M. Cornejo-Mazón

Effect of Thermal Treatment on the Antioxidant Activity and Content of Carotenoids and Phenolic Compounds of Cactus Pear Cladodes (Opuntia ficus-indica)

Cactus pears (Opuntia ficus-indica) are draught resistant plants originated in Mexico. Their flattened stem segments, called cladodes, have moisture, protein and fibre contents of 92, 1-2 and 4-6% respectively, and a pectin content in the range of 0.8-3.3% depending on the species. They also contain certain concentration of carotenoids which are of special interest because of their antioxidant activity. This work is aimed to identify and quantify the main carotenoids present in the stems and to evaluate the effect of thermal treatments on the antioxidant activity and concentration of carotenoids and phenolic compounds. The carotenoids -cryptoxanthin, -carotene and lutein were identified in the cladodes, the latter having the highest concentration. Thermal treatments increased the extractability of these pigments and the antioxidant activity was related to the carotenoids concentration. Total phenolic content decreased after the thermal treatments; however this result had little effect on the antioxidant activity. Mucilage present in the stems decreased the extractability of the carotenoids.

Effect of different treatments on the ability of α-lactalbumin to form nanoparticles

Nanoparticles of bovine α-lactalbumin (α-LA) prepared by desolvation and glutaraldehyde crosslinking are promising carriers for bioactive compounds in foods. The objective of this work was to study the effect of changes in hydrophobic interactions by using different desolvating agents (acetone, ethanol, or isopropanol) and the use of a heat or high-pressure treatment step before the desolvation process on the size, structure, and properties of α-LA nanoparticles. In all cases, a high average particle yield of 99.63% was obtained. Smaller sizes (152.3 nm) can be obtained with the use of acetone as the desolvating agent and without any pretreatment. This is the first time that α-LA nanoparticles in the size range of 100 to 200 nm have been obtained. These nanoparticles, with an isoelectric point of 3.61, are very stable at pH values >4.8, based on their ζ-potential, although their antioxidant activity is weak. The use of the desolvating agent with the smallest polarity index (isopropanol) produced the largest particles (293.4 to 324.9 nm) in all cases. These results support the idea that controlling hydrophobic interactions is a means to control the size of α-LA nanoparticles. No effect of pretreatment on nanoparticle size could be detected. All types of nanoparticles were easily degraded by the proteolytic enzymes assayed.

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.

Polysaccharide-Based Nanoparticles

The use of natural polymers such as polysaccharides in the design of nanoparticles for the protection and delivery of bioactive compounds and nutrients has acquired great importance. These polymers have many advantages including biocompatibility, biodegradability and in some cases bioactivity. They are abundant in nature and are obtained from plant materials and crustacean exoskeletons. Polysaccharides which have been used for the preparation of nanoparticles include starch, dextran, cellulose, pectin, chitin, chitosan, alginates and carrageenans among others. There are also several methods to form the particles including ionotropic gelation, spraying, spray drying, acid hydrolysis, ultrasound, homogenization, etc. This chapter intends to review these techniques, the characteristics of the nanoparticles and some of their applications.

Protein-Based Nanoparticles

Considerable research has been done recently in the field of protein-based nanoparticles as a system for bioactive compounds delivery. These carriers have considerable stability during storage as well as in vivo. Different proteins have been used for this purpose which include water-soluble and insoluble molecules with diverse encapsulating capacities. The preparation methods are also diverse and include among others emulsification, desolvation, coacervation, nanoprecipitation, liquid–liquid dispersion, and electrohydrodinamic atomization. This review presents different contributions to the field of protein nanoparticles dealing with the applications of different methods to diverse proteins and bioactive compounds.

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.

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.

Food Matrix Structure Quality Preservation: Water Removal Operation Conditions Control During Convective Drying

Food product development (FPD) is a systematic task with the objective of generating new products by either modifying any existing or producing a new and original one. Driven by consumers’ expectations, new knowledge, globalization, and shorter product cycles, among others, companies must survive in a dynamic and often unpredictable markets characterized by high levels of competitiveness (De-Greef et al. 2014).