Benjamín Ramírez-Wong

Physiochemical changes of starch during maize tortilla production

The physiochemical changes of starch in maize tortillas and their intermediate products commercially processed by the traditional way have been determined. Samples of maize, nixtamal, dough or masa, tortilla and nejayote (steep liquor) were analyzed. The samples were assayed for water absorption index (WAI), resistant starch (RS), X-ray diffraction patterns, viscosity and with Differential Scanning Calorimetry (DSC). Enthalpy of fusion (ΔH), initial temperature (T o ) and transition temperature (T p ) of gelatinization were obtained from DSC curves. Resistant starch contents increased as the products advanced in the process. Significant differences (p > 0.05) in the fusion enthalpy values of maize, nixtamal and masa could not be found. X-ray diffraction patterns of maize, nixtamal and masa did not show significant changes; however, when masa was transformed into tortillas there was a large loss in crystallinity. The viscoamylograph peak viscosities increased from maize to masa and decreased drastically in tortillas. The data showed that the tortilla baking stage caused the most pronounced changes in starch.

HPLC method validation for measurement of sulforaphane level in broccoli by-products

A simple and specific analytical method was developed and tested for the determination of sulforaphane in broccoli by-products. The method includes the optimization of the conversion of glucoraphanin to sulforaphane, followed by purification of extracts using solid-phase extraction and high-performance liquid chromatography (HPLC) analysis. The response surface methodology was used to find optimum conditions for the preparation and purification procedure. Chromatographic conditions for reversed-phase HPLC with UV photodiode array detection were as follows: column, Exil ODS C(18), 25 x 0.46 cm, 5 microm; column temperature, 36 degrees C; mobile phase, a 30 : 70 (v/v) mixture of acetonitrile:water; flow rate, 0.6 mL/min. The detection wavelength was UV 202 nm. Under these conditions, excellent linearity was obtained (r(2) = 1), and the overall recovery was 97.5 and 98.1% for fresh florets and lyophilized florets, respectively. The precision results showed that the relative standard deviation of the repeatability for florets fresh and lyophilized was 3.0 and 4.0%, respectively. Sulforaphane contents were determined in the edible portion of fresh broccoli, and broccoli crop remains.

A Novel Pectin Material: Extraction, Characterization and Gelling Properties

A novel pectin was acid extracted from chickpea husk (CHP). CHP presented a 67% (w/w) of galacturonic acid, an intrinsic viscosity of 374 mL/g and a viscosimetric molecular weight of 110 kDa. Fourier transform infrared spectroscopy spectrum of CHP indicated a degree of esterification of about 10%. The CHP-calcium system formed ionic gels with a storage (G′) modulus of 40 Pa and gel set time (G′ > G″) of 3 min at 1% (w/v), and a G′ of 131 Pa and gel set time of 1 min at 2% (w/v). The G′ of CHP gels was not greatly affected by temperature. The results attained suggest that chickpea husk can be a potential source of a gelling pectin material.

Micro- and Nanoparticles by Electrospray: Advances and Applications in Foods

Micro- and nanotechnology are tools being used strongly in the area of food technology. The electrospray technique is booming because of its importance in developing micro- and nanoparticles containing an active ingredient as bioactive compounds, enhancing molecules of flavors, odors, and packaging coatings, and developing polymers that are obtained from food (proteins, carbohydrates), as chitosan, alginate, gelatin, agar, starch, or gluten. The electrospray technique compared to conventional techniques such as nanoprecipitation, emulsion-diffusion, double-emulsification, and layer by layer provides greater advantages to develop micro- and nanoparticles because it is simple, low cost, uses a low amount of solvents, and products are obtained in one step. This technique could also be applied in the agrifood sector for the preparation of controlled and/or prolonged release systems of fertilizer or agrochemicals, for which more research must be conducted.

Physicochemical Changes of Starch in Maize Tortillas During Storage at Room and Refrigeration Temperatures

Physicochemical changes of starch and loss of texture were determined in maize tortillas during 72 h storage at room and refrigeration temperatures. Properties analyzed included apparent amylose content, content of enzyme resistant starch (RS) type III, and thermal properties determined with differential scanning calorimetry (DSC) and X-rays diffraction. In addition, tortilla firmness was assessed using an uniaxial compression test with a texture analyzer. Storage temperature did not significantly affect firming rate or starch properties, except from thermal properties. Firmness was developed mainly during the first 24 h storage, remained nearly the same during 24—48 h and slightly increased after 72 h storage. Resistant starch (RS) formation followed the same trend as development of firmness. A first order endothermic transition that can be attributed to amylopectin retrogradation was observed after 2 h storage at both temperatures. This transition shifted to higher temperatures during storage, the effect was specially evident for refrigerated tortillas. X ray diffraction patterns of stored tortillas suggested that crystallinity slightly increased during storage. Most of the loss of tortilla texture, determined as firmness, occurred during the first 24 h storage at room and refrigeration storage conditions. This loss of texture was likely due to starch retrogradation and the latter possibly increased content of resistant starch.

Effect of Flour Extraction Rate on White and Red Winter Wheat Flour Compositions and Tortilla Texture

ABSTRACTWheat flours commercially produced at 74, 80, and 100% extraction rates made from hard white winter wheat (WWF) and hard red winter wheat (WRF) were used to produce tortillas at a commercial-scale level. Flour characteristics for moisture, dry gluten, protein, ash, sedimentation volume, falling number, starch damage, and particle-size distribution were obtained. Farinograms and alveograms were also obtained for flour-water dough. A typical northern Mexican formula was used in the laboratory to test the tortilla-making properties of the flours. Then commercial-scale tortilla-baking trials were run on each flour. The baked tortillas were stored at room and refrigeration temperatures for 0, 1, 2, and 3 days. Maximum stress and rollability were measured every day. Tortilla moisture, color, diameter, weight, and thickness were measured for each treatment. Finally, tortilla acceptability was tested by an untrained sensory panel. Analyses of variance (ANOVA) were performed on the data. WWF had higher pro...

Preparation and characterization of durum wheat (Triticum durum) straw cellulose nanofibers by electrospinning.

Cellulose nanofibers from durum wheat straw ( Triticum durum ) were produced and characterized to study their potential as reinforcement fibers in biocomposites. Cellulose was isolated from wheat straw by chemical treatment. Nanofibers were produced via an electrospinning method using trifluoroacetic acid (TFA) as the solvent. The nanofibers were 270 ± 97 nm in diameter. Analysis of the FT-IR spectra demonstrated that the chemical treatment of the wheat straw removed hemicellulose and lignin. XRD revealed that the crystallinity of the cellulose was reduced after electrospinning, but nanofibers remained highly crystalline. The glass transition temperature (T(g) value) of the fibers was 130 °C, higher than that of cellulose (122 °C), and the degradation temperature of the fibers was 236 °C. Residual TFA was not present in the nanofibers as assessed by the FT-IR technique.

Preparation, Characterization and Release of Urea from Wheat Gluten Electrospun Membranes

Homogeneous and thin porous membranes composed of oriented fibers were obtained from wheat gluten (WG) using the electrospinning technique. SEM micrographs showed an asymmetric structure and some porosity, which, in addition to a small thickness of 40 μm, are desirable characteristics for the membranes’ potential application in release systems. The membranes were loaded with urea to obtain pastilles. FT-IR and DSC studies confirmed the existence of interactions via hydrogen bonding between urea and WG proteins. The pastilles were studied as prolonged-released systems of urea in water. The release of urea during the first 10 min was very fast; then, the rate of release decreased as it reached equilibrium at 300 min, with a total of ≈98% urea released. TGA analysis showed that the release system obtained is thermally stable up to a temperature of 117 °C. It was concluded that a prolonged-release system of urea could be satisfactorily produced using WG fibers obtained by electrospinning for potential application in agricultural crops.

Effect of extrusion processing parameters on anthocyanin content and physicochemical properties of nixtamalized blue corn expanded extrudates

Nixtamalized blue corn expanded extrudates were elaborated in a single screw extruder using feed moisture (FM) of 14, 15, 16, 16.5, 18.5 and 20.5%; ground corn with different particle size indexes (PSI, 83.97 and 94.15), and at a final extruder temperature of 130 and 140°C. The physicochemical properties of extrudates evaluated were moisture content, total anthocyanin and cyanidin 3-glucoside (C3G) content, color, density and expansion index. Extrudates processed at 16 and 16.5% of FM showed higher total anthocyanin and C3G contents. The extrudates processed with 16% FM, at 130°C and PSI of 83.97, showed the highest total anthocyanin content (211.1 mg · kg−1). Cyanidin 3-glucoside showed an increase (11.3%) in extrudates when compared with raw corn. The expansion index was higher for those made with FMs of 14, 15, 16 and 16.5%. The total anthocyanin and C3G contents were not correlated with any other parameter.

Effect of ionic strength on soluble protein removal from giant squid mantle (Dosidicus gigas) and functional evaluation of protein recovery

Myofibrillar protein are the principally responsible of gelling properties in fishery resource, hence, during protein concentrate or isolated proteins preparation, sarcoplasmic protein are discarded; however, myofibrillar protein can support low levels of sarcoplasmic proteins without affecting the gelling property. Therefore, the aim of this study was to gradually remove sarcoplasmic proteins from giant squid mantle by means of different ionic strengths (I). Solutions of NaCl with different ionic strengths (I=0.0, 0.1, and 0.3) were used to obtain 3 protein concentrates. The electrophoretic profile in SDS-PAGE showed differences in protein removal with a high solubility of mantle proteins. The texture profile analysis showed that hardness increased in mantle protein washed with higher I. The total reactive sulfhydryls showed significant changes (p<0.05) detecting major formation of S-S bonds with protein removal at an I of 0.3. Differential scanning calorimetry showed a minor denaturation temperature of the actomyosin complex when protein removal was performed with an I of 0.3. The present study indicates that removal of sarcoplasmic protein as a function of I results in better quality gels.