Browsing by Author "Amorim, Maria Manuela"
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- Grape stalk valorization for fermentation purposesPublication . Atatoprak, Tuğba; Amorim, Maria Manuela; Ribeiro, Tânia; Pintado, Manuela; Madureira, Ana RaquelWhite and red grape stalks biomass were fractioned to maximize its economic value by the production of fermentable sugars, as other value streams. High yields of extractives and lignin were first obtained, originating a biomass rich in cellulose and hemicellulose, which was subject to acid and enzymatic hydrolysis for production of fermentable sugars. Higher concentrations of sugars were obtained by enzymatic than by dilute acid hydrolysis. These biosugars were used for fermentation processes with Pichia stipitis and Saccharomyces cerevisiae. The presence of higher quantities of xylose favoured P. stipitis to produce higher ethanol yields than S. cerevisiae which is glucose lover. Cellulose nanocrystals were produced from the resulting biomass without monosaccharides. For the first time an integrated valorization of grape stalks followed by an application of one of the valorized streams is presented.
- In vitro ACE-inhibitory peptide KGYGGVSLPEW facilitates noradrenaline release from sympathetic nerve terminals: relationship with the lack of antihypertensive effect on spontaneous hypertensive ratsPublication . Marques, Cláudia; Amorim, Maria Manuela; Pereira, Joana Odila; Guardão, Luísa; Martins, Maria João; Pintado, Manuela Estevez; Moura, Daniel; Calhau, Conceição; Pinheiro, HélderThis study aimed to validate the antihypertensive activity of the angiotensin-converting enzyme (ACE)-inhibitor whey protein hydrolysate (WPH) obtained through the action of proteolytic enzymes fromCynara Cardunculus. The antihypertensive activity of WPH fractions containing peptides with molecularweight below 3 kDa (Whey < 3 kDa) and 1 kDa (Whey < 1 kDa) along with the antihypertensive activity ofthree potent ACE-inhibitory peptide sequences (DKVGINYW, DAQSAPLRVY and KGYGGVSLPEW), previ-ously identified in WPH, were also investigated. In parallel, the influence of KGYGGVSLPEW (the mostpotent ACE-inhibitory peptide sequence) on AT1receptors (a common pharmacological target of anti-hypertensive therapies beyond ACE), was evaluated. The effect of WPH and fractions (300 mg/kg) andpeptide sequences (5 mg/kg) on systolic, diastolic and mean blood pressure was evaluated by telemetryon Spontaneously Hypertensive Rats (SHR), after single oral administration. Despite their ACE-inhibitoryeffect in vitro, neither WPH, Whey <3 kDa, Whey <1 kDa or peptide sequences exhibited antihyperten-sive activity. In addition, KGYGGVSLPEW was not only devoid of AT1receptor antagonism but, on thecontrary, had a similar effect to that of Ang II by facilitating the noradrenaline release from sympatheticnerve terminals. In vitro ACE blockade does not always correlate with antihypertensive activity and food-derived peptides cannot be classified as antihypertensive agents based exclusively on in vitro assays. Theabsence of an antihypertensive effect may also be a result of the interaction of these compounds withother components of the systems involved in the blood pressure control.
- Sardine canning byproducts as sources of functional ingredientsPublication . Carvalho, Ana P.; Amorim, Maria Manuela; Rodríguez-Alcalá, Luís; Fontecha, Javier; Castro, Paula M. L.; Pintado, Manuela E.Sardine byproducts generated during the canning process entail a potential opportunity to drive them into a chain of high-added-value compounds while simultaneously decreasing the environmental impact of their discharge. This paper describes and discusses the biochemical variation of solid and liquid byproducts generated during the sardine canning process during one complete year. Additionally, byproducts were also evaluated in terms of their degradation over time as monitored through microbiological and chemical analysis. Finally, their valorization was ascertained through the recovery of lipid fractions rich in ω3 polyunsaturated fatty acids (PUFAs) as well as protein fractions with antihypertensive activity (ACE). The variability of the biochemical composition of byproducts during the year was significant, especially in terms of lipid content, and their degradation was strongly dependent on the conditions under which they were collected and stored. Both liquid and solid byproducts present ω6/ω3 ratios between 0.05 and 0.18 and thrombogenic indexes between 0.27 and 0.57, whereas low-molecular-weight fractions of protein extracts (<3 kDa) exhibited the strongest ACE activity (IC50 = 51 μg/mL). The potential viability of using liquid byproducts as sources of functional ingredients is an interesting alternative to the management of these effluents in the fish canning industry.