Browsing by Author "Braga, Mara E.M."
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- Edible films produced from agrifood by-products and wastesPublication . Jorge, Alexandre M.S.; Gaspar, Marisa C.; Henriques, Marta H.F.; Braga, Mara E.M.This study aims to develop edible films using agrifood by-products (pumpkin seeds, broken rice and orange pectin) and wastes (quince peel, potato peel, potato pulp, orange peel, pumpkin peel). The physicochemical characteristics of the films were investigated, including their mechanical and barrier properties. Higher amounts of plasticizer induced poorer mechanical and barrier properties in the films. The most promising ones were obtained with orange pectin, broken rice and pumpkin peel, with water contact angles (WCA) between 48° and 57°, maximum water vapor transmission rate and water vapor permeability of 575 g.m−2.d−1 and 108 × 10−12 g.Pa−1.s−1.m−1, respectively, Young's modulus between 350 and 800 MPa, maximum tensile strength between 9.0 and 26.25 MPa, and elongation at break between 2.28 and 9.3%. Orange pectin and broken rice are promising raw materials since they led to higher WCA, better barrier and mechanical properties. Broken rice and quince peel can be good substitutes for commercial starch and glycerol, respectively. Agro-industrial by-products and wastes revealed potential for the production of sustainable edible films.
- Edible hydrosoluble sachets produced with food by-products and natural additivesPublication . Jorge, Alexandre M.S.; Bento, Cristiana S.A.; Henriques, Marta H.F.; Gaspar, Marisa C.; Braga, Mara E.M.In this work, edible films were produced from orange pectin and broken rice (food by-products), combined with different natural additives, namely orange oil, zinc oxide, rice husk (RH) and calcium acetate (CA). The films obtained were fully characterized, presenting similar colour, opacity, thickness and thermal properties. Water contact angles (WCA) ranged from 55 to 85°; water vapor sorption (WVS) between 17.0 and 32.5% (w/w); with a maximum water vapor permeability (WVP) of 14.52 × 10−11 g m−1.s−1.Pa−1; Young's modulus between 0.88 and 3.0 GPa; tensile strength (TS) ranging from 6.0 to 19.0 MPa; elongation at break between 0.88 and 3.0%, and almost complete dissolution in water at 60 °C after 15 min. The WCA and mechanical properties of the films were compared with non-commercial and commercial biodegradable films. Orange pectin was the raw material that most influenced the films' properties. PCA (pectin and calcium acetate) and POO1.0RH (pectin, orange oil and rice husk) films showed the best mechanical and barrier properties, being applied as hydrosoluble sachets for white sugar. The organoleptic and physicochemical properties of the sachets were evaluated through sensory analysis and a 12-week shelf-life experiment, respectively. A high level of acceptability was obtained for the sugar sachets, with their physical structure and appearance practically unchanged throughout the tested shelf-life. Edible films obtained from these food by-products and natural additives were shown to be promising alternatives to synthetic sachets for use as sustainable food packaging.
- Fortified chocolate mousse with powder and extract from Moringa oleifera leaves for nutritional value improvementPublication . Gomes, Olívia J.S.; Leitão, Anabela; Gaspar, Marisa C.; Vitorino, Carla; Sousa, João J.S.; Sousa, Hermínio C. de; Braga, Mara E.M.; Gando-Ferreira, Licínio M.This study focuses on the characterisation and incorporation of Moringa oleifera leaf powder (MOP) from Luanda (Angola) and its extract (MOE) in fortified chocolate mousse. Dark green (DG) leaves presented superior nutritional values compared to other leaves. DG contained a higher concentration of mineral salts (10 ± 1 mg/100 g of dry leaves), phenolic compounds (267 ± 4 mg GAE/g), vitamins (1.9 ± 0.2 mg/g of dry extract) and strong antioxidant capacity (IC50, 115 ± 8 µg/mL). Therefore, DG leaves were used to fortify the chocolate mousse. The leaves were prepared in three samples: control, 2 % MOP (w/w) and 2 % MOE (v/v). Textural and rheological analysis of chocolate mousse samples revealed a pseudoplastic profile for all samples, with decreased texture attributes and viscosity due to the incorporation. The sensory evaluation demonstrated that MOP and MOE samples presented 93 % and 88 % resemblance to the original product regarding general acceptance, respectively.
- Sequential extraction of oxindole alkaloids from Uncaria tomentosa leaves by green pressurized solventsPublication . Botelho, José Rafael S.; Gaspar, Marisa C.; Sousa, Hermínio J.C. de; Braga, Mara E.M.; Freire, M.Uncaria tomentosa (Cat’s Claw) is a woody climbing vine known for its therapeutic effects, which have been validated in clinical trials. The leaves, often discarded in traditional uses, contain high quantities and a wide variety of oxindole alkaloids, such as rhynchophylline (Rhy), isomytraphylline (Imyt), or mitraphylline (Myt), with Myt typically being the major alkaloid found in extracts of this species. In this study, sequential extraction in two steps was employed to recover oxindole alkaloids. In the first step, pressurized liquid acetone was used, extracting approximately 17 % of the raw material mass, with no detectable alkaloids in the extract. In the second step, CO2-expanded liquid ethanol (25 % w/w) was used under varying temperature, pressure, and solvent density conditions. Extracts enriched with the oxindole alkaloids Rhy, Imyt, and Myt were obtained from the 2nd step extraction, with ratios ranging from 39:61 to 62:38 (Rhy:Myt + Imyt). These extracts demonstrated significant inhibition of lipoxygenase (up to 95 %) and acetylcholinesterase, indicating potential anti-inflammatory and neurological applications. Moreover, these effects were positively correlated with the proportion of Rhy relative to Myt + Imyt. Based on the alkaloid content and the observed potential bioactivities, optimized parameters, robustness and process stability were assessed using deterministic and stochastic statistical methods to maximise Rhy and minimise Imyt and Myt. Finally, this study presents the development and optimization of a robust process to obtain extracts with anti-inflammatory and neurological potential, adding value to U. tomentosa leaves and promoting the sustainable use of this plant as a raw material.
- Sustainable starch-based edible films with agrifood residues as potential carriers for the probiotic Lactobacillus rhamnosusPublication . Coimbra, Patrícia; Alarico, Susana; Empadinhas, Nuno; Braga, Mara E.M.; Gaspar, Marisa C.Edible films are promising carriers for probiotics and can be composed by agrifood residues, which are usually rich in polymers and bioactive compounds. In this work, starch-based films were enriched with three types of agrifood residues (quince, potato and orange peels) and the incorporation of the probiotic Lactobacillus rhamnosus was studied, as well as the addition of inulin as a protective prebiotic. The resulting films were characterized in terms of mechanical properties, physicochemical properties, lactobacilli viability and microbiological properties. The mechanical properties of the films generally decreased with the introduction of L. rhamnosus, although this was highly dependent on the film composition. All films exhibited water vapor permeabilities in the typical range of starch-based films and were not greatly affected by the inclusion of probiotics. The loss of probiotic viability during films production was strongly related to the pH of the film-forming solutions. Films with agrifood residues had a slower loss of probiotic viability during storage, when compared to plain starch films, which may be explained by the presence of antioxidant compounds. Inulin was expected to improve viability, but this was not observed. Microbiological analysis showed that agrifood residues powders contained natural contaminant bacteria that were partially eliminated during film formation. Moreover, none of the target foodborne pathogens were detected in the analyzed samples. Overall, the results suggest that edible films containing agrifood residues can be a promising material for the delivery of probiotics and/or as primary packaging for some food products.