Papers by Jorge Ricardo Wagner
El objetivo del trabajo fue analizar la estabilidad de emulsiones aceite en agua (o/w) preparadas... more El objetivo del trabajo fue analizar la estabilidad de emulsiones aceite en agua (o/w) preparadas con suero de soja o de tofu y sus proteínas aisladas. El suero de soja (SS) fue obtenido en laboratorio como sobrenadante isoeléctrico de la preparación de aislado nativo de soja (ANS); el suero de tofu (ST), residual líquido industrial, fue cedido por una empresa local. Ambos sueros fueron liofilizados dando SSL y STL. A partir del SS y ST se aislaron las proteínas PSS y PST respectivamente, por precipitación con acetona en frío y liofilización. A todas las muestras se le determinó el contenido proteico (N´6,25) a fin de preparar dispersiones acuosas de igual concentración proteica. Se prepararon dispersiones de las muestras en buffer fosfato de sodio 10 mM, pH 7,0, con una concentración de proteína de 0,1-1 % p/v. Las emulsiones o/w fueron preparadas homogeneizando 10 ml de las dispersiones acuosas con 5 ml de aceite de girasol (Ultraturrax T-25, 20.000 rpm, 1 min., 20ºC). Las emulsio...
El objetivo de este trabajo fue estudiar el efecto del tratamiento térmico y las condiciones de a... more El objetivo de este trabajo fue estudiar el efecto del tratamiento térmico y las condiciones de almacenamiento sobre la cristalización de azúcares en suero de soja liofilizado (SSL). El SSL se preparó por liofilización del suero de soja, que queda como sobrenadante isoeléctrico de la obtención de aislados. Los componentes mayoritarios del SSL son los carbohidratos (sacarosa y los oligosacáridos estaquiosa, rafinosa y verbascosa) seguido de los factores antitrípticos de Kunitz y Bowman-Birk y de la lectina (todos con actividad biológica), con una relación carbohidratos: proteína total de 3: 1. El análisis por calorimetría diferencial de barrido (DSC) en condiciones anhidras, del SSL almacenado sin previo tratamiento térmico, presentó una endoterma correspondiente a la fusión de cristales de azúcares con una temperatura de pico (Tp) a » 65°C. Se prepararon muestras de SSL tratado térmicamente en cápsulas selladas herméticamente y en condiciones anhidras, a una velocidad de 5°C/min has...
Fil: Ingrassia, Romina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquimicas y Farma... more Fil: Ingrassia, Romina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquimicas y Farmaceuticas. Instituto de Fisica Rosario (IFIR-CONICET); Argentina.
Food and Bioprocess Technology, 2018
The use of renewable resources to develop food contact materials, such as proteins or polysacchar... more The use of renewable resources to develop food contact materials, such as proteins or polysaccharides, and the use of industrial residues for alternative applications are trending topics for researchers and the industry. Yeast cell wall (YCW) is a very rich waste from the yeast extract industry. Due to this, the aim of this work is to develop new biodegradable films based on residual YCW and the study of the effect of plasticization on films properties. Residual YCW was used as base matrix and different concentrations of glycerol (0, 15, 25 and 35 wt%) were tested to obtain casted films. Homogeneous and yellow-brownish films, which allow seeing through them, were obtained from the YCW. Total soluble matter demonstrated that glycerol enhanced solubility of films but glycerol was retained in the polymer matrix. TGA studies indicated that YCW films exhibited substantial degradation at temperatures above 180°C. FTIR spectra of the casted films were representative of yeast cell wall material and SEM photographs showed that cell wall maintained their shape after film formation. As expected, Young's modulus and tensile strength values were decreased with the increasing amount of glycerol. However, elongation at break was not increased further with higher concentration of plasticizer and the addition of 15 wt% of glycerol seemed to be enough to improve mechanical properties. The linear increment of water vapour permeability with glycerol concentration was produced by the increase in water solubility in the film. Therefore, based on solubility in water, mechanical, and barrier properties, it is possible to propose yeast cells residues as filmforming material for biodegradable film developments.
Food Hydrocolloids, 2017
The aims of this work were to obtain different samples of insoluble soybean polysaccharides (ISPS... more The aims of this work were to obtain different samples of insoluble soybean polysaccharides (ISPS) from defatted soy flour and to study their potential application as O/W emulsifier. In this regard, the insoluble residue (okara) resulting from an aqueous extraction (60 C, pH 9.0), was submitted to an acidic extraction (pH 3.5, 120 C) without or with a pretreatment (high pressure homogenization or sonication). The insoluble residues of these extractions were dried (oven, 70 C or vacuum post-treatment with 2propanol, 40 C) yielding different ISPS samples. Aqueous dispersions of ISPS samples (1e2% w/w, pH 3 and 7), were used to prepare coarse and fine O/W emulsions. Emulsion stability against creaming and coalescence processes, and the rheological behavior were analyzed. ISPS samples obtained by okara pretreatment and vacuum dried post-treatment with 2-propanol allow to produces emulsions with high values of flocculation degree, increasing the stability of the particle size, and allowing the formation of stronger gel-like emulsions. These pretreatments expose internal sites of the polysaccharide and protein structures, increasing their superficial hydrophobicity and, therefore, allow a strong absorption of the macromolecules at the oil-water interface and/or the formation of external layers, increasing the rigidity of the interfacial film and contributing to the formation of hydrated flocs. Also, these treatments could solubilize certain compounds in okara that would interfere negatively in the formation of the interfacial film. Particularly, sample obtained by high pressures homogenization of the okara presented the best emulsifying properties and it was not significantly affected by variations in the pH of the emulsion. The results of this research work demonstrate a high potential of application of the ISPS samples as O/W emulsifier, under acid and neutral conditions, increasing the added value of an important by-product of the soybean industry.
European Journal of Lipid Science and Technology, 2017
Partial coalescence was studied in double (W 1 /O/W 2) emulsions prepared with skimmed milk, poly... more Partial coalescence was studied in double (W 1 /O/W 2) emulsions prepared with skimmed milk, polyglycerol polyricinoleate (PGPR) as lipophilic emulsifier, and different fats. Microstructural and rheological analyses were performed. Encapsulation efficiency (as a parameter of inner water retention) and solid fat content were estimated by differential scanning calorimetry. The presence of PGPR in dispersed lipid phase promoted partial coalescence especially at higher concentration. This promotion of partial coalescence may have been produced by the increase of collision frequency due to protein displacement by PGPR at the outer interface and/or the increase of capture efficiency due to the modification of fat crystals by PGPR. Partial coalescence was also favored when inner water droplets were released as a consequence of an osmotic unbalance between inner and outer aqueous phases. Thus, the addition of glucose in dispersed aqueous phase decreased the partial coalescence degree due to the higher encapsulation efficiency given by the balanced osmotic pressures. With respect to the effect of the employed fat on partial coalescence, the obtained data indicate that the phenomenon was favored at higher solid fat content in lipid phase. Results led to the conclusion that inner osmolality, encapsulation efficiency, and inhibition of partial coalescence were correlated. Practical applications: The originality of this work resides on boarding the subject of partial coalescence in W 1 /O/W 2 emulsions. The studied systems are proposed as potential lipid-reduced substitutes of dairy creams, with the employment of alternative non-dairy fats such as low trans vegetable fat. The combined analysis of partial coalescence and encapsulation efficiency allowed studying their reciprocal effects and evaluating the potentiality of the systems for the encapsulation of hydrophilic compounds. The variations of relative osmotic pressures in inner and outer aqueous phases, lipophilic emulsifier concentration, and solid fat content may lead to desirable or undesirable rheological properties depending on the required texture of the food emulsion. The findings of this work could be an important step pointing to control the factors leading to partial coalescence in W 1 /O/W 2 emulsions for food applications.
Food Hydrocolloids, 2018
Prosopis ruscifolia (or vinal tree) is an abundant plant from Argentina semiarid areas, whose see... more Prosopis ruscifolia (or vinal tree) is an abundant plant from Argentina semiarid areas, whose seeds contain a galactomannan type interesting gum: vinal gum. The aim of this work was to analyze the rheological behavior of vinal gum suspensions and the consequences of its interactions with commercial gums widely employed in the food industry. Vinal gum aqueous suspensions were in good agreement with the Cox-Merz rule at concentrations lower or equal to 1% (w/w), which establishes an empirical relationship between complex and apparent viscosity. The flow curves of vinal gum could be defined only by two parameters-Newtonian viscosity (η 0) and strain rate ( 0.1)-and the shear-thinning behavior of vinal gum complied with the generalized curve for other polysaccharides. In mixtures with xanthan gum, vinal gum exhibited a synergistic relationship on its elastic behavior (at a total gum concentration of 1% (w/w)). On the other hand, vinal gum showed no synergism with κ-carrageenan or sodium alginate at the same total concentration of polymer. Apparent viscosity of vinal gum aqueous suspensions showed Arrhenius type dependence with temperature, as other galactomannans. The rheological behavior was not dependent on shear time, and the thickening power of vinal gum was slightly affected by pH and ionic strength changes. The present work provides detailed information on rheological characteristics of a non-traditional galactomannan extracted from an abundant and available source, being a starting point for possible applications of vinal gum as thickening and/or stabilizing agent in food, pharmaceutical, paper, textile, oil and cosmetics industries.
Applied Biochemistry and Microbiology, 2013
Due to the structure and the composition of Paecilomyces variotii, the mycelia of this fungus cou... more Due to the structure and the composition of Paecilomyces variotii, the mycelia of this fungus could have potential applications as ingredients in wettable foods. For this use, drying could be employed, justifying the study of thermal behavior of P. variotii. The objectives of this work were to perform a study of thermal behavior of P. variotii isolates, to evaluate the hydration properties of these mycelia and to analyze the effect of different technological parameters on the latter properties. Wet cultures exhibited a wide endothermic transition, with mean values of peak temperature of 61 degrees C and denaturation enthalpy of4 J/g dry matter. Initial (50 degrees C) and final (80 degrees C) temperatures of the endothermic transition were used to dry the mycelia. Freeze-drying was also assayed. For all dried mycelia, a decrease in denaturation enthalpy between 40 and 50% was observed for drying at 50 degrees C and freeze-drying, and a drastic decrease of almost 100% for drying at 80 degrees C. According to the hydration properties, wet mycelia exhibited water holding capacity (WHC) value of 45 g water/g dry matter. Significant differences among dried mycelia, resulting WHC values in order: 50 degrees C > freeze-dried > 80 degrees C (p < 0.05) were revealed for each P. variotii strain. Fungi obtained by drying at 50 degrees C and by freeze-drying, showed a rapid water absorption (t(1/2) < 0.1 min). Ionic strength, pH and particle size of dried mycelia influenced the hydration properties.
LWT, 2018
Chia protein isolates (CPI) were obtained through isoelectric precipitation under two different c... more Chia protein isolates (CPI) were obtained through isoelectric precipitation under two different conditions in order to compare their structural properties. Extraction was carried out at pH 10 or 12, whereas precipitation pH was fixed at 4.5. Samples were named as CPI10 or CPI12, according to their extraction pH (10 or 12, respectively). The recovery of chia proteins was higher when the extraction was carried out at pH 12 (17% for CPI12 and 13% for CPI10); however, CPI12 protein content (775g/kg) was slightly lower than CPI10 protein content (782g/kg). Both samples showed similar SDS-PAGE pattern. Protein dispersions of both isolates led to highly stabilized particles due to their negative ζ potential (around-54 mV). CPI10 has a higher proportion of small particles in suspension, revealed by a lower d3,2 value. Spectroscopic techniques showed that CPI10 presented higher content of β-helix than CPI12, resulting in higher thermal stability. This observation was supported by FT-IR spectroscopy since CPI10 presented less unordered structure than CPI12. The energy of endotherms obtained in CPI12 was considerably lower than in CPI10. Extraction at higher alkaline conditions led to a more denatured protein conformation with a higher content of random structure (18.1% for CPI10 and 22.9% for CPI12).
Fil: Marquez, Andres Leonardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnolo... more Fil: Marquez, Andres Leonardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia. Area Ingenieria en Alimentos; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina
LWT, 2018
The aim of this work was to study the effect of the extraction pH on the functional properties of... more The aim of this work was to study the effect of the extraction pH on the functional properties of chia protein isolates (CPI). Samples were named as CPI10 or CPI12, according to their extraction pH, 10 or 12, respectively. Functional properties were significantly modified by the extraction pH. Color properties revealed that CPI12 presented a lower L* (47.8±0.9 for CPI10 and 30±1 for CPI12) due to enhanced protein-polyphenol interactions. Besides, a higher b* value was obtained for CPI12 (7.0±0.3 for CPI12 and 5.6±0.7 for CPI10), as a result of a higher ash content. CPI12 showed a higher WAC probably due to a higher exposure of polar amino acids (4.4±0.1 g/g and 6.0±0.2 g/g), whereas CPI10 showed a higher ability to bind oil (7.1±0.2 g/g and 6.1±0.2 g/g for CPI10 and CPI12, respectively). CPI10 proved more appropriate as an emulsion stabilizer than CPI12, which could be due to its higher surface hydrophobicity, protein solubility and negative net charge. The d 4,3 (μm) was 29.5±0.4 and 20.4±0.3 in emulsions stabilized with CPI12 and CPI10, respectively. Although both isolates underwent heat gelation, they exhibited a weak gel behavior. Overall, CPI10 may be more suitable for the food industry as a meat replacer or extender.
Applied Biochemistry and Microbiology, 2012
1 Instituto de Física Rosario (IFIR), Universidad Nacional de Rosario (UNR), CONICET, Facultad de... more 1 Instituto de Física Rosario (IFIR), Universidad Nacional de Rosario (UNR), CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Facultad de Ciencias Veterinarias, 2000 Rosario, Santa Fe, Argentina. 2 Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), B1900AJJ La Plata, Buenos Aires, Argentina. 3 Universidad Nacional de Quilmes (UNQ), CONICET, Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos (LIFTA), Departamento de Ciencia y Tecnología, B1876BXDBernal, Buenos Aires, Argentina.
Innovative Food Science & Emerging Technologies, 2016
Abstract Biodegradable alternatives to petroleum-based polymers are being developed for food pack... more Abstract Biodegradable alternatives to petroleum-based polymers are being developed for food packaging. Saccharomyces cerevisiae has been widely used for the production of fermented beverages and leavened foods. In this work, the application of high pressure homogenisation and a thermal treatment to the yeast biomass was studied to develop biodegradable films. The highest dispersibility indexes of protein (84.5 ± 3.3%), carbohydrates (24.3 ± 1.1%), RNA (40.6 ± 0.9%) and soluble solids released were found at high homogenisation pressure (125 MPa). Combinations of one or two homogenisations and a thermal treatment at 90 °C during 20 minutes were applied and dispersions were fully characterised, focusing on their film-forming capacity. The best combination was homogenisation, heat treatment and a further homogenisation, since it produced films that presented good attributes, great continuity and homogeneity without small cracks. However, hydration of films was increased from 0.31 to 0.48 gH2O/g.d.m with the number of homogenisation processes applied. Results revealed that yeast biomass is a viable source to be used in biodegradable films. Industrial relevance Saccharomyces cerevisiae yeasts have many applications in food industry. The development of biodegradable films based on yeast biomass carries many advantages such as, the possibility of using commercial pressed baker's yeast or an industrial residue from brewing industry, the use of a low-cost sources and the application of environmentally friendly procedures. The methodologies applied for the development of the film forming dispersion, high pressure homogenisation and thermal treatment, are able to be scaled-up to an industrial level.
LWT - Food Science and Technology, 2006
LWT - Food Science and Technology, 2009
Journal of Texture Studies, 2010
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Journal of Food Science, 1997
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Papers by Jorge Ricardo Wagner