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- New frontiers in the exploration of phenolic compounds and other bioactives as natural preservativesPublication . Oliveira, Izamara; Santos-Buelga, Celestino; Aquino, Yara Goulart de; Barros, Lillian; Heleno, Sandrina A.Phenolic compounds are secondary metabolites widely distributed in the plant kingdom, valued for their strong antioxidant and antimicrobial properties. These bioactive compounds are promising natural alternatives to artificial preservatives in the food industry, aligning with consumer demand for sustainable solutions that ensure food quality and safety. In this review, the structural complexity of bioactive phenolic compounds, which include their various subclasses and the chemical basis of their antioxidant and antimicrobial activity, is explored. This review examines innovative extraction methods designed to preserve the bioactivity of these compounds. Additionally, it examines their incorporation as natural preservatives, focusing on stability issues and applications in the food sector. The structural diversity of phenolic compounds underpins their broad applications in food preservation. These include antimicrobial and antioxidant properties, which contribute to food safety and offer potential health benefits. The use of agro-industrial biowastes as a sustainable supply of phenolics is a promising approach; however, standardization is necessary to obtain extracts with consistent and effective biological activity. Innovative techniques, such as encapsulation and integration into edible films, are being developed to improve the stability and effectiveness of these compounds, expanding their application in various food products
- Nutritional, chemical and bioactive characterization of Peumus boldus L.Publication . Oliveira, Izamara; Calhelha, Ricardo C.; Finimundy, Tiane C.; Santos-Buelga, Celestino; Heleno, Sandrina A.; Barros, LillianPeumus boldus L. (boldo) is known for its pharmacological effects associated with the chemical composition of its leaves. The objective of this work was to perform the nutritional, chemical and bioactive characterization of boldo leaves. The nutritional profile (crude fat, protein, ash, fiber, and carbohydrates) was determined using AOAC methods [1], while free sugars were determined by HPLC-RI and fatty acids by GC-FID. Moreover, organic acids were determined by HPLC-DAD, tocopherols by HPLC-fluorescence, and phenolic compounds by HPLC-DAD-ESI/MS. Afterwards, a hydroethanolic extract was prepared by maceration (80:20 v/v, ethanol:water), and the antioxidant potential was evaluated using the thiobarbituric acid reactive substances (TBARS) assay; antimicrobial capacity using the microdilution method against pathogenic microorganisms; cytotoxicity against tumor and non-tumor cell lines using the sulforhodamine B assay, and anti-inflammatory potential using RAW cells. For the nutritional profile results, the highest values were obtained for carbohydrates (78 ± 1 g/100 g dw, of which 48.0 ± 0.2 g/100 g dw corresponded to fiber), followed by proteins (8.2 ± 0.5 g/100 g dw), ash (10.0 ± 0.9 g/100 g dw) and fat (4.24 ± 0. 06 g/100 g dw), having an energetic value of 285 ± 2 kcal. Glucose (6.82 ± 0.03 g/100 g dw), followed by fructose (2.70 ± 0.04 g/100 g dw) and sucrose (1.50 ± 0.10 g/100 g dw) were the detected sugars. Ten fatty acids were found, with three main compounds standing out, namely palmitic (29.56 ± 0.05 %), oleic (19 ± 5 %) and linolenic (17 ± 2 %) acids. Five organic acids were identified, highlighting oxalic (1.26 ± 0.04 g/100 g dw) and quinic (1.24 ± 0.05 g/100 g dw) acids. The vitamin E isoforms γ-tocopherol (15 ± 1 g/100 g dw) and α-tocopherol (5.2 ± 0.3 g/100 g dw) were the ones identified in boldo leaves. Seventeen phenolic compounds were detected, from which proanthocyanidins were the most prominent, especially a proanthocyanidin dimer (34.69 ± 0.91 mg/g), and two proanthocyanidin trimers, 1 (32.12 ± 0.75 mg/g) and 2 (18.59 ± 0.67 mg/g). For the antioxidant potential (TBARS), an EC50 of 36.8 ± 0.2 μg/mL was determined, and for the antimicrobial capacity, lower minimum inhibitory concentrations (MIC) were seen especially against the foodborne bacteria Yersinia enterocolitica (1.25 mg/mL) and Staphylococcus aureus (1.25 mg/mL), as well as the clinical isolates E. coli (2.5 mg/mL), Morganella morganii (2.5 mg/mL), Enterococcus faecalis (2.5 mg/mL) and methicillin-resistant S. aureus (2.5 mg/mL). Boldo leaves showed cytotoxicy against nonsmall lung carcinoma (71 ± 4 μg/mL), gastric adenocarcinoma (159 ± 12 μg/mL), and breast carcinoma (280 ± 9 μg/mL) cells. They also showed anti-inflammatory activity for macrophage cell line (RAW cells) at 145 ± 13 μg/mL. Thus, besides being rich in nutrients, P. boldus revealed the presence of bioactive compounds which can be used for future applications in the food, cosmetic and pharmaceutical industries.
- Effects of the extraction techniques on the chemical composition and bioactive properties of lemon balm (Melissa officinalis L.) plants grown under different cropping and irrigation regimesPublication . Oliveira, Izamara; Chrysargyris, Antonios; Heleno, Sandrina A.; Carocho, Márcio; Calhelha, Ricardo C.; Dias, Maria Inês; Petrović, Jovana; Soković, Marina; Petropoulos, Spyridon Α.; Santos-Buelga, Celestino; Tzortzakis, Nikolaos; Barros, LillianThe present study aims to determine the combined effect of cropping system and irrigation regime on the chemical composition and bioactive properties of lemon balm aerial parts. For this purpose, lemon balm plants were grown under two farming systems (conventional farming vs organic farming) and two irrigation levels (full irrigation vs deficit irrigation) and harvested twice throughout the growing period. The collected aerial parts were subjected to three different methods of extractions, namely infusion, maceration and ultrasound-assisted extraction and the obtained extracts were evaluated in terms of chemical profile and bioactivities. Five organic acids with varied composition among the tested treatments were identified in all the tested samples for both harvests, namely, citric, malic, oxalic, shikimic and quinic acid. Regarding phenolic compounds composition, the most abundant ones were rosmarinic acid, lithospermic acid A isomer I and hydroxylsalvianolic E, especially for the maceration and infusion extraction methods. Full irrigation resulted in lower EC50 values than deficit irrigation only in the treatments of the second harvest, while variable cytotoxic and anti-inflammatory effects were recorded in both harvests. Finally, in most cases the lemon balm extracts has similar or better activity than the positive controls, while the antifungal activity of lemon balm extracts was stronger than the antibacterial effects. In conclusion, the results of the present study showed that the implemented agronomic practices, as well as the extraction protocol may significantly affect the chemical profile and bioactivities of lemon balm extracts, suggesting that both the farming system and the irrigation schedule may improve the quality of the extracts depending on the implemented extraction protocol.
- Análise sensorial de carne de lombo suína. Comparação das características sensoriais da carne de suínos da Raça Bísara alimentados com e sem castanha em relação à carne de suíno comercialPublication . Oliveira, Izamara; Teixeira, Alfredo; Rodrigues, Sandra; Kuss, FernandoO objetivo deste trabalho foi estudar o efeito nas características sensoriais de carne do lombo de suínos da raça Bísaro comparativamente à carne de suíno comercial. Foi ainda estudado o efeito do uso da castanha na alimentação de suínos da raça Bísaro. Para tal recorreu-se a um painel de provadores treinado que avaliou através de uma análise descritiva quantitativa atributos objetivos dos lombos em análise. Os procedimentos da análise sensorial foram feitos de acordo com as Normas Portuguesas. Os resultados indicaram que os lombos de suínos provenientes de raça Bísaro tem qualidades sensoriais superiores à carne de suíno comercial. É uma carne clara, com sabores e odores moderadamente intensos (mais intenso em Bísaro alimentados com castanha), bastante tenra e suculenta. A carne de suíno comercial apresentou características sensoriais inferiores à carne de bísaro. Podemos observar através destes as diferenças entre as raças pode ser devido ao devido ao sistema de criação e tipo de alimentação o qual teve grande influência sobre as características da carne, evidenciando uma elevada qualidade sensorial na carne suína da raça autóctone bísara.
- Chemical and bioactive screening of green polyphenol-rich extracts from chestnut by-products: an approach to guide the sustainable production of high-added value ingredientsPublication . Rodrigues, Daniele Bobrowski; Verissimo, Lavinia; Finimundy, Tiane C.; Rodrigues, Joana P.B.; Oliveira, Izamara; Fernandes, Isabel P.; Barros, Lillian; Heleno, Sandrina A.; Calhelha, Ricardo C.Opportunities for the valorisation of agro-industrial residues of the chestnut (Castanea sativa Mill.) production chain have been fostered with the production of multifunctional polyphenol-rich extracts with the potential to be introduced as natural additives or active components in several products. Nonetheless, it is crucial to explore the feasibility of different extracts from the various by-products for these applications through the exhaustive study of their composition and bioactivities without losing sight of the sustainable character of the process. This work aimed at the screening of the phenolic compound composition and bioactivities of different green extracts of chestnut burs, shells and leaves, as the first step to establish their potential application as natural ingredients, primarily as food preservatives. To this end, maceration (MAC) as a conventional extraction method besides ultrasound and microwave-assisted extractions (UAE and MAE) was employed to obtain the extracts from chestnut by-products using water (W) and hydroethanolic solution (HE) as solvents. Phenolic compounds were analysed by HPLC-DAD-(ESI-)MS/MS; the antioxidant capacity was assessed by colourimetric assays, and the antimicrobial activity was evaluated against several strains of food-borne bacteria and fungi. The leaf extracts obtained by MAC-HE and UAE-HE presented the highest concentration of phenolic compounds (70.92 & PLUSMN; 2.72 and 53.97 & PLUSMN; 2.41 mg.g(-1) extract dw, respectively), whereas, for burs and shells, the highest recovery of total phenolic compounds was achieved by using UAE-HE and UAE-W (36.87 & PLUSMN; 1.09 and 23.03 & PLUSMN; 0.26 mg.g(-1) extract dw, respectively). Bis-HHDP-glucose isomers, chestanin and gallic acid were among the most abundant compounds. Bur extracts (MAC-HE and UAE-HE) generally presented the highest antioxidant capacity as measured by TBARS, while the best results in DPPH and reducing power assays were found for shell extracts (MAE-W and MAC-HE). Promising antibacterial activity was noticed for the aqueous extracts of burs, leaves and hydroethanolic extracts of shells, with emphasis on the MAE-W extract of burs that showed bactericidal activity against E. cloacae, P. aeruginosa and S. aureus (MBC 5 mg.mL(-1)). Overall, it can be concluded that chestnut by-products, including burs, shells and leaves, are sources of polyphenolic compounds with significant antioxidant and antimicrobial activities. The choice of extraction method and solvent greatly influenced the composition and bioactivity of the extracts. These findings highlight the potential of chestnut by-products for the development of natural additives, particularly for food preservation, while also emphasizing the importance of sustainable utilization of agricultural waste materials. Further research is warranted to optimize extraction techniques and explore additional applications for these valuable bioactive compounds.
- Antimicrobial activity of rosemary, eucalyptus and propolis individual and mixed extractsPublication . Abir, Tebai; Oliveira, Izamara; Falcão, Soraia; Ben Rejeb, Ines; Barros, Lillian; Heleno, Sandrina A.Preservative-free meals and the use of natural products as natural alternatives are becoming more popular as consumers become more aware of the potential health problems associated with artificial food preservatives. The current study focused on exploring the potential of plant extracts (rosemary and eucalyptus) and propolis, or their mixtures, to develop a highly bioactive formulation. Extracts were prepared individually and mixtures of eucalyptus/propolis, eucalyptus/rosemary, and rosemary/propolis using hydroethanolic extracts (80% ethanol) in different ratios of 50:50, 60:40, and 40:60, respectively., were also prepared. The selected matrices were prepared by two different maceration processes: i) 1 g of the sample was macerated in 30 mL of 80% hydroethanolic solution using magnetic stirring; ii) 1 g of sample in 10 mL of hydroethanolic solution was macerated in a water bath at 70°C, this being, the recommended protocol for extraction of phenolic compounds from propolis [1]. The extracts were further analyzed for their antimicrobial ability by microdilution method using pathogenic microorganisms. The individual extracts of rosemary and eucalyptus showed remarkably strong antibacterial activity against most bacterial strains, often equivalent to that obtained with the common antibiotic’s streptomycin, methicillin, and ampicillin. Both mixtures, eucalyptus/rosemary (60:40) collected from maceration by magnetic stirring and eucalyptus/propolis (60:40) derived from maceration with water bath, showed the most promising results, with inhibition ability against all bacteria. As for the antifungal ability, no inhibition was obtained at the maximum tested concentration of 10 mg/mL. In addition to these encouraging results for antimicrobial activity, further bioactivity assays will be performed to evaluate the properties of the different extracts.
- New challenges and opportunities from secondary metabolitesPublication . Oliveira, Izamara; Albuquerque, Bianca R.; Ueda, Jonata Massao; Alves, Maria José; Ferreira, Isabel C.F.R.; Barros, Lillian; Heleno, Sandrina A.Secondary metabolites (SMs), usually of complex structure and low molecular weight, have remarkable biological activities and, unlike the primary metabolites, are presented in low concentrations and in certain groups of plants. These, in turn, arouse great interest, not only for the biological activities exerted by plants in response to environmental stimuli, but also for the immense pharmacological activity they possess. Many are of commercial importance, not only in the pharmaceutical area, but also in the food, agronomy, perfumery, and other important sectors. In general, secondary metabolites are natural compounds produced in plants with the main objective of protection against abiotic and biotic stresses, besides having important nutritional and pharmacological aspects in human nutrition, they are also sources of aromatic additives, dyes, antioxidants and exert numerous functions. There are many ways to extract these compounds, but green chemistry can generate economic benefits in industrial chemical processes, such as reducing the need for investments in storage and effluent treatment, as well as the payment of compensation for any environmental damage. In addition, the use of bioresidues as promising sources of secondary metabolites is a promising way to promote the circular economy and take advantage of these by-products through bioactive compounds and their application as additives in new food sources. Currently one of the challenges is to produce sources of secondary metabolites from domesticated plants, since these have differences from wild ones, and the domestication process could preserve defense traits, such as changing the significantly, in addition to domestication-related climate changes, which may also attribute other characteristics to the secondary metabolites. Moreover, another interesting biotechnology applied to obtain large-scale SMs naturally produced by fungi is heterologous expression, which consists in the transcription of one or more genes from the cluster data gene of the fungi producing the target compound in a secondary host, which in most studies are yeasts or filamentous fungi. The use of these compounds in turn must be in force within the parameters allowed by legislation for food incorporation and in the industry in general, since they differ according to the sources, uses, toxicological levels, and the regulations regarding their certifications. However, secondary metabolites emerge as a promising source for new opportunities of application, emphasizing their potential to act as strong and natural additives for several industrial purposes.
- Physical properties of 29 colored potato varietiesPublication . Oliveira, Izamara; Ueda, Jonata Massao; Rodrigues, Christian Teixeira; Heleno, Sandrina A.; Petropoulos, Spyridon Α.; Alexopoulos, Alexios; Carocho, Márcio; Barros, Lillian; Ferreira, Isabel C.F.R.The use of different varieties of potatoes ( Solanum tuberosum L.) with different colors may be appealing to consumers, namely in terms of their visual appearance, allowing their use as “chips” and other ready-to-eat snacks. This work studied the physical properties of 29 varieties of colored potatoes, analyzing their external color and the different dimensions of texture. The external color was measured with a portable colorimeter, analyzing the CIELab color space according to the L* (lightness), a* (red-green) and b* (blue-yellow) coordinates. The texture was determined using a “texture profile analysis” assay allowing the classification of their hardness, adhesiveness, springiness, cohesiveness and resilience. The samples were classified through an analysis of variance using Tukey’s test as a post-hoc, and finally were subjected to a linear discriminant analysis for further discrimination based on the studied parameters. According to the obtained results, the color of the potatoes showed significant statistical differences, although many of the samples were related to each other. The sample with the darkest color was “Blaue veltlin” variety, with an L* of 27.8, whereas the sample with the lightest colour was “Blaue ajanhuiri” variety. In terms of the values of parameter a* the cultivar with the greenest tone was also the “Blaue ajanhuiri”, while the one closer to the red quadrant was "Purple from Peru”. Finally, the analysis of parameter b* showed that “Blaue Neuseeländer” sample was the one with the highest blue tone and “Purple fiesta” the one with the highest intensity of yellow. Regarding the different texture dimensions, the samples showed homogenous values. All samples revealed no statistical difference for springiness, whereas regarding adhesiveness, the sample “Purple from Congo” was the most adhesive at -144 g/sec and “Linzer blaue” the less adhesive at -15 g/sec. Concerning the hardness parameter, “Blaue Anneliese” and “Blaue neuseeländer” were the samples with the hardest and softest texture, respectively. In addition, the most cohesive sample was “Pink from Bolivia”, whereas the least cohesive one was “Linzer blaue”. Chewiness had three different levels of significant difference with “Blaue Anneliese” being the least chewy and “Black princess” the most, while for resilience, the least resilient were “Pink from Bolivia” and “Hermanns blaue” and the most resilient was “Linzer blaue”. In terms of the linear discriminant analysis, the first two of five functions described 84.8% of variability (function 1 – 72.0%, function 2 – 12.8%), while the varieties that presented the highest variability were “Lilly rose”, “Red salad potato”, “Purple from Peru”, “Königspurpur” and “Highland burgundy”. In conclusion, the presented results showed a great variability among the tested potato varieties indicating that these could dictate the different uses of the final food product.
- Nutritional profile of papaya peels, pulp, and seeds (Carica papaya L.)Publication . Oliveira, Izamara; Heleno, Sandrina A.; Carocho, Márcio; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.; Barros, LillianPapaya (Carica papaya L.) is native to tropical America and is one of the most widely cultivated fruit plant in the world, especially in tropical areas where the average annual temperature is 25 °C. Due to its sensory characteristics, nutritional value, and functional properties (digestive and laxative), papaya is a very acceptable fruit. Nevertheless, after industrial processing peels and seeds are discarded generating waste that could be reused in the recovering of important molecules. Thus, the objective of this work was to determine the nutritional composition of papaya comparing the differences in the nutritional profile of the peels, pulp, and seeds. To achieve these results, the crude fat (Soxhlet extractor), protein (Macro-Kjedahl), ash (AOAC methodology 923.03), soluble sugars (HPLC-RI), fatty acids (GC-FID) and organic acids (HPLC-DAD) were determined. Regarding the results, for protein the values were relatively higher in seeds (43.6 ± 0.1 g/100 g dw) when compared to the peels (15.8 ± 0.3 g/100 g dw) and pulp (4.6 ± 0.2 g/100 g dw). Regarding fat, the values were also higher in the seeds (23.5 ± 0.9g/100 g dw) in comparison to the peels (1.46 ± 0.02 g/100 g dw) and pulp (0.78 ± 0.05 g/100 g dw). As for ash content, the values were higher for peels (10.6 ± 0.1 g/100 g dw), followed by seeds (8.0 ± 0.8 g/100 g dw) and pulp (4.7 ± 0.4 g/100 g dw). The carbohydrate content was higher in the pulp (89.9 ± 0.7 kcal) followed by the peel (72.2 ± 0.5 kcal) and seeds (25.0 ± 0.3 kcal). Three sugars, fructose, glucose, and sucrose were found, except for seeds that did not show the presence of sucrose. Glucose was the most abundant sugar in all fruit parts (56 ± 3 g/100 g dw for pulp; 21±1g/100 g dw for peels; 10±1 g/100 g dw for seeds). A total of 20 fatty acids were found, where linolenic acid (20.3 ± 0.4%) was the most abundant in the peels, palmitic acid (54.69 ± 0.02%) in the pulp and oleic acid (68.5 ± 0.1%) in the seeds. Four organic acids were quantified, where citric acid had the highest values in the seeds (8.0 ± 0.3 g/100 g dw), peels (3.88 ± 0.04 g/100 g dw) and pulp (2.00 ± 0.01 g/100 g dw), respectively. In general, it can be concluded that papaya has higher nutritional content in the seeds and peels when compared to the pulp, which is normally the consumable part, justified by its sweet taste and sensory aspects. However, the use of the residues of the peels and seeds would be of great value, since it has a significant nutritional potential reducing waste and enabling the creation of new products. In addition, future studies will be carried out testing its antimicrobial, ant-proliferative and antioxidant properties in cell-based assays, in order to further improve the bioactive quality of this fruit.
- Magnesium and manganese induced changes on chemical, nutritional, antioxidant and antimicrobial properties of the pansy and Viola edible flowersPublication . Oliveira, Izamara; Chrysargyris, Antonios; Finimundy, Tiane C.; Carocho, Márcio; Santos-Buelga, Celestino; Calhelha, Ricardo C.; Tzortzakis, Nikolaos; Barros, Lillian; Heleno, Sandrina A.composition was determined using standard methods. Free sugars, fatty acids, organic acids, tocopherols, and phenolic compounds were analyzed using various HPLC and GC devises. The extract’s antimicrobial, antioxidant, cytotoxicity, and anti-inflammatory activity were assessed. The results indicated that Mg enrichment negatively affected plant growth and mineral accumulation but improved photosynthetic performance. The edible flowers contained significant amounts of protein, low levels of fat, and varying sugar contents, such as glucose and fructose. Various fatty acids and phenolic compounds were identified, with different concentrations depending on the treatment. The flowers exhibited antioxidant potential, antimicrobial activity, cytotoxic effects, and antiinflammatory properties. The correlations between the investigated parameters not only expand knowledge on Mg and Mn interaction but also catalyze significant advancements in sustainable agriculture and food health, fostering a healthier and more conscious future.
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