Bernardo Prieto

Study of the biochemical changes during the processing of Androlla, a Spanish dry-cured pork sausage

Androlla is a dry-cured sausage manufactured with pork in the northwest of Spain (Galicia). In three batches of this product, manufactured by three different producers, samples of the mix before stuffing and from sausages after 1, 3, 7, 14, 21, 28 and 42 days of ripening were taken. In each sample, the overall chemical composition, physico-chemical parameters, nitrogen fractions and some degradative parameters of the fat were determined. The changes in the different compositional parameters throughout ripening were similar to those observed in other similar products and the values of these parameters, at the end of ripening, were inside the wide range of values reported in the bibliography for various dry-cured sausages. Sugars were not added in the mix and the lactic fermentation during ripening was not very intense. The values of non-protein nitrogen, α-aminoacidic nitrogen and total basic volatile nitrogen were increased significantly during ripening. The final levels of non-protein nitrogen were found to be within the range of values observed for other sausage varieties; however, the values of α-aminoacidic nitrogen and total basic volatile nitrogen were lower than those found in similar products. From the values of the acidity of the fat it can be concluded that the lipolysis that this product undergoes is moderate; the peroxide values are higher than those found in other sausages, however T.B.A. values are lower to those habitually described by other authors.

Biochemical changes throughout the ripening of a traditional Spanish goat cheese variety (Babia-Laciana)

The physico-chemical characteristics, proteolysis (classical nitrogen fractions, caseins and their degradation products and free amino acids), and lipolysis (fat acidity and free fatty acids) were studied throughout the ripening of three batches of Babia-Laciana cheese, a Spanish traditional variety made from raw goats’ milk. The main compositional characteristics of this cheese at the end of the ripening are its high content of total solids (TS) (78.0±2.4 g 100 g−1 of cheese) and fat (61.1±1.2 g 100 g−1 of TS), the presence of residual lactose (1.6±0.8 g 100 g−1 of TS) and its low content of sodium chloride (1.1±0.7 g 100 g−1 of TS) and ash (2.8±0.5 g 100 g−1 of TS). Its pH values (4.44±0.72) are extraordinarily low. The evolution and final values of the different nitrogen fractions show that this cheese undergoes a very slight proteolysis, a fact which was corroborated when the caseins and their degradation products were quantified: β-casein did not undergo any modification throughout ripening, while only 21% of the αs-caseins were degraded. Free amino acids content increased by a factor of about 7 throughout ripening, resulting in a high content of γ-amino butyric acid and a low content of glutamic acid at the end of the process. Fat acidity increased very slightly, approximately 4.5 times, during ripening, reaching final values of 3.5±2.2 mg KOH g−1 of fat. The total free fatty acids content showed a similar evolution to fat acidity. At the end of the ripening process, the main free fatty acid was C18:1, followed by C16 and C10.

Picón Bejes-Tresviso blue cheese : an overall biochemical survey throughout the ripening process

The gross and mineral composition, the main physico-chemical parameters, the proteolysis (classical nitrogen fractions and free amino acids) and the lipolysis (acidity index of the fat and free fatty acids) were studied throughout the ripening of three batches of Picon Bejes-Tresviso cheese, a Spanish blue-veined variety. The gross and mineral composition and the physico-chemical parameters do not differ very much from those observed in other Spanish and European blue cheeses. From the figures of the different nitrogen fractions it can be concluded that this cheese undergoes an extensive and profound proteolysis throughout the ripening period. Consequently high levels of total free amino acids were observed; the most abundant amino acids at the end of ripening were valine, leucine, lysine, phenylalanine and glutamic acid. Picon Bejes-Tresviso cheese also undergoes an intense lipolysis throughout ripening as the acidity index of the fat and the total free fatty acids values indicated; the most abundant free fatty acid was oleic, followed by palmitic and myristic acid.

Effects of ripening time and combination of ovine and caprine milks on proteolysis of Picante cheese

Proteolysis in Picante cheese was characterized by assaying for breakdown products throughout a 180 day ripening period using different combinations of ewe’s and goat’s milks. Parameters analysed were total nitrogen (TN), water-soluble nitrogen (WSN) and non-protein nitrogen (NPN) using Kjeldahl and spectrophotometric methods, and casein profile by electrophoresis. WSN at 180 days of ripening was 2529% TN. The maximum NPN values were attained by 180 days of ripening and corresponded to 87% and 92% of the WSN in OC and lOOC, respectively (where iC denotes a cheese manufactured with i% caprine milk). Statistically significant correlations were obtained between the various analytical methods of assay for nitrogen and ripening time. The spectrophotometric methods using either trinitrobenzenesulphonic acid or cadmium-ninhydrin proved satisfactory in assessing the ripening index (instead of the Kjeldahl method). Degradation of /J-caseins at 180 days was 18.8,26.4,40.2, 55.6 and 36.5% for OC, 25C, 5OC, 75C and 1 OOC, respectively. Degradation of cw,-caseins by 180 days was 35.9,40.2, 81.8,93.0 and 68.7% for OC, 25C, 5OC, 75C and lOOC, respectively. In general, a higher cheesemaking milk fraction of caprine milk was associated with higher amounts of y-caseins. 0 1997 Elsevier Science Ltd

Biochemical characteristics of dry-cured lacón

Dry-cured lacon is a salted and ripened meat product made in the north-west of Spain from the fore extremity of the pig following a technological process very similar to those of dry-cured ham. The gross composition, the most relevant physico-chemical parameters, the protein extractability, the nitrogen fractions, as well as some fat characteristics, were determined in 21 units of the end-product. With some minor exceptions, the compositional and physico-chemical parameter values do not differ very much from those observed in cured ham and other meat cured-products made from entire pieces. It can be deduced, from the values of the different nitrogen fractions, that dry-cured lacon, throughout its elaboration, undergoes a very light proteolysis. The values of free fatty acid contents indicate that the lipolysis is also not very intense. However, the peroxide values are higher than those found in dry-cured ham for a similar ripening period.

Influence of milk source and ripening time on free amino acid profile of Picante cheese

The evolution of concentration of free amino acids in Picante cheese throughout ripening was studied for several volumetric ratios of ewes and goats milks. The concentrations of all free amino acids, except asparagine, γ-aminobutyric acid, and cysteine, generally increased as ripening time elapsed. Analyses of variance have indicated that ripening time and, to a lesser extent, milk composition have significant effects on the overall concentration of free amino acids. The major free amino acids present in the various cheeses along the ripening period were valine, leucine, and phenylalanine; these three amino acids accounted for 50, 49, 57, 46 and 42% of total free amino acids at 0 days and 42, 42, 43, 39 and 36% of total free amino acids at 180 days for cheeses manufactured with 0, 25, 50, 75 and 100% goats milk, respectively. Significant differences could be detected in terms of amino acid profile when the relative proportions of ewes and goats milks were altered (eg valine changed from 251.79 ± 0.99 to 352.20 ± 16.49 mg/100 g of dry matter, leucine from 181.48 ± 1.77 to 226.00 ± 11.60 mg/100 g of dry matter, and phenylalanine from 120.39 ± 1.44 to 155.36 ± 8.39 mg/100 g of dry matter in 140-day ripened cheeses when plain ewes milk was replaced by plain goats milk). The correlation coefficients between the concentrations of valine, isoleucine, leucine and phenylalanine, on the one hand, and ripening time, on the other, were greater than 0.93.

“Quesucos de Liébana” cheese from cow's milk: biochemical changes during ripening

Abstract The changes in chemical composition, main physico-chemical parameters, classical nitrogen fractions, caseins and their degradation products, and some fat characteristics were studied during the ripening process of 10 batches of Quesucos de Liebana cheese, a traditional variety made in the north of Spain. The values of the different compositional and physico-chemical parameters at the end of the ripening did not differ significantly from those found in other cows milk cheeses elaborated with similar technology. The presence of residual lactose at the end of the ripening process is outstanding. The total soluble nitrogen increased by a factor of 2 at the end of the ripening compared to the values shown at the beginning. However, non-protein nitrogen increased very little. The final values of the different nitrogen fractions show that this cheese undergoes a proteolysis moderate in extension but not very intense and that the rennet is the main agent of the proteolysis produced during ripening. Using PAGE techniques, it was possible to show that, throughout ripening, 56% of α s -casein and 11% of β-casein turned out to be degraded. The TBA number and acidity index of the fat values show that the processes of lipolysis and fat autooxidation during the ripening of this cheese are not very intense.

Biochemical changes in Picón Bejes-Tresviso cheese, a Spanish blue-veined variety, during ripening

The changes in the gross chemical composition, physico-chemical parameters, nitrogen fractions, caseins and their degradation products, and some fat characteristics were studied during the ripening process of 10 batches of Picon Bejes-Tresviso cheese, a traditional blue-veined variety made in the north of Spain. The values of the different compositional and physico-chemical parameters at the end of ripening did not differ very much from those found in other Spanish and European blue-veined cheeses. The total soluble nitrogen and the non-protein nitrogen increased by factors of 5.4 and 8, respectively, at the end of ripening compared to the values found in cheese curd after salting. The final values of all the nitrogen fractions showed that Picon Bejes-Tresviso cheese undergoes extensive and in depth proteolysis. The intense degradation of the caseins during ripening was confirmed when the caseins and their degradation products were quantified using PAGE techniques. The autooxidation of the fat does not seem very important during the ripening of this cheese. Nevertheless, lipolysis was very intense; the acidity index of the fat values (free fatty acid contents) increased by a factor of about 20 during ripening.

How milk type, coagulant, salting procedure and ripening time affect the profile of free amino acids in Picante da Beira Baixa cheese

The concentration of total free amino acids (FAA) in Picante cheese increased with ripening time irrespective of the particular protocol used for manufacture (ie ratio of caprine to ovine milks, animal or plant rennet and number of salting steps). The experimental cheeses manufactured with 20% (v/v) caprine milk, coagulated with animal rennet and salted only once exhibited the highest content of total FAA by 120 days of ripening. All four manufacture parameters were statistically significant on the 0.5% level of significance in terms of total concentration of FAA. The dominating free amino acids present in the various experimental cheeses throughout the ripening period were valine, leucine and phenylalanine, each one representing more than 10% (w/w) of the total concentration of FAA. All four manufacture parameters were, in general, statistically significant with respect to the content of every single FAA, with particular emphasis on salting and ripening time.