264 research outputs found
Taste sensitivity and multisensory interactions in relation to the nutritional status
No full textINTRODUCTION
Obesity is considered a disease with a multifactorial etiology. Although it is well known that taste plays a crucial role in eating behavior literature data about the relationship between taste and nutritional status are controversial [1-3]. Among the causes involved in the development of this pathology, high availability of high-density energy products has created a favorable environment for the development of overweight. Consumers, however, are becoming more aware of what they eat and looking for low-energy products but which are palatable. Creating new formulations is not an easy task, considering that food perception is the result of multiple sensory modalities, including visual, taste, olfactory, and somatosensory inputs [4]. Some studies have been conducted on sensory interactions between taste and odor [5,6] although these mechanisms have not been considered in relation to the nutritional status of subjects.
Our research group recently conducted studies aimed at the evaluation of: taste sensitivity, in normal-weight (NW) and obese (OB) subjects and multisensory interactions and liking in model foods according to nutritional status.
MATERIALS AND METHODS
Taste sensitivity was assessed in 51 OB (recruited from ICANS) and 52 NW subjects by evaluating the taste thresholds for the basic tastes and fat stimulus (3-AFC, ASTM E679-04) and the fungiform papillae number (FP) [7].
51 OB (recruited from Istituto Auxologico Italiano) and 41 NW women evaluated liking and intensity of sensory properties of custard desserts prepared by adding different concentrations of two flavoring compounds (either vanilla or butter) or a thickener (xanthan gum) to a standard formulation. Three terns of custards desserts were obtained by adding increasing concentrations of vanilla (V1, V2) or butter aroma (B1, B2) or a thickening agent (xanthan, XG1, XG2) to a standard formulation (ST).
RESULTS AND DISCUSSION
The results showed that OB subjects differed in terms of taste sensitivity from NW subjects. More specifically, OB subjects involved were less sensitive to taste stimuli compared to the lean subjects (sweet p<0.001; savory p<0.01; bitter p<0.01; fat p<0.001; sour p<0.05; PF p<0.001).These differences may lead subjects with higher BMI to prefer foods rich, for example, in sugar and fat in order to compensate their reduced sensitivity [8].
Moreover, the multisensory interactions (odor-taste-texture) occurred differently in relation to BMI. Indeed, a model food (custard dessert) modified with aromas and thickener agents produced strongest sensory interactions (odor-taste, odor-flavor and odor-texture) in subjects with higher BMI compared to the control group. The addition of a stimulus signaling high-calorie products, such as butter aroma, modified the perception of different sensory characteristics in a more effective way in obese subjects compared to the normal-weight. For example, obese subjects perceived the modified samples with butter aroma, as significantly sweater (p <0.01) and creamier (p <0.05) than the standard formulation. Significant differences (p<0.05) in liking scores were found in the samples modified with the addition of butter aroma, with higher scores provided by OB compared to NW women. In both groups liking decreased with increasing concentration of thickener agent (p<0.05). No differences in liking scores were found considering samples with different amount of vanilla aroma [9].
CONCLUSIONS
It is evident that investigate the phenomenon of obesity applying an innovative sensory approach is interesting in order to better understand and stem the complex issue of overeating. How the mechanism of brain integration occurs in subjects with different nutritional status might be taken into account in order to develop new food products with a reduced caloric intake but which are still satisfying for the consumer.
ACKNOWLEDGMENTS
We would like to thank the team at the Department of Medical Sciences and Rehabilitation, IRCCS Istituto Auxologico Italiano (Milan, Italy) and the International Center for the Assessment of Nutritional Status (ICANS, Università degli Studi di Milano, Italy), who provided help in recruiting obese subjects.
REFERENCES
[1] De Graaf, C. (2005). D. Mela (Ed.), Food, diet and obesity, Wood head Publishing Limited, Cambridge, England, pp 137-159.
[2]Simchen, U., et al. (2006). Eur J Clin Nutr. 60:698–705.
[3]Bertoli, S., et al. (2014). World J Diabetes. 5(5): 717-723.
[4]Small, D.M. & Prescott, J. (2005). Exp. Brain Res, 166, 345–357.
[5]Lavin, J.G. & Lawless, H.T. (1998). Food Qual Prefer, 9(4), 283–289.
[6]Maga, J.A. (1974). Chem Senses, 1(1),115-119.
[7]Nachtsheim, R, & Schlich, E, (2013). Food Qual Prefer. 29, 137–145.
[8]Proserpio, C., et al. (2016a). Chem Senses, 41, 169–176.
[9]Proserpio, C., et al. (2016b). Appetite, 100, 203-209
Teaching the virtual generation
No full textUsing Gioia and Brass’ 1986 article, “Teaching the TV Generation,” as a point of
departure for considering our current instructional environment, we focus on a relatively
recent development that once again has implications for our teaching pedagogies: that
we are, in fact, no longer teaching a verbal, nor even just a visual, but now a virtual
generation of students. Technological and social changes in the wider environment can
have major implications for teaching and learning pedagogies—i.e., optimal teaching
and learning occur when teaching styles align with learning styles. For that reason, we
consider some key learning principles in light of the learning styles of our current
generation of students, who are quite facile with virtual technologies. We argue that the
effective use of some electronic learning tools can provide useful and engaging means
for their education by addressing this generation’s preferences for virtual media while
also enabling student-directed interactivity (via online searches, games, simulations, etc.).
We first articulate the conceptual grounds for arguing that there has been another shift
in the teaching and learning environment we now face—which implies some necessary
adaptation of traditional learning principles. We then discuss: (a) some technologies and
applications (mainly Internet-based tools and videogames) that can facilitate the
convergence between virtual generation (V-Gen) preferences and classroom interactions;
(b) some guidelines for using these technologies to fulfil these learning principles and; (c)
some pitfalls that can occur and how to avoid them
Kinetic study of vitamin D2 degradation in mushroom powder to improve its applications in fortified foods
No full textThe aim of this study was to develop a value chain approach to address the need for sustainable vitamin D-2 food sources. A combined process of UV-irradiation and air-drying was used to produce a Pleurotus ostreatus powder with a target amount of vitamin D-2 as an ingredient for functional foods. The kinetics of vitamin D-2 degradation was studied as a function of water activity (a(w)) in the range 0.11-0.75 at 30 degrees C, and temperature in the range 20-40 degrees C, at a(w) 0.32. The Guggenheim-Anderson-de Boer equation was applied to model experimental data of moisture content as a function of a(w) at 30 degrees C, and the resulting monolayer water activity was found to correspond to the a(w) level of 0.45. During storage under different environmental conditions, vitamin D-2 degradation followed first-order kinetics. The rate constants ranged from 0.00308 to 0.0121 d(1) at a(w) 0.11 and 0.75 at 30 degrees C, respectively. The Arrhenius equation was applied to calculate the activation energy for vitamin D-2 degradation at a(w) 0.32, which resulted 37.6 kJ/mol. The kinetics data obtained can be used as a basis to design the best formulation strategy to deliver this vitamin with functional foods
Main group element nets to a T
No full textT-shaped nets (three-coordinated nets with an angular metric, bond angles near 90°, 90°, 180°) are found in a number of extended structures. We explore in this paper the geometrical and electronic consequences of a stricter T-shape metric, where the distances between the vertices of the net are approximately equal and in the range of
a chemical bond. Every atom in such a net has a T-shaped environment. One can think of these nets as extensions of BrF3 or of substructures of various extended tellurium compounds. Several construction principles are found which allow an enumeration of a variety of one-, two-, and three-dimensional T-shape nets; not every threecoordinated
net lends itself to the stricter geometrical and distance metric. Not everything is possible; there are no zero-dimensional T-nets, and none made entirely of three atom segments. Previous ideas on electron-rich multicenter bonding lead to a simple way of calculating the magic electron counts for each net; these lie in the range of 6 to
6.67
Site preference of ligand and metal substitution in trigonal-bipyramidal metal carbonyl clusters
No full textGimarc's topological charge stabilization rule (TCS), for addressing site preference, has been extended to the realm of metal carbonyl clusters using Allen's energy indexes (Els) instead of charges. EIs have been computed within the extended Hückel (EH) approximation and, in order to assess an internal electronegativity scale for transition metals and to allow comparisons across the periodic table, a homogeneous set of EH parameters has been determined. EIs have been shown to behave similarly to charges on "clusters" with a rigid ligand stereochemistry like carboranes but, when one deals with metal carbonyl clusters and their intriguing ligand mobility, EIs are definitely superior to charges. EIs do address both "skeletal" and "ligand" site preferences according to the following rules of thumb: (i) more electronegative metal atoms occupy higher El sites of the uniform reference frame (URF) (i.e. the one with the lower local electronegativity) and (ii) (nucleophilic) ligand substitution preferentially occurs on the lowest energy index site of the URF (i.e. the one with the largest electrophilic character). Previous attempts to rationalize site preference in metal clusters were mainly concerned with the relative strengths of metal-metal and metal-ligand bonds and substantially disregarded electronegativity differences between different metal atoms. In contrast, we have shown that the latter are important whenever the actual URF allows for different EIs on different metal sites. In particular, differences in electronegativity have been shown to be important for M5L15and M5L12but not for M5L12bipyramidal metal carbonyl clusters. © 1997 American Chemical Society
Vertex-, face-, point-, Schläfli-, and Delaney-symbols in nets, polyhedra and tilings : recommended terminology
No full textWe review the various kinds of symbols used to characterize the topology of vertices in 3-periodic nets, tiles and polyhedra, and symbols for tilings, making a recommendation for uniform nomenclature where there is some confusion and misapplication of terminology
Designing All Graphdiyne Materials as Graphene Derivatives: Topologically Driven Modulation of Electronic Properties
No full textDesigning new 2D systems with tunable properties is an important subject for science and technology. Starting from graphene, we developed an algorithm to systematically generate 2D carbon crystals belonging to the family of graphdiynes (GDYs) and having different structures and sp/sp2 carbon ratios. We analyze how structural and topological effects can tune the relative stability and the electronic behavior, to propose a rationale for the development of new systems with tailored properties. A total of 26 structures have been generated, including the already known polymorphs such as α-, β-, and γ-GDY. Periodic density functional theory calculations have been employed to optimize the 2D crystal structures and to compute the total energy, the band structure, and the density of states. Relative energies with respect to graphene have been found to increase when the values of the carbon sp/sp2 ratio increase, following however different trends based on the peculiar topologies present in the crystals. These topologies also influence the band structure, giving rise to semiconductors with a finite band gap, zero-gap semiconductors displaying Dirac cones, or metallic systems. The different trends allow identifying some topological effects as possible guidelines in the design of new 2D carbon materials beyond graphene
Strutture fluorurate altamente interpenetrate: autoassemblaggio tramite legame ad alogeno
No full textStudi EPR di radicali indotti per irraggiamento gamma di solidi porosi modulari dello Zn contenenti molecole guest
No full text- …
