Microbiota intestinal: Origen y desarrollo. Modulación a través de la intervención dietética

La composición y actividad de la microbiota intestinal humana resulta de interacciones complejas que incluyen el genoma del huésped, su estado nutricional, hábitos sociales, entre otros.Investigaciones científicas recientes sugieren que las alteraciones de la microbiota intestinal conducen a trastornos inmunes y metabólicos que contribuyen al desarrollo de enfermedades no transmisibles tales como obesidad, síndrome metabólico, diabetes e incluso autismo y depresión.Este artículo revisa el origen y la composición de la microbiota intestinal, con especial énfasis en la colonización natural y desarrollo del microbioma neonatal, así como los impactos ejercidos por los antibióticos, el tipo de parto y de alimentación. Por último, se discuten algunas estrategias para la restauración del equilibrio microbiano. Una comprensión más profunda de estos conceptos permitirá optimizar estrategias terapéuticas que permitan manipular la microbiota para combatir enfermedades y mejorar la salud.The composition and activity of the human intestinal microbiota results from complex interactions that include the host genome, its nutritional status, social habits, among others. Recent scientific research suggests that intestinal microbiota disturbances lead to immune and metabolic disorders that contribute to the development of noncommunicable diseases such as obesity, metabolic syndrome, diabetes and even autism and depression. This paper reviews the origin and development of the intestinal microbiota, including the natural colonization and assembly of the neonatal microbiome as well as the impacts exerted by antibiotics, types of delivery and feeding. Then, potential strategies for restoration of these microbiota insults are also discussed. A deeper understanding of these concepts will optimize therapeutic strategies that allow modulating the composition of the microbiota to improve health.Fil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentin

Yogurt, ancestral milk base food of current great validity. Main nutritional, functional and technological aspects

El yogur es el alimento lácteo fermentado de mayor consumo a nivel internacional debido a sus propiedades organolépticas distintivas, su valor nutricional y elevada digestibilidad. Asimismo, numerosas investigaciones atribuyen a este producto efectos beneficios para la salud debidos principalmente a la presencia de bacterias lácticas (BAL) y a su alto contenido de calcio. El proceso de producción de yogur es sencillo, ya que consiste en una fermentación de leche pasteurizada por dos tipos de microorganismos (Streptococcus thermophilus y Lactobacillus delbrueckii subsp. bulgaricus) queactúan en forma simbiótica generando cambios fisicoquímicas y organolépticas. A pesar de ser considerado un proceso tecnológico simple, el desarrollo de etapas estandarizadas con control de puntos críticos es necesario para contribuir al desarrollo de atributos deseables y distintivos de este producto. En este trabajo se revisarán aspectos relevantes relacionados con las etapas de producción, formulación, efectos benéficos del yogur y nuevas tendencias en el mercado.Yogurt is the fermented dairy food with the highest internationally consumption due to its distinctive organoleptic properties, its nutritional value and high digestibility. Also, numerous researches attribute health benefits to the yogurt consumption, mainly due to the presence of lactic bacteria and to its high content of calcium. The process of yogurt production is simple, since it consists of a fermentation of pasteurized milk by two types of microorganisms (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) that act in symbiotic form generating physicochemical and organoleptic changes. Despite being considered a simple technological process, the development of standardized stages with control of critical points is necessary to contribute to the development of desirable and distinctive attributes of this product. In this work we will review relevant topics related to the beneficial effects of yogurt, the conventional processing of milk for its manufacture, as well as the main stabilizers used and their effect on the texture and final taste.Fil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Torres Quinteros, Lourdes. Universidad Nacional de Santiago del Estero; ArgentinaFil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Iturriaga, Laura Beatriz. Universidad Nacional de Santiago del Estero; Argentin

Efecto antifúngico y antimicotoxigénico de lactobacillus plantarum CRL 778 a diferentes valores de actividad de agua

Ocratoxina A (OTA) es una micotoxina producida por hongos filamentosos con un alto impacto en la seguridad alimentaria debido a su toxicidad. En la última década se ha reportado ampliamente a nivel mundial, la presencia de OTA en diversos alimentos. En este estudio se evaluó in vitro, la capacidad de Lactobacillus (L.) plantarum CRL 778 de controlar el crecimiento y la producción de OTA por Aspergillus (A.) niger 13D, a diferentes valores de actividad de agua (aw): 0.955, 0.964, 0.971, 0.982 y 0.995). La cepa láctica redujo significativamente (p < 0.05) ambos parámetros, siendo el efecto dependiente del valor de aw. La mayor inhibición del crecimiento (46.9%) se obtuvo a aw = 0.995, valor más adecuado para el crecimiento y producción de metabolitos antifúngicos (ácido láctico, ácido acético, ácidos fenil-láctico e hidroxi-fenil láctico) por la cepa láctica. Además, se observaron cambios morfológicos en las colonias de A. niger 13D, crecidas en presencia de L. plantarum CRL 778 a valores de aw de 0.971 y 0.995. El porcentaje máximo de reducción en la producción de OTA (90%) por la cepa láctica se observó a un valor de aw = 0.971, mientras la inhibición del crecimiento fúngico fue mayor cuando aw = 0.995. Estos hallazgos sugieren que L. plantarum CRL 778 podría emplearse para el control de la contaminación por hongos ocratoxigénicos en alimentos con valores de aw comprendidos entre 0.971-0.995.Ochratoxin A (OTA) is a mycotoxin produced by filamentous fungi with high impact in food safety due to its toxicity. In the last decade, the presence of OTA was widely reported in different foods. In this study, the ability of Lactobacillus (L.) plantarum CRL 778 to control growth and OTA production by Aspergillus (A.) niger 13D strain, at different water activity (aw) values (0.955, 0.964, 0.971, 0.982, and 0.995) was determined in vitro. Both parameters were significantly (p < 0.05) reduced by the lactobacilli and the effect depended on aw. Greatest growth rate inhibition (46.9%) was obtained at aw = 0.995, which is the most suitable value for growth and production of antifungal metabolites (lactic acid, acetic acid, phenyllactic and hydroxyl-phenyllactic acids) by L. plantarum CRL 778. Besides, morphological changes and inhibition of melanin synthesis were observed in colonies of A. niger 13D in presence of L. plantarum CRL 778 at aw ranged between 0.971 and 0.995. In addition, maximum reduction (90%) of OTA production took place at aw = 0.971, while inhibition of fungi growth was more evident at aw = 0.995. These findings suggest that L. plantarum CRL 778 could be used for control of ochratoxigenic fungal growth and OTA contamination in different fermented foods with aw values between 0.971 and 0.995.Fil: Dallagnol, Andrea Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentina. Universidad Nacional de Santiago del Estero; ArgentinaFil: Martos, Gladys Irma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Selection and Performance of Antifungal Lactic Acid Bacteria in Corn Mini-Silos

Silage is a method of forage conservation based on lactic fermentation. In order to improve the fermentative performance in corn silages, the aims of the present work were as follows: (I) to screen lactic acid bacteria with acidifying activity, (II) to study their antifungal activity against filamentous fungi and yeasts and (III) to evaluate their performance as antifungal in mini-silos. The acidifying activity was determined by measuring the pH and total titratable acidity. Those most acidifying bacteria were incubated in plates together with fungal markers strains to observe the presence or absence of inhibition halos, in addition to studying the nature of the antifungal metabolites by means of the treatment with proteases. The strain with the widest spectrum of action was selected to formulate an inoculum used in corn mini-silos. During storage, both silos determined humidity, acidification and microbiological composition, and then aerobic stability. The results showed that Lactoplantibacillus (L.) plantarum cultures had a higher production of lactic acid (7.7–17.5 g/L) than Pediococcus (8.8–10.9 g/L). L. plantarum CRL363 could inhibit the growth of filamentous fungi and some yeasts and consequently it was used in mini-silos. Compared to the control, the inoculated silo presented low pH values (4.02–4.85) and low fungi and yeast count until 20 days of storage, demonstrating the great potential of CRL363 strain for the formulation of inoculants for corn silage.Fil: Carrizo, Natalí Ivana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Carabajal Torrez, José Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Molina, Fatima Romina Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Fornaguera, Maria Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Martos, Gladys Irma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Lactic Acid Fermentation Improved Textural Behaviour, Phenolic Compounds and Antioxidant Activity of Chia (Salvia hispanica L.) Dough

U radu su izolirane autohtone bakterije mliječno-kiselog vrenja iz tijesta s dodatkom chia (Salvia hispanica L.) sjemenki, te razvrstane prema kinetici zakiseljavanja i proteolitičkoj aktivnosti. Soj C8 identificiran je kao soj bakterije Lactobacillus plantarum C8, te je upotrijebljen kao starter kultura za dobivanje kiselog tijesta s dodatkom chia sjemenki. Mliječno-kiselim vrenjem povećan je maseni udjel organskih kiselina (mliječne na 12,3 g, octene na 1,0 g i fenilacetatne kiseline na 23,8 μg po kilogramu tijesta), te antioksidacijska aktivnost, koja je porasla za 33-40 % u usporedbi s nefermentiranim tijestom s dodatkom chia sjemenki. Osim toga, ukupni se udjel fenolnih spojeva uvećao za 25 %, a njihov se sastav bitno promijenio nakon 24 h fermentacije s pomoću soja bakterije L. plantarum C8. Klorogena je kiselina pronađena jedino u fermentiranom tijestu (2,5 mg/g), dok je ferulinska kiselina detektirana već na početku vrenja, i to u 32 % većoj količini u kiselom tijestu s dodatkom chia sjemenki (5,6 mg/g). Upotrebom fermentiranog kiselog tijesta s dodatkom chia sjemenki poboljšana su ukupna svojstva bijelog kruha, uključujući fizikalna (npr. smanjena tvrdoća i otpor krušnih mrvica pri žvakanju) i antioksidacijska svojstva (u prosjeku za 25 %). Dobiveni rezultati pokazuju da kiselo tijesto s dodatkom chia sjemenki poboljšava tehnološka i antioksidacijska svojstava pšeničnog kruha. Osim toga, u radu je po prvi puta prikazano da bakterije mliječno-kiselog vrenja mogu fermentirati tijesto s dodatkom chia sjemenki, čime poboljšavaju ukupna svojstva kruha.In this work, autochthonous lactic acid bacteria (LAB) were isolated from chia (Salvia hispanica L.) dough and selected on the basis of the kinetics of acidification and proteolytic activity. Strain no. C8, identified as Lactobacillus plantarum C8, was selected and used as starter to obtain chia sourdough. Lactic acid fermentation increased the organic acid mass fractions (lactic, acetic and phenyl lactic acids to 12.3 g, 1.0 g and 23.8 μg per kg of dough respectively), and antioxidant activities, which increased by approx. 33–40 % compared to unfermented chia flour dough. In addition, total phenolic content increased 25 % and its composition was strongly modified after 24 h of fermentation by L. plantarum C8. Chlorogenic acid was only found in the fermented dough (2.5 mg/g), while ferulic acid was detected from the beginning of fermentation, being 32 % higher in chia sourdough (5.6 mg/g). The use of fermented chia sourdough improved the overall characteristics of white bread, including physical (e.g. reduced hardness and chewiness of the crumb) and antioxidant properties (25 % on average), compared to the white bread. These results indicate that the use of chia sourdough could be a promising alternative to improve the technological and antioxidant properties of wheat bread. In addition, this work has shown, for the first time, that lactic acid bacterium is able to ferment chia dough, improving its overall characteristics

Lactic Acid Fermentation Improved Textural Behaviour, Phenolic Compounds and Antioxidant Activity of Chia (Salvia hispanica L.) Dough

U radu su izolirane autohtone bakterije mliječno-kiselog vrenja iz tijesta s dodatkom chia (Salvia hispanica L.) sjemenki, te razvrstane prema kinetici zakiseljavanja i proteolitičkoj aktivnosti. Soj C8 identificiran je kao soj bakterije Lactobacillus plantarum C8, te je upotrijebljen kao starter kultura za dobivanje kiselog tijesta s dodatkom chia sjemenki. Mliječno-kiselim vrenjem povećan je maseni udjel organskih kiselina (mliječne na 12,3 g, octene na 1,0 g i fenilacetatne kiseline na 23,8 μg po kilogramu tijesta), te antioksidacijska aktivnost, koja je porasla za 33-40 % u usporedbi s nefermentiranim tijestom s dodatkom chia sjemenki. Osim toga, ukupni se udjel fenolnih spojeva uvećao za 25 %, a njihov se sastav bitno promijenio nakon 24 h fermentacije s pomoću soja bakterije L. plantarum C8. Klorogena je kiselina pronađena jedino u fermentiranom tijestu (2,5 mg/g), dok je ferulinska kiselina detektirana već na početku vrenja, i to u 32 % većoj količini u kiselom tijestu s dodatkom chia sjemenki (5,6 mg/g). Upotrebom fermentiranog kiselog tijesta s dodatkom chia sjemenki poboljšana su ukupna svojstva bijelog kruha, uključujući fizikalna (npr. smanjena tvrdoća i otpor krušnih mrvica pri žvakanju) i antioksidacijska svojstva (u prosjeku za 25 %). Dobiveni rezultati pokazuju da kiselo tijesto s dodatkom chia sjemenki poboljšava tehnološka i antioksidacijska svojstava pšeničnog kruha. Osim toga, u radu je po prvi puta prikazano da bakterije mliječno-kiselog vrenja mogu fermentirati tijesto s dodatkom chia sjemenki, čime poboljšavaju ukupna svojstva kruha.In this work, autochthonous lactic acid bacteria (LAB) were isolated from chia (Salvia hispanica L.) dough and selected on the basis of the kinetics of acidification and proteolytic activity. Strain no. C8, identified as Lactobacillus plantarum C8, was selected and used as starter to obtain chia sourdough. Lactic acid fermentation increased the organic acid mass fractions (lactic, acetic and phenyl lactic acids to 12.3 g, 1.0 g and 23.8 μg per kg of dough respectively), and antioxidant activities, which increased by approx. 33–40 % compared to unfermented chia flour dough. In addition, total phenolic content increased 25 % and its composition was strongly modified after 24 h of fermentation by L. plantarum C8. Chlorogenic acid was only found in the fermented dough (2.5 mg/g), while ferulic acid was detected from the beginning of fermentation, being 32 % higher in chia sourdough (5.6 mg/g). The use of fermented chia sourdough improved the overall characteristics of white bread, including physical (e.g. reduced hardness and chewiness of the crumb) and antioxidant properties (25 % on average), compared to the white bread. These results indicate that the use of chia sourdough could be a promising alternative to improve the technological and antioxidant properties of wheat bread. In addition, this work has shown, for the first time, that lactic acid bacterium is able to ferment chia dough, improving its overall characteristics

Characterization of substrate specificity and inhibitory mechanism of bile salt hydrolase from Lactobacillus reuteri CRL 1098 using molecular docking analysis

Objectives: To elucidate the molecular mechanisms involved in the substrate interaction of the bile salt hydrolase of Lactobacillus reuteri CRL 1098 (LrBSH) with bile acids (BAs) and to evaluate potential enzyme inhibitors based on computer and in vitro modeling assays. Results: Asp19, Asn79, and Asn171 participated in the LrBSH interaction with all BAs tested while Leu56 and Glu 222 played an important role in the interaction with glyco- and tauro-conjugated BAs, respectively. A great percentage of hydrophobic and polar interactions were responsible for the binding of LrBSH with glyco- and tauro-conjugated BAs, respectively. Remarkably, the four binding pocket loops participated in the substrate binding site of LrBSH unlike most of the reported BSHs. Inhibition assays showed that ascorbic acid, citric acid, penicillin G, and ciprofloxacin decreased LrBSH activity by 47.1%, 40.14%, 28.8%, and 9%, respectively. Docking analysis revealed that tetracycline and caffeic acid phenethyl ester had the low binding energy (−7.32 and −7.19 kcal/mol, respectively) and resembled the interaction pattern of GDCA (−6.88 kcal/mol) while penicillin (−6.25 kcal/mol) and ascorbic acid (−5.98 kcal/mol) interacted at a longer distance. Conclusion: This study helps to delve into the molecular mechanisms involved in the recognition of substrates and potential inhibitors of LrBSH.Fil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Taranto, Maria Pia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentin

Estudio de la actividad proteolítica de bacterias lácticas aisladas de nichos autóctonos de Santiago del Estero

Las bacterias lácticas capaces de crecer en leche utilizan su sistema proteolítico para hidrolizar la caseína, proteína mayoritaria de la leche, y así obtener los aminoácidos necesarios para su desarrollo. Estas reacciones proteolíticas son aprovechadas en muchos procesos fermentativos involucrados en la elaboración de alimentos con particulares características organolépticas y, en algunos casos, para aumentar el valor nutricional de los mismos. Sin embargo, la actividad proteolítica depende de la cepa y de parámetros fisicoquímicos como el pH. Es por ello, que el objetivo del presente trabajo fue evaluar la actividad proteolítica de 16 cepas lácticas aisladas a partir de quesos de cabra regionales empleando el método de Bradford, para determiner la concentración de proteínas totales, y la técnica del o-ftalaldehído (OPA), para cuantificar aminoácidos libres. Los resultados obtenidos mostraron valores de concentraciones comprendidos entre (4,99 – 12,10) mg de proteínas libres por litro y (122,09 – 169,49) mmoles de glicina por litro; siendo las cepas CB17 y CB8, las de mayor y menor actividad, respectivamente. Potencialmente, estas cepas podrían emplearse para ser incluidas en procesos fermentativos con el propósito de modificar características sensoriales, aumentar el valor nutricional y mejorar la digestibilidad de alimentos fermentados.Lactic acid bacteria capable of growing in milk use their proteolytic system to hydrolyze casein, the major milk protein, and thus obtain the necessary amino acids for their development. These proteolytic reactions are used in many fermentative processes involved in the preparation of foods with particular organoleptic characteristics and, in some cases, to increase their nutritional value. However, the proteolytic activity depends on the strain and physicochemical parameters such as pH. For this reason, the objective of this work was to evaluate the proteolytic activity of 16 lactic strains isolated from regional goat cheeses using the Bradford method, to determine the concentration of total proteins, and the o-phthalaldehyde technique (OPA), to quantify free amino acids. The results obtained showed concentration values between (4.99 – 12.10) mg of free proteins per liter and (122.09 – 169.49) mmols of glycine per liter; being the strains CB17 and CB8, those with the highest and lowest activity, respectively. Potentially, these strains could be used to be included in fermentative processes with the purpose of modifying sensory characteristics, increasing nutritional value and improving digestibility of fermented foods.Fil: Carol Paz, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentin

Biophysical and Structural Insights in α-Amylase and Bile Acids interaction

Amylase is an enzyme exposed to the effect of bile acids (BAs) in intestine. BAs may potential reduce the activity of the enzyme. In this paper, an insight in biophysical and structural terms on how taurodeoxycholic and deoxycholic acids (TDCA and DCA, respectively) interact with α-amylase is given, using UV-visible, fluorescence and infrared spectroscopy (FTIR), electron microscopy, dynamic light scattering (DLS) and molecular docking calculations. Fluorescence spectroscopy measurements, confirm that TDCA and DCA interact with α-amylase with high affinity causing conformational changes. Also, DCA significantly modify the thermal denaturation of the protein. Besides, DCA induces a decrease in α-helix and unordered region, together with an important increase in β-sheet, modifying the surface charges of the protein and inducing the formation of protein aggregates producing a loss of activity. Docking results indicate that TDCA interacts with the surface of the enzyme, while DCA may stabilize inside the active site of α-amylase thereby justifying its inhibitory mechanism. BAs acts as protein-unfolding agents and the mechanism is dependent on the structure of the bile acid under study. These findings provide a deeper understanding of the interaction of BAs with proteins and its role as protein-unfolding agents, at molecular level.Fil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Frias, Maria de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; Argentin

Antifungal and antiochratoxigenic properties of chemical preservatives of bread

The objective of this work was to study the efficiency of preservatives on growth and ochratoxin a (ota) production by Aspergillus niger 13 d at pH values often found in bakery products. the fungal growth inhibition was concentration and pH dependent. differences between calcium propionate (Cp) and potassium sorbate (ks) were found, observing that ks was less effective than Cp. no fungal growth was observed with 0.4% (w/w) of Cp at pH 6.0, while that the maximum concentration of ks (0.2%, w/w) was not able to inhibit 100% of fungal growth independentlyof pH evaluated. This study also demonstrates the influence of preservatives on ota production. ota was not detected when the growth was 100% inhibited, i.e., at pH 6.0 and 0.4% (w/w) of Cp. the concentration of Cp could be reduced at 0.3% (w/w) when the pH was lowered to 5.5 without risk of contamination with ota. In presence of ks, a moderate depletion of ota production was observed, however, the maximum concentration (0.2%, w/w) did not completely inhibit ota production. in addition, no stimulating effects on growth or ota levels were observed in any condition assayed. These “in vitro” studies must be corroborated by “in situ” conditions in bakery products and other Aspergillus fungus.Fil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Bustos, Ana Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin