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- Interrelationships among microbiological, physicochemical, and biochemical properties of Terrincho cheese, with emphasis on biogenic aminesPublication . Pinho, Olivia; Pintado, Ana I. E.; Gomes, Ana M. P.; Pintado, M. E.; Malcata, F. Xavier; Ferreira, Isabel M. P. L. V. O.Changes in the microbiological, physicochemical, and biochemical characteristics of Terrincho cheese as represented by native microflora, pH, water activity, soluble nitrogen fractions, free amino acids, and biogenic amines (e.g., ethylamine, dimethylamine, tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, cystamine, and spermine) during ripening were monitored. Terrincho is a traditional Portuguese cheese manufactured from raw ewe's milk. The main groups of microorganisms (lactococci, lactobacilli, enterococci, pseudomonads, staphylococci, coliforms, yeasts, and molds) were determined following conventional microbiological procedures. Free amino acids and biogenic amines were determined by reverse-phase high-performance liquid chromatography, following extraction from the cheese matrix and derivatization with dabsyl chloride. The total content of free amino acids ranged from 1,730 mg/kg of dry matter at the beginning of the ripening stage to 5,180 mg/kg of dry matter by day 60 of ripening; such an increase was highly correlated with the increase of watersoluble nitrogen in total nitrogen, 12% trichloroacetic acid–soluble nitrogen in total nitrogen, and 5% phosphotungstic acid– soluble nitrogen in total nitrogen throughout ripening. Histamine was consistently present at very low levels, whereas putrescine, cadaverine, and tryptamine were the dominant biogenic amines and increased in concentration during ripening. Ethylamine, tryptamine, phenylethylamine, and cystamine reached maxima by 30 days of ripening and decreased thereafter. Significant correlations between amino acid precursors and corresponding biogenic amines, as well as between biogenic amines and microbial viable numbers, were observed.
- Antioxidant activity of sugar molasses, including protective effect against DNA oxidative damagePublication . Guimarães, Carla M.; Gião, Maria S.; Martinez, Sidónia S.; Pintado, Ana I. E.; Pintado, Manuela E.; Bento, Luís S.; Malcata, F. XavierExtracts were obtained from molasses, a byproduct of the sugar industry, via a number of chromatographic steps. Their antioxidant capacity was studied, including the inhibitory effect upon DNA oxidative damage;the phenolic compound profile there of was ascertained as well. Two extracts exhibited significant antioxidant features, expressed by their capacity to decolorize ABTS radical cation and to scavenge hydroxyl free radicals (via deoxyribose assay). Those 2 extracts also brought about protection against induced DNA oxidative damage (via decreasing DNA scission, as assessed by electrophoresis).The phenolic compounds syringic acid,p-hydroxybenzoic acid, vanillic acid, p-hydroxybenzaldehyde, and ferulic acid were positively identified and quantified.
- Acidifying and aromatic properties of enterococcus strains in ovine and bovine milksPublication . Pimentel, L. L.; Soares, J. C.; Pintado, M. E.; Pintado, Ana I. E.; Gomes, Ana M. P.; Ferreira, A. C.; Malcata, F. X.
- Caseinolytic activity of fruit extract from Opuntia ficus-indica on bovine, caprine, and ovine Sodium CaseinatesPublication . Pintado, Ana I. E.; Macedo, Angela C.; Teixeira, Grimaneza; Pais, Salomé; Clemente, Alda; Malcata, F. XavierThe rates and extents of hydrolysis of RS- and â-caseins from bovine, caprine, and ovine sodium caseinates produced by an enzymatic extract of the fruit of Opuntia ficusindica, (L.) Miller were evaluated and compared with those produced by a commercial animal rennet. A mechanistic model based on a pseudo-first-order enzymatic reaction, in the presence of first-order deactivation of the enzyme, was postulated and successfully fitted to the experimental data. The animal rennet exhibited higher enzymatic efficiency than the fruit extract, irrespective of the source (i.e., bovine, caprine, or ovine) and the type (i.e., RS- or â-casein) of substrate. The enzymatic efficiency (kcat/Km) for RS-casein ranged from 72 to 220 and from 43 to 65 L g-1 h-1, and for â-casein from 242 to 742 and from 55 to 164 L g-1 h-1, for the animal rennet and the enzymatic extract of O. ficus-indica, respectively. Finally, it was observed that â-casein from caprine and ovine caseinates was degraded by O. ficus-indica faster than its RS counterpart, but the reverse was observed for bovine caseinate.
- Tolerance of Enterococci to bile saltsPublication . Pimentel, L. L.; Pintado, Manuela E.; Pintado, Ana I. E.; Gomes, Ana M. P.; Malcata, F. X.
- Probiotic Properties of Enterococci – Survival in simulated gastric juice and with bile saltsPublication . Pimentel, Lígia L.; Pintado, M. E.; Pintado, Ana I. E.; Gomes, Ana M. P.; Malcata, F. Xavier
- Identification and characterization of antibiotic susceptibility of enterococci isolated from Terrincho cheesePublication . Pimentel, Lígia L.; Pintado, Manuela E.; Pintado, Ana I. E.; Gomes, Ana M. P.; Malcata, F. Xavier
- Microbiological, biochemical and biogenic amine profiles of Terrincho cheese manufactured in several dairy farmsPublication . Pintado, Ana I. E.; Pinho, Olívia; Ferreira, Isabel M. P. L. V. O.; Pintado, M. E.; Gomes, Ana M. P.Terrincho is a Portuguese traditional cheese, bearing a protected denomination of origin (PDO) status, which is manufactured from raw ewes’ milk and ripened for a minimum period of 30 d. The objectives of this research effort were to characterize the microbiological and biochemical profiles of this cheese, manufactured in several dairy farms during the winter cheesemaking season (December through March), and establish tentative correlations between these profiles and formation of biogenic amines. For this goal, 29 cheeses from five batches, manufactured in as many dairy farms located throughout the PDO region, were analysed. The viable numbers of the total (mesophilic) microflora, enterococci, lactococci, lactobacilli, enterobacteria, staphylococci, pseudomonads, yeasts and moulds were determined by 30 d, following classical plate counting on specific media. Free amino acid and biogenic amine contents were determined by reverse-phase high-pressure liquid chromatography. The concentration of biogenic amines correlated well with microbial viable numbers, in both qualitative and quantitative terms; significant correlations were observed between enterococci and phenylethylamine (r ¼ 0.868, po0.0001), and between lactococci and cadaverine (r = 0.646, p <0.002) and tyramine (r = 0.868, p<0.0001). On the other hand, 220 g of Terrincho cheese would have to be consumed at a given time if the threshold of worst case risk was to be attained, which appears unrealistic for a typically single-doses meal ingredient. This study has contributed to deepen the knowledge on the microbiological and biochemical features of a unique Portuguese cheese throughout ripening, and to rationalize its safe consumption in terms of biogenic amines.
- Recuperación y revalorización del lactosuero para la producción de nuevos produtos con propriedades funcionalesPublication . Madureira, A. R.; Pintado, Ana I. E.; Gomes, Ana M. P.; Malcata, F. X.; Pintado, M. E.En los últimos años han surgido gran cantidad de alimentos funcionales a los que se les atribuyen diversas propiedades beneficiosas. Entre estos alimentos se encuentran aquellos que contienen proteínas del lactosuero así como aquellos que incorporan bacterias probióticas en su composición. En la actualidad existen matrices de proteínas de suero que contienen bacterias probióticas que se mantienen viables durante 28 días a temperaturas de refrigeración. Además, también se han realizado diferentes estudios relacionados con la actividad metabólica, las propiedades antimicrobianas y la resistencia a las enzimas del tracto gastrointestinal. Por último, se ha evaluado el uso de cepas de bacterias del ácido láctico con propiedades probióticas en la producción de exopolisacáridos en lactosuero.