Browsing by Author "Amaro, Ana L."
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- Antimicrobial potential of formulations, incorporating spent yeast derived from synthetic biotechnology, against Pseudomonas spp.Publication . Deuchande, Teresa; Fundo, Joana; Rodrigues, Daniela; Souza, Carla; Pintado, Manuela; Amaro, Ana L.Yeasts are currently used as cell factories for the sustainable production of high value biomolecules for applications in the pharmaceutical and cosmetic sectors. However, the production of such molecules through fermentation, conducted in bioreactors and making use of genetically engineered yeast strains, generates a number of waste-streams, with spent yeast as the second main by-product of fermentation processes, representing more than 20% of the total waste produced. Since this by-product is rich in several molecules including proteins, vitamins and several minerals, being also a natural source of glucans and mannoproteins with known bioactivities, it is of interest to develop valorization strategies for these residues. In this work, spent yeast was autolysed and a set of formulations, incorporating the resulting supernatant and pellet at different concentrations, were tested as potential antimicrobial solutions to prevent diseases in plants and fungi caused by Pseudomonas spp. The formulations were initially tested against P. aeruginosa and then against strains affecting cultivated mushrooms (Agaricus bisporus), P. tolaasi, and P. agarici; and a number of P. syringae strains responsible for plant diseases including the pathovars actinidifoliorium, tomato, pisi, syringae and atrofaciens. It has been recently shown that spent yeast hydrolysates possess antimicrobial activity against Salmonella enterica, Aeromonas salmonicida, Bacillus cereus and Bacillus subtilis (Martin et al. 2021), suggesting that spent yeast extracts may have potential antimicrobial effect against a range of microorganisms. To date, there are no studies showing the potential of spent yeast extracts against Pseudomonas strains. The results showed that the supernatant of the autolyzed yeast at 0.1% inhibited the growth of P. aeruginosa by about 20% and P. tolaasii by 10% but increased the growth of P. agarici by up to 34%. The combination of supernatant with lactose also slightly increased P. tolaasii growth inhibition (12%) but it reduced the inhibitory effect of supernatant against P. aeruginosa. With regard to plant pathogens, the formulations containing 0.1% and 0.3% of pellet inhibited by 25% the growth P. syringae pv. actinidifoliorium, the bacterium responsible for kiwi canker, but for all the other pathovars, the inclusion of spent yeast extracts in the formulation induced bacterial growth. Among all the tested formulations, the ones including supernatant and pellet at low concentrations were the most promising leading to slight growth inhibition of some environmental Pseudomonas spp.
- Characterization of spent yeast streams from precision fermentations driven by genetically engineered yeasts: valorization potential for a circular bioeconomyPublication . Deuchande, Teresa; Fundo, Joana F.; Rodrigues, Daniela; Pintado, Manuela E.; Amaro, Ana L.Currently, valuable biomolecules are sustainably produced through fermentation using genetically modified microorganisms. However, this industry also generates several waste streams, such as spent yeast (SY). To close the sustainability loop in bioproduction, it is essential to define valorization strategies for such waste streams. Hence, this study aimed to investigate the compositional differences among these novel SYs, intending to pave the way for devising highly effective and beneficial valorization strategies for these streams. In this work, SYs derived from the production of beer (SBY) and six biomolecules [β-farnesene (Fene), rebaudioside M (Reb M), manool (MN), patchouli (PAT), sandalwood (SDW), and sclareol (SCL)] through fermentations driven by engineered yeasts were characterized. The results showed that SY from Fene, MN, and PAT production have similar concentrations of protein (35.9–44% dw), minerals, and amino acids, being compatible with bulking and use as nitrogen sources. Those derived from Reb M production showed significantly higher levels of lipids (21 ± 2.6% dw) compared to all the other SYs (1.7–10.8% dw), whereas the ones derived from SCL production showed significantly higher levels of inorganic matter (45%) compared with those found in the other SYs (1.2–11.3% dw). The results showed that assessing the extent of compositional variation among different SYs derived from precision fermentations represents a primary step toward developing efficient valorization or biorefining strategies.
- Food safety aspects concerning traditional foodsPublication . Belc, Nastasia; Duţă, Denisa Eglantina; Iorga, Enuţa; Mohan, Gabriela; Moşoiu, Claudia Elena; Vasile, Adrian; Sanmartin, Angel Martinez; Torres, Maria Antonia Pedrero; Martinez, David Quintin; Amaro, Ana L.; Teixeira, Paula; Cardoso, Eduardo L.; Pintado, M. E.; Ferreira, Vânia; Magalhães, Rui; Almeida, GonçaloA significant challenge for traditional food production is to improve its competitiveness by identifying innovations that guarantee the safety of the products, while at the same time meeting general consumer demands and specific consumer expectations towards traditional food (European Research on Traditional Food, EC, DG_Research, 2007). Therefore, there is a real need to study traditional foods in order to preserve important elements of European culture and, if possible, enrich and improve the diet across the whole continent. The following chapter will cover aspects related with the safety aspects of the traditional products including legislation, the hazards coming from raw materials as well as hazards from processing. Some technological solutions for making traditional foods safer in longer time will be presented. Even it is compulsory to follow the authentic recipe and technology; some small innovation would be necessary, for example, in packaging for better preservation of the traditional foods in order to meet consumer’s demands in having larger quantities of traditional foods. Technological innovations must be implemented in the companies always maintaining the traditional methodologies but assuring food safety and increasing shelf life of traditional foods.
- Fresh-cut melon quality during storage: an NMR study of water transverse relaxation timePublication . Fundo, Joana F.; Amaro, Ana L.; Madureira, Ana Raquel; Carvalho, Alexandra; Feio, Gabriel; Silva, Cristina L. M.; Quintas, MafaldaMolecular mobility is a fundamental parameter which reflects the dynamic properties of food components and contributes to food degradation reactions comprehension. Fresh-cut fruits have become an important food market segment. However, processing of fruits promotes faster its physiological deterioration, biochemical changes and microbial degradation. The purpose of this work was to use NMR methodology as a tool to evaluate fresh-cut fruit quality, during storage at refrigerated conditions. The fresh-cut melon transverse relaxation time (T2) was measured for a period of 7 days of storage at 5 °C. The relationship between the obtained values, microstructure and quality parameters was investigated. In general, results show the existence of one class of water fluidity in the system, the one present in cells after processing. T2, a measure of this fluidity, is affected by the processing and storage time. Also, it is possible to find a close relationships between T2 and quality parameters of total colour difference (TCD), firmness and aw. As T2 increases TCD also increases, while firmness and aw decrease. These results highlight the usefulness of NMR methodology application in food science.
- Impact of different calcium dips and solution pH on quality of ready-to-eat baby-leaf spinachPublication . Oliveira, Ana L.S.; Amaro, Ana L.; Sain, Jason de; Pintado, M. E.The effect of calcium application and solution pH on ready-to-eat (RTE) baby-leaf spinach (Spinacia oleracea L.) texture and structure preservation was studied. Spinach leaves were treated with calcium chloride, calcium lactate and calcium propionate, at two different pH conditions (5 and 7), packaged and stored for 7 days at 5 C. After 24 h, the leaves crispness increased 49 and 29% for leaves treated with calcium chloride and lactate at pH 5 and the elasticity increased 100% after calcium propionate treatment at pH 7. During spinach shelf-life, the tissue flexibility decreased (20–60%) for all calcium treatments at pH 5 and 7 while tissue crispiness increased (7–40%) only for calcium treatments under pH 7. The electrolyte leakage increased throughout storage and was higher for all calcium treated samples when compared with controls. The chlorophyll content slightly decreased (12%) by the end of product shelf-life and did not differ according the calcium treatments. Total vitamin C content was lower in leaves treated with calcium chloride at pH 5 (31%) and pH 7 (19%) while the remaining treatments did not affect vitamin C content. The different calcium additives tested for potential texture quality maintenance did not provide the expected benefits on baby spinach leaves but increasing solution pH from 5 to 7 lead to an increased firmness by the end of shelf-life.
- Impact of minimal processing and storage on strawberry functional and nutritional qualityPublication . Amaro, Ana L.; Pereira, M. J.; Colelli, G.; Pintado, M. E.Strawberry (Fragaria spp.) is a widely consumed fruit valued not only for its attractive color, aroma and taste but also as a good source of biologically active compounds, such as vitamin C, flavonoids, namely anthocyanins, and other polyphenols. The consumption of strawberries has been associated to human health benefits due to their antioxidant, anticancer, Anti-Inflammatory and Anti-Neurodegenerative properties. Strawberries are presented in the market as fresh whole fruits or processed, as Readyto-Eat Fresh-Cut fruit or incorporated in processed foods and beverages. Lifestyles of modern consumers, along with the demand for natural, fresh, flavorful, convenient and high quality products, with health benefits, have raised the production and consumption of processed strawberry. Processed strawberries represent a convenient alternative to supply the dietary needs of fresh food, but Processing-Induced wounding can enhance quality loss, changes in bioactive compounds contents and consequently in antioxidant capacity. Processing and storage factors affecting strawberry physiological and nutritional quality may result in the ingestion of nutritionally altered fruit. The knowledge and control of minimal processing and storage conditions of strawberries allows modulation of their nutritional and functional quality. This chapter surveys the postharvest minimal processing factors and storage conditions that affect strawberry phytochemical and functional quality, with focus on biologically active compounds, and emphasizes how processing technologies impact these compounds.
- In vivo study of the effect of sugarcane bagasse lignin supplementation on broiler chicken diet as a step to validate the established chicken gastrointestinal tract in vitro modelPublication . Carvalho, Nelson Mota de; Souza, Carla Giselly de; Costa, Célia Maria; Castro, Cláudia; Fangueiro, Joana F.; Horta, Bruno; Outor-Monteiro, Divanildo; Teixeira, José; Mourão, José Luís; Pinheiro, Victor; Amaro, Ana L.; Costa, Patrícia Santos; Oliveira, Catarina S. S.; Pintado, Manuela Estevez; Oliveira, Diana Luazi; Madureira, Ana RaquelSince the global restrictions on antibiotics in poultry systems, there has been a growing demand for natural and sustainable feed additives for disease prevention and poultry nutrition. This study evaluated the effects of incorporating sugarcane bagasse (SCB) lignin into broiler chicken diets. The performance of the chickens, including body weight, feed intake, and mortality, as well as intestinal histomorphometry, and cecum content pH, microbiota, and volatile fatty acids were assessed. In addition, we also aimed to validate an in vitro gastrointestinal tract (GIT) model developed by Carvalho et al. (2023). One hundred and eight 1-day-old Ross 308 chicks were randomly and equally divided into two groups. The first group was fed a basal diet (BD group), while the second group was fed a basal diet supplemented with 1% (w/w) SCB lignin (BD + SCB lignin group) for 36 days. The in vivo conditions of the chicken GIT were replicated in an in vitro model. In the in vivo study, SCB lignin increased cecum acetate and butyrate levels while reducing Bifidobacterium and Enterobacteriaceae, without affecting productivity (body weight, feed intake, and mortality). The in vitro assessment reflected microbiota trends observed in vivo, although without statistical significance. The divergence in organic acid production between the in vivo and in vitro conditions likely resulted from issues with inoculum preparation. This study demonstrates that SCB lignin incorporation positively influences cecal microbiota composition without impacting the animals’ productivity and physiology, suggesting its potential as a functional feed additive. For a more reliable in vitro model, adjustments in inoculum preparation are necessary.
- Induced autolysis of engineered yeast residue as a means to simplify downstream processing for valorization: a case studyPublication . Fundo, Joana F.; Deuchande, Teresa; Rodrigues, Daniela A.; Pimentel, Lígia L.; Vidigal, Susana S. M. P.; Rodríguez-Alcalá, Luís M.; Pintado, Manuela E.; Amaro, Ana L.The objective of this work was to study the efficiency of different autolysis processes, combining different temperatures and pH conditions, when applied to a genetically engineered yeast residue. The determination of the supernatants’ dry weight showed that the autolysis time could be reduced to half, from 4 to 2 h, if the residue pH was increased from 5 to 8 at 50 °C (18.20% for 4 h and 18.70% for 2 h with a higher pH). This result allowed us to select a short autolysis time to proceed with the second part of the experiments. The application of this faster induced autolysis process enabled us to obtain supernatants with higher concentrations of relevant compounds, such as some amino acids and minerals. An increase in leucine (of around 7%), aspartic acid, valine, phenylalanine, isoleucine and serine (approximately 2%) was observed in the autolyzed samples, when compared to the untreated ones. Also, regarding minerals, the autolysis process allowed us to obtain significantly higher amounts of potassium in the treated samples’ supernatants. This work allowed the selection of a fast and low-cost induced autolysis process for synthetic biotechnology-derived spent yeast residue to attain a product rich in high-value compounds, which can be used in commercial applications, for example, as an animal feed additive.
- Modeling the effect of oxygen pressure and temperature on respiration rate of ready-to-eat rocket leaves. A probabilistic study of the Michaelis-Menten modelPublication . Pereira, M. J.; Amaro, Ana L.; Pintado, M.; Poças, M. F.Effective and efficient design of modified atmosphere packaging (MAP) systems for ready-to-eat (RTE) products requires knowledge on produce respiration rate under various temperatures and oxygen levels. In order to model the respiratory behavior of RTE rocket leaves under different storage conditions, leaves respiration rate was measured during storage under four initial oxygen partial pressures (2.5; 5; 10 and 20 kPa O2) and three temperatures (0, 5 and 10 °C), for 10 days. The respiratory quotient was determined and found to range between 0.6 and 1.3. Temperature showed a significant impact on respiration rate and the effect of oxygen partial pressures was found to be temperature-dependent. The oxygen pressure effect on respiration rate was accurately described using Michaelis–Menten kinetics, without inhibition by carbon dioxide, and the effect of temperature was well modeled by exponential functions. Monte Carlo simulation allowed quantification of the relative impact of the reduction of oxygen pressure and temperature on the decrease in respiration rate and the potential shelf life increase of RTE rocket leaves. Temperature contributed to more than 80% of the Michaelis–Menten model variance while oxygen pressure contributed only with 13%. The model obtained is a useful tool for defining packaging and storage conditions for a shelf-life extension of rocket leaves.
- Multi-trait analysis of post-harvest storage in rocket salad (Diplotaxis tenuifolia) links sensorial, volatile and nutritional dataPublication . Spadafora, Natasha D.; Amaro, Ana L.; Pereira, Maria J.; Müller, Carsten T.; Pintado, Manuela; Rogers, Hilary J.Rocket salad (Diplotaxis tenuifolia; wild rocket) is an important component of ready to eat salads providing a distinct peppery flavour and containing nutritionally relevant compounds. Quality deteriorates during post-harvest, in relation to time and storage temperature amongst other factors. Volatile organic compounds (VOCs) are easily measurable from rocket leaves and may provide useful quality indicators for e.g. changes in isothiocyanates derived from nutritionally important glucosinolates. VOC profiles discriminated storage temperatures (0, 5 and 10°C) and times (over 14days). More specifically, concentrations of aldehydes and isothiocyanates decreased with time paralleling a fall in vitamin C and a reduction in sensorial quality at the two higher temperatures. Sulphur containing compounds rise at later time-points and at higher temperatures coincident with an increase in microbial titre, mirroring a further drop in sensorial quality thus indicating their contribution to off-odours.