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- Bioactive packaging using antioxidant extracts for the prevention of microbial food-spoilagePublication . Moreira, Diana; Gullon, Beatriz; Gullon, Patricia; Gomes, Ana M.; Tavaria, FreniBioactive food packaging is an innovative approach for the prevention of the growth of food-spoilage microorganisms. Four active extracts from agroindustrial subproducts (Eucalyptus wood, almond shells, corn cobs and grape pomace) with demonstrated antioxidant activity have been investigated for bestowing antimicrobial activity to bioactive packaging. To carry out this evaluation, the antioxidant extracts were tested against five food pathogenic bacteria, namely, Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus and Salmonella spp. The results obtained showed that all the tested extracts inhibited the growth of all five pathogenic bacteria. From the analysis of the minimal bactericidal concentrations (MBCs), the Eucalyptus wood extract was the most active, being necessary only 2% (v/v) to inhibit Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus, whereas almond shells extract were less active requiring 4% (w/v) to inhibit the growth of Escherichia coli and Pseudomonas aeruginosa and the extract from corn cobs was bactericidal against Escherichia coli and Staphylococcus aureus at a concentration of 4% (w/v). After checking their antimicrobial activity, the antioxidant extracts have been incorporated into sodium alginate films and the maintenance of their antimicrobial properties was confirmed. This work showed that the antioxidant extracts from agroindustrial byproducts exhibited antimicrobial activity and were suitable for incorporation into edible films that could be used in bioactive packaging systems.
- In vitro assessment of the prebiotic potential of Aloe vera mucilage and its impact on the human microbiotaPublication . Gullón, Beatriz; Gullón, Patricia; Tavaria, Freni; Alonso, José Luis; Pintado, ManuelaAloe vera mucilage is reported to be rich in acemannan that is a polysaccharide with a backbone of beta-(1 -> 4)-D-mannose residues acetylated at the C-2 and C-3 positions and contains some side chains of galactose and arabinose attached to the C-6 carbon. The evaluation of the prebiotic potential of Aloe vera mucilage was carried out by in vitro fermentation using intestinal microbiota from six healthy donors as the inoculum. The prebiotic activity was assessed through the quantification of short chain fatty acids (SCFA) and the evaluation of dynamic bacterial population in mixed faecal cultures by fluorescence in situ hybridization (FISH). Our findings support the possible incorporation of the Aloe vera mucilage in the development of a variety of food products known as prebiotics aimed at improving gastrointestinal health.
- Structural features and assessment of prebiotic activity of refined arabinoxylooligosaccharides from wheat branPublication . Gullón, Beatriz; Gullón, Patrícia; Tavaria, Freni; Pintado, Manuela; Gomes, Ana M. P.; Alonso, José Luis; Parajó, Juan CarlosWheat bran (WB) samples were subjected to two stage processing (aqueous extraction and hydrothermal treatment) to assess their potential as a raw material for the manufacture of xylan-derived prebiotics. The liquid phase from the second stage, containing hemicellulose- derived soluble arabinoxylooligosaccharides (AXOS), was refined by consecutive steps of membrane filtration and ion exchange. The purified AXOS were characterised by matrixassisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF-MS) and chromatographic techniques. The most complex saccharide identified was made up of 19 pentoses. Human faecal slurry cultures were used to assess the bifidogenic activity of AXOS and their effects on the production of Short Chain Fatty Acids (SCFA) and lactic acid. The results were compared with data obtained using fructooligosaccharides (FOS), which are accepted as the gold standard of a prebiotic ingredient. The stimulatory effects reached by AXOS upon the bifidobacterial population were of the same order as those obtained with FOS. Higher SCFA production was observed with AXOS in comparison with FOS.
- In vitro fermentation of lupin seeds (Lupinus albus) and broad beans (Vicia faba): dynamic modulation of the intestinal microbiota and metabolomic outputPublication . Gullón, Patricia; Tavaria, Freni; Vasconcelos, Marta; Gomes, Ana MariaBroad beans (Vicia faba) and lupin seeds (Lupinus albus) are legumes rich in a wide range of compounds, which may represent a useful dietary approach for modulating the human gut microbiome. In this work, after in vitro digestion, legume samples were used as carbon sources in anaerobic batch cultures to evaluate their impact on the intestinal microbiota composition and on their metabolic products. The fermentations were monitored by a decrease in pH, generation of short chain fatty acids (SCFA) and lactate and the changes in the dynamic bacterial populations by fluorescence in situ hybridization (FISH). The total SCFA at the end of fermentation was 81.52 mM for lupin seeds and 78.41 mM for broad beans accompanied by a decrease of the pH for both legumes. The microbial groups that increased significantly (P < 0.05) were Bifidobacterium spp., Lactobacillus-Enterococcus, Atopobium, Bacteroides-Pretovella, Clostridium coccoides-Eubacterium rectale, Faecalibacterium prausnitzii and Roseburia intestinalis. This impact on the intestinal microbiota suggests that lupin seeds and broad beans may be used in the development of novel functional foods, which can be included in dietary strategies for human health promotion.