TEMPORAL STUDY OF SUCROSE AND FRUCTOSE RELATIVE SWEETNESS

Time-Intensity (T-I) and Gustatory Reaction Time (GRT) methodologies were used to study the relative sweetness of sucrose and fructose at 25C. Eleven panelists evaluated nine concentrations (5 to 45%, w/v) of sucrose and fructose by T-I and seven parameters were determined. Higher values were obtained for fructose at 25, 30 and 35% for Maximum Intensity; at 35, 40 and 45% for the Area Under the Curve; at 40 and 45% for Time to decline the Intensity to half of its maximum value and at 45% for Rate of Increase. Ten subjects evaluated seven concentrations (3 to 15%, w/v) of sucrose and fructose by the GRT procedure. Fructose had shorter GRT than sucrose at 3 and 4.5%. Thus, fructose at 25, 30 and 35%, has a more intense and at 40% more persistent sweetness than sucrose and is detected earlier than sucrose at concentrations near gustatory threshold.     

A COMPARISON OF METHODOLOGY APPLIED TO THE SELECTION OF A PANEL FOR SENSORY EVALUATION OF INSTANT COFFEE

Twenty judges performed a variety of chemosensory tasks in order to select the best scores to form a panel for coffee evaluation. An average of correct responses (P%), one-way analysis of variance (ANOVA) and principal components analysis (PCA) were compared. The tests involved: ability to recognize the four basic tastes, identification and matching of odors, taste intensity evaluation and perception of small differences in taste. P% accounted for 71.17 ± 4.34% and 10 of the judges had scores greater than the final average. ANOVA and PCA resulted in 2 different panels consisting of 9 and 12 judges, respectively. The panel was composed by the nine panelists selected by the three methods. The other three panelists that were doubtful could improve to the point of acceptance with additional training. These methods should be used simultaneously to have more security in the acceptance or rejection of panelists.     

SOURNESS–SWEETNESS INTERACTIONS IN DIFFERENT MEDIA: WHITE WINE,ETHANOL AND WATER*

The aim of this work was to study the sourness–sweetness interactions in water, white wine and alcoholic environment to interpret sweet/sour perception in low concentrations within the range normally encountered in white wine. Nine trained assessors rated sweetness and sourness intensity in mixtures of fructose (11.1, 25.0 and 38.9 mM) and tartaric acid (pH 3.0, 3.4 and 3.8) in water and wine (experiment 1) or ethanol solutions at 2.0, 4.0 and 12.0% v/v (experiment 2). The range of quantitative responses was larger for sourness than for sweetness in the three media. The global sourness intensity perception in wine mixtures was significantly lower than in water and ethanol mixtures, indicating the effect of other wine components. The suppressive effect of tartaric acid on fructose sweetness was stronger than the suppressive effect of fructose on tartaric acid sourness.     

Morphology and phylogenetic interpretation of a new Cambrian edrioasteroid (Echinodermata) from Spain

Abstract: The edrioasteroid, Aragocystites belli gen. nov. sp. nov. from the middle Cambrian Murero Formation of Spain, is described based on a small number of very well‐preserved specimens. Important anatomical characteristics include star‐shaped and pseudoclavate theca, rare or absent epispires, well‐developed interradially positioned oral plates and several unorganized cover plates associated with each widely exposed flooring plate. A phylogenetic analysis including several Cambro–Ordovician species shows it is more derived than Stromatocystites and Totiglobus but is a sister group to a clade comprising Cambraster and Edriodiscus. Ontogenetic observations based on juveniles of 5 mm in diameter suggest that this species changed thecal shape markedly during growth. A. belli gen. nov. sp. nov. probably lived in quiet environments where it attached directly to the sea floor on stabilized substrates.     

Thoracic structure and enrolment style in middle Cambrian Eccaparadoxides pradoanus presages caudalization of the derived trilobite trunk

Abstract: The ability to enrol effectively evolved several times among trilobites. Here, we show that, unlike most redlichiid trilobites that could not enrol, both morphotypes of Eccaparadoxides pradoanus from the middle Cambrian of Spain enrolled so as to enclose most of the ventral surface beneath the exoskeleton and possessed specialized articulating devices that facilitated this behaviour. The holaspid thorax of all E. pradoanus was divided into two principal regions. The boundary between these marked a transition from anterior segments with short pleural spines, fulcra and ridge‐and‐groove inner pleural regions to posterior segments with longer, acuminate pleural spines that lack fulcra and inner pleural regions. Devices that aid articulation, such as fulcra with short articulating pleural surfaces, the petaloid articulating facet and long articulating half rings, are concentrated in the anterior region. These features, and the large number of specimens preserved in various degrees of enrolment, suggest an enrolment procedure in which the rear part of the trunk, containing both the posterior thorax and the pygidium, rotated as a single unit without significant internal flexure. As these posterior trunk articulations were apparently not required to permit enrolment, concentrating flexure in the anterior may have presaged the caudalized condition seen in many derived trilobite groups that encapsulated, in which a larger proportion of the trunk segments were allocated to the mature pygidium, and therefore unable to articulate.     

A COMPUTERIZED SYSTEM FOR CONTROLLING AND MEASURING GUSTATORY REACTION TIMES

Reaction Time (RT) procedures are widely used in cognitive and behavioral experiments. In the sensory realm RT has been traditionally applied to measure visual, auditory or motor responses. The application of the RT method to gustatory stimuli has proved to be difficult. Attempts to develop automatic control techniques have been restrained by difficulties related to the control of variables, e.g. physiochemical characteristics of chemical solutions and the procedure for stimulus presentation. In this report we describe a computer based system that was designed to measure the reaction time to taste solutions dropped on the tongue. The equipment consists of a pumping system, an interface between the computer and the pumping system, the software required to control the interface and to measure reaction time, and a push button to detect the subject's response. The system can be used as a tool for both research and evaluation tests.     

Isolation and characterization of eight polymorphic microsatellite markers from pink conch (Strombus gigas)

Many marine organisms have pelagic larvae, and these are often important agents of dispersal. The larval phase and the multiple paternity that occur in marine gastropods such as Strombus gigas are crucial for the success of this species throughout the Caribbean Sea. To analyse these factors, we developed eight microsatellite loci specific to S. gigas. On the same set of individuals, the microsatellite loci exhibited a greater level of polymorphism than previously studied allozyme markers and thus, will permit fine‐scale analysis and larval pool studies.     

Testing for a decline in diversity prior to extinction: Languedocian (latest mid‐Cambrian) distribution of cinctans (Echinodermata) in the Iberian Chains,NE Spain

Abstract: The middle Cambrian strata of the Iberian Chains (north‐eastern Spain) and the Montagne Noire (southern France) record an adaptative radiation of cinctans and trilobites, which spanned the Leonian–early Languedocian interval. A diachronous diversity peak was reached by both benthic groups when favourable palaeoenvironmental conditions (clayey vs. silty substrates) were established. The acme in diversity was followed by a gradual decline and a barren interval associated with the onset of the mid‐Languedocian regression, well constrained throughout the western Mediterranean region. For trilobites, the aftermath of the regression is characterized by a late‐Languedocian major faunal turnover of families, followed by a renewed Furongian–early Tremadocian radiation related to the stepwise immigration of trilobite invaders from northern and eastern Gondwana, under persistent transgressive conditions. In contrast, the cinctans reappeared only patchily in late‐Languedocian monospecific coquinas and finally disappeared before the Furongian. Thus, the late Languedocian is a crucial interval in which to analyse the decline in diversity and final extinction of cinctans in the aftermath of the mid‐Languedocian regression.