Browsing by Author "Gomes, A."
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- Effect of pH upon viability of probiotic strains when in contact with fruit pulpsPublication . Rodrigues, C.; Sousa, S.; Pinto, A.; Brandão, T.; Silva, J.; Pintado, M.; Silva, C.; Morais, A.; Teixeira, P.; Gomes, A.; Almeida, D.In recent years many probiotic-containing products have been developed, being dairy and dried products the main vehicles for probiotic intake. Fruit juices have also been studied, with less good results, probably due to their low pH values, as well as to the presence of other components, adverse to the survival of the probiotic strains. In order to pinpoint possible reasons therefore, in this study we tried to evaluate the effect of the fruit pulp pH upon the survival of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis BB-12. Two fruit pulps, with different pH values, were used, namely lemon (pH=2.5) and avocado (pH=6.5), and their pH was adjusted (to 2.5, 4.5 and 6.5), in order to access the effect upon probiotic survival over one week storage. Viability was evaluated at 0, 3 and 7 days. Results showed that, although the pH value is indeed important, it is not the only reason for low viability of probiotics when incorporated in fruit pulps. Viability was, as expected, the highest when the pulps had a pH value of 6.5. At 4.5, avocado still had considerable viable cell numbers after one week contact with the pulp, while for lemon, at the same pH, no probiotics were detected after 3 days. At 2.5, for both pulps, no viable cells were detected after only 3 days. These results indicate that, although pH is important, other constituents of the fruits are also responsible for the degree of survival of probiotics in fruit matrices.
- Effect of storage conditions on stability of free and encapsulated – in plain or cysteine-supplemented alginate, Lactobacillus acidophilus KiPublication . Sousa, S.; Gomes, A.; Pintado, M.; Silva, J.; Costa, P.; Amaral, M.; Rocha-Santos, T.; Rodrigues, D.; Freitas, A.Lately, many functional food products have been widely released. Functional foods are foods which promote health beyond providing basic nutrition (Sanders, 1998). Probiotic bacteria are currently used in the development of functional food products (Pimentel-González, 2009; Siró et al., 2008), yet sometimes face technological challenges when incorporated in food matrices with more aggressive environments – salt, acid or oxygen concentrations. In order to be effective, the suggested concentration for probiotic bacteria is 106 CFU/g of a product (Shah, 2000). Encapsulation is an efficient technique to overcome such difficulties since microcapsules help in their protection from both the product intrinsic properties and the gastrointestinal tract conditions. Besides the challenges originated by the food matrices and the gastrointestinal tract there is also the challenge of conservation of the viable microorganisms throughout production and storage of the delivery food product which is also a reason for encapsulating probiotics (Allan-Wojtas et al., 2008) since the encapsulation technique can also help to protect the probiotics from the storage conditions of the product and thus increase its shelf-life in which the microorganisms are inside their effectiveness range. In this research work stability of calcium alginate capsules, produced by extrusion by aerodynamically assisted flow, throughout six months storage was studied. The effect of four storage temperatures (21, 4, -20 and -80 ºC) upon the viability of free and encapsulated cells of Lactobacillus acidophilus Ki was assessed. Two types of microcapsules were produced – one with calcium alginate and another where L-cysteine·HCl was utilized as a supplement to the calcium alginate matrix.
- Effect of the application of bioactive extracts on the storage time of smoked horse mackerel (Trachurus trachurus) with reduced saltPublication . Barros, D.; Nova, P.; Cunha, S.; Barbosa, C.; Pintado, M.; Gomes, A.; Vaz-Velho, M.Smoking of food is one of the oldest preservation methods and quite popular among fish and meat preservation strategies. The process combines salting, drying, heating and smoking steps. Salting and smoking, besides their preserving effects, are important to add flavour so appreciated by traditional foods consumers1-3. However, reducing salt intake is an important public health issue. Thus, both food industry and food services are interested in reducing the salt content of products4. Moreover, today's consumer is also looking for more natural foods with high nutritional value and functionality 5,6. Special attention has been given to the addition of bioactive compounds mainly with antioxidant and antimicrobial activities7-9. The general objective of the present study was the valorisation of low commercial value and abundant fish species such as horse mackerel (Trachurus trachurus) by developing smoked products with reduced salt content and fortified with natural bioactive compounds extracted from seafood and forest by-products. The fish, obtained in the local auction market, was smoked in a semi-industrial smoking oven for 4 h at 70 °C with a final thermal shock step of 1 h at 90 °C. Smoked fillets were divided into four groups and sprayed with one of four bioactive extract solution (100 mg/ml): two different solutions of mussel extract with peptides <3kDa, one solution of microalgae extract, Tetraselmis sp. with peptides <3KDa and a pine bark extract (Pinus pinaster Aiton subsp. atlantica) solution. A control sample without any spraying completed the set of five samples. Smoked fillets were vacuum-packed and stored at 4-6 °C, over 30 d. Quality changes, over the 30 days of storage, were studied by monitoring microbiological and physicochemical properties at weekly intervals. For microbial enumeration a pack was opened weekly, and 30 g of smoked fish was taken aseptically, from different sites, and homogenised for 90 s in a stomacher and subsequently decimally diluted. Total viable counts were performed on pour plates according to EN ISO 4833-1:2013; psycrotrophic microorganisms according to ISO 17410:2001; Enterobacteriaceae counts according to ISO 21528-2:2017 and yeasts and molds according to NP 3277-1:1987. Detection of Salmonella and Listeria monocytogenes was done according to ISO 6579-1: 2017 and ISO 11290-1:2017, respectively. Physicochemical properties analysed included: salt (NaCl) content, aw, moisture, pH, peroxide value index (PV) and thiobarbituric acid index (TBA), antioxidant activity (DPPH and ABTS methods), colour and firmness. Sensory evaluation by quantitative descriptive analysis (11 attributes) was performed by four trained panellists. Average total viable cell numbers were similar among all samples (including control) except for mussel extract MuE (CPC) that maintained levels above 8 log CFU, form 2 wk of storage onwards; the remaining samples demonstrated a steady increase in total viable cell numbers (30 ºC) only from 21 d onwards and reached final numbers between 6-7 log CFU. Enterobacteriaceae were reported constantly between 1-2 log CFU, molds were undetectable and yeasts reached higher viable numbers (3 log CFU) in smoked fillets with mussel extracts. Salmonella and Listeria were not detected throughout storage. In terms of antioxidant activity samples were quite stable over time. Concerning degradation indicators, such as TBA and PV, no tendency was noticeable. TBA index after 7 d of storage was low and stable and PV was unstable. Nevertheless, panellists found some off-flavours during their evaluation especially in the samples with mussel extract and microalgae extract that was more intense after 15 d of storage (Figure 1). The pine bark-treated samples presented more similarity with the control samples throughout storage. Texture and firmness were generally stable over time and with small differences between treatments, control samples showing higher values. Principle component analysis applied to physicochemical data (Figure 2) showed that antioxidant activity and pH, moisture and water activity discriminate samples over time (PC1) and, sample treatment with mussel extract MuE(ESB) as well. In this output, samples with higher values are projected towards the left side and this was also clear in pine bark (PBE) treated samples. Samples with mussel extract (MuE(ESB)) are quite stable (PC1) except for those with 7 d of storage. Overall, these results indicate the potential of these treatments to extend shelf-life of fish products and contribute to reintroduce sea and forest by-products into the food chain along adding value to abundant and undervalued fish products.
- Evaluation of oat syrup, from oat beverage by-products for sugar reduction in food productsPublication . Gomes, A.; Gonçalves, J.; Paupério, A.; Alves, V.; Pintado, M.The agro-food industry is responsible for the annual production of millions of tons of food waste. At the same time, consumers are more informed and conscious about their food choices, seeking convenient, healthy, and sustainable products. In response, the industry proposes to provide natural products with limited additives, while still meeting sensory, nutritional, and safety requirements. Oats (Avena sativa L.) are the sixth largest cereal crop worldwide, becoming increasingly popular with health-conscious consumers because of their exceptional nutritional profile. They are particularly rich in dietary fibre, phytochemicals and essential nutrients such as vitamins and minerals. In this context, oats are chosen by consumers who prioritize health-promoting properties, as well as sensory appeal. This study aimed to transform an oat drink by-product into a new added-value product, that can be used as a sugar-replacement ingredient in food products. To release the by-product sugars, different hydrolysis processes were carried out. Thermal hydrolysis using water was carried out with proportions of 4:10 and 1:1 (residue: solvent). From this by-product hydrolysis, the supernatant residue was separated by centrifugation (10,000rpm, 10min) and the concentrations of sugars (mono and disaccharides) were analysed from the liquid fraction using the HPLC. The Brix for the obtained supernatant was also determined, as well as the sweetness index as a function of sucrose. Aqueous thermal hydrolysis (1:1 ratio, temperature of 121 ºC for 15 minutes, and pressure of 1 atm) was found to be the most effective process, resulting in fibres with good sweetening power. According to sugars HPLC profiles, the resulting supernatant liquid exhibited a sucrose concentration of 72.35 ± 8.13 g, glucose concentration of 56.59 ± 6.23 g, and fructose concentration of 2.89 ± 0.05 g per 100 g of sample, with a sweetness index of 1.24. The liquid fraction was then concentrated to produce an oat syrup with a Brix value of approximately 67º, indicating high levels of dissolved solids. In conclusion, this oat syrup exhibits promising sweetening properties and could potentially serve as a substitute for sucrose in certain food products, contributing to reducing food waste and promoting further a circular economy.
- Formulation strategies for enhancing growth of akkermansia muciniphila and its survival through lyophilisation and storage at air ambientPublication . Freitas, A.; Almeida, D.; Machado, D.; Mendo, S.; Gomes, A.Gut bacterium Akkermansia muciniphila has been recognized as a new potential probiotic due to promising outcomes in the prevention and treatment of several human diseases. However, despite its multiple beneficial effects, its viability is compromised by the presence of oxygen. This has so far precluded its application namely in the development of nutraceutical/therapeutic formulations. In order to enhance growth of A. muciniphila and its survival through lyophilisation and storage at air ambient, formulation strategies are presented based on use of prebiotic compounds, antioxidants and cryoprotectants. According to our best knowledge, there is no information regarding lyophilisation procedures involving A. muciniphila as well as its subsequent storage at ambient air.
- In situ CLA and CLNA production: a potential strategy to elaborate food products enriched in bioactive fatty acidsPublication . Pimentel, L. L.; Fontes, A. L.; Gomes, A.; Rodríguez-Alcalá, L. M.Conjugated linoleic acid (CLA) and, more recently, conjugated linolenic acid (CLNA) isomers have shown potential to be applied as new functional ingredients, given its bioactive potential to exert benefits to human health. These fatty acids are naturally produced by rumen bacteria that convert linoleic acid (LA) and linolenic acid (LNA) into their conjugated forms. However, strains of lactobacilli, bifidobacteria and propionibacteria have also revealed capacity to produce these compounds. Thus, the aim of this work was to test the in situ production of CLA and CLNA isomers in a dairy matrix using a potential producing strain, in order to verify the suitability of this strategy for CLA and CLNA enrichment in food products. Bifidobacterium breve NCIMB 702258 was selected for this study as previously showed CLA/CLnA production capacity. Its CLA/CLNA-producing ability was firstly tested by incubation in MRS medium containing LA, -LNA or both (at 0.5 mg/mL each) for 24 h at 37 ºC. Fatty acid concentration was analyzed in the supernatant through gas chromatography and it was revealed LA and -LNA conversion rates of, respectively, 30.36% and 67.33%, when substrates were added separately, and of 14.83% and 55.40%, when together, being CLNA production higher than CLA in both situations. Bifidobacterium breve producing capacity was then tested in a food matrix (semi- skimmed milk, 1.6% fat) under the same conditions applied in MRS medium. CLA/CLNA isomers production was positive although substrate conversion rates were lower than those obtained in MRS medium. -LNA conversion was higher than LA when the substrates were added separately (28.09% and 24.19%, respectively), but not when both LA and -LNA were assayed together (14.55% and 27.60%, respectively). In conclusion, in situ production of microbial CLA and CLNA isomers is a strategy with potential to be applied in the future elaboration of CLA- and CLNA-enriched food products.
- Salivary calprotectin: a potential biomarker in inflammatory bowel disease?Publication . Rodrigues, C.; Gomes, A.; Leal, J.; Mendes, K.; Correia, M. J.; Pereira, P.; Martins, R.; Nélio, V.; Rosa, N.; Soares, C.; Ministro, P.
- The relationship between body mass index and internet problematic use, eating disturbances, sleep difficulties, and psychological distress in portuguese university studentsPublication . Soares, M. J.; Pereira, A. T.; Maia, B.; Gomes, A.; Macedo, A.Introduction: Body mass index (BMI), in overweight and obese individuals, have been associated with sedentary habits, unhealthy use of internet, eating disturbances, sleep difficulties, and psychological distress. Objectives: To investigate the association between BMI and internet use patterns and problematic use, eating disturbances, sleep difficulties, and psychological distress among Portuguese university students Methods: 456 students (76.9% females; meanSD age=20.301.90 years old) fulfilled a questionnaire that include questions on sociodemographic data, internet use patterns, eating habits during internet use, the Portuguese version of the Generalized Problematic Interne Use Scale 2 (GPIU), the Eating Attitudes Test 25, the Depression, Anxiety, Stress Scale 21, and the Basic Scale on Insomnia Complaints and Quality of Sleep (BaSIQS). Results: BMI mean score was of 22.01 (SD=2.91, range 15-35), underweight were 6.1%, normal weight 81.1%, overweight 10.7% and obese 2%. Significant correlations were found between BMI and individual’s perception that online activity’s impair the quality of their interpersonal relationships (r=.104, p<.05), consume of sweet/ salty/ starchy foods during online activity´s (r=.107, p<.05), global eating disturbances (r=.174, p<.01), diet concerns (r=.301, p<.01), bulimic behaviours (r=.204, p<.01), social pressure to eat (r=-.430, p<.01), psychological distress (r=.114, p<.05), stress (r=.101, p<.05), anxiety (r=.128, p<.01). None of the GPIU and BaSIQS total and dimensions scores were significantly related to BMI. Conclusions: The results do not support the association between students BMI and internet use patterns and problematic use. The kind of food consumed during online activity´s, eating disturbances and psychological distress should be addressed by intervention strategies for overweight students.