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Influence of native lactic acid bacteria on the microbiological, biochemical an...
Macedo, Angela C.; Tavares, Tânia G.; Malcata, F. XavierCheesemaking from batches of raw ewe’s milk was carried out via inoculation with wild strains of Lactococcus lactis subsp. lactis ESB110019 and Lactobacillus plantarum ESB5004 independently, or combined with each other. Those two strains had been isolated from the native microflora of typical Serra da Estrela cheese. One control batch was processed in parallel without addition of any starter. The evolution in v...
Esterase activities of intracellular extracts of wild strains of lactic acid ba...
Macedo, Angela C.; Tavares, Tânia G.; Malcata, F. XavierLactococcus lactis subsp. lactis strain ESB110019 and Lactobacillus plantarum strain ESB5004, novel strains that were previously isolated from the wild adventitious microflora of certified Serra da Estrela cheeses, were assayed for esterase activity using, as substrates, ortho- and para-nitrophenyl derivatives of fatty acids. Both strains preferentially hydrolyzed short-chain fatty acids; L. lactis ESB110019 ex...
Purification and characterization of an intracellular aminopeptidase from a wil...
Macedo, Angela C.; Tavares, Tânia G.; Malcata, F. XavierAn intracellular hydrolase able to cleave Image -lysine-p-nitroanilide was purified from Lactobacillus plantarum strain ESB5004 via two steps of precipitation with ammonium sulfate (at 30 and 50% (w/v)), followed by hydrophobic interaction and ion-exchange chromatographies. The aminopeptidase was purified up to 11-fold, with a final yield of ca. 1%. Its native molecular weight is ca. 70 kDa, and it is apparentl...
Caseinolytic activity of fruit extract from Opuntia ficus-indica on bovine, cap...
Pintado, Ana I.; 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 an...
Peptide hydrolase system of lactic acid bacteria isolated from Serra da Estrela...
Macedo, Angela C.; Veira, Marta; Poças, Raquel; Malcata, F. X.Lactobacillus paracasei subsp. paracasei ESB 230, Leuconostoc mesenteroides subsp. mesenteroides ESB 136, Lactococcus lactis subsp. lactis ESB 117 and Enterococcus faecium ESB 50, previously isolated from certi"ed Serra da Estrela cheeses, were tested for their aminopeptidase, dipeptidyl aminopeptidase, endopeptidase, dipeptidase and carboxypeptidase activities. The crude cell-free extracts (CFE) of Lb. paracas...
Technological optimization of the manufacture of Serra cheese
Macedo, Angela C.; Malcata, F. XavierIn order to optimize the process of cheesemaking of Serra cheese, the most famous traditional Portuguese cheese manufactured with raw ewes' milk at farm level, several cheeses were produced according to a second-order composite factorial design using temperature of coagulation, amount of plant rennet added and amount of salt added to fresh cheese as the manipulated technological variables. Sensory, microbiologi...
Changes of lactose, lactic acid, and acetic acid contents in Serra cheese durin...
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...
Role of adventitious microflora in proteolysis and lipolysis of Serra cheese: p...
Macedo, Angela C.; Malcata, F. XavierSix different types of bacteria (five strains of lactic acid bacterium and one strain of coliform) isolated from 35-day-old Serra cheese were assayed for proteolytic and lipolytic activities on milk agar and tributyrin agar, respectively. Peptidase and lipase activities were further studied via analytical assaying of free amino acids by spectrophotometry and of free fatty acids by HPLC in in vitro curdled milk ...
Secondary proteolysis in Serra cheese during ripening and throughout the cheese...
Macedo, Angela C.; Malcata, F. X.Experimental Serra cheeses were manufactured from raw ewe’s milk and thistle flowers following a two-way factorial design. The content of nitrogen soluble in water (WSN), in 2% trichloroacetic acid (2% TCA-N), in 12% TCA (TCA-N) and in 5% phosphotungstic acid (5% PTA-N), and the pH and salt-in-moisture concentration were measured throughout the ripening period (sampling at 0, 7, 21 and 35 days) and the cheese-m...
Changes of mineral concentrations in Serra Cheese during ripening and throughou...
Macedo, Angela C.; Malcata, F. XavierSeasonal changes of the ash content and mineral concentrations in Serra cheese were studied over a typical 35-day ripening period. Statistically significant differences (at the 5% level) exist between the ash content and the concentrations of Na, K, Ca, P, Mg and Zn in cheeses during ripening. The highest concentrations of Na was obtained in cheese ripened for 7 days, whereas the concentrations of K, Ca, P, Ng ...
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