
Teresa María López-DíazUniversity of Leon | UNILEON · Department of Hygiene and Food Technology
Teresa María López-Díaz
Master in Veterinary Sciences, PhD
About
55
Publications
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1,447
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Introduction
I work with fungi of interest in foods. In the last years, in the control of Penicillium (spoilage and mycotoxingenic species) in cheese.
Skills and Expertise
Additional affiliations
November 2001 - present
Position
- Lecturer-Associate Professor
Description
- Professor in the Food Sci. and Technology Degree, and the Master in Research in Veterinary and Food Sciences of the university of León. My research is focused on the search and study of toxigenic moulds, mainly of Penicillium, on foods and their control.
Publications
Publications (55)
Citation: López-Díaz, T.M.; Alegría, Á.; Rodríguez-Calleja, J.M.; Combarros-Fuertes, P.; Fresno, J.M.; Santos, J.A.; Flórez, A.B.; Mayo, B. Blue Cheeses: Microbiology and Its Role in the Sensory Characteristics. Dairy 2023, 4, 410-422. https:// Abstract: Blue cheeses are those whose matrix is veined with a blue, blue-grey, or blue-green colour due...
Lytic bacteriophages (phages) offer a great potential as biocontrol agents for spoilage Clostridium tyrobutyricum, responsible for butyric acid fermentation in semi-hard and hard ripened cheeses, resulting in late gas blowing defect. With this aim, we have isolated, identified and characterized new lytic phages of C. tyrobutyricum, and have evaluat...
Given the importance of lactic acid bacteria (LAB) in dairy products, this study assessed the antimicrobial properties of lactobacilli against some toxigenic Penicillium spp and pathogenic bacteria commonly found in cheese. Lactobacilli previously isolated from an artisanal Brazilian cheese (n = 32) were identified to species level by amplification...
Please cite this article as: J. Ramos-Pereira, J. Mareze, D. Fernández, et al., Antifungal activity of lactic acid bacteria isolated from milk against Penicillium commune, P. nordicum, and P. verrucosum, International Journal of Food Microbiology (2021), https://doi. Abstract Penicillium spp. is considered a major spoilage fungus of cheeses. The us...
The aim of this work was to assess the antifungal and antioxidant activity of essential oils and ethanolic extracts from distilled solid by-products from aromatic plants (Artemisia dracunculus, Hyssopus officinalis, Lavandula stoechas, Origanum vulgare and Satureja montana) against 14 fungi strains isolated from sheep cheese and identified at speci...
This study was carried out to assess the survival of Shiga toxin-producing E. coli (STEC) and atypical enteropathogenic Escherichia coli (aEPEC) during the traditional manufacturing and ripening of Spanish hard cheese from raw cow’s milk. Milk samples were spiked with up to 3.1–3.5 log cfu/mL of one strain of STEC (O140:H32 serotype) and one of aEP...
Twenty-seven samples of raw goat's milk were collected from four farms in the NorthWest of Spain with the aim of analysing counts of various mesophilic bacteria and of determining the physical and chemical composition during different seasons of the year. Overall mean values for mesophilic aerobic microorganisms (Standard Plate Counts, SPCs) were a...
Online social networks are increasingly used by the population on a daily basis. They are considered a powerful tool for science communication and their potential as educational tools is emerging. However, their usefulness in academic practice is still a matter of debate. Here, we present the results of our pioneering experience teaching a full Bas...
Appendix 1: Table 1. Twitter course syllabus
Appendix 2: Figure 3. Image captures of representative tweets posted during #microMOOCSEM course
Appendix 3: Table 2. Structure of #microMOOCSEM lessons
Appendix 4: Table 3. Activity of the Twitter account @SEMicrobiologia before and after the course
Appendix 5: Figure 4. Evolution of the number of follo...
Use of antimicrobial films (active packaging) incorporating some essential oils and preservatives to control Penicillium in cheese
In order to discover the main microbial populations present throughout the process of beet sugar extraction and to identify the steps where possible control measures could be implemented, four Spanish beet sugar extraction factories were investigated. Eighteen stages were sampled at each factory and analyzed for several microbial groups and physico...
Classification of 74 yeasts isolated during manufacture and ripening of Cabrales cheese was attemped by phenotypic and molecular methods. Phenotypic classification included the use of commercial kits and classical biochemical analyses. Molecular classification was performed by restriction fragment length polymorphism (RFLP) of the ITS1-5.8S-ITS2 re...
Thirty five white and blue-greenish filamentous fungi, dominant during ripening of Cabrales cheese, were morphotypically and genotypically identified. Morphotypic analysis identified Penicillium spp. (12 isolates), Penicillium roqueforti (11 isolates), Geotrichum candidum (10 isolates), Acremonium charticola (1 isolate), and one isolate that could...
The investigation included six batches of artisan Cabrales cheese manufactured at different times of the year by two different producers and followed over a 90-day ripening period. Profound variations were found between batches due to the different mixtures of milk used from cow, goat and sheep and due to differences in temperature and humidity dur...
RESUMEN Se ha llevado a cabo una evaluación físico-química del queso tipo Colonial, una variedad de queso elaborado a partir de leche cruda de vaca, de corta o ninguna maduración y que no se encuentra bajo normalización del Ministerio de Agricultura de Brasil. Fueron estudiadas cien (100) muestras del queso tipo Colonial, elaborado con leche cruda...
The investigation included six batches of artisan Cabrales cheese manufactured at different times of the year by two different producers and followed over a 90-day ripening period. Profound variations were found between batches due to the different mixtures of milk used from cow, goat and sheep and due to differences in temperature and humidity dur...
The effect of various factors and compounds used in the manufacturing of ‘Cantimpalos chorizo’, a fermented meat sausage made in Spain, on the growth of three strains of Penicillium olsonii isolated from the surface of the sausage has been investigated. In addition, one strain of Penicillium nalgiovense (ATCC 66742), used as starter culture in ferm...
The surface mycoflora of "chorizo de Cantimpalos", a Spanish variety of fermented meat sausage characterised by a natural white covering, has been investigated. Among 54 mould strains isolated, 38 belonged to Penicillium subgenus Penicillium. The major species found (18 isolates) was identified as Penicillium commune, and the other dominant species...
Yeast populations on 24 lots of Spanish fermented sausages, made by four factories (F1, F2 and F4, artisanal; F3, industrial) were investigated throughout manufacture and the influence of different variables evaluated. In addition, 41 yeast strains were identified at the species level using two miniaturised systems: ATB32C (API System) and Vitek Ye...
Nearly 500 strains isolated from different media used to study the aerobic mesophilic and lactic acid flora of Valdeón cheese (a Spanish hand-made blue cheese) have been identified. Nearly 95% of aerobic mesophiles were lactic acid bacteria (LAB). From these, Enterococcus (40·4%) and Lactococcus (42·2%) were the dominant genera, with Lactobacillus...
The aim of this study was to determine the presence of hemolytic and elastolytic enzymes in several strains of Plesiomonas shigelloides in relation to the availability of iron in culture media. Hemolytic activity and elastolytic activity were detected in strains of P. shigelloides and were enhanced when the strains were grown in an iron-depleted me...
Initial numbers of bacteria associated with wild (brown trout and pike) and cultured (rainbow trout) freshwater fish as well as with the water in which they were caught were determined. Subsequently, a total of 979 randomly selected isolates were characterized and identified to the genus level. For all counts performed (aerobes, psychrotrophs, anae...
Mesophilic aerobic sporeforming bacteria were investigated during the manufacture and ripening of 6 batches of Castellano cheese, a hard variety made from ewe's milk. Mean counts in raw ewe's milk ranged between 1.54 (farmhouse made batches) and 4.75 log10 cfu ml-1 (industrial batches). Their mean level in pasteurized milk (industries) was 3.1 log1...
Mesophilic aerobic sporeforming bacteria were investigated during the manufacture and ripening of 6 batches of Castellano cheese, a hard variety made from ewe's milk. Mean counts in raw ewe's milk ranged between 1.54 (farmhouse made batches) and 4.75 log10 cfu ml-1 (industrial batches). Their mean level in pasteurized milk (industries) was 3.1 log1...
Brine shrimp and conductimetric Saccharomyces cerevisiae bioassays were used to investigate the toxicity of green barley malt prepared at 16 and 25°C from grain inoculated with a strain of Aspergillus clavatus known to produce the mycotoxins cytochalasin E and patulin during malting. Pure cytochalasin E was considerably more toxic to brine shrimp l...
Production of patulin and cytochalasin E by four strains of Aspergillus clavatus during small-scale laboratory malting of barley at 16 and 25 degrees C was investigated. Fungal biomass, measured as ergosterol, appeared to be greater at 25 than at 16 degrees C, but marked differences were observed between the degree of colonization by the different...
The incidence of psychrotrophic bacteria was investigated in a Spanish fresh ewes' cheese (Villalón). Counts of mesophiles and psychrotrophs were (log cfu/g) 5.72 +/- 1.10 and 3.90 +/- 1.01, respectively, for factory cheeses made from pasteurized-milk. Figures for hand-made cheeses made from raw-milk were 7.35 +/- 0.48 and 6.94 +/- 0.65, respective...
Presumptive aeromonads were detected in 8 batches of Villalón cheese produced in dairy plants from pasteurized ewe's milk, the mean count being 2.85 ± 0.24 log CFU/g. Only four isolates from 2 batches were confirmed as motile aeromonads and they fitted the description of Aeromonas hydrophila. During cheese making of 5 batches of farmhouse-made raw...
Samples of cheeses naturally contaminated with moulds (12 samples of mouldy Manchego cheese and 10 of a naturally ripened blue cheese) were analysed for the presence of mycotoxins (aflatoxins BI and MI, sterigmatocystin, patulin, penicillic acid and mycophenolic acid in Manchego cheese, and mycophenolic acid and roquefortine in blue cheese). In add...
Nine strains of Penicillium roqueforti isolated from a traditional Spanish blue cheese (Valdeon cheese) along with two commercial strains were investigated for their ability to grow at different concentrations of salt and at different temperatures as well as for their proteolytic and lipolytic activities. Low concentrations of salt (1-3%) were stim...
The production of extracellular proteases by two strains of Aeromonas hydrophila of dairy origin was determined in two media at two different temperatures. With one exception (strain QV12 in skim milk agar), the specific proteolytic activity (OD at 440 nm mg(-1) protein) of extracellular products of each A. hydrophila strain was higher at 4 degrees...
Lactococcus lactis subsp. lactis strain Lac 388 (isolated from goats' cheese made without starter) had inhibitory activity against three strains of Aeromonas hydrophila either by the plating method or by the associative culture approach (broth, skim milk and ewes' milk). Low pH was only partially responsible for the antagonism. Inhibition due to hy...
The mycoflora of a Spanish blue cheese made in a natural way (Valdeón cheese) was investigated. Moulds and yeasts isolated in cheeses at different stages of manufacture and at the stage of consumption were identified to species level and the proteolytic and lipolytic activities of the major strains estimated. Penicillium was the main genus identifi...
The influence of water activity (adjusted with three humectants: sodium chloride, glycerol and polyethylene glycol) on the growth of three strains of Aeromonas hydrophila at 28, 10 and 3.8°C was studied. Minimum water activity for growth (MWAG) of Aer. hydrophila varied with strain, temperature and type of humectant. MWAG ranged from 0.940 to 0.973...
Three bacterial groups were detected during the shelf-life of lamb carcasses stored at refrigeration temperatures: coryneforms (mostly Brochothrix thermosphacta), Gram-positive cocci (staphylococci) and Gram-negative bacilli (Pseudomonas spp. and Moraxella spp.). Influence of categorical variables such as sampling day, sampling area and sampling me...
A total of 758 strains (659 bacteria and 99 fungi) isolated from samples taken at different steps during beet sugar extraction in four Spanish factories were identified. From the lactic acid bacteria (LAB) found (54% of bacteria), gum forming bacteria (Leuconostoc spp.) were clearly dominant (76.1% of LAB), coming from diverse sources (mainly beets...
El presente proyecto se ha llevado a cabo en el Departamento de Higiene y Tecnología de los Alimentos de la Universidad de León. Los tres profesores que han formado parte del mismo pertenecen al área de Nutrición y Bromatología del citado departamento. El objetivo del proyecto es la mejora de la calidad de la docencia de diversas asignaturas de la...
Se ha llevado a cabo una evaluación físico-química del queso tipo Colonial, una variedad de queso elaborado a partir de leche cruda de vaca, de corta o ninguna maduración y que no se encuentra bajo normalización del Ministerio de Agricultura de Brasil. Fueron estudiadas cien (100) muestras del queso tipo Colonial, elaborado con leche cruda de vaca...