Papers by María Cristina Añón
Native Crops in Latin America, 2022
Native Crops in Latin America, 2022
Food and Bioprocess Technology, 2014
The effect of maize resistant starch (MRS) and transglutaminase (TG) on rheological and thermal p... more The effect of maize resistant starch (MRS) and transglutaminase (TG) on rheological and thermal properties of pan bread dough was studied. The MRS was added as an alternative to increase the fiber ingestion while TG supplies the gluten dilution, catalyzing protein bonds. A second order Central Composite Design (2²) with three central and four star points was applied and the results were compared to those of pan bread dough prepared without MRS and TG, as control. The presence of MRS and TG significantly (P<0.05) influenced the maximum resistance to extension achieving the highest value for the dough formulated with 8.8 g/100g of MRS and 0.12 g/100g of TG. A modified power-law model was fitted to the stress-strain data obtained from biaxial test, indicating that partial substitution of wheat flour by MRS resulted high n index (degree of strain hardening). Only starch gelatinization enthalpy significantly changed (P<0.05) by MRS and TG contents, increasing with the increase of TG. The temperatures obtained from thermograms are compared to those obtained from DSC curves from aqueous suspensions of MRS, indicating gelatinization temperatures above 100 ºC.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
Food protein product, gluten protein, was chemically modified by varying levels of sodium stearoy... more Food protein product, gluten protein, was chemically modified by varying levels of sodium stearoyl lactylate (SSL); and the extent of modifications (secondary and tertiary structures) of this protein was analyzed by using Raman spectroscopy. Analysis of the Amide I band showed an increase in its intensity mainly after the addition of the 0.25% of SSL to wheat flour to produced modified gluten protein, pointing the formation of a more ordered structure. Side chain vibrations also confirmed the observed changes.
Scandinavian Journal of Gastroenterology, 1998
Secretion of dietary antigens into breast milk has been extensively documented. The presence of t... more Secretion of dietary antigens into breast milk has been extensively documented. The presence of these antigens is of relevance because they could be involved in the modulation of the immune response in neonates. The objective of this study is to determine the gliadin concentration in milk, colostrum, and serum samples from healthy lactating mothers on a normal diet. Gliadin levels in milk samples from a group of six mothers after a brief period of gluten restriction were also determined. The molecular weight of secreted gliadins was also analysed. Gliadin concentration was determined with a highly sensitive competitive enzyme-linked immunosorbent assay, modified so as to eliminate anti-gliadin antibody interference. The level of gliadin/IgA anti-gliadin immune complexes in milk, colostrum, and serum samples was determined. Gliadin was detected in all 49 milk samples. Its concentration varied between 5 and 1200 ng/ml (mean, 178 ng/ml). In colostrum (n = 14) gliadin levels were higher (range, 28-9000 ng/ml; mean, 883 ng/ml), not being detectable in one case. Gliadin was detectable in 14 of 31 serum samples, in which levels were lower than in milk and colostrum samples (mean, 41 ng/ml). Neither a correlation between gliadin levels in milk, colostrum, and serum samples from the same subject nor a relation between gluten intake and gliadin concentration in milk samples from six subjects under a 3-day gluten-free diet could be found. Higher levels of immune complexes were observed in colostrum samples than in milk and serum samples. No correlation was detected between gliadin concentration and the level of immune complexes. The analysis of milk and colostrum samples by immunoblotting showed bands of immunoreactive gliadin presenting Mr similar to those of native proteins from wheat extracts. Very high levels of gliadin were detected in milk samples from healthy mothers on an unrestricted diet. Gliadin levels were higher than those reported for dietary antigens in other studies. Breast milk contained non-degraded gliadins and gliadin/anti-gliadin IgA immune complexes.
Meat Science, 1982
One problem that arises when freezing liver b~ plate freezers is the whitish colour acquired by t... more One problem that arises when freezing liver b~ plate freezers is the whitish colour acquired by the liver surface when subjected to high freezing rates. The purpose of this paper aims to establish optimum operating conditions for freezing beef liver pieces in a minimum time while maintaining an acceptable colour on the surface. Samples were subjected to different freezing rates and minimum surf ace freezing time was established in order to obtain an acceptable colour. This was quantified in terms of lightness using a surface colorimeter. Histological analysis of the samples showed that the size of the ice crystals formed on the contact surface with the coolant is the factor that determines the changes in colour as a result oJ'diJfused light reflection phenomena. On the basis of mathematical heat transfer models with simultaneous change of phase, the minimum characteristic surf ace freezing time was related to the process operating variables (initial temperature of the liver, coolant temperature, interfacial heat transfer resistance, thickness of the piece), and the optimum freezing conditions were determined, reducing total processing times to a minimum. NOMENCLATURE a,m,p,q,r Bi b tl ko L Numerical constants defined in eqn. (7). Biot number; Bi = hb/k o. Half-thickness. lnterfaciai heat transfer coefficient (W/m 2 K). Thermal conductivity of unfrozen liver (W/m °C). Lightness. 299
Livestock Science, 2010
Bovine chromosome 5 has been widely studied because several QTLs have been detected there, in par... more Bovine chromosome 5 has been widely studied because several QTLs have been detected there, in particular for growth and fat traits. Even though most of the beef is produced under pasture based conditions, only little research has focused on this kind of systems. Two QTL regions, neighboring the Myogenic factor 5 gene, and Insulin-like Growth Factor 1 (IGF1) gene, were selected. Within them, four BTA5 microsatellites (BP1, ETH10, IGF1 and RM029) were used to establish their association with growth and fat traits in a pasture based feeding system. The Estimated Breeding Values tested were: 400 (W400) and 600 Days Weight (W600), Rib Eye Area (REA), Rib Fat, Rump Fat, and Intra Muscular Fat. For growth traits significant associations (p ≤ 0.05) between BP1 and REA, and between IGF1 and W600, were detected. For fat traits significant association (p ≤ 0.05) between ETH10 and Rib Fat and Rump Fat was detected. When considering a pair of closer marker genotypes, IGF1/ETH10 was significantly associated (p ≤ 0.05) with W400 and W600. These results show that QTL for growth and fat traits that were previously reported in two regions of BTA5, are also expressed in a commercial pasture based system, where animals are not always fed to express their maximum genetic potential.
Journal of Food Science, 2007
ABSTRACT: Amaranth protein–lipid (PL) and protein (P) films were elaborated and compared with am... more ABSTRACT: Amaranth protein–lipid (PL) and protein (P) films were elaborated and compared with amaranth flour films in order to determine the contribution of the interactions between the biopolymer (starch and protein) and the lipids to the film properties. The films were made by the casting method, using the same glycerol concentration (0.9 g glycerol/100 g solution). A separation of the lipid fraction in the PL films and a polymorphic transformation of the corresponding fatty acids were observed by differential scanning calorimetry (DSC) and verified by an analysis of the microstructure by scanning electron microscopy (SEM). The flour films showed no separation of the lipid fraction, evidence that the lipids were strongly associated with the proteins and homogenously distributed throughout the starch network, contributing to the good mechanical properties when compared to the PL films and to the excellent barrier properties when compared to both the PL and P films. The protein‐pro...
Journal of Food Engineering, 2009
The influence of drying conditions (air temperature and relative humidity) on mechanical properti... more The influence of drying conditions (air temperature and relative humidity) on mechanical properties, solubility in water, and color of two kinds of soy protein isolate film: a commercial one (CSPI) and other obtained under laboratory conditions (LSPI) were evaluated using the response surface methodology (RSM). Soy protein films were prepared by casting using glycerol as plasticizer. The films were dried in a chamber with air circulation under controlled conditions of relative humidity (24%, 30%, 45%, 60%, 66%) and air temperature (34, 40, 55, 70, 76°C). It was verified that mechanical properties of films made from LSPI and CSPI are influenced in a very different way by the drying conditions due to a diverse initial protein conformation in both materials, as was revealed by DSC and SDS-Page studies. The solubility of the LSPI film was affected by temperature and relative humidity, being lowest ($50%) for films obtained at high RH and temperatures ranging from 45 to 76°C. For CSPI films, in contrast, solubility did not depend on the drying process and it remained relatively constant ($40%). The optimal drying conditions determined by RSM were: 70°C and 30% RH for CSPI films and 60°C and 60% RH for LSPI films. Dried under these conditions, CSPI films presented a higher tensile strength, lower elongation at break, lower solubility and better water and oxygen permeability than LSPI ones.
Journal of Food Biochemistry, 1994
The metachromutic behavior of wheat, barley and rye prolamins. separated by polyacrylamide gel el... more The metachromutic behavior of wheat, barley and rye prolamins. separated by polyacrylamide gel electrophoresis (PAGE) and staining with Coomassie Brilliant Blue R-250, is described. Metachromasia was detected both visually and by abuble beam densitometric analysis of sodium dodecyl sulfate-PAGE and acidic-PAGE (A-PAGE) atpH3.1. Differential readings were recorded at 525 nm, with reference at 625 nm. Metachromatic components were found in the homologous groups, (a) S-poor prolamins: w-gliadins, C-hordeins, w-secalins and (b) high molecular weight (Hm-prolamins: HMW-glutenins, D-hordeins and HMWsecalins, in wheat, barley and rye, respectively. In contrast, proteins having this characteistic have not been found in oat.
Journal of Agricultural and Food Chemistry, 1994
Wheat, rye, and barley prolamins were separated using optimized elution conditions by cation exch... more Wheat, rye, and barley prolamins were separated using optimized elution conditions by cation exchange FPLC on an analytical Mono-S column. Wheat gliadins were resolved into a larger number of peaks than has been obtained hitherto. Most fractions contained a mixture of components as determined by SDS-PAGE and A-PAGE. At least one fraction was obtained for each group of gliadins that contains only one major component with minimal contamination by other components. Only w-gliadins occurred in five of the fractions. A preparative S-Sepharose Fast Flow column, run under similar chromatographic conditions, was used to isolate w-gliadins. This procedure could be used as the first step for the purification of individual gliadin components. Chromatography on the Mono-S column was highly reproducible and showed promise as a means of differentiating wheat cultivars. Furthermore, FPLC was applied t o fractionate prolamins from barley and rye.
Journal of Agricultural and Food Chemistry, 1999
Purification of gliadin subclasses has been difficult since they share many biochemical and physi... more Purification of gliadin subclasses has been difficult since they share many biochemical and physicochemical properties. In this report, the optimization of a preparative electrophoretic method to fractionate gliadins is described. Separation was performed in preparative 7% polyacrylamide gels at pH 3.1. The separation performance was tested using analytical electrophoresis at pH 3.1 and capillary electrophoresis. Preparative gels of different lengths were employed. Using 5-cm preparative gels, several fractions of alpha-, beta-, and gamma-gliadins and fast-mobility and slow-mobility omega-gliadins were collected in 40 h of separation. Resolution was maintained at a protein load of up to 30 mg in each run. The highest efficiency of recovery was achieved using aluminum lactate as the collecting buffer. Fractionation with 10 cm in length gels improved resolution but increased operation times. Gels of 2 cm in length did not separate alpha/beta- and gamma-gliadins efficiently but were useful to separate the two main fractions of omega-gliadins in shorter times. In conclusion, preparative electrophoresis at low pH allowed the separation of alpha-, beta-, gamma-, and omega-gliadin fractions from crude material under nondenaturing conditions.
Journal of Agricultural and Food Chemistry, 1991
The effect of protein composition and degree of protein denaturation on the solubility, water-imb... more The effect of protein composition and degree of protein denaturation on the solubility, water-imbibing capacity (WIC), viscosity, and gelation capacity of commercial soy protein isolates was studied. It was found that the degree of denaturation may affect protein solubility, but very denatured proteins with high solubility were also detected. Isolates containing completely denatured proteins showed low gelation capacity. This characteristic is closely related to the relative amounts of the 75 and 11s proteins, since 6-7s subunit and basic 11s polypeptide were present in decreased concentrations in the soluble protein fraction. Isolates with a high degree of denaturation and intermediate solubility values presented the maximal WIC. Results confirmed that the apparent viscosity of soy protein dispersions is intimately related to WIC.
Journal of the American Oil Chemists' Society, 1990
The effect of storage temperature on the consistency of commercial margarine was analyzed by visc... more The effect of storage temperature on the consistency of commercial margarine was analyzed by viscometry, differential scanning calorimetry (DSC), microscopy at low temperature and X‐ray diffraction. The results obtained show that samples harden at 13°C and soften at 4°C. The greater strength of samples was apparently associated with crystals of higher melting points. Recrystallization takes place during storage leading to more stable solid solutions with higher melting points.
Journal of the American Oil Chemists' Society, 2007
The influence of the conditions for isolation of soy protein on the content of genistein and its ... more The influence of the conditions for isolation of soy protein on the content of genistein and its conjugated forms was studied. The major components of the genistein series isolated from soybean flour were malonyl genistin (54.3%), genistin (36.9%), and equal amounts (4.4%) of genistein and acetyl genistin. A modification in the conjugation profile of genistein between pH 4.5 and 8.0 and above pH 10 was attributed to the action of β‐glucosidase and the saponification reaction, respectively. A decrease in the content of total genistein in the insoluble flour residue and in the soy protein isolate (SPI) with increasing extraction pH was detected, while in the whey, the total genistein content was not affected by pH. The effect of pH variation during acid precipitation on the content of genistein and its conjugated forms, at a constant extraction pH (8.0), was also studied. Under these conditions, the highest absolute content of total genistein in the SPI was obtained at pH 3.5 and the ...
International Journal of Food Science & Technology, 2007
Summary.Freezing of bovine muscle has a denaturating effect on myofibrillar proteins, Differ‐enti... more Summary.Freezing of bovine muscle has a denaturating effect on myofibrillar proteins, Differ‐ential Scanning Calorimetry (DSC) studies of fresh and frozen muscle at different freezing rates show a decrease on denaturation enthalpies; the lower the freezing rate the greater the loss. When measuring the specific areas (ratio between each partial area in cm', and the dry weight of the sample, in mg) of the DSC thermograms, it can be observed that the area ascribed to myosin decreases with freezing, while the area corresponding to actin is not affected. These results are in agreement with the ATPase activity decreases as a consequence of freezing observing higher losses at lower freezing rates. The denaturation observed could be a result of a partial unfolding of the myosin head being more pronounced at low freezing rate.
Food Science and Technology International, 2002
... Thermal Denaturation Kinetics of Yeast Proteins in Whole Cells of Saccharomyces cerevisiae an... more ... Thermal Denaturation Kinetics of Yeast Proteins in Whole Cells of Saccharomyces cerevisiae and Published by: http://www.sagepublications.com ... Page 2. Thermal Denaturation Kinetics of Yeast Proteins in Whole Cells of Saccharomyces cerevisiae and Kluyveromyces fragilis ...
Food Research International, 2010
The effects of calcium and high pressure (HP) treatment on the thermal properties of soybean prot... more The effects of calcium and high pressure (HP) treatment on the thermal properties of soybean proteins were analyzed in soybean protein isolate (SPI), a b-conglycinin-enriched fraction (7SEF), a glycininenriched fraction (11SEF), and whey protein concentrate (WPC). For b-conglycinin, the temperature of denaturation (Td) decreased with up to 12.5 mM or 6.2 mM calcium in SPI and 7SEF, respectively. This parameter increased when calcium was more concentrated. The Td of glycinin increased for every assayed calcium concentration. The values of changes in Td (DTd) depended on calcium concentration and the proportion of b-conglycinin and glycinin in the samples. Activation energy decreased for glycinin in the presence of calcium. HP treatment promoted denaturation of b-conglycinin and glycinin. Calcium protected both proteins in SPI, 7SEF and 11SEF at 200 MPa, and protected glycinin in SPI and 7SEF at 400 and 600 MPa. Nevertheless, calcium increased the degree of denaturation of b-conglycinin in 7SEF at 600 MPa. In the absence of calcium, partially-HP-denatured polypeptides exhibited the same or lower Td than controls, whereas in its presence, they exhibited higher Tds than their respective controls.
Food Hydrocolloids, 2013
The ability of soybean proteins to form cold-set gels, using high pressure (HP) processing as den... more The ability of soybean proteins to form cold-set gels, using high pressure (HP) processing as denaturing agent and calcium incorporation was evaluated. Different protein preparations were assayed: soybean protein isolate (SPI), a b-conglycinin enriched fraction (7SEF) and a glycinin enriched fraction (11SEF). 7SEF formed aggregated gels with low water holding capacity whereas 11SEF did not form self-standing gels. SPI formed the better gels: ordered and with high water holding capacity. SPI gels were relatively soft and their visual aspect, rheological and texture properties, and water holding capacity depended on HP level (400e600 MPa), CaCl 2 concentration (0.015e0.020 mol L À1) and protein concentration (85e95 g L À1), thus gels with different characteristics may be obtained. The gels comprised a three dimensional network stabilized by non-covalent interactions with spaces filled of proteins in aqueous solution. The results indicate that it is possible to use HP and subsequent calcium incorporation to form self-standing cold-set gels from soybean proteins. These gels may be of interest to incorporate heat-labile compounds or probiotics during the gelation step.
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Papers by María Cristina Añón