Inmaculada Franco

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.

Biogenic amine content during the manufacture of dry-cured lacón, a spanish traditional meat product : Effect of some additives

The content of nine biogenic amines (agmatine, tryptamine, 2-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine) was determined throughout the manufacture of dry-cured lacón, a traditional dry-salted and ripened meat product made in the north-west of Spain from the fore leg of the pig following a similar process to that of dry-cured ham. The effect of the use of additives (glucose, sodium nitrite, sodium nitrate, sodium ascorbate and sodium citrate) on the biogenic amine content during manufacture was also studied. Tryptamine and spermine were the main biogenic amines in fresh meat, while tryptamine and cadaverine were the most abundant at the end of the manufacturing process. During ripening the total amine content increased significantly (P<0.05) in the batches made both without and with additives. The use of additives significantly (P<0.05) increased the total amine content and the content of tryptamine, tyramine and histamine. The total biogenic amine content at the end of the manufacturing process was low as expected for a product in which there is little active microbial metabolism during manufacture.

Proteolytic and lipolytic modifications during the manufacture of dry-cured lacón, a Spanish traditional meat product: Effect of some additives

The extractability of sarcoplasmic and myofibrillar proteins, the myofibrillar proteins and their degradation products, classical nitrogen fractions, free amino acids, acidity of the fat, and free fatty acids were determined throughout the manufacturing process of dry-cured lacón, a traditional dry-salted and ripened meat product made in the northwest of Spain from the foreleg of the pig, following a similar technological process to that of dry-cured ham. The effect of the use of additives (glucose, sodium nitrite, sodium nitrate, sodium ascorbate and sodium citrate) on the proteolytic and lipolytic changes was also studied. Throughout the manufacture, approximately 87% of the sarcoplasmic proteins and 91% of the myofibrillar proteins became insoluble. There was a significant (p<0.05) decrease of the myosin heavy chain, actin, and myosin light chains 1, 2 and 3, and also a significant (p<0.05) increase in the components generated as a result of the degradation of these myofibrillar proteins. The content of the different nitrogen fractions and of the free amino acids indicated that protein degradation during the manufacture of dry-cured lacón is only moderate. Data on the acidity of fat and of free fatty acids also indicated that lipolysis in dry-cured lacón is lower than in hams. The use of additives did not significantly influence the protein and lipid degradation, which occur throughout the manufacturing process.

The composition of Arnoia peppers (Capsicum annuum L.) at different stages of maturity

‘Arnoia’ peppers (Capsicum annuum L. var. annuum cv. Arnoia) are cultivated in areas surrounding the Arnoia River, in Galicia (northwest Spain). Some physical and chemical changes associated with maturation and storage conditions have been reported. Changes in gross composition, the main physico-chemical parameters and mineral composition were evaluated in peppers collected directly from plants and at two different states of maturity (green and red fruits), and in commercially available peppers (green fruits). The total soluble solid content and titratable acidity increased significantly during ripening. The fat, ash and protein contents were generally significantly higher in the red pepper than in the green peppers. The total ascorbic acid in red peppers was 27% higher than that of green peppers. The vitamin C content of commercially available green peppers was up to 39% lower than in the freshly picked peppers. Potassium was the most abundant mineral in green and red peppers. Green peppers purchased in the supermarket contained higher amounts of calcium and sodium than the freshly picked peppers. The levels of zinc, manganese and copper were similar in all of the different samples.

Influence of inclusion of chestnut in the finishing diet on fatty acid profile of dry-cured ham from Celta pig breed

The effect of the inclusion of chestnut in the finishing diet on fatty acid profile of dry-cured Celta ham was studied. Twelve hams of each type (from three different diets: concentrate, mixed and chestnut) were used. Significant differences between treatments (P<0.001) were found regarding total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). Ham samples from the mixed and chestnut groups had less SFA (35.57% and 35.63%, respectively) with respect to ham samples from the concentrate group (40.33%), while hams from the mixed and chestnut batches showed higher values of MUFA than hams from the concentrate group (50.70 vs. 49.79 vs. 43.85, P<0.001, respectively). From a nutritional point of view, Celta hams from chestnut diets could be considered as healthier regarding their fatty acid profiles (low n-6/n-3 ratio and high hypocholesterolemic/Hypercholesterolemic ratio). Discriminant analysis selected five variables (C(16:0), C(16:1cis-9), C(20:2), C(20:3n-6) and C(20:4n-6)) and calculated two discriminating functions which verifies the presence of chestnut in the finishing diet.

Production of biogenic amines "in vitro" in relation to the growth phase by Enterobacteriaceae species isolated from traditional sausages

Histidine, lysine, ornithine and tyrosine decarboxylase activities were tested in 79 strains of Enterobacteriaceae (41 of Hafnia alvei, 17 of Serratia liquefaciens, 5 of Enterobacter cloacae, 4 of Citrobacter braakii, 2 of Proteus vulgaris, 2 of Proteus mirabilis, 2 of Providencia stuartii, 2 of Klebsiella terrigena, 1 of Rahnella aquatilis, 1 of Salmonella arizonae, 1 of Citrobacter youngae and 1 of Escherichia coli) isolated from Botillo, a Spanish traditional sausage. In general, the strains were positive for all four activities, with the exception of two strains of H. alvei and the E. coli strain, which did not display histidine decarboxylase activity. The strains of P. mirabilis and P. stuartii did not exhibit any of the four activities tested. Accumulation of putrescine and cadaverine was studied throughout growth of the 75 strains that displayed ornithine and lysine decarboxylase activities. Biogenic amines were produced particularly in the exponential phase, with maximum accumulation occurring after between 12 to 72 h, depending on the biogenic amine and microbial species considered. Maximum accumulation of putrescine varied greatly between species and within the same species, and ranged from 18 mg/l in the R. aquatilis strain to 7325 mg/l in a H. alvei strain. Maximum accumulation of cadaverine varied less than that of putrescine, and ranged from 30 mg/l in the R. aquatilis strain to 1935 mg/l in a S. liquefaciens strain.

Technological and safety characteristics of Staphylococcaceae isolated from Spanish traditional dry-cured sausages.

The aim of this study was to determine the technological properties (nitrate reductase, proteolytic and lipolytic activities; and the ability to grow at the temperature and pH values of fermenting sausage, and at high NaCl concentrations) and safety characteristics (amino acid decarboxylase and enterotoxigenic activities) of 38 strains of Staphylococcaceae (11 of Staphylococcus epidermidis, 15 of Staphylococcus equorum, 5 of Staphylococcus pasteuri and 7 of Staphylococcus saprophyticus) isolated from Androlla and Botillo, two Spanish traditional sausages, in order to evaluate their suitability as potential starter cultures in the manufacture of these sausages. Most strains were able to grow at 10 °C, in the presence of 10% and 15% NaCl and at pH values of 5.5 and 5.0, except for S. equorum strains, growth of which was reduced at these pH values. The proteolytic activity assessed by the agar plate method showed that 89.5% and 52.6% of the strains were able to hydrolyze sarcoplasmic and myofibrillar proteins, respectively. These results were not confirmed by electrophoretic assays as only 47.2% of the strains changed the SDS-PAGE profile of actin, myosin and/or sarcoplasmic protein extracts. The assessment of the lipolytic activity by titration showed that only 21.0% of the strains can hydrolyze pork fat to any extent; whereas the profiles of the freed fatty acids were different in the different strains. Most of the strains showed decarboxylase activity against histidine, lysine, ornithine and tyrosine, but the quantities of biogenic amines produced were in most cases <25 ppm and <5 ppm for putrescine and cadaverine, respectively. Only four strains (10.5%), of S. epidermidis, produced enterotoxin C.

Strains of Staphylococcus and Bacillus isolated from traditional sausages as producers of biogenic amines

Histidine, lysine, ornithine, and tyrosine decarboxylase activities were tested in 38 strains of Staphylococcus (15 of S. equorum, 11 of S. epidermidis, 7 of S. saprophyticus, and 5 of S. pasteuri) and 19 strains of Bacillus (13 of B. subtilis and 6 of B. amyloliquefaciens) isolated from two Spanish traditional sausage varieties. The four decarboxylase activities were present in most of the strains studied, but some variability was observed between strains within each microbial species. Accumulation of putrescine and cadaverine was assessed in the culture media of the strains that displayed ornithine and lysine decarboxylase activities. The aminogenic potential of the strains was low, with amounts accumulated lower than 25 mg/L for the putrescine and than 5 mg/L for the cadaverine, with the exception of a strain of S. equorum that produced 1415 mg/L of putrescine, and of a strain of S. epidermidis that accumulated 977 mg/L of putrescine and 36 mg/L of cadaverine.

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.