Francisco Pérez-Nevado

Rapid differentiation of lactic acid bacteria from autochthonous fermentation of Iberian dry-fermented sausages

The populations of lactic acid bacteria (LAB) in different types of Iberian dry-fermented sausages from central-west Spain were identified. A simple and rapid electrophoretic method of whole-cell protein profiles was evaluated, correlating it with 16S rRNA gene sequence analysis and biochemical identification by API 50 CHL. A total of 96 isolates were identified by SDS-PAGE showing stable profiles corresponding to 30-45 polypeptides in the range 95-8kDa that were clearly different for the different species and were grouped with those of the 9 reference strains used in this study. The SDS-PAGE method showed that the predominant species were Pediococcus acidilactici (48%) followed by Lactobacillus plantarum (23%) and Lactobacillus brevis (18%). The identifications obtained by this approach were confirmed by sequencing the V2-V3 region of the 16S rRNA gene and by a BLAST search of the GenBank database. However, biochemical identifications by API 50 CHL showed different errors at the genus and species level. In sum, the SDS-PAGE analysis showed itself to be a rapid and accurate differentiation method for the most commonly encountered LAB isolates in dry-fermented sausages.

Characterisation of microbial deep spoilage in Iberian dry-cured ham.

The purpose of this work was to investigate the micro-organisms involved in overlooked bone taint spoilage of dry-cured Iberian hams. The physico-chemical characteristics of spoiled hams with 12 and 24 months of ripening, showing initial signs of alteration, were analyzed and their correlations with microbial counts studied. The spoilage potential of different microbial groups was assessed by the relationship between the microbial counts and the proteolysis level of spoilage as observed in the degradation of myofribrillar and sarcoplasmic protein fractions and in the changes in free amino acids. Non-enteric gram-negative bacteria (NEGN) were the dominant microbial group, showing a positive correlation with the moisture of spoiled hams. The Catalase-positive cocci (GPCP) growth was favoured by high NaCl concentrations in the spoiled hams, whereas the counts of Enterobacteriaceae were negatively affected by high NaCl concentration. The highest proteolytic microorganisms were the Gram-negative microbial groups playing Enterobacteriaceae a major role in the undesirable changes of the texture properties of the spoiled hams. With respect to the sensorial analysis, a synergy between NEGN and GPCP was observed in most of the strongly spoiled samples.

Identification of fungal contamination and determination of mycotoxigenic molds by micellar electrokinetic capillary chromatography in smoked paprika

The purpose of this work was to analyze the fungal contamination in smoked and unsmoked paprika processed from different cultivars of pepper and to investigate the ability of these and other mycotoxigenic molds to grow and synthesize mycotoxins in smoked paprika. Eighteen mycotoxins were evaluated using micellar electrokinetic capillary chromatography. No relevant differences were found in fungal contamination between smoked and unsmoked paprika. The number of yeasts obtained was low, ranging from 0.4 to 3.29 log CFU g(-1); most of the yeast strains were identified as Cryptococcus spp. followed by Candida spp. All mold counts were <4 log CFU g(-1). Aspergillus, Cladosporium, Penicillium, and Fusarium were the predominant hyphomycete genera. Six mycotoxins were identified in the extracts of several strains isolated from paprika and incubated on malt extract agar. Penicillium expansum followed by Penicillium citrinum and Penicillium raistrickii were the dominant mycotoxigenic fungi isolated. Most of themycotoxin-producing fungi produced detectable amounts of mycotoxins when grown on paprika agar.

Application of ISSR-PCR for rapid strain typing of Debaryomyces hansenii isolated from dry-cured Iberian ham.

Yeast populations of dry-cured Iberian ham isolated from seven industries in the province of Badajoz were characterized by ISSR-PCR using the (CAG)4 primer and PCR-RFLP of the ITS1-5.8S rRNA-ITS2 fragment, and identified by DNA sequencing. A total of 242 isolates were analyzed, indicating the primary species present was Debaryomyces hansenii at 80.9% of the isolates followed by Candida zeylanoides at 10.3% of the isolates. The remainders of isolates were identified as Yamadazyma triangularis, Sporobolomyces roseus, Meyerozyma guilliermondii, Rhodotorula slooffiae, and Cryptococcus victoriae. The ISSR-PCR method was a fast and reliable method which was able to discriminate species at a level comparable to restriction analyses of the ITS1-5.8S rRNA-ITS2 region. This method allowed for strain typing of D. hansenii, yielding 29 different PCR patterns within 196 isolates. Moreover, ISSR-PCR using the (CAG)4 primer indicated that this technique could be a promising tool for rapid discrimination of yeast starter cultures and spoilage species in dry-cured Iberian ham.

A low-cost procedure for production of fresh autochthonous wine yeast.

A low-cost procedure was designed for easy and rapid response-on-demand production of fresh wine yeast for local wine-making. The pilot plant produced fresh yeast culture concentrate with good microbial quality and excellent oenological properties from four selected wine yeasts. The best production yields were obtained using 2% sugar beet molasses and a working culture volume of less than 60% of the fermenter capacity. The yeast yield using 2% sugar grape juice was low and had poor cell viability after freeze storage, although the resulting yeast would be directly available for use in the winery. The performance of these yeasts in commercial wineries was excellent; they dominated must fermentation and improved its kinetics, as well as improving the physicochemical parameters and the organoleptic quality of red and white wines.

Evaluación del estado nutricional de estudiantes adolescentes de Extremadura basado en medidas antropométricas

INTRODUCTION AND OBJECTIVESnNutrition is one of the pillars for proper body development and optimal nutritional status. Anthropometric methods are most commonly used for body composition analysis and are an essential part in the assessment of the nutritional status of individuals and population groups. This study aims to assess the nutritional status of adolescents from Extremadura (Spain); to determine variations in body composition according to the percentiles obtained; and to propose these values as a reference to the nutritional status of the adolescent population in Extremadura.nnnMATERIAL AND METHODSnA cross sectional study in the community of Extremadura was performed, including a total of 816 students of Secondary School Education of both sexes; and of all ages in the adolescence stage. The selected secondary schools belonged to populations of different sizes (less than 5,000 to more than 60,000 inhabitants). From the measurements taken, different anthropometric indices were determined and the percentiles 3, 10, 25, 50, 75, 90, 95 and 97 for weight, height and complexion were found.nnnRESULTS AND CONCLUSIONSnThere were significant gender differences for height, weight, triceps skinfold, arm muscle area and arm fat area. Boys showed greater figures for height, weight and arm muscle area; however, the triceps skinfold and arm fat area was higher in girls. When compared to other national studies, the average height of our population was lower by about 3 cm in both sexes; the average weight was similar, but our adolescents had a higher proportion of fat in the arm. Extremadura girls seem to have a faster growth, reaching final height at an earlier age than the national average, although this height is below average. The boys had a continuous growth in all ages, maintaining national averages.

Spoilage yeasts: What are the sources of contamination of foods and beverages?

Foods and beverages are nutrient-rich ecosystems in which most microorganisms are able to grow. Moreover, several factors, such as physicochemical characteristics, storage temperature, culinary practices, and application of technologies for storage, also define the microbial population of foods and beverages. The yeast population has been well-characterised in fresh and processed fruit and vegetables, dairy products, dry-cured meat products, and beverages, among others. Some species are agents of alteration in different foods and beverages. Since the most comprehensive studies of spoilage yeasts have been performed in the winemaking process, hence, these studies form the thread of the discussion in this review. The natural yeast populations in raw ingredients and environmental contamination in the manufacturing facilities are the main modes by which food contamination occurs. After contamination, yeasts play a significant role in food and beverage spoilage, particularly in the alteration of fermented foods. Several mechanisms contribute to spoilage by yeasts, such as the production of lytic enzymes (lipases, proteases, and cellulases) and gas, utilisation of organic acids, discolouration, and off-flavours. This review addresses the role of yeasts in foods and beverages degradation by considering the modes of contamination and colonisation by yeasts, the yeast population diversity, mechanisms involved, and the analytical techniques for their identification, primarily molecular methods.