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In response to the increasing consumers' mistrust in synthetic additives, the meat industry is focused on searching sources of natural antioxidants. Two different sources of natural antioxidants i) a mixture of garlic, cinnamon, cloves and rosemary essential oils and ii) a Rosa canina L. extract, were compared with a commercial antioxidant additive (Artinox®) for their ability to control protein and lipid oxidation in cooked hams after a settling period of 30 days and at the end of a chilled storage (150 days). The mixture of essential oils was the most effective against lipid oxidation while R. canina L. extracts were the most effective in controlling protein carbonylation at day 150. Accordingly, the use of these antioxidants via brine injection is a successful strategy to enhance the oxidative stability of cooked hams without modifying their physicochemical properties.

Forty-five lamb loins were subjected to sous-vide cooking at different combinations of temperature (60, 70 and 80 °C) and time (6, 12 and 24 h) to assess the effect on the oxidative stability of lipids and proteins. Heating induced both lipid and protein oxidation in lamb loins. Higher cooking temperature-time combinations increased conjugated dienes and decreased thiobarbituric reactive substances (TBARS) values and hexanal. Total protein carbonyls increased throughout time at all cooking temperatures considered, while α-aminoadipic (AAS) and γ-glutamic semialdehydes (GGS) increased when cooking at 60 °C but not at 80 °C. Links between the decrease in secondary compounds from lipid oxidation due to cooking at higher temperatures and for longer times with the increased levels of 3-methylbutanal and greater differences between total protein carbonyls and AAS plus GGS were hypothesised.

The efficiency of extracts from Arbutus unedo L. (AU), Crataegus monogyna L. (CM), Rosa canina L. (RC), and Rubus ulmifolius Schott. (RU) to inhibit lipid oxidation in raw, cooked and cooked and chilled (2°C/12 d) porcine burger patties, was investigated. The modification of the fatty acid profile during processing treatments (cooking and chilling), the quantitative measurements of thiobarbituric acid reactive substances (TBA-RS), and lipid-derived volatiles, were used as indicators of lipid oxidation. Polyunsaturated fatty acids (PUFA) gradually decreased during cooking and the subsequent storage of cooked burger patties with this decrease being significantly greater (P

The effect of the addition of natural antioxidants from strawberry tree (Arbutus unedo L.; AU) and dog rose (Rosa canina L.; RC), in frankfurters elaborated with or without the addition of antioxidant additives (sodium ascorbate and nitrite) was studied. Six different types of experimental frankfurters were prepared depending on the addition of phenolic-rich extracts from RC and AU and the presence (P) or absence (C) of antioxidant additives. Thiobarbituric acid reactive substances (TBARS)-numbers significantly increased during chilled storage of C-frankfurters while additives and fruit phenolics inhibited lipid oxidation in P-frankfurters. The amount of protein carbonyls significantly increased in all treatments except in P-AU frankfurters. The discoloration process that occurred during the chilled storage was reduced by the addition of substances with proven antioxidant activity (P-frankfurters). Texture characteristics as hardness, springiness, cohesiveness and gumminess also suffered a significant deterioration in C-frankfurters. The use of phenolic fruit extracts in combination with traditional antioxidant additives is a successful strategy to enhance the oxidative stability of frankfurters without modifying their color and texture properties.

The effect of the partial NaCl replacement by other salts (potassium, calcium, and magnesium chloride) on the formation of volatile compounds through the processing of dry-cured ham was studied using solid-phase microextraction (SPME). Three salt formulations were considered, namely, I (100% NaCl), II (50% NaCl and 50% KCl), and III (55% NaCl, 25% KCl, 15% CaCl(2), and 5% MgCl(2)). There was an intense formation of volatile compounds throughout the processing of dry-cured hams, particularly during the "hot-cellar" stage. The differences between treatments were found to be more remarkable at the end of the curing process. Hams from formulations I and II had significantly higher amounts of lipid-derived volatiles such as hexanal than hams from formulation III, whereas the latter had significantly higher amounts of Strecker aldehydes and alcohols. Plausible mechanisms by which salt replacement may affect the generation of volatile compounds include the influence of such replacement on lipid oxidation and proteolysis phenomena. The potential influence of the volatiles profile on the aroma of the products is also addressed in the present paper.

Nitrate and nitrite are commonly added to dry-cured ham to provide protection against pathogen microorganisms, especially Clostridium botulinum. Both nitrate and nitrite were monitored with ion chromatography in dry-cured hams salted with different NaCl formulations (NaCl partially replaced by KCl and/or CaCl2, and MgCl2). Nitrate, that is more stable than nitrite, diffuses into the ham and acts as a reservoir for nitrite generation. A correct nitrate and nitrite penetration was detected from the surface to the inner zones of the hams throughout its processing, independently of the salt formulation. Nitrate and nitrite achieved similar concentrations, around 37 and 2.2 ppm, respectively in the inner zones of the ham for the three assayed salt formulations at the end of the process, which are in compliance with European regulations.

[EN] The reduction of the content of sodium chloride in dry-cured ham was studied in to prevent the problems related to high sodium intake (i.e. the hypertension). One of the possibilities to reduce the sodium content is the partial replacement of sodium chloride by mixtures of potassium, magnesium and calcium chloride salts. The effect of two salting formulations (formulation II: 50% NaCl-50% KCl and formulation III: 55% NaCl, 25% KCl, 15 CaCl 2 and 5 MgCl 2) on the protease activity through the dry-curing process and on the sensory characteristics of the final product was evaluated and compared to those of control hams (formulation I, 100% NaCl). Sensory attributes were all affected in the hams containing CaCl 2 and MgCl 2 while hams containing 50% KCl and NaCl (formulation II) were better valued, except for the attribute taste probably due to the potassium contribution to bitter taste. © 2011 Elsevier Ltd., This work was supported by grant AGL2004-05064-C02-01 from Ministry of Education and Science (Madrid, Spain) and FEDER. FPI/MEC scholarship to M. Armenteros is also acknowledged.

Sodium intake above nutritional recommendations may involve harmful consequences to health such as the increased risk of cardiovascular diseases. Dry-cured ham constitutes a product with a relatively large amount of sodium. Thus, to obtain a healthier product for consumers with reduced sodium content, two formulations containing KCl alone (formulation II) or mixed with CaCl2 and MgCl2 (formulation III) have been proposed to partially replace NaCl. Lipolysis and lipid oxidation occurring in hams processed with these formulations have been studied since they have direct influence on the final flavor. No significant differences in acid lipase activity or lipid oxidation were found at the end of the process between the alternative formulations and formulation I (control with 100% NaCl). Differences in some free fatty acids, generated along the processing, were detected among treatments and at the end of dry-curing. Data suggests a slight trend towards a major lipolysis during treatment III.

The effect of partial replacement of NaCl by KCl in the dry-curing of loins has been evaluated by biochemical and sensory analysis of the final products. Endoproteolytic enzymes like cathpesins B and B + L appeared to be more active when more KCl and less NaCl were present in the curing salt while cathepsin H remained unaffected. Proteolysis was reflected by SDS–PAGE in the higher density of the sarcoplasmic proteins bands within the range 55.0–28.0 kDa. Alanyl aminopeptidase (AAP) was unaffected while arginyl and leucyl aminopeptidases were more activated by KCl. On the other hand, methionyl aminopeptidase and dipeptidylpeptidase I and III were more inhibited as KCl increased in the curing salt blends. The sensory analysis revealed no significant differences between control loins with 100% NaCl and those with up to 50% of KCl substitution. Furthermore, loins elaborated with 50% of each salt obtained the highest scores.

This study is focused on the effect of sodium chloride alternative salts (KCl, MgCl2 and CaCl2) on porcine muscle proteases (cathepsins, dipeptidylpeptidases and aminopeptidases). In general, KCl exerted a very similar effect to NaCl for all the studied enzymes, while the effect of divalent salts (CaCl2 and MgCl2) was more pronounced. Cathepsins, dipeptidyl peptidase III, dipeptidyl peptidase IV and alanyl aminopeptidase activities were strongly inhibited by all the chloride salts especially by divalent ones. Dipeptidyl peptidase II and leucyl aminopeptidase were little affected and methionyl aminopeptidase was only inhibited by divalent salts. Dipeptidyl peptidase I was strongly activated by low concentrations of the chloride salts except NaCl. Arginyl aminopeptidase was activated by NaCl and KCl and low amounts of MgCl2, while CaCl2 showed a strong inhibitory effect. This is very important as these enzymes play important roles in dry-cured meats and their activity is, in general, regulated by sodium chloride. Thus, reductions in the sodium concentration with subsequent increases of other alternative cations may have relevant consequences on enzyme activity that should be taken into account when processing dry-cured meats.

An attempt to decrease the NaCl content in dry-cured products through the use of three different salting treatments (II: 55% NaCl, 25% KCl, 15% CaCl(2), 5% MgCl(2); III: 45% NaCl, 25% KCl, 20% CaCl(2), 10% MgCl(2); and IV: 30% NaCl, 50% KCl, 15% CaCl(2), 5% MgCl(2)) in comparison to a control (I: 100% NaCl) was assayed to evaluate the biochemical and sensory characteristics in the final product. Most proteolytic enzyme activities from the loins submitted to the experimental salting treatments, especially treatments II and IV, remained higher than those salted traditionally (control). The higher aminopeptidase activity was also reflected in a larger release of free amino acids. Finally, a sensory paired comparison test revealed that those loins salted with the treatment II were not significantly different from the loins salted traditionally (100% NaCl), so that this treatment could be successfully used for sodium reduction.

268 páginas.-- Tesis Doctoral del Departamento de Tecnología de Alimentos de la Universidad Politécnica de Valencia (UPV) y del Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC).-- Fecha de lectura: 24 de Febrero de 2010., [Español]: En esta tesis se abordó en primer lugar el estudio “in vitro” del efecto del NaCl, KCl, MgCl2 y CaCl2 sobre la actividad de las enzimas proteolíticas musculares (catepsinas, dipeptidilpeptidasas y aminopeptidasas). Se comprobó que el KCl no ejercía ningún efecto significativamente diferente al del NaCl sobre la actividad de dichas enzimas, mientras que se necesitaron concentraciones mucho más bajas de sales divalentes (CaCl2 y MgCl2) para conseguir el mismo efecto inhibidor. Seguidamente, se aplicaron una serie de tratamientos de salado en lomo curado, en los que se había sustituido parcialmente el contenido de NaCl por sales de K+, Ca2+ y Mg2+, y se evaluó el efecto de dicha sustitución sobre la proteolisis, lipólisis y la calidad sensorial del producto final. A partir de estos resultados se seleccionaron los tratamientos de salado que obtuvieron mejores resultados: 50 % NaCl- 50 % KCl y 55 % NaCl, 25 % KCl, 15 % CaCl2 y 5 % MgCl2. Estas formulaciones fueron utilizadas para la fabricación de dos lotes de jamones con bajo contenido en sal, alrededor de 2.5 % en producto final, en los que se llevó a cabo el estudio de la proteolisis a lo largo del proceso de elaboración de los mismos, y de la calidad sensorial del producto final. Asimismo, se elaboraron otros dos lotes de jamones utilizando una técnica alternativa de salado, el salado a vacío, con un contenido en sal de producto terminado de entre el 4.5-5.5 % y se evaluó la calidad sensorial del producto final. Los resultados obtenidos en jamón curado indican que, la sustitución parcial del NaCl por mezclas de sales de cloruro de K+, Mg2+ y Ca2+ en las proporciones indicadas, no alteraba de manera significativa el fenómeno proteolítico que tuvo lugar durante su elaboración. Asimismo, el análisis sensorial mostró que los jamones elaborados con mezclas de NaCl-KCl al 50 % y concentraciones de sal alrededor de 2.5 % fueron bien valorados por el panel de catadores, mientras que en los que contenían una mayor cantidad de sal (4.5 a 5.5 %) se detectaron defectos, especialmente en cuanto al sabor amargo, debido al alto contenido en K+., [English]: In this thesis an “in vitro” study on the effect of NaCl, KCl, MgCl2 and CaCl2 on muscle protease activities (cathepsins, dipeptidylpeptidases and aminopeptidases) was performed. It was found that KCl did not exert any significant different effect than that due to NaCl on the activity of theses enzymes, while divalent salts (CaCl2 and MgCl2) required much lower concentrations to obtain a similar enzyme inhibition rate than NaCl. Then, a series of salting treatments on dry-cured loin with partial replacement of NaCl content by chloride salts of K+, Mg2+ and Ca2+ were applied, and their effects on proteolysis, lipolysis and sensory quality of the final product were assessed. From these results, those salting treatments which had obtained the best marks, consisting of 50 % NaCl-50 % KCl and 55 % NaCl, 25 % KCl, 15 % CaCl2 y 5 % MgCl2 were selected. These formulations were used for the manufacture of two batches of hams with low total salt content, around 2.5 % at the final product, with the aim to study the proteolysis phenomena during the processing and the sensory characteristics of the final product. Also, other two batches of hams using an alternative technique of salting vacuum impregnation with a total salt content among 4.5-5.5 % at the final product were elaborated and the sensory quality of the final product evaluated. These results pointed out that the partial replacement of NaCl in the dry-cured ham by the indicated K+, Mg2+ and Ca2+chloride salts mixtures, did not alter significantly the proteolytic phenomena ocurring during processing. Additionally, the sensory analysis showed that the hams manufactured with NaCl-KCl at 50 % and total concentrations of salt around 2.5 % were the most valued by the non-trained panel, whereas some defects appeared in those salted using more total salt content (4.5 -5.5 %), particularly related to bitter taste, due to the high K+ content., Beca F.P.I (BES-2005-9382) del Ministerio de Ciencia e Innovación enmarcada dentro de los proyectos AGL 2004-05064-C02-01 y AGL 2007-65379-C02-01.

Liquid chromatography–electrospray ionisation–mass spectrometry (LC–ESI–MS) was applied as an advanced methodology to study the suitability of using α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) as protein oxidation markers in meat products. The results obtained were compared to those obtained by using the DNPH-method and fluorescence spectroscopy for the analysis of protein carbonyls. Lipid oxidation was also investigated in order to elucidate the relationship between lipid and protein oxidation measurements. Both semialdehydes were originally detected in a food system which proves that lysine, arginine and proline are degraded as a result of oxidative reactions to yield AAS and GGS in meat products. A lack of consistency was observed between the MS results for AAS and GGS and the values obtained by the DNPH-method and the fluorescence spectroscopy. Unlike the last two methods, AAS and GGS measurements have proved to be unaffected by the composition or the structure of the food matrix providing precise information about the fate of particular amino acids during processing of muscle foods. These semialdehydes, and particularly GGS, could be used as indicators of protein oxidation in meat products like TBARS numbers are commonly used as lipid oxidation markers. In fact, a significant correlation was found between GGS values and TBARS highlighting the timely interaction between lipid and protein oxidation.

An intense proteolysis of muscle proteins, mainly due to the action of endogenous proteolytic enzymes, has been reported to occur during the processing of dry-cured ham. This gives rise to an important generation of free amino acids and peptides of small size that contribute directly or indirectly to flavor characteristics of the final product. The nature and properties of the free amino acids generated during postmortem proteolysis have been well established. However, little is known about the identity of peptides generated during the processing of dry-cured ham. In the present paper, we describe the isolation (by ethanol precipitation followed by size exclusion and reverse phase chromatographies) and identification (by matrix-assisted laser desorption/ionization time-of-flight MS and collision-induced dissociation MS/MS) in a Spanish dry-cured ham of the following four oligopeptides: (A) TKQEYDEAGPSIVHR, (B) ITKQEYDEAGPSIVHRK, (C) DSGDGVTHNVPIYE, and (D) DSGDGVTHNVPIYEG. This is the first time that these peptide fragments have been reported in dry-cured ham at the end of processing. Sequence homology analysis revealed that the four peptides originated from muscle actin, indicating an extensive hydrolysis of this protein during dry-curing. Some of the cleavage sites corresponding to these fragments in actin were reproduced by other authors through the incubation of this myofibrillar protein in the presence of cathepsin D (EC 3.4.23.5), thus supporting a relevant action of this enzyme during the processing of dry-cured ham.