FOOD TECHNOLOGY (2)

Author: LOSADA IGLESIAS VANESA.
Year: 2005.
University: VIGO [www.uvigo.es].
Place of defense: FACULTAD DE BIOLOGÍA.

Author: LORENZO RODRÍGUEZ JOSÉ MANUEL.
Year: 2005.
University: VIGO [www.uvigo.es].
Place of defense: FACULTAD DE CIENCIAS DE OURENSE.
Place of preparation: FACULTAD DE CIENCIAS DE OURENSE.

Summary: The lacón crudo-curado is a traditional meat product produced in northwestern Spain from the leading edge of the pork, cut across the articulation escápulo-humeral, according to a processing technology very similar to that used in the manufacture of the ham crudo-curado. The objective of this work was to study both microbiological and biochemical changes that occur during the development of this product, as part of a job description and attempted to improve its quality. Recently, the industries have begun using additives in their development in order to improve the appearance and quality of the final product. This thesis was also studied the effect of the use of some additives on the microbiological and biochemical changes over the development. The microbiota halotolerante was the microbial majority group during the process of drawing up development. Staphylococcus xylosus was the most abundant microbial species and constant. The genus Lactobacillus was the most abundant between lactic acid bacteria, Lactobacillus curvatus predominated in the areas of lacón produced without additives, while L.sakei was the most abundant lactic bacteria in the batch produced from additives. The pH barely changed during the development, while water activity decreased significantly and progressively over the process. The rate of transformation of hemo-pigmentos in nitrosil-hemo pigments was significantly higher in the items developed with additives. Of the values of the different fractions nitrogen it can be concluded that the lacón suffers along its development a little proteolysis. The content of free amino acids at the end of the development was quite less than that observed in cured hams. The index values of acidity fat (indicative of the intensity of lipolysis) and the contents of the various free fatty acids were increased in a meaningful way during development, but without reaching the final values observed in hams. The use of additives is not influenced in one way or marked in the biochemical characteristics nor the microbiological product, only the formation of color (compounds nitrosil-hemo) was clearly enhanced by the use of additives.

Author: SANZ PEREZ DAVID.
Year: 2005.
University: ZARAGOZA [www.unizar.es].
Place of defense: FACULTAD DE VETERINARIA.
Place of preparation: FACULTAD DE VETERINARIA.

Summary: The objective of this research was to establish the causes of the inhibitory effect of the sheep's milk free of antibiotics on microbiological screening tests, as well as finding solutions to the problem of false positives. The results showed that less than 1% of the nearly 2,000 milks sheep investigated for over 2 years old had antibiotics in concentrations above the limits of detection of the test. The data published so far in this investigation that began pointing to the presence of natural inhibitors in the milk of sheep -sistema lactoperoxidase, lactoferrina and lisozima- as primarily responsible for the occurrence of false positives. However, the inhibitory effect of the samples was correlated only with its content in lysozyme, with a low significance. In addition, it established the minimum inhibitory concentrations for commercial screening test most commonly used globally each of the antimicrobial natural studied (lactoperoxidase, lactoferrina and lysozyme). The results suggest that although in very special circumstances and individual animal could be achieved in these inhibitory concentrations, it is very doubtful that industrial tanks, which produces a significant dilution phenomenon, the appearance of false positives can be caused by any of these components. We investigated other possible causes of the inhibitory effect of milk samples from sheep not attributable to the presence of antibiotics and showed that the azidiol, used as a preservative in the samples by the dairy companies could be responsible for the emergence of some false positives . We threshold concentrations of chloramphenicol and sodium azide - presentes in the composition of azidiol and responsible for their actions antimicrobiana- able to inhibit various commercial test, demonstrating that were within the range used by some companies in the sector. Once demonstrated the inhibitory effect of azidiol used by some laboratories interbranch is optimized implementation of a solution capable of reducing the enzyme inhibitory effect of this preservative, eliminating the occurrence of false positives. In order to assess the effects on the concentration of residues of antibiotics and sulphonamides of heating recommended (80-100 ° C for several minutes) to eliminate the effect of inhibitors natural milk, it was determined the termorresistencia of different antibiotics and sulphonamides as well as the termodependencia their reactions termodestrucción. Our data show that the treatments did not significantly affect pasteurization to the concentration of antibiotic was investigated, which makes possible the implementation of a heat treatment to the samples before analysis. This technique, although it can sometimes be useful, is not applicable to large laboratories, given that hardly can be automated. Finally, we addressed the problem trying to find a microbial species most suitable for the manufacture of the test. Of the more than 15 strains investigated initially were gradually discarded for various reasons -escasa capacity sporulation, inadequate sensitivity to antibiotics, metabolic activity, too slowly, etc most up to identify the most appropriate. Their conditions were established for sporulation, washing and preparation of the suspensions of spores, as well as the most appropriate indicator of metabolism, pH and composition of the most convenient means of detection. These studies made it possible to develop an initial prototype on which defined the optimal concentration of microorganisms in the test and conditions of incubation time and temperature. The main advantage of the new test developed compared to currently marketed is its high sensitivity to macrolides and aminoglycosides. As is well 8 know, the 37th test currently marketed reasonably well detect the presence of beta-lactámicos, but their detection thresholds for other groups antibiotics are well above the maximum residue limits recommended by the EU.

Author: Marcos Muntal Begoña.
Year: 2006.
University: GIRONA [www.udg.es].
Place of defense: Instituto de Tecnología Agroalimentaria.
Place of preparation: IRTA-Instituto de investigación y tecnología agroalimentaria.

Summary: The increasing demand for minimally processed products and ready-to-eat poses a major challenge for food security and has led to the development of treatments that allow soft inhibit microbial growth while preserving the quality of food. The collected works of this thesis raised various strategies involving the combination of barriers for microbial growth to improve the safety of meat products ready for consumption. With the aim of improving the safety of sausages crudos-curados, was assessed by the application of high hydrostatic pressure treatment and the addition of crops initiators sausages in weak acid (fuet and chorizo). Moreover, to reduce the risk of L. During monocytogenes conservation Ham loncheado was avaluó the combined effect of the addition of natural antimicrobial (lactato-diacetato and enterocinas), added directly or through the antimicrobial packaging, and treatment of high hydrostatic pressure.

Author: HERNÁNDEZ LEÓN ALEJANDRO.
Year: 2006.
University: EXTREMADURA [www.unex.es].
Place of defense: ESCUELA DE INGENIERÍAS AGRARIAS.
Place of preparation: ESCUELA DE INGENIERIAS AGRARIAS.

Summary: Mixtures of paprika La Vera with pimentones variety unauthorized produce a significant decrease in the quality of paprika La Vera besides imposing a fraud. The development of rapid and sensitive methods for detecting fraudulent mixtures is essential to ensure the quality and authenticity of paprika hosted Protected Designation of Origin "Pimentón of La Vera." To achieve this end have been used molecular biology techniques based on the development of PCR revealed that mixtures of pimentones of up to 5% (w / w). The analysis of protein profiles through Capillary Electrophoresis mined in areas of mixed peppers also enabled the detection of 5% (w / w) of foreign paprika. Both methods were effective and appropriate for analyzing mixtures at trade shows, so can be used by the PDO "Pimentón La Vera" as tools for detecting fraudulent mixtures.

Author: MARCILLA BALAGUER ALICIA.
Year: 2006.
University: POLITÉCNICA DE VALENCIA [www.upv.es].
Place of defense: Dep. Tecnologia de Alimentos.
Place of preparation: Universidad Politécnica de Valencia.

Summary: The Valencia is the first exporter of fresh citrus in the world, why are the main object of study by the Instituto Valenciano de Investigaciones Agrarias (IVIA). Currently there are many studies on the effect of post-harvest treatments in citrus though few of them have been carried out using a panel of trained tasters for the sensory evaluation. Attributes such as brightness, weight loss, acidity, sweetness and composition in volatile but can be evaluated using instrumental methods, sensory or organoleptic analysis is also necessary to determine the effects of post-harvest treatments in its flavor and aroma. The sensory analysis has traditionally been regarded as a second-class discipline with a low scientific value, but currently is able to generate accurate and reproducible. In this paper we have used the sensory analysis as a tool for determining the quality of citrus subjected to different post-harvest treatments: quarantines cold more controlled atmospheres (mandarins' Marisol 'and' Clemenules') or irradiation (mandarins' Clemenules' ), applying coatings business with varying amounts in total solids (18, 15, 10 and 7%) in mandarins' Clemenules', 'Fortune' and 'Marisol' and oranges' Valencia '. It has formed a panel of trained tasters citrus IVIA with staff that has allowed us to study the correlation between the chemical composition of the fruit and its organoleptic characteristics.

Author: CÁCERES QUEMADA ESTER.
Year: 2006.
University: COMPLUTENSE DE MADRID [www.ucm.es].
Place of defense: FACULTAD DE VETERINARIA.
Place of preparation: DPTO. NUTRICIÓN, BROMATOLOGÍA Y TECNOLOGÍA DE LOS ALIMENTOS (FAC. VETERINARIA, UNIVERSIDAD COMPLUTENSE DE MADRID).

Summary: The basic concepts in nutrition are undergoing a significant change, surpassing the traditional notion of a "proper diet" in the sense of providing only enough nutrients to ensure the survival of individual metabolic needs and satisfy their hunger and sense of well-being. Currently, the emphasis is focused on the potential of genetic food for health promotion, improved welfare and reducing the risk of contracting diseases. In this area appear "functional foods", defined as those who provide a healthy profit regardless of its nutritional value. Most foods that have been enriched with functional ingredients are milk and dairy products, beverages and cereals. However, meat products have been little studied in this regard. Therefore, the objective of this work has been to design new products healthier meat using two basic strategies: reducing fat and incorporating functional ingredients for the meat is in deficit, as fructooligosacáridos (FOS), calcium, fatty acids polinsaturados n3, folic acid and vitamin E. To achieve these objectives have been developed sausages using a traditional formula of mortadella, reducing their fat percentage and incorporating the ingredients listed. These experimental batches have undergone physical and chemical analysis, instrumental and sensory to determine the changes that occur in them. This has been achieved sausages with good organoleptic quality and stable for 90 days in refrigeration at 4 ° C with a reduction of fat in a 40% to 12% of FOS; calcium in sufficient quantities to 100g of the product provide the 20 and 25 % of the RDA of calcium; polyunsaturated fatty acids concentration such that 50 g of product contribution to 100 and 90% of the recommended intake of EPA and DHA and with a relationship n6/n3 near 2; folic acid in sufficient quantity to 50 g product contribute to 100% of the GDR in states of high need and vitamin E in the form of acetato-dl-alfa-tocoferol so that 50g product contribute to 50% of the GDR.

Author: GINER SEGUÍ JOAQUÍN JESÚS.
Year: 2006.
University: LLEIDA [www.udl.es].
Place of defense: E.T.S. DE INGENIERÍA AGRARIA.
Place of preparation: ESCUELA TÉCNICA SUPERIOR DE INGENIERÍA AGRARIA.

Summary: The heat treatment is the method most commonly used to prevent adverse effects that can trigger enzymes in fruit juices. The disadvantages inherent in these treatments have sparked interest in exploring other alternatives. This paper has studied the feasibility of treatment with electric pulses of high field strength (PEAIC) as a non-thermal method to reduce the activity of some enzymes of special relevance in the industry juices. Also, the evolution of the activities of the enzymes after exposure to PEAIC has been reflected through different types of models (models and kinetic energy). The enzymes were considered: polifenoloxidasa (PPO) of apple, pear and peach; pectinesterasa (EP) tomato and a commercial enzyme preparation (PRECO), and poligalacturonasa (PG) PRECO. With the various teams PEAIC used two types of discontinuous and a continuous flow, we were able to significantly reduce the activity of enzymes tested. The effectiveness to inactivate enzymes depended on the sensitivity of each enzyme to PEAIC together with the conditions of treatment. In general, increasing the intensity of the electric field, treatment time, energy density and applied electrical pulse width, reducing the activities of enzymes treated with PEAIC was higher. The polarity of the electric field had a significant effect on the inactivation of the PPO Peach. The model biexponencial allowed explain developments in phases activación-inactivación enzyme. The relationship between the enzyme activity and energy provided by the system PEAIC could be expressed through decreasing exponential relationship, and when the evolution of the enzyme activity took convex profile or initial sharp decline, models based on the Weibull equation proved to be more suitable . Applying PEAIC can be a feasible alternative for stability in developing enzyme juices. The models used allow linking with good precision the enzymatic activity with the conditions of treatment with PEAIC.