1,720,978 research outputs found
Mixed-acid fermentation and polysaccharide production by Lactobacillus helveticus in milk cultures
Get PDFLactobacillus helveticus grown in milk with pH control at 6.2 had a slower growth rate (μ = 0.27 h-1) and produced less exopolysaccharide (49 mg 1-1) but increased lactic acid production (425 mM) compared to cultures without pH control (μ = 0.5 h-1, 380 mg exopolysaccharide 1-1, and 210 mM lactate), respectively. Both cultures displayed a mixed-acid fermentation with formation of acetate, which is linked not only to citrate metabolism, but also to alternative pathways from pyruvate.Fil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Taranto, Maria Pia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán; Argentin
Semi-defined media for the exopolysaccharide (EPS) production by Lactobacillus helveticus ATCC 15807 and evaluation of the components interfering with the EPS quantification
Get PDFGrowth and exopolysaccharide (EPS) production by Lactobacillus helveticus ATCC 15807 was evaluated in semi-defined media. Lactose (as carbon source) and CaCl2 proved to be the major stimulating factors for an optimal EPS synthesis while the highest specific EPS yield was obtained when CaCl2 and MnSO4 were the only salts added to the medium. Both EPS and cell growth were slightly affected by the nitrogen source. The analysis of the interference components (EPS-eq) in uninoculated media revealed an overestimation in EPS of ca. 76% due to beef extract and yeast extract, and of 64% due to the presence of peptone. Nevertheless, in fermented cultures, the level of interference may be lower since nitrogen compounds are used by the microorganism during growth and residual lactose showed to be easily removed by dialysis before EPS quantification.Fil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Sesma, Fernando Juan Manuel. 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; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentin
Exopolysaccharide biosynthesis by Lactobacillus helveticus ATCC 15807
Get PDFExopolysaccharide (EPS) production and the activities of the enzymes involved in sugar nucleotide biosynthesis in Lactobacillus helveticus ATCC 15807 under controlled pH conditions were investigated. Batch fermentations using lactose as energy source showed higher EPS synthesis by L. helveticus ATCC 15807 at pH 4.5 with respect to pH 6.2, the enzyme α-phosphoglucomutase (α-PGM) being correlated with both total and specific EPS production. When glucose was used as carbon source instead of lactose, the lower EPS synthesis obtained was linked to a decrease in α-PGM and galactose 1-phosphate-uridyltransferase (GalT) activities, the reduction of the latter being more pronounced. Higher EPS production by L. helveticus ATCC 15807 at the acidic constant pH of 4.5 requires that both α-PGM and GalT activities are high. These enzymes are needed to synthesize UDP-glucose and UDP-galactose for supplying the corresponding monomers for EPS biosynthesis. Although differences are observed in EPS production by this strain regarding the energy source (lactose or glucose), the monomeric composition of the polymers produced is independent of the carbohydrate used. The obtained results contribute to a better understanding of the physiological factors that affect EPS biosynthesis by lactobacilli, which could help in the correct handling of the fermentation parameters within the fermented dairy industry.Fil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mozzi, Fernanda Beatriz. 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; Argentin
Food-grade heteropolysaccharides: ongoing research and future trends of biopolymers from lactic acid bacteria
Get PDFExopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) play a major role in the manufacturing of fermented foods, especially fermented dairy products. Although the presence of heteropolysaccharides (HePSs) seems not to confer any advantage to cell growth or survival, in situ production typically imparts a desirable viscous, sometimes ‘ropy’ texture to fermented foods and milk products. These food-grade biopolymers are economically important for the food industry. Current challenges are to improve the yield of HePSs from LAB and to produce HePSs with a particular functionality on the basis of a better understanding of their biosynthesis and the relationship between their structure and function.Fil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: De Vuyst, Luc. Vrije Unviversiteit Brussel; BélgicaFil: Mozzi, Fernanda Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin
Prevention of bread mould spoilage by using lactic acid bacteria with antifungal properties.
Get PDFThe ability of lactic acid bacteria (LAB) to inhibit Aspergillus, Fusarium, and Penicillium, the main contaminants in bread, was evaluated. Only four strains (Lactobacillus plantarum CRL 778, Lactobacillus reuteri CRL 1100, and Lactobacillus brevis CRL 772 and CRL 796) from 95 strains tested displayed antifungal activity. The major antifungal compounds were acetic and phenyllactic acids. The fermentation quotient (FQ = 2.0) and the leaven volume (80 cm3) of doughs with LB and yeasts were higher than doughs without LB. The inclusion of antifungal LAB strains in the starter culture allowed a reduction in the concentration of calcium propionate by 50% while still attaining a shelf life similar to that of traditional bread containing 0.4% CP.Fil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Rollan, Graciela Celestina. 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; Argentin
Functionality of exopolysaccharides produced by lactic acid bacteria in an in vitro gastric system
Get PDFAims: To evaluate whether slime-exopolysaccharides (EPS) or capsular-polysaccharide (CPS) production could protect the polymer-producing strains Streptococcus thermophilus CRL 1190 and Lactobacillus casei CRL 87 against the harsh conditions of an in vitro gastric system (GS). EPS stability on the GS was studied. Methods and Results: An in vitro GS model containing human saliva and gastric juice was standardized. Polymer functionality on the cell viability and metabolic activity of the EPS-producing strains in the GS acidic conditions was evaluated. Two isogenic EPS/CPS deficient mutants were used for comparison. EPS or CPS conferred no significant protection on the cell viability of the studied strains after passage through the GS conditions. However, the phospho- and β-galactosidase activities of the EPS+ strains were higher than those of the EPS-. Cytoplasmic alterations in the wild-type and mutant strains and partial degradation of both EPS were detected. Conclusions: The presence of EPS/CPS protected the metabolic activity of the assayed LAB strains, but had no effect on survival at low pH. Significance and Impact of the Study: The presence of EPS/CPS as well as polymer resistance to the harsh conditions of the human GS could impact positively in probiotic strains to exert their properties in the host.Fil: Mozzi, Fernanda Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Gerbino, Oscar Esteban. 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; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin
Optimization of lactic ferment with quinoa flour as bio-preservative alternative for packed bread
Get PDFThe consumers demand for food with high nutritional quality and free of chemical additives increases the need to look for new products and preservation strategies. Quinoa (Chenopodium quinoa) is an Andean pseudocereal highly appreciated because of its nutritional properties. Moreover, it is an optimal substrate for growing and production of improved amounts of antifungal compounds by Lactobacillus plantarum CRL 778. The aim of this work was to optimize a lactic ferment for packaged breads with improved nutritional value and prolonged shelf life by applying a statistical experimental design model. The addition of 30% quinoa to the wheat semi-liquid ferment (QWF) could highly improve the amino acids release (4.3 g/L) during fermentation. Moreover, this quinoa proportion was sufficient to obtain the same concentration of the antifungal compounds, phenyllactic and hydroxiphenyllactic acids (PLA and OH-PLA) as with 100% quinoa (ca. 36 and 51 mg/L, respectively). Statistical model analysis showed that citrate and skimmed milk enhanced significantly all evaluated parameters specially PLA (ca. 71 mg/L), HO-PLA (ca. 75 mg/L) and lactate (27 g/L) with a p value < 0.005. The synergic effects of higher antifungal compounds production, acids release and pH decrease allowed lowering the amount (about 50 %) of the chemical preservative calcium propionate commonly added to bread. Moreover, these breads show increased shelf life.Fil: Dallagnol, Andrea Micaela. Universidad Nacional de Misiones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pescuma, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Rollan, Graciela Celestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Centro de Referencia Para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentin
Physicochemical and antioxidant properties of a gastroprotective exopolysaccharide produced by Streptococcus thermophilus CRL1190
Get PDFThe exopolysaccharide EPS1190 was isolated with high purity from skim milk fermented by the strain Streptococcus thermophilus CRL1190, the major EPS amount being recovered at stationary growth-phase (70.7 mg/L after 16 h). This polymer revealed moderate antioxidant activity in vitro and useful technological properties such as good emulsifying and flocculating capacity at low concentrations, high aqueous solubility (9.1 mg/mL), water and oil holding capacity (528.5 % and 1266 %, respectively) as well as thermal behavior. Thermogravimetric, Differential Thermal Analysis and Differential Scanning Calorimetry curves showed that the biopolymer was thermally stable up to 216 °C with a crystalline deformation in an endothermic process (△H = 284.46 J) at a melting temperature of 74.08°C. Furthermore, a degradation temperature (Td) of 295.4 °C was observed. These results postulate that EPS1190 could be used in the food industry due to its special micro-structure (scanning electron microscopy of EPS1190 demonstrated a homogeneous matrix with micro-porous and rough structure), its good performance and functionality in both aqueous and oil systems, which would remain at high temperatures.Fil: Lobo, Rene Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Gómez, María Inés. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin
New trends in cereal-based products using lactic acid bacteria
No full textThe global importance of cereals to human diet and, moreover, to the history of civilization, in particular agriculture, cannot be overstated. Nutritionally, cereals are an important source of dietary proteins, carbohydrates, vitamins E and B-complex, iron, trace minerals, and fiber. Major cereal crops produced worldwide include wheat, rice, maize, rye, and barley, their main application being in bread manufacture (20–106kg per capita annually). Only wheat and rye are suitable for the elaboration of leavened bread because of the presence of sufficient amounts (8%–14%) of the complex protein gluten. Other common uses of cereals are in the preparation of fermented traditional products, such as Ogi (maize, millet, or sorghum), Kenkey (maize), and Gari (cassava root), as well as drinks. In these fermented cereal-based products, different species of lactic acid bacteria (LAB) belonging to the genus Lactobacillus, Leuconostoc, Weissella, Pediococcus, Lactococcus, Enterococcus, and Streptococcus are involved. Lactic fermentation improves food quality not only by enhancing flavor development and increasing the nutritional value of food but also by extending their shelf life and by removing toxic and anti-nutritional factors. Cereals have become suitable substrates for innovation in the market for functional foods containing prebiotics and/or probiotic LAB strains.Fil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Gerez, Carla Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Rollan, Graciela Celestina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin
Techno-functional properties of HoPS from lactic acid bacteria of different origins as potential food additives
No full textHomopolysaccharides (HoPS) produced by lactic acid bacteria (LAB) are highly versatile, biocompatible and safe compounds. In this work, six HoPS from different species of Weisella and Leuconostoc were identified as thermally stable dextrans, with endothermic crystalline deformations between 214 and 239 °C. These dextrans proved to have greater solubility and capacities to retain water and oil than similar polymers in other reports. Furthermore, a surface morphology study presented cubic grumps, stratify mesh with irregular grumps, and highly compact filaments. Assays in vitro revealed moderate antioxidant, browning and foaming activities as well as technological properties, such as anti-syneresis, emulsifying and flocculating activities, even at low concentrations. Taking into account bipolymers' microstructure, functionalities and performance in both, aqueous and hydrophobic matrixes, plus their capacity to maintain themselves at elevated temperatures, we consider these HoPS beneficial and natural food additives.Fil: Lobo, Rene Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Figueroa, Theo. Ludwig Maximilians Universitat; AlemaniaFil: Navarro, Diego Alberto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Subsede del Centro de Investigaciones en Hidratos de Carbono | Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono. Subsede del Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Gómez, María Inés. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Torino, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin
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