Browsing by Author "Malcata, F. X."
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- Acidifying and aromatic properties of enterococcus strains in ovine and bovine milksPublication . Pimentel, L. L.; Soares, J. C.; Pintado, M. M. E.; Pintado, A. I. E.; Gomes, A. M. P.; Ferreira, A. C.; Malcata, F. X.Enterococci are lactic acid bacteria present in a wide variety of dairy and other food products. Although their presence in the former has been considered an indicator of poor hygienic conditions, nowadays a number of biotechnological and probiotic useful characteristics are already known. A few compounds resulting from the bacterium metabolism contribute to the aroma of cheese. Knowledge of those components, as well as of the acidifying capacity is very important to the dairy industry, including application toward selection of strains as better starters. The aim of this research effort was to study the role of some enterococci in ovine and bovine milks, in terms of acidifying properties and aroma potential. A total of seven strains, previously isolated from traditional Portuguese cheeses, were assayed for: Enterococcus faecium 28A, E. durans 13 and E. faecalis 6 (from Serra da Estrela cheese); and E. faecium 42, E. durans 15, E. faecalis 3 and E. casseliflavus 40 (from Terrincho cheese). Sterilized ovine and bovine milks were inoculated with 2% (v/v) inoculum and incubated at 37 °C. Microbiological viable counts on M17 agar, pH and titrable acidity were determined in duplicate at 0, 1, 4 and 7 d of incubation. Free fatty acids, recognized as strong odorants in Serra da Estrela and other traditional Portuguese cheeses, were quantified in each sample using SPME – GC/MS. All strains showed similar growth patterns, either in bovine or ovine milks, and reached levels of 108 –109 cfu/ml by 1 d of incubation (except E. durans 13, which exhibited a better growth in bovine than ovine milk). An important decrease in pH was observed in both types of milk by 1 d, for all strains. The highest reduction was observed for E. casseliflavus 40 and E. durans 15 in bovine milk, and for E. faecium 42 and E. durans 13 in ovine milk. Enterococcus faecalis 6 revealed the poorest acidification power.
- 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.
- Amino acid catabolism and generation of volatiles by lactic acid bacteriaPublication . Tavaria, F. K.; Dahl, S.; Carballo, F. J.; Malcata, F. X.Twelve isolates of lactic acid bacteria, belonging to the Lactobacillus, Lactococcus, Leuconostoc, and Enterococcus genera, were previously isolated from 180- d-old Serra da Estrela cheese, a traditional Portuguese cheese manufactured from raw milk and coagulated with a plant rennet. These isolates were subsequently tested for their ability to catabolize free amino acids, when incubated independently with each amino acid in free form or with a mixture thereof. Attempts were made in both situations to correlate the rates of free amino acid uptake with the numbers of viable cells. When incubated individually, leucine, valine, glycine, aspartic acid, serine, threonine, lysine, glutamic acid, and alanine were degraded by all strains considered; arginine tended to build up, probably because of transamination of other amino acids. When incubated together, the degradation of free amino acids by each strain was dependent on pH (with an optimum pH around 6.0). The volatiles detected in ripened Serra da Estrela cheese originated mainly from leucine, phenylalanine, alanine, and valine, whereas in vitro they originated mainly from valine, phenylalanine, serine, leucine, alanine, and threonine. The wild strains tested offer a great potential for flavor generation, which might justify their inclusion in a tentative starter/nonstarter culture for that and similar cheeses. (Key words: flavor, catabolism, starter cultures, cheese)
- Antinociceptive and anti-inflammatory effects of novel dietary protein hydrolysate produced from whey by proteases of Cynara cardunculusPublication . Tavares, T. G.; Spindola, H.; Longato, G.; Pintado, M. E.; Carvalho, J. E.; Malcata, F. X.Antinociceptive and anti-inflammatory effects of a peptide concentrate mix (PepC) obtained from whey protein, via hydrolysis with cardosins from Cynara cardunculus, was tested in vivo. The antinociceptive effect was assessed using writhing, hot-plate and formalin tests in mice, and the anti-inflammatory effect using the paw oedema test. PepC at 300 mg kg(-1) bw conveyed a significant result in the writhing test when co-administered with 1 and 3 mg kg(-1) bw indomethacin, similar to administration of higher doses of indomethacin alone. Conversely, no statistically significant differences were observed in the paw oedema test when the same PepC concentration was co-administered with dexamethasone at 3, 10 and 30 mg kg(-1) bw. PepC at 1000 mg kg(-1) bw did not cause any remarkable outcome in the hot-plate test. PepC appears to possess anti-inflammatory and peripheral antinociceptive activities, so it may be a candidate for nutraceutical ingredient.
- Application of chitosan in the textile industry to control microbial growthPublication . Tavaria, F. K.; Soares, J.; Oliveira, V.; Silva, R.; Morgado, J.; Malcata, F. X.; Pintado, M. E.
- Assessment of proteolysis and lipolysis in Serra cheese: effects of axial cheese location, ripening time and lactation seasonPublication . Macedo, A. C.; Costa, M. L.; Malcata, F. X.The degrees of proteolysis and Iipolysis in Serra cheese were measured in cheese samples obtained from experiments laid out as a three-way facto rial design replicated twice. The independent variables studied were the location within the cheese (from the center to the surface), the position in the lactation season (from October to June) and the ripening time (from 0 to 35 days). Ali three variables had statistically significant effects on the concentration of water soluble peptides (WSP), but only the ripening time and the period within the lactation season affected the fat acidity (FA). The extents (alter the given ripening period) and the rates (averaged over the ripening period) of generation of WSP and FA were highest for spring and lowest for autumn. The lowest values for both the proteolysis extent and the proteolysis rate were obtained for the rind. The rates of proteolysis and lipolysis tended to decrease with ripening time; most of the lipolysis occurred during the first week, but proteolysis was still in progress by 35 days of ripening.
- Biochemical profiles in the microalga Pavlova lutheri: combined effects of light intensity and temperaturePublication . Carvalho, A. P.; Monteiro, C. M.; Malcata, F. X.
- Biochemical profiles in the microalga Pavlova lutheri: combined effects of light intensity and temperaturePublication . Carvalho, A. P.; Monteiro, C. M.; Malcata, F. X.
- Biological properties of chitosanPublication . Tavaria, F. K.; Costa, E. M.; Gens, E. J.; Pintado, M. E.; Malcata, F. X.
- Changes of lactose, lactic acid, and acetic acid contents in Serra cheese during ripeningPublication . Macedo, Angela C.; Malcata, F. X.Changes in the quantities of lactose, lactic acid and acetic acid in Serra cheese were monitored using a triplicate two-way factorial design over a ripening period of 35 days (sampling at 0, 7, 21 and 35 days) throughout the cheesemaking season (sampling in November, February and June). The amount of lactose in total solids of cheese (TS) decreased slowly from 6.17% to 0.21% (w/wTS) as ripening time elapsed. As a result of sugar metabolism, the lactic acid content increased from 0.07% at day 0 to 2.10% (w/wTS) by 35 days, whereas the acetic acid content increased from 0.00% to 0.24% (w/wTS) during the first week. The lactose content was statistically correlated with the lactic acid content but not with the acetic acid content.