Browsing by Author "Martins, Valter F. R."
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- Biodegradable films with polysaccharides, proteins, and bioactive compounds from lobosphaera sp.: antioxidant and antimicrobial activitiesPublication . Martins, Valter F. R.; Lopes, Ana I.; Machado, Manuela; Costa, Eduardo M.; Ribeiro, Tânia B.; Poças, Fátima; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Microalgae are a sustainable source of bioactive compounds and nutrients that do not compete with crops for arable land. Lobosphaera sp. was used to produce biodegradable films. Bioactive compounds, polysaccharides, and proteins were extracted from this microalga. The total phenolic content (TPC) and antioxidant activity (ABTS, DPPH, and ORAC) of the bioactive-rich extract were determined, and its composition was analyzed for phenolics using LC-ESI-QqTOF-HRMS and for lipids using GC-FID. The cytotoxicity of this extract on Caco-2 cells was also assessed. Different types of films were produced based on alginate (2%) (film A) and alginate with polysaccharides-rich (PS-rich) extract (0.5%) (film B); PS-rich extract and bioactive-rich extract (0.25%) (film C); protein-rich (P-rich) extract (0.5%) (film D); and P-rich extract and bioactive-rich extract (film E). The antioxidant activity and physical parameters of the films, such as thickness, color, water vapor permeability, solubility, tensile strength (TS), and elongation at break (EAB), were determined. The TPC of the bioactive-rich extract was 1.07 ± 0.05 mg GAE/100 mg DW, and its antioxidant activity was 2.44 ± 0.27, 1.67 ± 0.15, and 11.90 ± 1.22 µmol TE/100 mg DW for ABTS, DPPH, and ORAC, respectively. The extract showed no cytotoxicity to gut cells at concentrations equal to or below 1.0 mg/mL. Film E obtained the best results for the antioxidant activity, 451.06 ± 14.68 and 212.81 ± 39.12 µM TE/mg film for ABTS and DPPH, respectively. In addition, the films enriched with the bioactive-rich extract (films C and E) presented antimicrobial activity against Listeria monocytogenes. These films controlled the mold and yeast growth in strawberries during a four-day storage at 25 °C. All films were completely soluble in water and hydroethanolic solutions but only partially solubilized in acetic acid (3%). TS and EAB were not significantly different among the films. It was possible to produce biodegradable films using microalga Lobosphaera sp. with good bioactivity and physical characteristics.
- Biological and physico-chemical properties of lobosphaera sp. Packed in metallized polyethylene terephthalate/polyethylene (PETmet/PE)Publication . Martins, Valter F. R.; Alves, Ana J.; Poças, Fátima; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.This study evaluated the effects of different storage conditions, varying in light exposure, relative humidity (RH), and packaging materials, on the physicochemical stability of Lobosphaera sp. biomass, the retention of bioactive compounds, and the bioactivity of its extracts. Under light and 75% RH, the biomass absorbed moisture over time, reaching 0.779 +/- 0.003 g/g dry weight (DW) after three months. This was accompanied by a decline in luminosity, chroma, and hue values. In contrast, samples stored under other conditions showed minimal changes, indicating that high humidity, combined with light exposure, compromises biomass stability. Packaging in metalized polyethylene terephthalate (PETmet/PE) effectively preserved the water content, color, and carotenoid levels during a two-month storage period. Bioactive compounds extracted via hydroethanolic ultrasound-assisted extraction yielded 15.48 +/- 1.35% DW. Total phenolic content (TPC) of the extracts declined over time in both PETmet/PE and low-density polyethylene (LDPE) packaging, though the decrease was less pronounced in PETmet/PE. Antioxidant activity, assessed via the ABTS assay, remained stable, regardless of storage duration or packaging. Antimicrobial activity of the extract decreased over time but remained more effective against Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes), with PETmet/PE packaging better preserving antimicrobial efficacy than LDPE. These findings underscore the importance of optimized storage conditions and packaging for maintaining the quality and bioactivity of Lobosphaera sp. biomass and its extracts.
- Biostimulant effect of two fucus sp. algal residues on pea, rice, and tomato germination and growthPublication . Sperotto, Raul A.; Rosa-Martínez, Elena; Martins, Valter F. R.; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.; Vasconcelos, Marta W.Introduction: Seaweed-based bioproducts are increasingly recognized for their phytostimulatory properties, promoting plant growth and enhancing resistance to various stresses. Notably, Fucus vesiculosus, a brown seaweed, has shown promise as a biostimulant1. Exopolysaccharides (EPSs) constitute different classes of organic macromolecules that can have multiple applications. This study investigates the bioestimulant effects of Fucus sp. on the germination and early growth of pea, rice, and tomato, utilizing two algal extracts—one with EPS and another without EPS. The goal was to assess the impact of the algal residues on seed germination and initial plant development and provide insights into their potential as sustainable biostimulants. Conclusions: The three crops responded differently to applying algae extracts in the substrate as a biostimulant. The most promising results were obtained for rice and tomato since they showed a biostimulating effect on crop growth in the early stages of development, which was demonstrated mainly in the significant increase in plant dry biomass. Ultimately, the algae residue without EPS (BS-EPS at both concentrations) gave better results than the algae residue with EPS, as it significantly promoted the development of rice and tomato seedlings.
- A comparative study of drying technologies for apple and ginger pomace: kinetic modeling and antioxidant propertiesPublication . Araujo, Beatriz Z. R.; Martins, Valter F. R.; Pintado, Manuela E.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Apple and ginger mixed pomace is a by-product that can be valorized by drying. In this study, mixed pomace was subjected to hot-air drying (HAD) at 45, 62, and 70 °C and stepwise at 45 °C followed by at 62 °C or the reverse, at 62 °C followed by at 45 °C (2.5 mm layer), and microwave drying (MWD) at 100, 180, and 300 W (2.5 mm and 1.5 mm layers) and stepwise at 100 W followed by at 3000 W (2.5 mm layer). The results show that the Crank model well fitted the HAD kinetics, with a water effective diffusivity (Deff) of 2.28 ± 0.06 × 10−10–4.83 ± 0.16 × 10−10 m2/s and energy of activation of 23.9 kJ/mol. The step approach of drying at 45 °C followed by at 62 °C resulted in a higher Deff than the reverse approach (drying at 62 °C followed by at 45 °C). The Midilli et al. model presented a good fit for the MWD kinetics. The drying time was calculated using these models to achieve 12% moisture content in the pomace and found to be 125.0 ± 9.2–439.5 ± 118.2 min for HAD, and 11.1 ± 0.2–61.5 ± 6.0 min for MWD. The specific energy required was 410.78 ± 6.30–763.79 ± 205.4 kWh/kg and 1.32 ± 0.01–2.26 ± 0.05 kWh/kg, respectively. MWD at 180 W preserved the total phenolic content and the antioxidant activity (ABTS, DPPH) better than HAD at 62 °C. The former technology also preserved the pomace color well, with a low color difference, ΔE, of 7.39 ± 1.1. Therefore, MWD is more promising than HAD to dry apple and ginger pomace, reducing the environmental impact of the drying process due to its lower energy consumption, shorter drying time, and better quality. The dried product could be converted into apple and ginger pomace flour to be used as a novel food ingredient.
- Comparison among different green extraction methods of polyphenolic compounds from exhausted olive oil pomace and the bioactivity of the extractsPublication . Martins, Valter F. R.; Ribeiro, Tânia B.; Lopes, Ana I.; Pintado, Manuela E.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.The use of by-products as a source of bioactive compounds with economic added value is one of the objectives of a circular economy. The olive oil industry is a source of olive pomace as a by-product. The olive pomace used in the present study was the exhausted olive pomace, which is the by-product generated from the air drying and subsequent hexane extraction of residual oil from the olive pomace. The objective was to extract bioactive compounds remaining in this by-product. Various types of green extraction were used in the present study: solvent extraction (water and hydroalcoholic); ultrasound-assisted extraction; Ultra-Turrax-assisted extraction; and enzyme-assisted extraction (cellulase; viscoenzyme). The phenolic profile of each extract was determined using HPLC-DAD and the total phenolic content (TPC) and antioxidant activity (ABTS, DPPH, and ORAC) were determined as well. The results showed significant differences in the yield of extraction among the different methods used, with the enzyme-assisted, with or without ultrasound, extraction presenting the highest values. The ultrasound-assisted hydroethanolic extraction (USAHE) was the method that resulted in the highest content of the identified phenolic compounds: 2.021 ± 0.29 mg hydroxytyrosol/100 mg extract, 0.987 ± 0.09 mg tyrosol/100 mg extract, and 0.121 ± 0.005 mg catechol/100 mg extract. The conventional extraction with water at 50 °C produced the best results for TPC and antioxidant activity of the extracts. The extracts from the USAHE were able to inhibit Gram-positive bacteria, especially Bacillus cereus, showing 67.2% inhibition at 3% extract concentration.
- Edible films with protein and bioactive compounds from arthrospira sp.Publication . Martins, Valter F. R.; Poças, Fátima; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Arthrospira sp. is an alternative source of protein in the food chain, but it may also be considered a source of phenolic compounds with interesting properties, such as antioxidant and antimicrobial properties. In active packaging, these two properties are essential. In the present work, two extracts were produced: one extract rich in protein and another in bioactives. These two extracts were used in the production of an edible film composed of alginate (2%) + protein extract (0.5%) + bioactive extract (0.25%) with high antioxidant activity: ABTS of 1537.50 ± 191.87 and DPPH of 190.75 ± 15.53 µM TE/mg film. All the edible films produced had good physical properties, such as 100% solubility in water and ethanolic solutions. The films with alginate and protein-rich extract and or without bioactive-rich extract presented lower water vapor permeability—12.28 ± 3.01 g⋅mm−2⋅day−1⋅kPa−1 and 14.39 ± 3.64 g⋅mm⋅m−2⋅day−1⋅kPa−1, respectively—than the alginate film. In addition, the film with alginate- and protein-rich extract presented an acceptable color.
- Exploring the development of a clean-label vegan burger enriched with fermented microalgaePublication . Bassani, Joseane C.; Martins, Valter F. R.; Barbosa, Joana; Coelho, Marta; Sousa, Clara; Steffens, Juliana; Backes, Geciane T.; Pereira, Hugo; Pintado, Manuela E.; Teixeira, Paula C.; Morais, Alcina M. M. B.; Morais, Rui M. S. C.Haematococcus pluvialis and Porphyridium cruentum are red microalgae with high biotechnological potential due to their rich composition of bioactive compounds. However, their intense flavor limits their application in food products. This study evaluated the impact of fermentation with Lactiplantibacillus plantarum (30 ?C for 48 h; LAB-to-biomass ratio of 0.1:1; 106 CFU/mL) on the physicochemical and functional properties of H. pluvialis and P. cruentum biomasses. Particular attention was given to antioxidant activity (ABTS and ORAC assays), color, amino acid profiles, and volatile organic compound (VOC) profiles, all of which may influence sensory characteristics. Results demonstrated that non-fermented H. pluvialis exhibited significantly higher antioxidant activity (AA) than P. cruentum. After fermentation, H. pluvialis showed an ABTS value of 3.22 ± 0.35 and an ORAC value of 54.32 ± 1.79 µmol TE/100 mg DW, while P. cruentum showed an ABTS of 0.26 ± 0.00 and an ORAC of 3.11 ± 0.13 µmol TE/100 mg DW. Total phenolic content (TPC) of fermented H. pluvialis and P. cruentum was 1.08 ± 0.23 and 0.18 ± 0.026 mg GAE/100 mg DW, respectively. Both AA and TPC increased after fermentation. Fermentation also significantly affected biomass color. FTIR analysis showed intensification of protein and carbohydrate vibrational bands post-fermentation. GC-MS analysis of VOCs showed that P. cruentum contained 42 VOCs before fermentation, including trans-?-ionone, 4-ethyl-6-hepten-3-one, hexanal, and heptadienal, which are responsible for fishy and algal odors. Fermentation with Lb. plantarum significantly reduced these compounds, lowering trans-?-ionone to 0.1453 mg/L and eliminating 4-ethyl-6-hepten-3-one entirely. H. pluvialis contained 22 VOCs pre-fermentation; fermentation eliminated hexanal and reduced heptadienal to 0.1747 ± 0.0323 mg/L. These changes contributed to improved sensory profiles. Fermentation also induced significant changes in the amino acid profiles of both microalgae. The fermented biomasses were incorporated into vegan burgers made from chickpea, lentil, and quinoa. Color evaluation showed more stable and visually appealing tones, while texture remained within desirable consumer parameters. These findings suggest that Lb. plantarum fermentation is an effective strategy for improving the sensory and functional characteristics of microalgal biomass, promoting their use as sustainable, value-added ingredients in innovative plant-based foods.
- Integrated valorization of fucus spiralis alga: polysaccharides and bioactives for edible films and residues as biostimulantsPublication . Martins, Valter F. R.; Coelho, Marta; Machado, Manuela; Costa, Eduardo; Gomes, Ana M.; Poças, Fátima; Sperotto, Raul A.; Rosa-Martínez, Elena; Vasconcelos, Marta; Pintado, Manuela E.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Fucus spp. seaweeds thrive in the cold temperate waters of the northern hemisphere, specifically in the littoral and sublittoral regions along rocky shorelines. Moreover, they are known to be a rich source of bioactive compounds. This study explored the valorization of Fucus spiralis through the extraction of bioactives and polysaccharides (PSs) for food applications and biostimulant use. The bioactives were extracted using microwave hydrodiffusion and gravity (MHG), where the condition of 300 W for 20 min resulted in the highest total phenolic content and antioxidant activity of the extract. Cellular assays confirmed that the extract, at 0.5 mg/mL, was non-cytotoxic to HaCat cells. Polysaccharides (PSs) were extracted from the remaining biomass. The residue from this second extraction contained 1.5% protein and 13.35% carbohydrates. Additionally, the free amino acids and minerals profiles of both solid residues were determined. An edible film was formulated using alginate (2%), PS-rich Fucus spiralis extract (0.5%), and F. spiralis bioactive-rich extract (0.25%). The film demonstrated significant antioxidant properties, with ABTS and DPPH values of 221.460 ± 10.389 and 186.889 ± 36.062 µM TE/mg film, respectively. It also exhibited notable physical characteristics, including high water vapor permeability (11.15 ± 1.55 g.mm.m−2.day−1.kPa−1) and 100% water solubility. The residues from both extractions of Fucus spiralis exhibited biostimulant (BS) effects on seed germination and seedling growth. BSs with PSs enhanced pea germination by 48%, while BSs without PSs increased the root dry weight of rice and tomato by 53% and up to 176%, respectively, as well as the shoot dry weight by up to 38% and up to 74%, respectively. These findings underscore the potential of Fucus spiralis within the framework of a circular economy, wherein both extracted bioactives and post-extraction by-products can be used for sustainable agriculture and food applications.
- Monoterpene hydroxy lactones isolated from Thalassiosira sp. microalga and their antibacterial and antioxidant activitiesPublication . Morais, Alcina M. M. B.; Kumla, Decha; Martins, Valter F. R.; Alves, Ana; Gales, Luis; Silva, Artur M. S.; Costa, Paulo M.; Mistry, Sharad; Kijjoa, Anake; Morais, Rui M. S. C.Two monoterpenoid lactones, loliolide (1) and epi-loliolide (2), were isolated from the crude dichloromethane extract of a microalga, Thalassiosira sp.). The structures of loliolide (1) and epi-loliolide (2) were elucidated by 1D and 2D NMR analysis, as well as a comparison of their 1H or/and 13C NMR data with those reported in the literature. In the case of loliolide (1), the absolute configurations of its stereogenic carbons were confirmed by X-ray analysis, whereas those of epi-loliolide (2) were determined by NOESY correlations. Loliolide (1) and epi-loliolide (2) were tested for their growth inhibitory activity against two Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) bacteria, as well as one clinical isolate (E. coli SA/2, an extended-spectrum β-lactamase producer-ESBL) and two environmental isolates, S. aureus 74/24, a methicillin-resistant (MRSA), and E. faecalis B3/101, a vancomycin-resistant (VRE) isolates. The results showed that none of the tested compounds exhibited antibacterial activity at the highest concentrations tested (325 μM), and both revealed low antioxidant activity, with ORAC values of 2.786 ± 0.070 and 2.520 ± 0.319 µmol TE/100 mg for loliolide (1) and epi-loliolide (2), respectively.
- Recent highlights in sustainable bio-based edible films and coatings for fruit and vegetable applicationsPublication . Martins, Valter F. R.; Pintado, Manuela E.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.The present review paper focuses on recent developments in edible films and coatings made of base compounds from biological sources, namely plants, animals, algae, and microorganisms. These sources include by-products, residues, and wastes from agro-food industries and sea products that contribute to sustainability concerns. Chitosan, derived from animal biological sources, such as crustacean exoskeletons, has been the most studied base compound over the past three years. Polysaccharides typically constitute no more than 3–5% of the film/coating base solution, with some exceptions, like Arabic gum. Proteins and lipids may be present in higher concentrations, such as zein and beeswax. This review also discusses the enrichment of these bio-based films and coatings with various functional and/or bioactive compounds to confer or enhance their functionalities, such as antimicrobial, antioxidant, and anti-enzymatic properties, as well as physical properties. Whenever possible, a comparative analysis among different formulations was performed. The results of the applications of these edible films and coatings to fruit and vegetable products are also described, including shelf life extension, inhibition of microbial growth, and prevention of oxidation. This review also explores novel types of packaging, such as active and intelligent packaging. The potential health benefits of edible films and coatings, as well as the biodegradability of films, are also discussed. Finally, this review addresses recent innovations in the edible films and coatings industry, including the use of nanotechnologies, aerogels, and probiotics, and provides future perspectives and the challenges that the sector is facing.