M. L. Herrera

Classical conditioning in the vegetative and minimally conscious state

Pavlovian trace conditioning depends on the temporal gap between the conditioned and unconditioned stimuli. It requires, in mammals, functional medial temporal lobe structures and, in humans, explicit knowledge of the temporal contingency. It is therefore considered to be a plausible objective test to assess awareness without relying on explicit reports. We found that individuals with disorders of consciousness (DOCs), despite being unable to report awareness explicitly, were able to learn this procedure. Learning was specific and showed an anticipatory electromyographic response to the aversive conditioning stimulus, which was substantially stronger than to the control stimulus and was augmented as the aversive stimulus approached. The amount of learning correlated with the degree of cortical atrophy and was a good indicator of recovery. None of these effects were observed in control subjects under the effect of anesthesia (propofol). Our results suggest that individuals with DOCs might have partially preserved conscious processing, which cannot be mediated by explicit reports and is not detected by behavioral assessment.

Nano and Micro Food Emulsions

Emulsions with microdroplets, sometimes called conventional emulsions, and nanodispersions, or thermodynamically stable emulsions (surprisingly called microemulsions), can be easily manufactured on an industrial scale up. Due to their satisfactory stability over a certain storage time and high bioavailability, they have attained particular interest as delivery systems for bioactive substances, such as carotenoids, phytostetol, polyunsaturated fatty acids, g-oryzanol, lipophilic vitamins, and numerous other compounds. Garti and co-workers (Amar et al. 2003; Spernath et al. 2002), for example, prepared food-grade conventional emulsions containing carotenoids with considerable success. Recently, studies have shown the successful approach of using nanoemulsions to improve stability in food applications. Tan and Nakajima (2005) and Yuan et al. (2008) prepared β-carotene nanodispersions using high-pressure homogenization and studied their physicochemical properties. Other applications include the encapsulation of limonene, lutein, omega-3 fatty acids, astaxantin, and lycopene (Chen et al. 2006), the encapsulation of α-tocopherol to reduce lipid oxidation in fish oil (Weiss et al. 2006), and the use of nanoemulsions to incorporate essential oils, oleoresins, and oil-based natural flavors into food products such as carbonated beverages and salad dressings (Ochomogo and Monsalve-Gonzalez 2009).

Colloidal properties of sodium caseinate-stabilized nanoemulsions prepared by a combination of a high-energy homogenization and evaporative ripening methods

Nanoemulsions stabilized by sodium caseinate (NaCas) were prepared using a combination of a high-energy homogenization and evaporative ripening methods. The effects of protein concentration and sucrose addition on physical properties were analyzed by dynamic light scattering (DLS), Turbiscan analysis, confocal laser scanning microscopy (CLSM) and small angle X-ray scattering (SAXS). Droplets sizes were smaller (~100nm in diameter) than the ones obtained by other methods (200 to 2000nm in diameter). The stability behavior was also different. These emulsions were not destabilized by creaming. As droplets were so small, gravitational forces were negligible. On the contrary, when they showed destabilization the main mechanism was flocculation. Stability of nanoemulsions increased with increasing protein concentrations. Nanoemulsions with 3 or 4wt% NaCas were slightly turbid systems that remained stable for at least two months. According to SAXS and Turbiscan results, aggregates remained in the nano range showing small tendency to aggregation. In those systems, interactive forces were weak due to the small diameter of flocs.

Conditions to Prolonged Release of Microencapsulated Carvacrol on Alginate Films as Affected by Emulsifier Type and PH

Alginate from algal biomass is used as edible film and the incorporation of antimicrobial agents improves its performance to increase the shelf-life of fresh foods. However, environmental conditions and intrinsic properties of films influence their release. The aim of this study was to investigate the effect of the concentration and type of encapsulating agent and pH of emulsions on the physical and antimicrobial properties of alginate-carvacrol films. Films containing alginate, carvacrol as antimicrobial agent, and Tween 20 or trehalose (0.25 and 0.75% w/w) as encapsulating agents were obtained from suspensions at pH 4 and pH 8. Physical characterization of emulsions and films and antimicrobial properties (E. coli and B. cinerea) was evaluated. Results showed that droplets size depended on trehalose concentration, but emulsion stability depended on pH and type of encapsulating agent, being more stable samples with trehalose at pH 4. Although films with Tween 20 presented the highest opacity, they showed the best antimicrobial properties at initial time; however, during storage time, they lost their activity before samples with trehalose and relative humidity (RH) was the principal factor to influence their release. Therefore, sample formulated with 0.25% trehalose at pH 4 and stored at 75% RH had the best potential as edible film for fresh fruits.

Applications of Confocal Laser Scanning Microscopy (CLSM) in Foods

Much of the work in the area of physical properties of fats is aimed at determining the relationship among triglyceride structure, crystal properties, crystallization conditions, and macroscopic properties of fats. In finished product containing fat, some of these many macroscopic properties include spredability of margarine, butter and spreads; snap of chocolate; blooming of chocolate; and graininess, smoothness, mouthfeel, water binding, and emulsion stability of spreads [1]. Plastic fats consist of a crystal network in a continuous oil matrix. Many articles in the past have been focused on establishing relationships between lipid composition or polymorphism and macroscopic properties of fats without much consideration of the microstructure of the fat crystal network. Germane to a thorough understanding of plastic fat rheology is a characterization of its microstructure. Not including microstructure as a variable will lead to failure in the prediction of macroscopic properties. In many other non fat or low fat products macroscopic properties depend on their structural organization. Emulsion stability, which is one of the most important physical properties of multiple-phase systems, is strongly determined by oil droplet size and interactions among components that determine spatial distribution of lipid and aqueous phases. Thus, control of food properties for various applications requires a better understanding of the relationships between the food microstructure and macroscopic properties.

New insights about flocculation process in sodium caseinate-stabilized emulsions

Flocculation process was studied in emulsions formulated with 10wt.% sunflower oil, 2, 5 or 7.5wt.% NaCas, and with or without addition of sucrose (0, 5, 10, 15, 20 or 30wt.%). Two different processing conditions were used to prepare emulsions: ultraturrax homogenization or further homogenization by ultrasound. Emulsions with droplets with diameters above (coarse) or below (fine) 1μm were obtained. Emulsions were analyzed for droplet size distribution by static light scattering (SLS), stability by Turbiscan, and structure by confocal laser scanning microscopy (CLSM) and small angle X-ray scattering (SAXS). SAXS data were fitted by a theoretical model that considered a system composed of poly dispersed spheres with repulsive interaction and presence of aggregates. Flocculation behavior was caused by the self-assembly properties of NaCas, but the process was more closely related to interfacial protein content than micelles concentration in the aqueous phase. The results indicated that casein aggregation was strongly affected by disaccharide addition, hydrophobic interaction of the emulsion droplets, and interactions among interfacial protein molecules. The structural changes detected in the protein micelles in different environments allowed understanding the macroscopic physical behavior observed in concentrated NaCas emulsions.

Relationship between nano/micro structure and physical properties of TiO 2 -sodium caseinate composite films

Films obtained by casting, starting from conventional emulsions (CE), nanoemulsions (NE) or their gels, which led to different structures, with the aim of explore the relationship between structure and physical properties, were prepared. Sodium caseinate was used as the matrix, glycerol as plasticizer, glucono-delta-lactone as acidulant to form the gels, and TiO2 nanoparticles as reinforcement to improve physical behavior. Structural characterization was performed by SAXS and WAXS (Small and Wide Angle X-ray Scattering, respectively), combined with confocal and scanning electron microscopy. The results demonstrate that the incorporation of the lipid phase does not notably modify the mechanical properties of the films compared to solution films. Films from NE were more stable against oil release than those from CE. Incorporation of TiO2 improved mechanical properties as measured by dynamical mechanical analysis (DMA) and uniaxial tensile tests. TiO2 macroscopic spatial distribution homogeneity and the nanostructure character of NE films were confirmed by mapping the q-dependent scattering intensity in scanning SAXS experiments. SAXS microscopies indicated a higher intrinsic homogeneity of NE films compared to CE films, independently of the TiO2 load. NE-films containing structures with smaller and more homogeneously distributed building blocks showed greater potential for food applications than the films prepared from sodium caseinate solutions, which are the best known films.

Trans Fats Replacement Solutions in South America

Publisher Summary The dietary intake of Trans Fatty Acids (TFAs) contents produced during hydrogenation and used to make margarines and shortenings has been considered to have a negative impact on cardio-vascular health, as well as to contribute to the occurrence of some cancers, among other diseases. Scientific research connecting trans fats consumption to an increased risk in the occurrence of such diseases resulted in regulatory changes through legislation and actions of governmental and nongovernmental organizations and health agencies in different countries. This chapter focuses on the trans fats replacement solutions in South America. It considers the regulation of trans fats and intake recommendation in Brazil and Argentina, TFA content of Brazilian and Argentinean foods before and after mandatory trans fat labeling, and alternatives to reduce trans fat in foods in Brazil and Argentina. The processes used for modification of fats without the formation of trans fat are total hydrogenation, interesterification, and fractionation. Changes in the hydrogenation process used to produce low amounts of trans isomers have been reported. As a part of trans fat replacement solutions, in addition to vegetable oils with high oxidative stability, such as high-oleic sunflower oil and bovine sebum when solids are required, other solutions may be applicable to the Argentinean industry.

Methods for Stability Studies

The efficient development and production of high-quality emulsion-based products depend on knowledge of their physicochemical properties and stability. A wide variety of different analytical techniques and methodologies have been developed to characterize the properties of food emulsions. Analytical instruments and experimental methodologies are needed for research and development purposes to elucidate the relationship between droplet characteristics and the bulk physicochemical and sensory properties of food emulsions, such as stability, texture, flavor, and appearance. They are also needed in quality control laboratories and in food production factories to monitor food emulsions and their components before, during, and after production so as to ensure that their properties conform to predefined quality criteria and/or to predict how the final product will behave during storage. This chapter describes the most commonly used methods for stability studies, with a focus on conventional food emulsions. Some of these techniques are also used in nanoemulsions. Several examples of applications are described in detail.