Olga Heredero Díaz

Proteolysis in dry fermented sausages: The effect of selected exogenous proteases

The effect of three commercial proteases (pronase E from Streptomyces griseus, aspartyl proteinase from Aspergillus oryzae and papain) on protein breakdown and the sensory characteristics of dry fermented sausages was investigated. Water soluble, non-protein, 5% phosphotungstic acid soluble, 5% sulphosalicylic acid soluble and total volatile basic nitrogen contents increased during fermentation, stabilizing later until the end of ripening (26th day). Nitrogen values were always greater in the aspartyl proteinase added batch in comparison with the other protease added batches. Total free amino acid changes showed a similar pattern to those observed for the 5% sulphosalicylic acid soluble nitrogen. The electrophoretic studies demonstrated that proteolysis of high molecular weight myofibrillar and sarcoplasmic proteins was more prominent in protease added batches. It was especially intensive in papain one. The dominant amino acids at the end of ripening were similar in all batches. Tyramine and histamine increased throughout ripening. No significant differences in sensory properties were found between control and pronase E and papain added batches, but they were significantly different (p < 0.01) from the sausages containing aspartyl proteinase, due to an excessive softening. The effect of exogenous enzyme addition on the flavour potentiation of dry fermented sausage is discussed.

Effect of the addition of pronase E on the proteolysis in dry fermented sausages

The effect of the addition of pronase E at two different concentrations on protein breakdown during the ripening of dry fermented sausage was studied. In all batches, water-soluble, non-protein and 5% phosphotungstic acid soluble nitrogens increased sharply during the first days of ripening, then became stabilized until the end of the process (26th day), and the total volatile nitrogen consistently increased during ripening. The greater the pronase E added the higher were the values reached for all these fractions. The changes in total free amino acids showed a similar pattern to that observed for the phosphotungstic acid soluble nitrogen. Histamine and tyramine progressively increased throughout the ripening. By sensory evaluation, no significant differences between the control batch and the batch with the lowest amount of added pronase E were found, but both batches were significantly different (P < 0·1) from the batch manufactured with the highest concentration of pronase E, which was classed as objectionable by the panellists because of its excessive softness.

Effect of the addition of pancreatic lipase on the ripening of dry-fermented sausages — Part 1. Microbial, physico-chemical and lipolytic changes

The effect of the addition of nine different amounts (3-500 units) of pancreatic lipase on the microbial and physico-chemical parameters and lipid fractions during the ripening of dry fermented sausages has been studied. No differences between conventional and lipase-added sausages were found for pH, dry matter and water activity. The addition of lipase caused a greater accumulation of products resulting from the triglyceride breakdown, mainly diglycerides and free fatty acids (FFA). The maximum rate of lipolysis was observed during the first week of the ripening process, specially in the fermentation phase. The greater the pancreatic lipase added, the higher lipolysis observed. At the end of the ripening, the levels of total FFA were clearly higher (1·5 to 5-fold) in all lipase-added batches than in the controls. This fact gave rise to the accumulation of a great amount of FFA, which can contribute either by themselves to the flavour of the sausage or can be available as substrates for further transformations which may generate other flavour compounds.

Effect of the Addition of Papain on the Dry Fermented Sausage Proteolysis

The effects of the addition of two different concentrations of papain on the proteolysis development and the sensory characteristics of dry fermented sausage were studied. In all batches, water soluble, non-protein, 50 g litre -1 phosphotungstic acid soluble, 50 g litre -1 sulphosalicylic acid soluble and total volatile basic nitrogens increased during fermentation (first 2 days). The changes were more pronounced and the values greater when the highest level of papain was added. After fermentation, nitrogen levels became stabilised until the end of ripening (26 days). The electrophoretic studies showed that the proteolysis of high molecular weight myofibrillar and sarcoplasmic proteins was more prominent in protease-added batches. A similar pattern was observed for free amino acids compared with that found in 50 g litre -1 sulphosalicylic acid nitrogen. Histamine and tyramine increased through ripening. Although the addition of papain increased the proteolysis phenomena, no improvement of the sausage flavour was observed in the sensory analysis.

Effect of the addition of pancreatic lipase on the ripening of dry-fermented sausages — Part 2. Free fatty acids, short-chain fatty acids, carbonyls and sensory quality

The effect of the addition of nine different amounts (3-500 units) of pancreatic lipase on the composition of free fatty acids (FFA), short-chain fatty acids and carbonyls, as well as the sensory quality, has been studied on dry fermented sausages. The lipase produced a greater release of all fatty acids in relation to the control sausages. The greater the pancreatic lipase content, the higher the release of these fatty acids, the most important ones being myristic, palmitoleic and oleic acids. A lower release of linoleic acid was observed, probably because of its oxidative degradation. At the end of the ripening in all lipase-added batches, a clear increase of the carbonyl content was noticed in relation to conventional sausages. No consistent changes were observed in the short-chain fatty acid fraction. In the sensory evaluation, the highest significant differences (P < 0·01) between control sausages and lipase-added batches were observed when 60 and 90 lipase units were used. According to the chemical and sensory analyses, it can be concluded that the addition of 60 and 90 units to sausages seems to be useful to enhanced the flavour of these products.

Effect of freezing on theβ-hydroxyacyl-CoA-dehydrogenase (HADH) activity of fish meat

ZusammenfassungÄnderungen in der Aktivität der β-Hydroxyacyl-CoA-dehydrogenase (HADH) im Fleisch von Tintenfisch, Makrele, Thunfisch, Seebrassen, Seezunge und Seehecht als Folge des Gefrierens bei −10 °C, −18 °C, −35 °C, −80 °C und −196 °C wurden untersucht. Mit Ausnahme kleiner Seehechte war die HADH-Aktivität wäßriger Extrakte des Fleisches bei allen gefrorenen und dann aufgetauten Fischen signifikant höher (p<0,0001) als bei ungefroren gelagerten Tieren. Dies ist Folge des Austrittes von HADH aus den Zellen während des Gefrierens. Die HADH-Aktivitäten von gefrorenem/aufgetautem Tintenfisch und Seebrassen sowie ungefrorenen Makrelen, Seebrassen und Seehechten wurden auch durch Lagern auf gestoßenem Eis beeinflußt.AbstractChanges in the β-hydroxyacyl-CoA-dehydrogenase (HADH) activity of squid (Loligo vulgaris), mackerel (Scomber scombrus), tuna (Thunnus alalunga), sea bream (Pagellus centrodontus), sole (Solea solea), hake and small hake (Merluccius merluccius) meat due to freezing treatment at −10° C, −18° C, −35° C, −80° C or −196° C were investigated. With the exception of the small hake, the HADH activity of aqueous extracts from meat was significantly higher (p<0.0001) in all frozen/thawed fish species studied than in unfrozen animals because during freezing there was a release of HADH. HADH activity values of frozen/thawed squid, unfrozen mackerel, frozen/thawed and unfrozen sea bream and unfrozen hake were affected by the storage time in crushed ice.

Los efectos profesionales de la crisis de la televisión pública española: el creador audiovisual low cost y las nuevas tecnologías

The Spanish television sector, where the effects of the economic crisis and the lack of alternative financing their toll, is set at the national level as a pseudo-oligopoly around a public entity, TVE, and two large audiovisual business groups, Mediaset, with Telecinco and Cuatro as backbones, and Atresmedia, with Antena 3 and La Sexta. The consequences of the shift that has transformed TVE in a publicly funded entity, without commercial advertising and political programs at no cost, with the technological renovation, the democratization of distribution of content by themselves and cheaper cost, marks the day of the new low cost creators, who must adapt to the effects of the crisis professionals of public broadcasting to avoid running out of an increasingly competitive and uncertain market. The description of these effects, both in the working system of audiovisual creator of the century, as in his professional profile, by the identification of the causative factors of his conversion are the goals of this research. Thus, through a literature review and a qualitative analysis with unstructured in-depth interviews to the professionals involved, the article verifies two hypothesis: first, that the transformation of the system of audiovisual creative work in TVE has increased its precariousness and, secondly , that their professional profile has been extended to non-artistic functional areas (finance, production, editing , etc.).

El arte en la publicidad. Tipologías del uso del arte visual en la comunicación comercial

La saturacion publicitaria en un mercado globalizado altamente competitivo, en el que las diferencias funcionales entre los productos apenas existen, obliga a las marcas a innovar en la busqueda de nuevas estrategias comunicativas que generen valor y engagement con el consumidor. En este sentido, la inclusion de referencias al arte visual en la comunicacion comercial se propone como un modelo valido, fundamentado empiricamente en el efecto de transfusion del arte. La clasificacion de la diversidad de formas que puede adoptar esta estrategia es el objetivo de este articulo, que en base al modelo de Hjemslev aplicado al estudio del significante del lenguaje publicitario mediante la dicotomia expresion/contenido, define once tipologias distintas, de las que se incluyen varios ejemplos.

Changes in water activity of selected solid culture media throughout incubation

The water activities (aw) of selected culture media commonly used in food microbiology have been determined and the effects of the volume of medium poured in Petri dishes, temperature and time of incubation on aw reduction studied. The aw values consistently fell throughout incubation. However, in culture media with aw > 0·94, the reduction of aw was negligible for microbial growth at incubation temperatures