FOOD BIOCHEMISTRY

Author: ALBILLOS GARCÍA SILVIA M..
Year: 2003.
University: BURGOS [www.ubu.es].
Place of defense: CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: From the industrial point of view and is very interesting scientific brought under control reactions that occur during the manufacture of cheese, as they are the determinants of carcteristicas flavor, texture and appearance of the final product. Specifically, the proteolysis of casein is the most important phenomenon in terms of quantifying the degree of maturation. It is therefore essential monitoring and identification of genetic main components involved in the process of ripening cheese. The objectives in this study were three. Do Obtimar conditions of separation of casein in milk samples from cows and sheep, by capillary electrophoresis (CE), using two types of capillaries (fused silica and neutral). B-Track products released by the enzymatic hydrolysis of caseí pattern bovine applying palsmina, quimosina and commercial preparation Neutrase ® C analyze samples of cheese from sheep and blended (vaca-oveja) from different times of healing to correlate their profile protico with time to maturity through multivariate analysis. The results showed that include an additive lilimérico cellulose (HPMC) in the buffer separation improved resolution with the capillary sílice.Sin however, the best conditions of separation was achieved for the capillary at neutral pH 3; voltage 25, 09 kV; HPMC 0.05% (w / v); urea 6 Mya 21 ° C. With these conditions are getting a clear separation of all genetic variants of the casein y2a, Y1B, y1A1, y3B, Y1a2 and Y3a and peptide asP derived from casein as1.De hydrolysis with renin highlighted the caseína-Ias1 and peptide f (1-23/24) and caseína-Ias0 and casein fragments BI 'A1 and A2 and casein BI''A1 AND A2 products released during the hidrólisid with Neutrase ® appreciated the presence of casein I - as1 and I-aso, and some casein y. Applying the technique of capillary electrophoresis, it is possible to monitor the primary proteolysis in sheep's cheese and cheese mix of different tempos of mafuración. The sheep's cheese, in the first days of ripening, proteolysis took place mainly as casein (especially as1 II) cheese mixture caseins that are suffering higher hydrolysis were as1 and as0 cow, detected a hydrolysis of casein B Preferred sheep in front of the cow. The multivariate analysis (PCR And PLSC) of the results of capillary electrophoresis showed that it was possible to predict the time maduraciónde samples of sheep's cheese and mix with an error average 3.6 and 7.8 days, respectively.

Author: PAZOS PALMEIRO MANUEL.
Year: 2004.
University: SANTIAGO DE COMPOSTELA [www.usc.es].
Place of defense: FACULTAD DE QUÍMICA.
Place of preparation: FACULTAD DE QUÍMICA.

Summary: We investigated the effectiveness of polyphenols extracted from the bagasse pressed white Parellada grapes (Vitis vinifera) for the inhibition of the oxidation lioidica into the muscle of fish species or fats semigrasas as mackerel or horse mackerel during frozen storage . The extract obtained from bagasse polyphenolic grape was composed mainly of monomers and oligomers of catechins, or procianidinas and to a lesser extent by flavonoles glycosylated. This polyphenolic extract various fractions were isolated composite catechins varying degrees of polymerization and percentage of galoización. Polifenólicos obtained compounds were characterized in terms of their polar nature and properties in vitro: antiradical power, reducing capacity and chelating agent. The properties in vitri showed that all the polyphenols were potentially given its antioxidant activity antiradical, reductive and chelating agent. Additionally, we performed a preliminary evaluation of the antioxidant activity of polyphenols in two model systems fast and rich marine lipids, fish oil and fish oil emulsion in water. The polyphenols were subsequently tested for inhibition of rancidez in muscle and minced fish fillets. In the experiment fillets, were investigated different procedures for the incorporation of polyphenols: a) spray, b) application layer Glazing c) combination of a washing prior fillets with water, with the purpose of removing substances prooxidante nature, with the subsequent spraying of polyphenols. To delve into the mechanism of antioxidant polyphenols were onboard the study of interactions between polyphenols with some of the ingredients endogenous muscle fish. Specifically, it investigated the effect of polyphenols in maintaining some of the antioxidant compounds System muscle fish (tocopherol, ubiquinona and glutathione) and the inhibition of the activity of systems prooxidantes present in the muscle: hemoglobin, enzymatic iron and non iron enzyme. The results show that procianidinas with a polymerization and galoización half have a high activity delaying rancidez into the muscle of fish. The data obtained indicate that the mechanism of antioxidant polyphenols are involved at least two processes: the activity of polyphenols to activate des prooxidantes muscle systems and their effectiveness in maintaining levels of endogenous antioxidants, especiafrnente of tocofero!. The results provided further suggest that phenolic compounds are able to recover / regeneration tocopherol levels during the spread of rust in the muscle of fish.