Browsing by Author "Salsinha, Ana S."
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- In vitro gastrointestinal digestion impact on the antioxidant activity of extracts produced from the microalgae chlorella vulgaris and nannochloropsis oceanicaPublication . Cunha, Sara A.; Salsinha, Ana S.; Silva, Joana Laranjeira; Pintado, ManuelaMicroalgae are rapidly cultivable growing photosynthetic organisms rich in compounds with high biological values, such as antioxidants, with interest for food industry. Although microalgae extracts may present several health benefits, it is necessary to understand if their properties are maintained throughout the gastrointestinal (GI) digestion, after the exposure to enzymes and different pH ranges. Thus, this work studied the impact of in vitro gastrointestinal digestion on the antioxidant activity of extracts produced from the microalgae Chlorella vulgaris and Nannochloropsis oceanica, with the goal of evaluating their potential as functional food ingredients. Chlorella extract was produced by acid and enzymatic hydrolysis (cellulase and subtilisin) and Nannochloropsis extract by enzymatic hydrolysis (cellulase and subtilisin). Both were submitted to simulated GI conditions. The antioxidant activity was determined by ORAC and ABTS assays in four stages of GI simulation (before digestion, and after mouth, stomach and intestine digestion). Both extracts showed increased ORAC and ABTS values throughout the GI digestion. This increase was statistically significant for Chlorella in terms of ABTS values in all phases, and in ORAC after stomach and intestine digestion. For Nannochloropsis, only the increase in ABTS values was statistically different after stomach and intestine digestion (pThis study showed that both extracts maintain their antioxidant activity throughout in vitro GI digestion, with a little increase being observed, which may be explained by the formation of smaller and more bioactive peptides. These results shows that Chlorella and Nannochloropsis extracts may be considered sustainable antioxidant ingredients for the development of functional food.
- In vitro gastrointestinal digestion impact on the antioxidant activity of extracts produced from the macroalgae gracilaria gracilis and ulva rigidaPublication . Cunha, Sara A.; Nova, Paulo; Salsinha, Ana S.; Gomes, Ana; Pintado, ManuelaThe interest in edible algae has been growing over the years due to their richness in molecules with nutritional and bioactive potential, such as proteins, essential amino acids, vitamins and minerals. Furthermore, due to their interesting protein content, they have been described as a source of bioactive peptides, with scientifically documented antioxidant, anti-hypertensive and antimicrobial properties. In this work, water-soluble extracts were produced from the macroalgae Gracilaria gracilis and Ulva rigida, with focus on their antioxidant potential. Furthermore, the impact of in vitro gastrointestinal (GI) digestion on the antioxidant activity of both extracts was studied, with the goal of evaluating their potential as functional food ingredients. Extracts were produced by enzymatic hydrolysis, with a cellulase and a subtilisin protease, using a previously optimized method. Then, both were submitted to simulated GI conditions, similar to those found in the human digestive system. The antioxidant activity was determined by ORAC and ABTS assays in four stages of GI simulation (before digestion, and after mouth, stomach and intestine digestion). The antioxidant activity did not decrease throughout the different stages of digestion. Interestingly, the antioxidant capacity increased after some phases. For instance, both extracts presented higher ORAC values after all digestion phases, when compared to the non-digested extract, being statistically significant after stomach digestion, for G. gracilis extract (p < 0.05). On this study, both extracts maintained their antioxidant activity during in vitro GI digestion, with an increase after almost all digestion phases, when compared to the non-digested extract. The observed increase may be explained by the production of smaller and more bioactive peptides, by the action of the gastrointestinal enzymes, such as pepsin and pancreatin. In conclusion, since antioxidant activity is maintained throughout the GI tract, these results showed that G. gracilis and U. rigida extracts may be considered potential ingredients for the development of functional foods with antioxidant properties.
- Influence of shaking and viable cell numbers on microbial conjugated linoleic acid (CLA) productionPublication . Fontes, Ana L.; Pimentel, Lígia L.; Salsinha, Ana S.; Rodríguez, Juan M.; Domingues, M. Rosário; Rodríguez-Alcalá, Luis M.; Gomes, Ana M.
- Microbial production of conjugated linoleic acid and conjugated linolenic acid relies on a multienzymatic systemPublication . Salsinha, Ana S.; Pimentel, Lígia L.; Fontes, Ana L.; Gomes, Ana M.; Rodríguez-Alcalá, Luis M.Conjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNAs) have gained significant attention due to their anticarcinogenic and lipid/energy metabolism-modulatory effects. However, their concentration in foodstuffs is insufficient for any therapeutic application to be implemented. From a biotechnological standpoint, microbial production of these conjugated fatty acids (CFAs) has been explored as an alternative, and strains of the genera Propionibacterium, Lactobacillus, and Bifidobacterium have shown promising producing capacities. Current screening research works are generally based on direct analytical determination of production capacity (e.g., trial and error), representing an important bottleneck in these studies. This review aims to summarize the available information regarding identified genes and proteins involved in CLA/CLNA production by these groups of bacteria and, consequently, the possible enzymatic reactions behind such metabolic processes. Linoleate isomerase (LAI) was the first enzyme to be described to be involved in the microbiological transformation of linoleic acids (LAs) and linolenic acids (LNAs) into CFA isomers. Thus, the availability of lai gene sequences has allowed the development of genetic screening tools. Nevertheless, several studies have reported that LAIs have significant homology with myosin-cross-reactive antigen (MCRA) proteins, which are involved in the synthesis of hydroxy fatty acids, as shown by hydratase activity. Furthermore, it has been suggested that CLA and/or CLNA production results from a stress response performed by the activation of more than one gene in a multiple-step reaction. Studies on CFA biochemical pathways are essential to understand and characterize the metabolic mechanism behind this process, unraveling all the gene products that may be involved. As some of these bacteria have shown modulation of lipid metabolism in vivo, further research to be focused on this topic may help us to understand the role of the gut microbiota in human health.
- Recovery of ripening capacity in 'Rocha' pears treated with 1-MCP through the application of 1-NAA: physiological and molecular analysis insightsPublication . Dias, Cindy; Brandao, Teresa R. S.; Salsinha, Ana S.; Amaro, Ana L.; Vasconcelos, Marta W.; Ferrante, António; Pintado, ManuelaStoring 'Rocha' pear treated with 1-methylcyclopropene (1-MCP) in controlled atmosphere is a common commercial strategy to extend pear storage time and prevent postharvest disorders. However, this strategy represents a challenge to the fruit industry because 1-MCP treatment obstructs the normal fruit ripening, potentially affecting the quality to consumers. To explore possible mechanisms to reactivate ripening, 'Rocha' pears treated with 1-MCP were exposed to 2 and 4 mM 1-naphthaleneacetic acid (1-NAA) and stored at 20 ± 2 °C for 15 days. Typical ripening indicators, such as firmness, skin color, ethylene and aroma volatiles production, sugar content, and the genetic expression of ethylene-related enzymes (ACS and ACO) and receptors (PcETR1, PcETR2, and PcETR5) were determined over the 15 days of storage. A PCA analysis incorporating both physiological and biochemical data showed that 1-NAA promoted the recovery of ripening capacity in 1-MCP treated pears. Treating pears with 1-NAA led to increased activity of genes like PcACS1, PcACS4, and PcETR2, which are involved in ethylene signalling and production. This resulted in higher levels of ethylene and compounds associated with ripening, as well as softer texture, more yellow color, and higher sucrose content. The boost in ethylene-related gene activity likely heightened ethylene sensitivity and production in the treated pears. Consequently, these fruits showed accelerated softening, color change, and aroma development. This suggests that 1-NAA treatment can reverse the ripening inhibition caused by 1-MCP, possibly by enhancing ethylene sensitivity and production. This mechanism could enable consistent ripening of 'Rocha' pears after they are taken out of cold storage, and it may have similar effects on other fruits.