CBQF - Documentos de Conferências / Conference Objects
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- Synergistic combination of essential oil and organic acid: substitute for potassium sorbate in fruit preparationPublication . Sorathiya, Kavita; Melo, Adma; Rodrigues, Cristina; Paulico, Luís; Barracosa, Rita; Correia, Daniela; Hogg, Maria Conceição; Pintado, M. ManuelaBackground: Chemical preservatives, such as potassium sorbate (PS), are widely used in food preservation; however, they raise concerns due to potential health risks and increasing consumer demand for clean-label products. The replacement of synthetic antimicrobials with natural antimicrobial has emerged as a sustainable strategy to improve food quality and shelf life. Propionic acid (PA) and lemongrass essential oil (LEO) exhibit potential antimicrobial activity and their combination enhances inhibition of spoilage and pathogenic microorganisms. This study investigated PA and LEO combinations as natural preservatives to enhance microbiological safety and extend the shelf life of strawberry preparations for use in yogurts. Method: Different treatments were investigated using the strawberry preparation with the addition of different concentrations of the combinations of LEO and PA ranging from ¼ to 2xMIC, and PS (0,1%) as the negative control, and standardized inoculum of bacteria (10? CFU/mL - Lactobacillus plantarum, Escherichia coli), yeast (10³ CFU/mL - Candida intermedia, Pichia fermentans) and fungi (10² or 10? spores/mL - Penicillium glabrum, Aspergillus niger) for 28 days. All systems were kept at refrigeration temperature (5 ± 2°C) and microbial growth was evaluated on days 0, 1, 7, 14, 21 and 28. Results: The combination of LEO and PA at 2× MIC exhibited greater antifungal activity than PS. The combination of ¼× MIC inhibited 10² spores/g but not at 10? spores/g, while the combinations of ½× MIC and MIC inhibited fungal growth at both inoculum levels (10² and 10? spores/g). No bacterial or yeast growth was detected at any time point across all tested concentrations of the LEO + PA combination. Conclusions: The results showed that LEO and PA are effective natural alternatives to replace PS for fruit preparation. However, further studies are needed to understand the effect of this combination on the fruit preparation when incorporated into yogurt and sensory tests to evaluate the effect of these antimicrobials on the sensory attributes of the final product.
- From waste to worth: upcycling peanut skin via green extraction for bioactive applicationsPublication . Afonso, Tiago B.; Bonifácio-Lopes, Teresa; Costa, Eduardo; Costa, Ana Filipa; Oliveira, Juliana A. S. A.; Pintado, Manuela E.Aim: The valorisation of agro-industrial by-products represents a strategic approach toward reducing food processing waste while fostering circular bioeconomy practices. Peanut skin, a by-product of peanut processing, is particularly rich in phenolic compounds with significant antioxidant and antimicrobial properties, making it a promising candidate for sustainable applications in the cosmetic and textile industries. This study explores the upcycling of peanut skin via eco-friendly extraction technologies to obtain phenolic-rich bioactives suitable for skin-related applications and functional textiles. Method: We investigated the impact of four extraction methodologies - hydroethanolic, aqueous, alkaline, and ultrasound-assisted extraction (UAE) - on the yield and chemical composition of peanut skin extracts. Analytical assessments included quantification of protein, total carbohydrates, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity via the ORAC assay. The phenolic composition was further elucidated through LC-ESI-QqTOF-HRMS. Additionally, the antimicrobial efficacy of the extracts was tested against representative Gram-negative and Gram-positive bacteria. Furthermore, the metabolic impact of the extracts on a human keratinocyte cell line (HaCat) was also assessed to evaluate biocompatibility. Results: Among the methods tested, the UAE yielded the highest total phenolic content (512.93 mg GAE/g DE) and antioxidant activity (2770.17 ?mol TE/g DE). The phenolic profile revealed that peanut-skin extracts were rich in type-A and type-B procyanidin dimers and trimers, with type-A dimers being the most abundant, accounting for up to 36.47% of the total phenolics in UAE. These compounds are known for their strong antioxidant and antimicrobial efficacy. Antimicrobial assays showed that alkaline extracts exhibited the most potent activity, inhibiting Staphylococcus aureus and S. epidermidis at 5 mg/mL and 2.5 mg/mL, respectively. Hydroethanolic and UAE extracts exhibited moderate inhibition at higher concentrations. In contrast, the aqueous extracts were inactive against all tested bacteria. When considering the extracts impact on HaCaT cells, the lowest cytotoxicity was observed for the hydroethanolic extract (500 ?g/mL), and the highest for UAE (62.5 ?g/mL). Conclusion: These findings highlight the potential of UAE for enhancing the recovery of phenolic compounds from peanut skin. The high antioxidant and antimicrobial activities of the enriched extracts, supports their application in skin-related products including textiles.
- The power of community: catalysing food safety innovations for allPublication . Fonseca, Diana R.; Cortez, João; Teixeira, Paula
- Synergistic effect of nickel and melatonin on drought tolerance in pea (pisum sativum)Publication . Spoloar, Bruna Oliveira Reinheimer; Silva, Marta Nunes da; Geraldo, Rafaela; Moro, Adriana Lima; Vasconcelos, MartaIntroduction: The intensification of drought events due to climate change threatens global food security. Pea (Pisum sativum) is a key legume for sustainable agriculture, as it fixes nitrogen, improves soil fertility, and has high nutritional value. However, it is highly sensitive to water stress. Nickel (Ni) is an essential micronutrient in nitrogen metabolism, while melatonin (MEL) regulates oxidative stress. As such, the aim of this work was to evaluate the isolated and combined effects of Ni and MEL on the physiological, biochemical, and productive responses of pea plants under drought stress. Results: The combined application of Ni and MEL in drought-stressed plants promoted: Increased aerial and root biomass (+27%) and nodule number (+27%), indicating greater nitrogen fixation efficiency. Improved protein content in roots, leaves, and seeds and higher number of pods per plant (+33%) and grain biomass (+21%). Reduced chlorophyll degradation (+15% SPAD), H?O? concentration (-45%) and lipid peroxidation (-38% MDA), suggesting lower oxidative stress. Conclusions: Ni and melatonin synergy improves pea nutrition, strengthens antioxidant capacity, and maintains cellular integrity, leading to higher productivity under drought stress. This approach may enhance legume resilience to climate change, promoting sustainable agriculture.
- Alkaline extraction of phenolic compounds from Eucalyptus leaves: influence on antioxidant and antimicrobial activityPublication . Afonso, Tiago B.; Bonifácio-Lopes, Teresa; Costa, Eduardo; Macedo, Tiago; Moreira, Joana; Oliveira, Juliana; Pintado, ManuelaIntroduction: The valorization of agro-industrial by-products is a strategic approach to reducing biomass waste while advancing circular bioeconomy practices. Eucalyptus leaves, an abundant residue from the forestry and pulp industries, are particularly rich in phenolic compounds with well-known antioxidant and antimicrobial activities. These bioactivities highlight the potential of eucalyptus extracts for sustainable applications in the cosmetic and textile industries. However, their efficient recovery requires optimized extraction methodologies capable of disrupting the complex plant matrix and maximizing compound release. The aim of this study was to investigate how variations in eucalyptus particle size and alkali concentration can enhance the recovery of phenolic-rich extracts with bioactive potential. Conclusions: Alkaline extraction proved capable for recovering phenolic compounds from eucalyptus leaves, yielding extracts with relevant antioxidant and antimicrobial activities. However, the extracts showed cytotoxicity at the tested concentrations, highlighting the need for further optimization of extraction parameters and the establishment of safe concentration ranges before potential use in applications such as cosmetics or textiles.
- Alkaline extraction of phenolic compounds from Eucalyptus leaves: influence on antioxidant and antimicrobial activityPublication . Afonso, Tiago Barros; Bonifácio-Lopes, Teresa; Costa, Eduardo; Macedo, Tiago; Moreira, Joana; Oliveira, Juliana; Pintado, ManuelaBackground: The valorization of agro-industrial by-products is a strategic approach to reducing biomass waste while advancing circular bioeconomy practices. Eucalyptus leaves, an abundant residue from the forestry and pulp industries, are particularly rich in phenolic compounds with well- known antioxidant and antimicrobial activities. These bioactivities highlight the potential of eucalyptus extracts for sustainable applications in the cosmetic and textile industries. However, their efficient recovery requires optimized extraction methodologies capable of disrupting the complex plant matrix and maximizing compound release. In this work, we explored alkaline extraction, focusing on the influence of particle size and alkali concentration on the recovery of phenolic-rich extracts with bioactive potential. Methods: Eucalyptus leaves were processed at two particle sizes (4 mm and 10 mm) and extracted using NaOH at two concentrations (0.1 M and 0.3 M). Extracts were analyzed for total phenolic and flavonoid content as well as antioxidant capacity using ORAC assay. Phenolic composition was characterized by LC-ESI-QqTOF-HRMS. Furthermore, the antimicrobial efficacy of the extracts was tested against different Gram-negative and Gram-positive bacteria as well as the yeast Malassezia furfur. Additionally, the biocompatibility of the extracts was evaluated on a human keratinocyte cell line (HaCaT). Results: Smaller particle sizes (4 mm) combined with lower NaOH concentrations (0.1 M) yielded extracts with higher total phenolic and flavonoid content. In terms of antioxidant activity, no significant differences were observed between the different extracts. LC-ESI-QqTOF-HRMS analysis revealed the presence of phenolic acids (e.g., quinic and gallic acid) and flavonoids (e.g., quercetin-3-O-glucuronide) with compositional differences across conditions. All extracts displayed strong antimicrobial activity against Gram-positive bacteria and M. furfur, with MIC values below 1.25 mg/mL in most cases. However, cytotoxicity assays indicated reduced HaCaT viability at concentrations ? 500 ?g/mL. Conclusions: Alkaline extraction proved effective for recovering phenolic compounds from eucalyptus leaves, yielding extracts with strong antioxidant and antimicrobial activities. These findings support their potential for skin-related applications, including cosmetics and functional textiles, although further optimization of extraction conditions and safety thresholds is required.
- Exploring persistence markers through fatty acid profiles of listeria monocytogenes under distinct temperature conditionsPublication . Magalhães, Rui; Machado, Manuela; Teixeira, PaulaIntroduction: Listeria monocytogenes, the causative agent of listeriosis, is a major foodborne pathogen. It is a ubiquitous, facultative anaerobic, gram-positive bacterium. Listeriosis can be a severe illness particularly affecting vulnerable groups: the elderly, immunocompromised individuals, pregnant women and neonates. Listeria monocytogenes exhibits remarkable adaptability to diverse and challenging environments, demonstrating an exceptional capacity to thrive in conditions such as refrigeration temperatures or high salt concentrations or other factors found in food processing environments (FPE). This resilience is a key factor in its ability to persist within food processing facilities and proliferate in various food products. Only certain strains are routinely isolated from these FPEs (persistent strains) while others are isolated sporadically (non-persistent strains). Objectives: This study aimed to identify fatty acids that could serve as persistence markers in isolates from the GenoPhenoTraits4Persistence collection, classified as persistent (P) or non- persistent (NP). Conclusions: Fatty acid profiles at 10 ?C demonstrate clear clustering according to clonal complex, indicating that membrane lipid composition is predominantly influenced by genetic lineage. Variations in persistence status do not account for differences in lipid profiles, implying that persistence in food-processing environments is governed by factors beyond membrane fatty acid composition. The detection of branched-chain fatty acids iso-C15 and iso-C17, along with ?C19 at low temperatures, underscores their significance in L. monocytogenes adaptation to environmental stresses, particularly temperature changes and membrane fluidity regulation. Principal component analysis (PCA) confirmed strong clustering of fatty acid profiles by clonal complex, reinforcing the role of genetic background in shaping membrane lipid composition. Persistence status failed to explain the variability observed, suggesting that survival in food-processing settings depends on mechanisms other than fatty acid makeup. These lipid markers will be further investigated to determine their potential role in the adaptation and resilience of these strains under challenging conditions.
- Impact of food soils on biofilm formation by listeria monocytogenes and salmonella on stainless-steel surfacesPublication . Bessa, Beatriz; Almeida, Pedro; Carvalho, Marta; Fonseca, Diana R.; Teixeira, Paula
- Innovative microfluidic paper-based analytical device for the determination of zinc(II) in children’s urine samplesPublication . Melo, Maria M. P.; Rangel, António O. S. S.; Mesquita, Raquel B. R.Zinc(II) is an important metal ion, present in the human body, that plays vital roles in biological processes, specifically in child growth, development, and improvement of cognitive behaviour. Its deficiency can cause serious health risks, which makes urinary zinc(II) analysis very relevant, as it is considered a biomarker of children’s psychological development and can even indicate urinary tract diseases. Zinc supplementation has been applied as a preventive therapeutic measure, resulting in a positive effect on child development, which makes supplementation monitoring critical to ensure child growth worldwide. Paper-based sensors have gained relevance over the years in providing reliable, rapid, inexpensive, and user-friendly analytical analysis. When combining this tool with fluids of non-invasive collection, namely urine, it enables an effective monitoring of health-related issues frequently, especially in children, who often oppose taking blood. As such, in this work, an innovative microfluidic paper-based analytical device (µPAD) was developed, based on the colorimetric reaction between zinc(II) and dithizone, in an alkaline medium. The sensor quantifies zinc(II) within a dynamic range of 0.050-0.750 mg/L, where the reaction occurs for 5 minutes and the given signal remains stable for 30 minutes, with a LOD (limit of detection) of 0.010 mg/L and a LOQ (limit of quantification) of 0.034 mg/L. Before loading the sample in the µPAD and after its assembly with layered paper discs impregnated with the reagents, it can be used for up to one week, if stored in air or vacuum conditions and at room temperature. The accuracy assessment of this method was carried out by comparing and validating the results of different urine samples (directly used or diluted 1:2) in the µPAD and in the AAS (atomic absorption spectrometry). The developed µPAD offers a point-of-care analysis of urinary zinc(II) levels in children, an important tool for practical clinical diagnosis. It can also be employed for testing zinc(II) levels in food supplements.
- GenoPheno4Trait Project: genomic and phenotypic traits contributing to persistence of Listeria monocytogenes in food processing environmentPublication . Magalhães, Rui; Noronha, Lucia; Sousa, Ana; Teixeira, PaulaObjective: Improve food safety and decrease food waste by reducing food contamination with Listeria monocytogenes securing a sufficient supply. L. monocytogenes: a foodborne pathogen responsible for listeriosis. Listeriosis can lead to: abortion, premature stillbirth, septicemia, meningitis, encephalitis, brain abscess, endocarditis and death.