Eva M. Santos

Characterisation of Micrococcaceae isolated from different varieties of chorizo.

A total of 426 strains of Micrococcaceae bacteria isolated from chorizo (a traditional Spanish fermented sausage) were identified. The chorizos were sampled from three regions of Castilla and León in Spain: Burgos, Segovia and Salamanca. Two factories were chosen in each region and the samples were taken at three stages of ripening. Staphylococcus xylosus was the most predominant species isolated (95%). Twelve strain types of S. xylosus were established according to their fermentation patterns, and two of them, S. xylosus type 2 and S. xylosus type 5, made up the majority of the strains of S. xylosus isolated (27 and 52%). Production of acetoin, nitrate reductase, urease activity, proteolytic and lipolytic activity were determined for all isolates. The percentage of strains of S. xylosus producing acetoin depends on the manufacturing location. In general, the proteolytic and lipolytic activities of the S. xylosus isolated from chorizo from Castilla and León were low and moderate; 97% of the strains showed nitrate reductase and urease activity. According to our results and to previous investigations, it seems that S. xylosus type 5, showing nitrate reductase and urease activity, low-moderate proteolytic and lipolytic activities and not producing acetoin would be suitable as a starter culture. Of the strains isolated in this study, 38% comply with these requirements.

The effect of sugar concentration and starter culture on instrumental and sensory textural properties of chorizo-Spanish dry-cured sausage

In this study, instrumental and sensory textural properties of chorizo with different levels of glucose (0.1%, 0.5% and 1.0%) and with different starter cultures (Lactobacillus sakei K29, Pediococcus sp. P22 and Pediococcus sp. P208) were studied as well as the relationship between them. The ripening process was followed by physico-chemical and microbiological analysis. Starter culture and concentration of glucose had a highly significant effect on pH, moreover an interactive effect of both factors was found; and also of day of ripening and both starter culture and concentration of glucose. In general terms, changes of pH over time are influenced by the presence of sugar and starter culture even if all chorizos showed at first a rapid decrease, a stay or slow decrease, and a final rise. Texture profile analysis (TPA) proved that hardness and chewiness differ significantly among chorizos with or without starter cultures, except in the batch with 0.1% sugar. Furthermore, the highest values in both textural parameters were found in batches with 0.5% and 1% sugar. The texture differences between chorizos just described were also noticeable in the sensorial evaluation. Likewise, instrumental textural attributes showed significant correlations with sensorial analysis.

Physicochemical and sensory characterisation of Morcilla de Burgos, a traditional Spanish blood sausage

Morcilla de Burgos is a popular cooked blood sausage produced in the region around Burgos in the north of Spain. Physicochemical and sensory properties of this traditional product were investigated in order to support the claim for a Protected Geographical Indication. Products from 14 manufacturers were analysed for pH, water activity (a(w)), moisture, ether-extractable fat, starch, protein, total sugar, ash, iron and sodium contents as well as sensory parameters related to visual, olfactory, texture and flavour attributes. Principal component analysis confirmed the existence of three varieties of Morcilla de Burgos. Morcillas from group I were characterised by a notable blood smell and blood and pepper flavour, a high pH, and a(w) and a high protein content. Morcillas from group II were characterised by strong cumin smell and flavour and a high softness. Morcillas from group III had a high onion odour, high presence of onion and high contents of fat, total sugar and fibre.

Determination of quinolones in milk samples using a combination of magnetic solid-phase extraction and capillary electrophoresis

A magnetic solid‐phase extraction (MSPE) method combined with capillary electrophoresis for the simultaneous determination of seven quinolones (QNs) (danofloxacin, ciprofloxacin, marbofloxacin, enrofloxacin, difloxacin, oxolinic acid, and flumequine), using (S)‐(+)‐6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid as internal standard, in milk samples was developed. The variables involved in the preconcentration magnetic procedure were: the composition of the magnetic support composition, the sample pH, and the weight of magnetic adsorbent used. The variables were optimized using a simplex‐lattice design. Different magnetite covered with octyl‐phenyl silica adsorbents were synthesized by varying the molar ratio of phenyltrimethylsilane and octyltrimethoxysilane; the solids were evaluated for QN preconcentration. Under optimal conditions, a linear range was obtained from 27 to 1000 μg L−1 with limits of detection ranging from 9 to 12 μg L−1 for the seven QNs. The absolute recoveries of the seven QNs at three different spiked levels (40, 150, and 400 μg L−1) ranged from 74% to 98% with a relative standard deviation less than 10% in all cases. The proposed method was applied to analyze 20 whole milk samples of different brands. All samples were positive for the presence of QN residues; in some cases, extract dilution was required. The concentrations found are in the range from 31.1 to 5047.3 μg L−1. Marbofloxacin was the most frequently found. The method proposed offers advantages in terms of simplicity, sensitivity, efficiency, cost, and analysis time making it an alternative for the analysis of QNs in whole milk samples.

Effectiveness of combined preservation methods to extend the shelf life of Morcilla de Burgos

Morcilla de Burgos is the most famous blood sausage in Spain. However, while producers are interested in extending its shelf life, the consumer is increasingly demanding more natural food. This situation has led to the current search for new and mild preservation technologies. Two batches of four different products: control without any treatment, control with organic acid salts (CnOAS; a 3% mixture of potassium/sodium l-lactate), control with high hydrostatic pressure processing (CnHPP; 600MPa-10min), and a combination of both treatments (OAS+HPP), were carried out to evaluate any synergistic effect that occurs when combining OAS and HPP, and the influence of different preservative treatments on the spoilage bacterial population and their evolution. HPP (with or without addition of OAS) can be considered the most suitable method for preserving morcilla de Burgos as it does not produce negative changes in sensory attributes. No clear selective effect of different treatments on the composition of the spoilage bacteria was seen and similar spoilage patterns were observed independently of the preservation treatment used.

Utilización de cultivos iniciadores en la elaboración de chorizo y su influencia en las propiedades sensoriales / Use of starter cultures in dry-fermented sausage (chorizo) and their influence on the sensory properties

The influence of different starter cultures on the sensory properties of chorizo, especially on texture, was studied. This work focused on the differences observed between the use of the commercial lactic acid bacteria Lactobacillus sake (Lc) and Pediococcus sp (Pc), as well as on the differences between these commercial strains and another Lactobacillus sake (A216) isolated from traditional chorizo. Three batches of chorizo were processed, each batch made up of four different types that contained or lacked one of the three starter cultures. Concerning capacity of acidification, the results indicated that there were no differences between the use of Lactobacillics sake or Pediococcus sp when 0.1% glucose is used. Furthermore, there were no differences in the sensory properties of the final product. Sausage processed with noncommercial Lactobacillus sake (A216) had a more intense flavour and was preferred by consumers because of its texture and overall characteristics. The use of starter culture had a favourable influence on sausage processing, reducing its manu facture time and improving some sensory properties of the final product.

Identificación y caracterización de bacterias acidolácticas aisladas de chorizos tradicionales elaborados en Castilla y León / Identification and characterization of lactic acid bacteria isolated from traditional chorizo made in Castilla-León

A total of 516 strains of lactic acid bacteria isolated from chorizo made in Castilla-León (Spain) were characterized. Strains were isolated at three different stages: minced meat, half ripened chorizo and ripened chorizo. According to the Schillinger and Lücke classification, 355 strains (68.8%) were Lactobacillus sake, 85 strains (16.5%) were Lactobacillus curvatus, 32 strains (6.2%) belonged to the genus Pediococcus, and 44 strains which were not included in the previous species were grouped as Lactobacillus sp. Strains of L. sake and L. curvatus could be separated into four groups each, on the basis of fermentation of maltose and lactose. Group S1 (maltose-, lactose-négative L. sake) predominated (39.5%). Many strains of this group fermented the following carbohydrates: glucose, ribose, galactose, sucrose, melibiose and trehalose.

Magnetic solid phase extraction based on fullerene and activated carbon adsorbents for determination of azo dyes in water samples by capillary electrophoresis

A magnetic solid phase extraction method coupled to capillary electrophoresis for the simultaneous determination of three azo dyes (sunset yellow, allura red and tartrazine) in wastewater samples was proposed. The method employs the dispersion of magnetic adsorbents in the sample. Variables involved in the retention–elution procedures were optimized using a simplex centroid design. The optimal conditions were: an adsorbent composition of magnetite–activated carbon–fullerene (10 : 0.59 : 0.41), a sample pH of 4.0, and a sample volume (μl) : weight of adsorbent (mg) ratio of 0.01. Under optimal conditions, a linear range was obtained from 3.0–40.0 mg l−1 with limits of detection ranging from 1.0–2.0 mg l−1. The average recoveries of each dye at two spiked levels (10 and 25 mg l−1) ranged from 95–106% with relative standard deviations of less than 10% in all cases. The proposed method was applied to analyze wastewater samples from different locations. Two samples gave positive responses to the presence of tartrazine residues. The method proposed offers advantages in terms of simplicity, sensitivity, high efficiency, low cost, and short analysis time, making it an alternative for the analysis of azo dyes in water samples and other complex matrices.

Determination of Lipoxygenase Activity in Cereals Grains Using a Silver Nanoparticles Assay

A spectrophotometric method based on the use of silver nanoparticles is presented for the determination of lipoxygenase activity in cereal grains. The method involves the synthesis of prism silver nanoparticles with a maximum absorption at 752 nm, followed by the abatement of the signal as a consequence of the oxidation produced by hydroperoxides generated in the enzymatic reaction. The quantification of the hydroperoxides produced by reaction of lipoxygenase with linoleic acid allows the determination of the enzyme activity in cereal grains. Under optimal conditions, the linear range of the calibration curve ranges from 1.0 to 5.0 μM, with a limit of detection of 0.34 μM. The method was validated comparing the results with those obtained by ferrous-xylenol orange method. A relative standard deviation ).

Active packaging films with natural antioxidants to be used in meat industry: A review

Spoilage of meat products during processing, distribution and exposure in the markets have an important negative impact on meat industry from an economic point of view. Two of the main problems of meat and products during processing and subsequent storage are lipid oxidation and deterioration due to microorganism growth. In this context, several packaging alternatives have been developed by meat industry in order to limit these losses and to extend the meat products´ shelf life. Over the last years, the use of active packaging has been proposed as an alternative to traditional packaging. The principle of active packaging, particularly antioxidant active packaging, consists of including active agents in the packaging which interact with meat and/or its environment, either by trapping pro-oxidant compounds or by releasing antioxidant compounds in order to delay degradation due to lipid oxidation. Therefore, the use of active packaging is presented as a future option to solve the problems derived from oxidative deterioration of meat and meat products. However, its use will depend on the costs involved in the development of this active packaging. Therefore, this review will give an overview about the use of active packaging and natural antioxidants, the active film development techniques, as well as the use of biopolymers as substitutes for synthetic polymers and their direct application in the meat industry.