Darío I. Téllez-Medina

Biochemical and Molecular Analysis of Some Commercial Samples of Chilli Peppers from Mexico

The genus Capsicum provides antioxidant compounds, such as phenolics and carotenoids, into the diet. In Mexico, there is a wide diversity of species and varieties of chilli peppers, a fruit which has local cultural and gastronomic importance. In the present study, the relationship of the carotenoid and phenolic profiles with the RAPD fingerprint of three different commercial cultivars of chilli peppers of seven regions of Mexico was investigated. Through RAPD, the species of chilli were differentiated by means of different primers (OPE-18, MFG-17, MFG-18, C51, and C52). The genetic distance found with OPE 18 was in the order of 2.6. The observed differences were maintained when the chromatographic profile of carotenoids, and the molecular markers were analyzed, which suggest a close relationship between carotenoids and the genetic profile. While the chromatographic profile of phenols and the molecular markers were unable to differentiate between genotypes of chilli peppers. In addition, by using infrared spectroscopy and statistical PCA, differences explained by geographic origin were found. Thus, this method could be an alternative for identification of chilli species with respect to their geographic origin.

Morphological and physicochemical characterization of agglomerates of titanium dioxide nanoparticles in cell culture media

Titanium dioxide nanoparticles (TiO2 NP) are possible carcinogenic materials (2B-IARC) and their toxicity depends on shape, size, and electrical charge of primary NP and on the system formed by NP media. The aim of this work was to characterize agglomerates of three TiO2 NP by evaluating their morphometry, stability, and zeta potential (ζ) in liquid media and their changes with time. Sizes of agglomerates by dynamic light scattering (DLS) resulted to be 10-50 times larger than those obtained by digital image analysis (DIA) given the charged zone around particles. Fractal dimension (FD) was highest for agglomerates of spheres and belts in F12K, and in E171 in FBS media. E171 and belts increased FD with time. At time zero, using water as dispersant FD was larger for agglomerates of spheres than for of E171. Belts suspended in water had the smallest values of circularity (Ci) which was approximately unchanged with time. All dispersions had ζ values around -30 mV at physiological pH (7.4) and dispersions of NP in water and FBS showed maximum stability (Turbiscan Lab analysis). Results help in understanding the complex NP geometry-size-stability relationships when performing in vivo and in vitro environmental-toxicity works and help in supporting decisions on the usage of TiO2 NP.

Water droplet spreading and recoiling upon contact with thick-compact maltodextrin agglomerates.

BACKGROUND The food and pharmaceutical industries handle a number of compounds in the form of agglomerates which must be put into contact with water for rehydration purposes. In this work, liquid-solid interaction between water and maltodextrin thick-compact agglomerates was studied at different constituent particle sizes for two compression forces (75 and 225 MPa). RESULTS Rapid droplet spreading was observed which was similar in radius to the expected one for ideal, flat surfaces. Contact angle determinations reported oscillations of this parameter throughout the experiments, being indicative of droplet recoiling on top of the agglomerate. Recoiling was more frequent in samples obtained at 225 MPa for agglomerate formation. Agglomerates obtained at 75 MPa exhibited more penetration of the water. Competition between dissolution of maltodextrin and penetration of the water was, probably, the main mechanism involved in droplet recoiling. Micrographs of the wetting marks were characterized by means of image analysis and the measurements suggested more symmetry of the wetting mark at higher compression force. CONCLUSION Differences found in the evaluated parameters for agglomerates were mainly due to compaction force used. No significant effect of particle size in recoiling, penetration of water into the agglomerate, surface texture and symmetry was observed.

Digital image analysis and fractal metrics as potential tools to monitor colour changes in fresh-cut papaya (Carica papaya L.)

ABSTRACT Quality changes induced in fresh papaya slices after cutting were evaluated using digital image analysis of colour and fractal metrics besides structural changes. Radial slices of papaya (65% and 85% ripe) were exposed to a controlled environment to simulate extreme conditions on a salad bar. Colour variation and mechanical-structural changes depended on surface dehydration, exposure time, and ripening stage. Relationship between fractal dimension, lacunarity, and time showed evidence of patterns associated with non-homogeneous colour changes related to structural variations. Fractal metrics had potential to reflect noticeable colour changes that would be useful for monitoring shelf stability of minimally processed papaya.

Hypocholesterolemic and Anticarcinogenic Effect of Vicia faba Protein Hydrolyzates

ABSTRACT In recent years, the consumption of vegetal-source proteins has been studied to determine their preventing effect on the development of several chronic diseases. The initial purpose of this report was to determine the effect of a hypercholesterolemic diet (HCD) given to mice, alone or with azoxymethane (AOM), on various obesity biochemical biomarkers, as well as on the induction of colon aberrant crypts (aberrant crypt foci; ACF). At the end of the 5-week assay, animals fed the HCD showed alterations in the level of total cholesterol, high- and low-density lipoproteins, and in the Atherogenic Index; besides, a significant elevation was observed in the number of ACF. Our second aim was to examine the effect of a Faba Protein Hydrolyzate (FPH) on mice fed the HCD. We first obtained protein hydrolyzates from the seeds of Vicia faba, determined the in vitro antioxidant potential with two tests, and, subsequently, evaluated the effect on obesity biomarkers and on the number of ACF. In the first case, we found that, generally, the best protective effect was obtained with the low dose of FPH (10 mg/kg) administered to animals fed the HCD, and injected AOM. With respect to the number of ACF, we observed that this dose was more effective, inhibiting such lesions to almost the level determined for the normocholesterolemic diet (NCD). Therefore, our results demonstrated the relevance of a HCD to develop anomalies in obesity biomarkers in mouse, as well as to increase the number of precarcinogenic lesions. Our results also showed a protective response with the administration of FPH, particularly with a specific dose, suggesting the need for extending research on the matter by widening the spectra of doses, in order to clearly define its potential to counteract the damage induced by the HCD, as well as to confirm if antioxidation in mice was involved in such an effect.

Morphometric Analysis of Transverse Surface of Fractured Maltodextrin Agglomerates

Fracture creates complex surfaces. The aim of this work was to characterize the irregular surface generated in the fracture of maltodextrin thick-agglomerates using gray level intensities and texture features extracted by digital image analysis. Results showed that particle size had no significant effect on texture features and had a significant interaction with load. A 50 N load caused rougher surfaces, while a 500 N load produced smooth surfaces. Obtained values of texture fractal dimension were not higher than 2.23 and were related to image entropy.

Multiscale and Nanostructural Approach to Fruits Stability

Fruit ripening is a biochemical process that involves irreversible physiological changes leading to senescence. Freshness and quality of fruit depend on the texture, appearance and sensory attributes, which are determined by several biotic and abiotic factors that constrain fruit shelf life. These aspects have been analysed through a number of methods including modern and novel approaches involving a multiscale integration at the nano-, micro-, meso- and macroscales as a way to understand all phenomena as a whole. This chapter includes an explanation of how the multiscale approach by two integrative pathways, nano to macro and macro to nano, might contribute to the understanding of the stability of a complex system by considering cell morphology and some nanoscale technologies to precisely extend fruit stability. In the future, this multiscale approach may lead to the development of novel technological alternatives to retard senescence.

Detection of Cyanuric Acid and Melamine in Infant Formula Powders by Mid-FTIR Spectroscopy and Multivariate Analysis

Chemometric methods using mid-FTIR spectroscopy were developed in order to reduce the time of study of melamine and cyanuric acid in infant formulas. Chemometric models were constructed using the algorithms Partial Least Squares (PLS1, PLS2) and Principal Component Regression (PCR) in order to correlate the IR signal with the levels of melamine or cyanuric acid in the infant formula samples. Results showed that the best correlations were obtained using PLS1 (R2: 0.9998, SEC: 0.0793, and SEP: 0.5545 for melamine and R2: 0.9997, SEC: 0.1074, and SEP: 0.5021 for cyanuric acid). Also, the SIMCA model was studied to distinguish between adulterated formulas and nonadulterated samples, giving optimum discrimination and good interclass distances between samples. Results showed that chemometric models demonstrated a good predictive ability of melamine and cyanuric acid concentrations in infant formulas, showing that this is a rapid and accurate technique to be used in the identification and quantification of these adulterants in infant formulas.

An 1 H NMR-based metabolomic approach to compare the chemical profiling of retail samples of ground roasted and instant coffees

The present non-targeted 1H NMR-based fingerprinting approach along with multivariate analysis established differences between representative aqueous extracts of commercial ground roasted coffee (GRC) and instant (soluble) coffee (IC) samples. The latter were prepared either by spray drying or freeze drying. When comparing a total of 33 compounds between GRC and IC, the latter product contained a remarkable increase in 5-(hydroxymethyl)furfural and carbohydrates, as well as a clear decrease in trigonelline, N-methylpyridinium, caffeine, caffeoylquinic acids and 2-furylmethanol. Furthermore, the current protocol was able to detect the subtle chemical differences between spray-dried and freeze-dried IC. The aforementioned metabolites could serve as target molecules in the attempt to preserve, as much as possible, the organoleptic and nutraceutical properties of GRC during the industrial drying processes used in the production of the two commercial types of IC.

Zeta Potential of Food Matrices

Food matrices contain electrically charged particles, which interact with each other and with the media and are produced via several interface processes and mechanisms. The understanding of electric charge interactions is complex and essential towards the development of food systems since they can determine the type of particle-particle and particle-media interactions. They strongly affect stability, rheological behavior, sedimentation, re-dispersion, filtration, shelf life, texture, flavor, and color; thus, importantly influencing food structure and stability. One of the most useful parameters that allow the study of electric interactions in food systems is the zeta potential (ZP). It is possible to find a variety of laboratory instruments designed for its evaluation. ZP is an important property for the characterization of dispersed systems in which sample preparation and measuring methods play a key role to obtain reliable and reproducible results. The use of this parameter has increased in a number of fluid food systems such as alcoholic beverages, juices, extracts, coffee, milk, yoghurt, and edible films, most of which are described in this review. There is a wide amplitude in the number of relevant publications in the literature involving ZP for different products and this is reflected in the length of the different sections of this document. This work depicts a thorough review of the main theoretical principles, applications, and relevance of this parameter in food science and technology.