Survival of foodborne pathogens in natural cracked olive brines

This work reports the survival (challenge tests) of foodborne pathogen species (Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica) in Aloreña de Málaga table olive brines. The inhibitions were fit using a log-linear model with tail implemented in GInaFIT excel software. The olive brine had a considerable inhibitory effect on the pathogens. The residual (final) populations (Fp) after 24 h was below detection limit (<1.30 log cfu/mL) for all species assayed. The maximum death rate (k) was 9.98, 51.37, 38.35 and 53.01 h, while the time for 4 log reductions (4D) was 0.96, 0.36, 0.36 and 0.24 h for E. coli, S. aureus, L. monocytogenes and S. enterica, respectively. Brine dilutions increased Fp and 4Dr, while decreased k. A cluster analysis showed that E. coli had an overall quite different behaviour being the most resistant species, but the others bacteria behaved similarly, especially S. aureus and S. enterica. Partial Least Squares regression showed that the most influential phenols on microbial survival were EDA (dialdehydic form of decarboxymethyl elenolic acid), HyEDA (EDA linked to hydroxytyrosol), hydroxytyrosol 4-glucoside, tyrosol, and oleoside 11-methyl ester. Results confirm the adverse habitats of table olives for foodborne pathogenic microorganisms.The research leading to these results has received funding from the Junta de Andalucía through PrediAlo Project (AGR7755: www.predialo.science.com.es) and FEDER European funds. Thanks to Copusan S.C.A (Alozaina, Málaga, Spain) for supplying the fruits and facilities for the development of experiments. FNAL wishes to thank the Spanish Government and CSIC for his Ramón y Cajal postdoctoral research contract, while VRG thanks the AgriFood Campus of International Excellence (ceiA3), Bank of Santander, Spanish Government and ‘Aloreña de Málaga’ Olive Manufacturing Association, for her pre-doctoral fellowship (training program of Ph.D. in companies). Authors also express their gratitude to F. Rodríguez-Gómez, M. Brenes, and C. Romero from Instituto de la Grasa (CSIC, Seville) for their invaluable help during HPLC analyses.Peer Reviewe

Procedimiento para la obtención de una solución favorecedora del crecimiento de plantas a partir de aguas de lavado del proceso de elaboración de aceitunas verdes estilo español y uso de dicha solución

La presente invención se refiere a un procedimiento para la obtención de una solución favorecedora del crecimiento de plantas a partir de aguas de lavado del proceso de elaboración de aceitunas verdes estilo español o sevillano, caracterizado porque comprende las siguientes etapas: (a) acidificación del agua de lavado hasta un valor de pH inferior a 3 unidades; (b) almacenamiento del agua en condiciones anaeróbicas; y (c) elevación del pH del concentrado hasta un valor superior a 4 unidades. Así mismo se refiere a la solución obtenida a partir de dicho procedimiento y a su uso para favorecer el crecimiento de plantas.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Instituto Andaluz de Investigación y Formación Agraria, Pesquera, Alimentaria y de la Producción EcológicaA1 Solicitud de patente con informe sobre el estado de la técnic

Microbial Ecology of Watery Kimchi

© 2015 Institute of Food Technologists®. This article has been contributed by US Government employees and their work is in the public domain in the USA. The biochemistry and microbial ecology of 2 similar types of watery (mul) kimchi, containing sliced and unsliced radish and vegetables (nabak and dongchimi, respectively), were investigated. Samples from kimchi were fermented at 4, 10, and 20 °C were analyzed by plating on differential and selective media, high-performance liquid chromatography, and high-throughput DNA sequencing of 16S rDNA. Nabak kimchi showed similar trends as dongchimi, with increasing lactic and acetic acids and decreasing pH for each temperature, but differences in microbiota were apparent. Interestingly, bacteria from the Proteobacterium phylum, including Enterobacteriaceae, decreased more rapidly during fermentation at 4 °C in nabak cabbage fermentations compared with dongchimi. Although changes for Proteobacterium and Enterobacteriaceae populations were similar during fermentation at 10 and 20 °C, the homolactic stage of fermentation did not develop for the 4 and 10 °C samples of both nabak and dongchimi during the experiment. These data show the differences in biochemistry and microbial ecology that can result from preparation method and fermentation conditions of the kimchi, which may impact safety (Enterobacteriaceae populations may include pathogenic bacteria) and quality (homolactic fermentation can be undesirable, if too much acid is produced) of the product. In addition, the data also illustrate the need for improved methods for identifying and differentiating closely related lactic acid bacteria species using high-throughput sequencing methods.This work was carried out as part of the international collaborative R&D program funded by the Agency for Korea Natl. Food Cluster (2013), and supported in part by a grant from Pickle Packers Intl. Inc., Washington, D.C., U.S.A. The authors thank the Spanish Government (MECD) for the postdoctoral fellowship support for Dr. E. Medina-Pradas.Peer Reviewe

Antimicrobianos polifenólicos y oleosídicos en alimentos derivados de la aceituna

El olivo es una de las plantas cultivadas más antiguas. Su origen se remonta a los años 4000-3000 antes de nuestra Era en la región de Palestina. El olivo, Olea europaea L., pertenece a la familia Oleaceae y es la única especie de la familia con fruto comestible. Alrededor del 90 % de las aceitunas producidas se destina a la obtención de aceite de oliva y el resto se consume directamente como acei tunas de mesa (COI, 2007). Durante siglos, tanto el aceite de oliva como extractos de hojas de olivo se han empleado para tratar múltiples enfermedades, muchas de ellas de origen microbiano. Incluso en el Medievo, los alquimistas utilizaban el símbolo mostrado en la Figura 1 para designar al aceite de oliva como una entidad química distinta. En el siglo XIX usaban extractos de hojas de olivo para combatir la malaria y hoy son numerosas las empresas que comercializan estos extractos para el tratamiento, entre otros usos, de enfermedades de origen microbiano. Sin embargo, los productos más importantes que se obtienen del olivo, desde un punto de vista comercial, son las aceitunas de mesa y el aceite de oliva. Debido a la demanda creciente de alimentos con propiedades beneficiosas para la salud y de sustancias antimicrobianas de origen natural, los objetivos concretos de esta Tesis Doctoral fueron: a) Identificar los compuestos con mayor actividad antimicrobiana del aceite de oliva y aceitunas de mesa. b) Comparar la importancia de su actividad frente a la de otros compuestos (naturales y sintéticos) y alimentos. c) Explicar los problemas de inhibición del crecimiento de bacterias lácticas en aceitunas de mesa. d) Identificar una fuente importante de compuestos antimicrobianos de origen natural en los alimentos derivados de las aceitunas

Presence of toxic microbial metabolites in table olives

© 2015 Medina-Pradas and Arroyo-López. Table olives have an enormous importance in the diet and culture of many Mediterranean countries. Albeit there are different ways to produce this fermented vegetable, brining/salting, fermentation, and acidification are common practices for all of them. Preservation methods such as pasteurization or sterilization are frequently used to guarantee the stability and safety of fermented olives. However, final products are not always subjected to a heat treatment. Thus, microbiota is not always removed and appropriate levels of acidity and salt must be obtained before commercialization. Despite the physicochemical conditions not being favorable for the growth of foodborne pathogens, some illness outbreaks have been reported in the literature. Street markets, inappropriate manipulation and storage conditions were the origin of many of the samples in which foodborne pathogens or their metabolites were detected. Many authors have also studied the survival of pathogens in different styles of table olive elaboration, finding in general that olive environment is not appropriate for their presence. Inhibitory compounds such as polyphenols, low availability of nutrients, high salt content, low pH levels, bacteriocins, or the addition of preservatives act as hurdles against undesirable microorganisms, which contribute to obtaining a safe and good quality product.This paper has received funding from Junta de Andalucía regional Government through the PrediAlo project (AGR-7755: www.predialo.science.com.es) and EU’s Seventh Framework Program (FP7/2007-2013) under grant agreement n°243471 (PROBIOLIVES: www.probiolives.eu). FA-L wishes to express thanks to the Spanish government for his Ramón y Cajal postdoctoral research contract, while EM-P would like to thank The Junta de Andalucía for his postdoctoral research contract.USD 875 APC fee funded by the EC FP7 Post-Grant Open Access PilotPeer Reviewe

Endogenous enzymes involved in the transformation of oleuropein in Spanish table olive varieties

© 2014 American Chemical Society. The main Spanish table olive varieties supplied by different olive cooperatives were investigated for their polyphenol compositions and the endogenous enzymes involved in their transformations during two growing seasons. Olives of the Manzanilla variety had the highest concentration in total polyphenols, followed by the Hojiblanca and Gordal varieties. The Gordal and Manzanilla cultivars showed the highest polyphenol oxidase activities. The Gordal cultivar presented a greater β-glucosidase and esterase activity than the others. An important influence of pH and temperature on the optimal activity of these enzymes was also observed. The polyphenol oxidase activity increased with temperature, and peroxidase activity was optimal at 35 °C. The β-glucosidase and esterase activities were at their maximum at 30 and 55°C, respectively. The oxidase and β-glucosidase activities were at their maximum at the pH of the raw fruit. These results will contribute to the knowledge of the enzyme transformation of oleuropein in natural table olives.This work was supported by Project AGL 2009-07512 from the Spanish government and European Union (European Regional Development Funds). E.R. thanks MINECO for her FPI fellowship.Peer Reviewe

Oleuropein hydrolysis in natural green olives: Importance of the endogenous enzymes

The bitter taste of olives is mainly caused by the phenolic compound named oleuropein and the mechanism of its hydrolysis during the processing of natural green olives was studied. First, a rapid chemical hydrolysis of oleuropein takes place at a high temperature of 40 °C and at a low pH value of 2.8, but the chemical hydrolysis of the bitter compound is slow at the common range of pH for these olives (3.8-4.2). However, decarboxymethyl elenolic acid linked to hydroxytyrosol and hydroxytyrosol have been found in a high concentration during the elaboration of natural green olives. When olives were heated at 90 °C for 10 min before brining, these compounds are not formed. Hence, the debittering process in natural green olives is due to the activity of β-glucosidase and esterase during the first months of storage and then a slow chemical hydrolysis of oleuropein happens throughout storage time.This work was supported by projects AGL 2009-07512 and AGL-2013-42739-R from the Spanish Government and European Union (European Regional Development Funds). Eva Ramírez wishes to thank MINECO for her FPI fellowship. Thanks also to Alejandra Expósito for technical assistance.Peer Reviewe

Survival of foodborne pathogenic bacteria in table olive brines

26 Páginas; 4 Tablas; 2 FigurasFermented or acidified vegetable foods are considered microbiologically safe although the survival of certain pathogens has occasionally been reported in these products. The aim of this research was to investigate the fate of Escherichia coli, Salmonella enterica, Listeria monocytogenes and Staphylococcus aureus when they were added to different industrial olive brines, as well as to correlate their survival with the presence of phenolic and oleosidic substances. Brines of different cultivars prepared following the Spanish-style method or preserved in acidified brine were inoculated with a cocktail of four strains of each species. The evolution of their populations was analyzed by cultural methods when the brines were kept at 4 °C or room temperature and in aerobiosis or anaerobiosis. All the pathogens investigated died off but their death rate was variable depending on the composition of the brines in phenolic compounds, temperature and oxygen availability. The time needed to reduce the inoculated pathogen populations by 5 log oscillated between less than 5 min and up to 17 days in the least deleterious conditions.This work was supported by the Spanish government through grant AGL-2009-07512 (partially financed by EU FEDER funds).Peer reviewe

Characterization of the microbial diversity in yacon spontaneous fermentation at 20°C

© 2015 Published by Elsevier B.V. The prebiotic fructooligosaccharide content of yacon makes this root an attractive alternative for the supplementation of a variety of food products. The preservation of yacon by fermentation has been proposed as an alternative to increase the probiotic content of the root concomitantly with its shelf life. Thus the fermented yacon could have significant functional content. The objective of this research was to characterize the biochemistry and microbiology of spontaneous yacon fermentation with 2% NaCl and define the viability of the proposed process. The biochemical analysis of spontaneous heterolactic fermentation of yacon showed a progressive drop in pH with increased lactic and acetic acids, and the production of mannitol during fermentation. The microbial ecology of yacon fermentation was investigated using culture-dependent and culture-independent methods. Bacterial cell counts revealed a dominance of lactic acid bacteria (LAB) over yeasts, which were also present during the first 2. days of the fermentation. Results showed that the heterofermentative LAB were primarily Leuconostoc species, thus it presents a viable method to achieve long term preservation of this root.The author thanks Ms. Sandra Parker and Ms. Janet Hayes at the USDA-ARS, SAA Food Science Research Unit located in Raleigh, NC for the administrative support and technical assistance, respectively. We also thank Nevermore Farm in Arbuckle, CA, USA for supplying yacon. This research was partially supported (10%) by the National Institutes of Health grant number P30 DK34987, and a Simmons award. A Postdoctoral Fellowship from the Spanish Government (MECD) fully funded Dr. E. Medina.Peer Reviewe