Araceli Castañeda-Ovando

Food Analysis by Microextraction Methods Based on the Use of Magnetic Nanoparticles as Supports: Recent Advances

In the last years, nanotechnology progress has impact several fields of food science. In food analysis, new nanomaterials have been developed in order to extract minority food components. Recently, magnetic nanoparticles (MNPs) have been used as sorbents in methodologies based on dispersive solid-phase microextraction. The main advantage of MNPs as sorbent is their magnetic behavior, which it allows to separate from the food matrix minor components with the aid of a magnet. This MNP property avoids tedious centrifugation and filtration steps, and in turn decreasing sample preparation times and source of errors. The MNPs as sorbent do not need to package in a column, and the separation process is quickly. Other advantages of MNPs in the microextraction of food components are low cost, high concentration factors, and low detection limits; this has allowed the diversification of its applications. Several methods and compounds have been used in the design and functionalization of MNPs, this review focuses in the description of these, especially for the analysis of contaminants (for example, pesticides, heavy metals, drugs, compounds produced during food processing, adulterants, among others).

Microextraction method of medium and long chain fatty acids from milk

The aim of this research was to develop a method for microextraction and quantification of long and medium chain fatty acids from milk. The proposed method was carried out on three steps: (1) lipids extraction from 10 μL of whole or skimmed milk containing omega-3 fatty acids (FAs) during 12, 24, 48, 72 and 96 h, in 2 mL chloroform: methanol mixture (2:1); (2) acid methylation of FAs; and (3) quantification of FAs methyl esters by gas chromatography. Using this method, the percentage recovery of FAs was higher (67% for whole and 85% for skimmed milk) compared with AOAC method 905.02 recovery (49% and 83%, respectively). Good reproducibility and repeatability (<3%) were obtained. The method developed can be useful for researching and in routine quality control. Additionally, it is simpler, faster and cheaper than the reference procedure since it requires minimum sample and solvents volume as well as fewer steps.

Purification of Anthocyanins with o-Dihydroxy Arrangement by Sorption in Cationic Resins Charged with Fe(III)

In the present work, a new purification method of anthocyanins with o-dihydroxy arrangement is proposed. This method is based on a ligand-exchange mechanism, using a cationic exchange resin loaded with metallic ions in order to increase the affinity of the resin to the anthocyanin(s) with o-dihydroxy arrangement. This method was used to purify the main anthocyanin (cyanidin-3-glucoside; Cy-3-glc) from the anthocyanic methanolic extract of blue corn. The best sorption result was using Fe(III) in its ion form. The purification procedure begins with the formation of a metal-anthocyanin complex (Cy-3-glc-Fe) which was optimal at pH 5, followed by a NaOH 0.1 M elution process in order to eliminate anthocyanins without o-dihydroxy arrangement, sugars, and organic acids. Finally, the pure anthocyanin is obtained by adding HCl 0.1 M which breaks the metal-anthocyanin complex.

Peptide separation of commercial fermented milk during refrigerated storage

Milk is an important source of bioactive compounds. Many of these compounds are released during fermentation and refrigerated storage. The aim of this study was to determine the release of peptides by lactic acid bacteria in commercial fermented milk during refrigerated storage. The size and profile of peptides were analyzed by polyacrylamide gel electrophoresis and sizeexclusion HPLC. During electrophoresis, it was observed that the peptides were released from caseins, whereas β-lactoglobulin was the whey protein with the highest degradation. HPLC analysis confirmed the pattern of peptide formation observed in electrophoresis. Two fractions lower than 2 kDa with aromatic amino acids in their structure were separated. These results were consistent with those reported for structures of peptides with antihypertensive activity. Therefore, the presence of aromatic amino acids in the peptide fractions obtained increases the likelihood of finding peptides with such activity in refrigerated commercial fermented milk. In conclusion, during cold storage, peptides with different molecular weights are released and accumulated. This could be due to the action of proteinases and peptidases of the proteolytic system in lactic acid bacteria.

Evaluacion del contenido de metales y su efecto en la estabilidad de antocianinas Metal content evaluation and its effect on the stability of anthocyanins

Anthocyanins are natural pigments interesting in the area of food due to the large color range they exhibit and their beneficial effects on health as a result of their antioxidant properties. Their use in food is limited by the low stability of the compounds contained in the antioxidant extracts.  Stabilization by metal complexation is one of the most important mechanisms for anthocyanin stability. In this work, the main metals contained in blue creole corn are quantified by inductively coupled plasma atomic emission spectroscopy followed by the evaluation of the stability constant of the selected ion metals with the main anthocyanidin (cyanidin); finally the effect of metal ion addition on the color stability is presented. The results obtained demonstrate that the main found metals are capable of complexing and stabilizing the cyanidin according to stability constants estimated by capillary electrophoresis (log β1 = 5.3, 5.0, 5.5 and 4.0 for Ca (II), Cu (II), Fe (II) and Fe (III), respectively).

Effect of thermoultrasound on aflatoxin M 1 levels, physicochemical and microbiological properties of milk during storage

The aim of this research was to determine the physicochemical properties, microbial counts and aflatoxin M1 (AFM1) levels of thermoultrasonicated, pasteurized and untreated milk (control) at days 1, 7 and 14 of storage. Thermoultrasound treatment was performed at a rate of 20 kHz for 10 or 15 min and 95% amplitude on homogenized and non-homogenized milk samples. Results showed that most physicochemical parameters were within the Mexican norms established for milk. Ultrasound treatment for 15 min reduced solids precipitation (p < 0.05) in unhomogenized milk during storage as compared to the pasteurized milk. All samples complied with aerobic mesophilic counts limits set by the Mexican norm except the control and the homogenized milk sample which was thermoultrasonicated for 10 min. Enterobacteriaceae counts of pasteurized and 15 min-thermoultrasound homogenized milks complied with the norm. The lowest levels of AFM1 were found in the 10 min-thermoultrasound unhomogenized milk (0.15 ± 0.05 pg AFM⁠1E/mL) one day after storage. Thermoultrasound did not affect the color of samples but homogenized milk treated for 10 min exhibited less total color difference. A high phenolic content was found in thermoultrasound and pasteurized milks on day 1. Thermoultrasound could be an alternative to milk pasteurization that preserves the physicochemical and microbiological quality of milk while reducing AFM1 levels.

Organic Acids, Antioxidants, and Dietary Fiber of Mexican Blackberry (Rubus fruticosus) Residues cv. Tupy

Blackberry fruit processing generates residues comprised of peel, seeds, and pulp that are abundant in flavonoids, colorants, and organic acids. The objective of this study was to determine the organic acids, antioxidants, and dietary fiber content of blackberry residues and compare antioxidants and dietary fiber content of a prune-based commercial product. The ABTS, DPPH, and FRAP methodologies were used for antioxidant capacity. The blackberry residues exhibited a high amount of malic acid (5706.37 mg/100 g db), phenols (4016.43 mg GAE/100 g db), and anthocyanins content (364.53 mg/100 g db) compared with the commercial product. These compounds contributed to the antioxidant capacity (by ABTS) of both products but were 20 times higher in blackberry residues. The fruit residues were able to reduce iron (by FRAP) 4.4 times compared to the prune-based product. Total dietary fiber (44.26%) and functional properties as water retention capacity (2.94 g/g), swelling capacity (5.00 mL/g), and fat absorption capacity (1.98 mL/g) of blackberry residues were significantly higher than those of the commercial sample. The results demonstrated that, due to its antioxidant compounds and functional properties, the blackberry residue can be considered a source of components with potential benefit to human health.

Development of Cellulose Acetate Microcapsules with Cyanex 923 for Phenol Removal from Aqueous Media

Microcapsules of cellulose acetate with Cyanex 923 were prepared and used in this study for phenol removal from water and synthetic textile wastewater. The influence of several factors on the microcapsules extraction efficiency was studied, as well as characterization and phenol adsorption isotherm. Microcapsules characterization demonstrated the extractant reagent encapsulation, while in a batch mode procedure, good adsorption of phenol (ca. 5.5 × 10−3 mol Kg−1) has been reached. A slight decrease in phenol extraction percentage was obtained when synthetic textile wastewater was used (ca. 4.955 × 10−3 mol Kg−1), although a decrease in color was observed due to dye microcapsule extraction. Results indicate that this method is a promising alternative to conventional phenol removal technologies for aqueous samples of low phenol concentrations or in textile effluents.