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- Prebiotic effects of olive pomace powders in the gut: In vitro evaluation of the inhibition of adhesion of pathogens, prebiotic and antioxidant effectsPublication . Ribeiro, Tânia; Costa, Célia Maria; Bonifácio-Lopes, Teresa; Silva, Sara; Veiga, Mariana; Monforte, Ana Rita; Nunes, João; Vicente, António A.; Pintado, ManuelaOlive pomace is a biowaste rich in polyphenols and insoluble dietary fibre with high potential to develop new value chains towards a sustainable and circular bioeconomy. Regarding gut health, olive pomace phenolics and insoluble dietary fibre (after possible fermentation) could act as antioxidants, antimicrobial and prebiotic agents. These potential beneficial effects on the gut were analysed for two powders from olive pomace: liquid-enriched powder (LOPP) - mostly source of phenolics - and pulp-enriched powder (POPP) - main source of insoluble dietary fibre. LOPP and POPP were subjected to an in vitro simulated gastrointestinal digestion followed by in vitro faecal fermentation. The undigested fraction retained in the colon was analysed regarding its potential antioxidant, antimicrobial and prebiotic effects. LOPP and POPP did not impact the gut microbiota diversity negatively, showing a similar ratio of Firmicutes/Bacteroidetes compared to a positive control (FOS). LOPP exhibit a positive (similar to FOS) effect on the Prevotella spp./Bacteroides spp. ratio. Both powders promoted more the production of short-chain fatty acids (mainly acetate > butyrate > propionate) than FOS and showed also significant total phenolic content and oxygen radical absorbance capacity during faecal fermentation until 48 h. Besides that, these powders showed mucin-adhesion inhibition ability against pathogens, principally POPP against Bacillus cereus (22.03 ± 2.45%) and Listeria monocytogenes (20.01 ± 1.93%). This study demonstrates that olive pomace powders have prebiotic effects on microbiota, including the stimulation of short-chain fatty acids production, potential antioxidant and antimicrobial activity which could improve the human gut health.
- Total and sustainable valorisation of olive pomace using a fractionation approachPublication . Ribeiro, Tânia B.; Oliveira, Ana L.; Costa, Cristina; Nunes, João; Vicente, António A.; Pintado, ManuelaOlive pomace management represents a great concern to the olive oil industry. This work focused on the development of a “zero waste” strategy for olive pomace based on a fractionation approach resulting in the obtention of different value-added fractions. The physicochemical composition of edible fractions obtained (liquid and pulp) was analysed. The potential use as a solid biofuel of the non-edible fraction (stones) was evaluated. High amounts of hydroxytyrosol (513.61–625.76 mg/100 g dry weight) were present in the liquid fraction. Pulp fraction was demonstrated to be a good source of fibre (53–59% dry weight) with considerable antioxidant activity both from free and bound phenolics. The stones fraction exhibited substantial high heating values (18.65–18.94 megajoule (MJ/kg). All these results support the added value of the olive pomace fractions combining the biofuel potential from the stones fraction and the functional food ingredients’ potential both from liquid and pulp fractions. The present methodology seems to be a feasible whole valorisation approach to achieve the circularity in the olive oil sector, prioritising obtaining high over low added-value products.
- Study of olive pomace antioxidant dietary fibre powder throughout gastrointestinal tract as multisource of phenolics, fatty acids and dietary fibrePublication . Ribeiro, Tânia; Campos, Débora; Oliveira, Ana; Nunes, João; Vicente, António A.; Pintado, ManuelaPulp-enriched powder (POPP) was obtained from olive pomace solid fraction, a derived from the new value chain established for olive by-products. As a multifunctional powder, POPP retains several bioactive compounds (fatty acids, dietary fibre and phenolics) under potential synergic interaction, even more, reactive throughout the digestion. So, in this study, the potential multifunctionality of POPP was evaluated after the gastrointestinal tract. A significant loss of phenolics occurred during oral digestion (62.48 %). However, the potential role of dietary fibre as phenolics’ carrier and its possible liberation in the stomach allowed recovering a significant amount of phenolics (77.11 %) and a bioaccessibility index of at least 50 % (mainly for tyrosol and its glucoside). POPP also provides high content of dietary fibre mainly insoluble fibre (69.68 g/100 g dry weight) linked to a substantial amount of bound phenolics (7.63 mg of gallic acid equivalents/g fibre dry weight), with a positive effect on the fatty acids bioaccessibility [decreased the saturated (5-6 %) and facilitated the unsaturated fatty acids bioaccessibility (4-11%)]. PCA analysis became evident the negative effect of simulated gastrointestinal digestion upon POPP as mainly linked to phenolics’ loss. Despite all negative effects of the simulated digestion on POPP bioactive composition, phenolics and unsaturated fatty acids showed to be bioaccessible in significant amount, and the amount of bound phenolics associated to fibre retained in the colon have the potential to exert gut health benefits.
- Incorporation of olive pomace ingredients into yoghurts as a source of fibre and hydroxytyrosol: antioxidant activity and stability throughout gastrointestinal digestionPublication . Ribeiro, Tânia B.; Bonifácio-Lopes, Teresa; Morais, Pilar; Miranda, Arménio; Nunes, João; Vicente, António A.; Pintado, ManuelaLiquid-enriched powder (LOPP) and pulp-enriched powder (POPP) obtained from olive pomace were incorporated into yoghurt, not only, to increase its content in dietary fibre, hydroxytyrosol and unsaturated fatty acids, but also to understand the lipids-phenolics interaction by simultaneous incorporation of olive oil. POPP (2%) and LOPP (1%) addition to yoghurt allowed fulfilling the condition of being a “source of fibre” and provided 5 mg of hydroxytyrosol and derivatives in a standard yoghurt (120 g), respectively. Yoghurts’ unsaturated fatty acids profile was positively influenced by the addition of only POPP and olive oil + LOPP or + POPP. All OP powder-fortified yoghurts exhibited higher total phenolic content and antioxidant activity than the control (p<0.05). After in vitro digestion the bioaccessibility of total phenolics (more 25.58%) and hydroxytyrosol (more 68.71%) in LOPP-yoghurts was improved by the addition of olive oil. In conclusion, OP powders´ incorporation gave additional and essential healthy properties to yoghurt.
- Are olive pomace powders a safe source of bioactives and nutrients?Publication . Ribeiro, Tânia B.; Oliveira, Ana; Coelho, Marta; Veiga, Mariana; Costa, Eduardo M.; Silva, Sara; Nunes, João; Vicente, António A.; Pintado, ManuelaBACKGROUND Olive oil industry generates significant amounts of semi-solid wastes, namely the olive pomace. Olive pomace is a by-product rich in high-value compounds (e.g. dietary fibre, unsaturated fatty acids, polyphenols) widely explored to obtain new food ingredients. However, conventional extraction methods frequently use organic solvents, while novel eco-friendly techniques have high operational costs. The development of powdered products without any extraction step has been proposed as a more feasible and sustainable approach. RESULTS The present study fractionated and valorised the liquid and pulp fraction of olive pomace obtaining two stable and safe powdered ingredients, namely a liquid-enriched powder (LOPP) and a pulpenriched powder (POPP). These powders were characterized chemically, and their bioactivity was assessed. LOPP exhibited a significant amount of mannitol (141 g/ kg), potassium (54 g/ kg) and hydroxytyrosol/ derivatives (5 mg/g). POPP exhibited high amount of dietary fibre (620 g/ kg) associated to significant amount of bound phenolics (7.41 mg GAE/ g fibre DW) with substantial antioxidant activity. POPP also contained an unsaturated fatty acids composition similar to olive oil (76% of total fatty acids) and showed potential as a reasonable source of protein (12 %). Their functional properties (solubility, water‐holding and oil‐holding capacity), antioxidant capacity and antimicrobial activity were also assessed, and their biological safety was verified. CONCLUSION The development of olive pomace powders to apply in the food industry could be a suitable strategy to add-value to olive pomace and obtain safe multifunctional ingredients with higher health-promoting effects than dietary fibre and polyphenols itself.