiotic and bioprotective cultures to extend the shelf life of the product. Regarding the sensory attributes of buttermilk, samples P and PBC received the highest overall liking, followed by sample ABC. Sample A received the lowest scores, as had occurred with the butter samples. However, in all cases, the scores obtained by the buttermilk samples were lower compared to the ones of the corresponding butter. It can be concluded that both probiotic butter and buttermilk present high levels of lactobacilli and lactococci and can maintain their probiotic potential throughout the storage period.

28 April 2023 in Membranes
Verified
Journal Article
Open access
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APArona Pires
Arona Pires
GTGözdenur Tan
Gözdenur Tan
DGDavid Gomes
David Gomes
SDSusana Dias
Susana Dias
OROLGA DIAZ RUBIO
OLGA DIAZ RUBIO
Carlos PereiraCarlos Pereira
Carlos Pereira
Membrane filtration technologies are the best available tools to manage dairy byproducts such as cheese whey, allowing for the selective concentration of its specific components, namely proteins. Their acceptable costs and ease of operation make them suitable for application by small/medium-scale dairy plants. The aim of this work is the development of new synbiotic kefir products based on sheep and goat liquid whey concentrates (LWC) obtained by ultrafiltration. Four formulations for each LWC based on a commercial kefir starter or traditional kefir, without or with the addition of a probiotic culture, were produced. The physicochemical, microbiological, and sensory properties of the samples were determined. Membrane process parameters indicated that ultrafiltration can be applied for obtaining LWCs in small/medium scale dairy plants with high protein concentration (16.4% for sheep and 7.8% for goats). Sheep kefirs showed a solid-like texture while goat kefirs were liquid. All samples presented counts of lactic acid bacteria higher than log 7 CFU/mL, indicating the good adaptation of microorganisms to the matrixes. Further work must be undertaken in order to improve the acceptability of the products. It could be concluded that small/medium-scale dairy plants can use ultrafiltration equipment to valorize sheep’s and goat’s cheese whey-producing synbiotic kefirs.

14 March 2022 in Sustainability
Verified
Journal Article
Open access
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PSPedro R. Soares
Pedro R. Soares
RPRosinda Leonor Santos Pato
Rosinda Leonor Santos Pato
SDSusana Dias
Susana Dias
DSDaniela Valente Valente Simões dos Santos
Daniela Valente Valente Simões dos Santos
Crop–livestock integration fosters a holistic view of the agricultural system, which is nowadays particularly relevant due to the rising environmental concerns. Laying hens can contribute to improvement of soil chemical properties, but their effects in soil fertility are not fully known. This study aimed to evaluate the effects of grazing laying hens on soil fertility. To meet this goal, we assessed the effects of indigenous laying hens in 22 soil parameters, including chemical, physical, and microbiological parameters, in two farms from the central region of Portugal: an organic horticultural field (A) and a conventional orchard (B). At farm A, the animals grazed during the dry period for 84 continuous days, at a density of 4 m2 per hen. At farm B, the animals grazed during the wet period, at a density of 3.50 m2 per hen, in two periods (34 + 33 days), with a 50 day break period in between grazing. The hens contributed to an increase in the extractable macronutrients phosphorus (P2O5) and potassium (K2O), mineral nitrogen (NH4+-N and NO3−-N), and exchangeable bases calcium (Ca2+) and magnesium (Mg2+) in both farms, making these central parameters to consider in their grazing management. At farm A, where soil disturbance is higher, the grazing did not affect soil moisture retention but positively affected soil dry bulk density and contributed to an increase in total aerobic bacteria and nitrogen-fixing bacteria abundances. At farm B, where the hens’ presence led to the understory eradication, soil moisture retention, total aerobic bacteria, nitrogen-fixing bacteria, and fungi abundances were negatively affected, while soil dry bulk density was unaffected. These results show that hens can significantly contribute to improve soil fertility, but more research is needed regarding their grazing management.