bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Accuracy of Galerkin Methods in the Time Domain
Authors: Fung T.C.
Published: March 2007

In this article, the solution accuracy of the time Galerkin methods is studied. The Bubnov-Galerkin method and the Petrov-Galerkin method are considered. The second-order differential equations are expressed in the first-order form before the Galerkin methods are applied. It is well known that the orders of accuracy for the Bubnov-Galerkin method and the Petrov-Galerkin method are m and 2m, respectively, at the end of a time interval if polynomials with m undetermined coefficients are used as interpolation functions in the time inter val. In this article, the accuracy of the interpolated solutions within the time interval is investigated by making a comparison with the exact solutions. It is found that the order of accuracy for both the Bubnov-Galerkin method and the Petrov-Galerkin method is, in general, m only within the time interval under consideration. It is also found that there are some locations with one order higher in accuracy. Besides, it is shown that for the Petrov-Galerkin method to maintain higher order accuracy at the end of the time interval, the excitation should be accurate up to order 2m.
Damage Diagnosis of Rotors: Application of Hilbert Transform and Multihypothesis Testing
Authors: Feldman Michael , Seibold Susanne
Published: March 2007

In this paper, a combined approach to damage diagnosis of rotors is proposed. The intention is to employ signal-based as well as model-based procedures for an improved detection of size and location of the damage. In the first step, Hilbert transform signal-processing techniques allow for a computation of the signal envelope and the instantaneous frequency, so that various types of nonlinearities due to damage may be identified and classified based on measured response data. In the second step, a multihypothesis bank of Kalman filters is employed for the detection of the size and location of the damage based on the information of the type of damage provided by the results of the Hilbert transform.
Active Vibration Isolation of Multi-Degree-of-Freedom Systems
Authors: Haddad Wassim M. , Razavi Ali , Hyland David C.
Published: March 2007

One of the principal objectives of vibration isolation technology is to isolate sensitive equipment from a vibrating structure or to isolate the structure from an uncertain exogenous disturbance source. In this paper, a dynamic observer-based active isolator is proposed that guarantees closed-loop asymptotic stabil ity and disturbance decoupling between the vibrating structure and isolated structure. The proposed active isolator is applied to a uniaxial vibrational system and compared to an optimal linear-quadratic design.
Partial and Segmented Modal Sensors for Beam Structures
Authors: Friswell M.I.
Published: March 2007

The idea of using shaped sensors, and to a lesser extent actuators, for beam- and plate-type structures has been a subject of intense interest for many years. Typically for beam-type problems, the sensor width is varied along the length of the beam. The shape of the sensor is obtained by considering the modes of the beam and usually requires that the sensor covers the whole beam. This paper extends the previous results for distributed sensors for beams in two ways: the optimum sensor shapes that cover only a portion of the beam-type structures are derived and the optimum shapes for segmented sensors, that enable multiple modes to be sensed, are derived. The effect of geometric tolerances and the sensor output response to higher modes has been established. Although it is possible to derive the required sensor shapes, geometric tolerances will often make these sensors difficult to manufacture. The approach is demonstrated with a pinned-pinned beam example.
Ship Vibration Control Using a Force-Adjustable Mechanical Actuator
Authors: Cho Dae-Seung , Lee Soo-Mok , Chung Kyoon-Yang
Published: March 2007

A mechanical actuator to generate adjustable force and its control algorithm have been developed to reduce ship structural vibration of a single harmonic component of main engine rotating frequency The actuator generates a unidirectional sinusoidal force using the vectorial sum of centrifugal forces of two coun terrotating unbalanced masses. The adjustable-force generation during its operation has been embodied by the mechanism to adjust the eccentric distance of the mass using a link system. The control algorithm using the vibration magnitude and phase signals of both the actuator and main engine has been adopted to reduce ship structural vibration. The algorithm automatically detects the optimal phase and force magnitude. That should be supplied by using the variation of controlled vibratory response according to the phase difference between the main engine and the actuator. This algorithm can be applied without any prior identification of the dynamic characteristics of ship structures. In the control experiments for the superstructure vibration of two large merchant ships, the developed system showed good performance in reducing the vibration levels to 1/6 ~ 1/2 of the uncontrolled levels.
Fuel/Time Optimal Control of Flexible Space Structures: A Frequency Domain Approach
Authors: Hartmann Rolf , Singh Tarunraj
Published: March 2007

This paper considers the design of open-loop fuel/time optimal controllers for flexible space struc tures using a frequency domain approach. The control system consists of a time-delay filter whose output signal is the optimal control profile when it is subject to a step input. A constrained parameter optimization problem is formulated to minimize a weighted combination of fuel consumed and total maneuver time for a rest-to-rest maneuver. The parameters to be optimized for are the delays of a time-delay filter. The number of switches of the fuel/time optimal control profile is shown to be a function not only of number of flexible modes but also of the weighting parameter, which is illustrated via numerical examples.
Stability of Journal Bearing-Rotor Systems With Interval- Bearing Parameters
Authors: Moustafa Kamal A.F.
Published: March 2007

This paper addresses the stability problem of vibrating rotors supported by hydrodynamic journal bearings with interval parameters. Bearing oil film properties change considerably with changing operating conditions, and bearing clearance can only be known within a certain tolerance interval. This leads to substan tial changes in the stability conditions of the underlying system. The considered vibrating system is modeled such that the oil film coefficients are intervals rather than single-valued quantities. Each stiffness and damp ing coefficient is given as a range of values. An interval analysis technique is applied to evaluate the stability of the system. Numerical simulations are presented to illustrate the results.
Bridging the Discharge Process: Staff and Client Experiences Over Time
Authors: Forchuk Cheryl , Schofield Ruth , Martin Mary-Lou , Sircelj Matthew , Woodcox Vicki , Jewell Jackie , Valledor Tessie , Overby Barbara , Chan Lilian
Published: March 2007

Before the "Bridge to Discharge" innovation, hospital and community services were largely separate, and the consumer group was rarely included in direct clinical issues. The "Bridge to Discharge"project involves a partnership among a psychiatric hospital schizophrenia program, a public health program, and a consumer group to assist indi viduals who had experienced lengthy psychiatric admissions reintegrate into the com munity. This article reports the qualitative evaluation of client and staff responses every other month regarding the changes in this project. Clients described "hope"for a life outside the hospital and the importance of working with staff they knew. Role changes for both the inpatient nurses and the public health nurse reflect role expan sions and a broader attention to client issues. Partnerships among hospital, communi ty, and consumer groups have the potential to assist clients to make the transition to successful community living. Understanding the changes over time resulting from inno vations will assist nurses and others in planning for appropriate services and sup ports. ( J Am Psychiatr Nurses Assoc [1998]. 4, 128-133)
Perception is the Thing: Presenting Variant Worldviews in the International Business Communication Classroom
Authors: Limaye Mohan R.
Published: March 2007

Two assumptions underlie the teaching of international business communication. First, perceptual variations exist within a country, and they sharpen even more across countries and cultures. International business communication students need to be aware of such differences on substantive issues. Second, critical pedagogy maintains that making students think and revisit their worldviews through an encounter with discomforting or decentering ideas is a valuable teaching and learn ing tool. Exposing students in my class to controversial propositions caused them to demonstrate a gamut of reactions from agreement and disagreement to anger, pity, disbelief, and a sense of discovery.
Peer versus Self Assessment of Oral Business Presentation Performance
Authors: Campbell Kim Sydow , Mothersbaugh David L. , Brammer Charlotte , Taylor Timothy
Published: March 2007

Pedagogical practice related to oral business presentations has received little research attention despite the pervasiveness of oral presentations in business class rooms and their perceived importance to workplace success. This study collected data on three groups (self, peers, and instructor) to address four research ques tions related to (a) the usefulness of self and peer ratings as substitutes for instruc, tor evaluation of oral business presentations and (b) the relationship between vari ous content and non-content factors on overall perceptions of presentation quality. Data from this study suggest that (1) both holistic and analytical peer assessments are reasonable substitutes for instructor assessment when raters are trained; (2) self assessment does not closely reflect either peer or instructor assessments; and (3) peer assessment of delivery characteristics, command of material, and content strongly predict peer ratings of overall presentation quality.
The Business of the Business Writing Center
Authors: Griffin Frank
Published: March 2007

The question of how best to serve students in a business writing center leads to a consideration of the rhetorical relationship among students, writing center consult ants, teaching faculty, and employers in the students' professions. Most rhetorical models consider only the writing center as occupying the middle ground between students and teaching faculty. A revision of that model, one in which the writing center and teaching faculty share the middle ground, is more appropriate for a business writing center. Moreover, writing assignments best serve business student writers when students must situate themselves within the discourse community of a post-graduation employer. Instead of fostering an adversarial relationship, business writing centers function most effectively for students when the center complements the classroom faculty.
Management Communication Strategy in Case Assignments: The Double-Message Approach
Authors: Stevens Betsy
Published: March 2007

Case studies, used extensively in business communication classes, offer an advantage by presenting students with real-life situations to which they can respond using writ ten business genres. Cases, however, limited by their cryp tic and condensed nature, may not fully communicate the context of the event. Understanding context has become increasingly important as issues of race, gender, and mul ticultual communication have emerged in the workplace. The double-message approach offers a solution by asking students to write a context memorandum along with their response to the case protagonist.
Teaching Listening: Some Thoughts on Behavioral Approaches
Authors: Brownell Judi
Published: March 2007

This paper provides an overview of the issues involved in providing listening instruction to those who work or who are preparing to work in organizations. Questions are posed regarding the nature of listening and listening instruction. A behavioral approach is suggested, and the benefits and concerns regarding this perspective are examined.
Augmenting Instruction in Business Communication Courses with the Internet
Authors: Cohen Lance
Published: March 2007

Faced with shrinking budgets and changing standards at their colleges and universities, instructors of business communication are looking for new ways to prepare stu dents for careers in business. Using computer-mediated technologies, instructors can develop activities outside the classroom to motivate and inform students. Augmenting business communication courses with e-mail and Internet protocols, instructors can reach larger segments of their classes, stimulate discussions, create simulations, and strengthen their relationships with students. Using imagi native techniques, students and instructors can work together to develop a new kind of educational community whose communications are mediated by computers.
Business Communication Technologies: A New Course
Authors: Clampitt Phillip G. , Meyer Tim
Published: March 2007

This article describes a new course that focuses on the impact of evolving communication technologies on business. Two core questions are addressed in the class: First, how does a manager or employee choose the appropriate channel for a given communication situation? Second, how does an organization choose which technologies are appropriate for its business needs? In the course, we answer those questions by examining strategic models, assessing specific technologies, and presenting case studies. The article discusses these ideas and evaluates the effectiveness of the course.
Building a Model for Distance Collaboration in the Computer-Assisted Business Communication Classroom
Authors: Sanders Lopez Elizabeth , Nagelhout Edwin
Published: March 2007

Traditionally, research about collaboration in business communication classes has focused on small-group interaction and peer review of documents. Yet, computer classrooms and electronic networks used for teaching business communication today are affecting how traditional collaboration works and are opening up new possibilities for collaborative activity. One exciting possibility is using network technology to promote collaboration beyond the four walls of a single classroom. This article outlines a model for distance collaboration between business writing classrooms using network technology and discusses new ways to teach national and international audience awareness, problem solving, and the contextual nature of cases.
The Status of Computer Use in Business Commu nication Instruction
Authors: Nelson Sandra J. , Smith Douglas C. , Mayer Kenneth R. , Galle William P.
Published: March 2007

The results of an ABC Undergraduate Studies Committee survey of members to determine the status of computer use in business communication courses are presented in this article. The majority of business communication instructors require students to complete all assignments on the com puter, and some instructors provide software training. Stu dents predominantly are using WordPerfect on networked IBM or IBM-compatible computers in labs managed by the college.
Capacity for Empathy: Confronting Discrimina tion in Managing Multi cultural Work Force Diversity
Authors: King Albert S.
Published: March 2007

This commentary focuses exclusively on problems of dis crimination as a major obstruction in managing diversity and incorporates an experiential training exercise for con fronting discrimination to better understand the difficulties in "going beyond equality" in managing diversity. The exer cise communicates the needed capacity for empathy or ability to cope with the emotional reactions of unequal treat ment that inevitably occur when socially or ethnically dif ferent people work together in organizations. The exercise and results of a recent field study reported herein focus on traditional forms of black and white discrimination. How ever, the procedure and instrument are general and may be modified to fit unique situations.
Faculty Perceptions of Students' Business Communication Needs
Authors: Plutsky Susan
Published: March 2007

Today's student populations comprise more minority students, more students for whom English is a second language, and more older students than in the past. These changes prompted this descriptive study in which business faculty members' perceptions about the business commumcation curriculum are examined. Faculty perceive their students to have problems with basic writing skills as well as with sophisticated writing concepts and techniques. Faculty seem to agree on the content that should be included in a business communi cation course. As a result, guidelines are recommended for those who revise the business communication course.
A User-Oriented Focus to Evaluating Accountants' Writing Skills
Authors: Catanach Anthony H. , Golen Steven
Published: March 2007

Accounting educators recently have focused increased attention on the role of the formal curriculum in developing writing skills. Prior research results may be of limited use in curriculum development because these studies rely almost exclusively on the testing of accountants. This article argues that the user of accounting information also is an important party in the communication process. Therefore, the user's input should be considered when evaluating the writing skills of accountants.
Intercultural Differences Between Chinese and Americans in Business
Authors: Nowak Laura , Dong D.
Published: March 2007

As business relationships with China increase, management of multinational enterprises and joint ventures in the U.S. and in China realizes that success depends on attention to cultural differences. This article was written by a Chi nese professor of business communication who benefited from a business internship in San Francisco and an American professor of finance who wit nessed cultural differences in business during a recent exchange visit in Shanghai. The article highlights several cultural differences that promote understanding and reduce the difficulties of dealing with these disparate cul tures. The Chinese point of view of these cultural differences makes this article uniquely valuable.
An Implementation Model for a Communication Across the Curriculum Program
Authors: Jankovich Jackie L. , Powell Karen Sterkel
Published: March 2007

In response to the demand for business graduates with good communication skills, many schools are examining ways to enhance and strengthen their com munication programs to ensure students' development of these skills. This paper presents a model for implementing a Communication Across the Cur riculum (CAC) program that is based on an integrated approach to developing students'communication skills. The model is based on the authors'experience as coordinators of the CAC program at their university.
The Frequency and Seriousness of Communication Barriers in the Auditor- Client Relationship
Authors: Golen Steven P. , Catanach Anthony H. , Moeckel Cindy
Published: March 2007

The accounting profession has called for increased attention to communica tion skill development in accounting curricula. Since independent accountants rely extensively on client communications when gathering evidence during external audits, identifying and minimizing communication barriers with clients can improve audit efficiency and effectiveness. This study evaluated client perceptions of the seriousness and frequency of potential communica tion barriers in external audits. Factor analysis revealed both a credibility/background factor and hostility/conflict factor to be the most seri ous barriers. Subjects perceived personality differences, "know-it-all" attitude, "either-or" thinking, resistance to change, and jumping to conclusions as occurring most frequently.
Writing on the Front Line: A Study of Workplace Writing
Authors: Mabrito Mark
Published: March 2007

Althoteoh researchers have studied extensively the workplace writing of col lege-degreed professionals, less is known about the writing habits of those without such degrees. This study examined the on-the-job writing of one such group—60 front-line supervisors in a Midwest steel manufacturing plant. Responses to a questionnaire, interviews, and an analysis of 246 documents produced information about the frequency, type, purpose, and length of writ ing produced along with the challenges the supervisors faced as writers on the job. This information will help business communications instructors enhance their understanding of writing on the front line.
Connecting Accounting and Communication: A Survey of Public Accounting Firms
Authors: Stowers Robert H. , White G.Thomas
Published: March 2007

Communication skills are valued highly in public accounting firms, where profes sionals at all levels communicate as part of their jobs. However, respondents to a 1997 survey reported that the development of effective communication skills was not part of formal accounting education and that partners and managers want their entry-level professionals to have these skills at the onset. Further, these skills increase in importance as accounting professionals progress from entry-level to manager to partner. Educational institutions need to develop programs that include communication topics and courses to prepare accountants for the challenges of their profession.
Effects of high hydrostatic pressure processing and of glucose oxidase-catalase addition on the color stability and sensorial score of grape juice / Efectos del tratamiento con altas presiones y de la adición de glucosa oxidasa-catalasa en la estabilidad del color y en la evaluación sensorial del zumo de uva
Authors: Castellari M. , Matricardi L. , Arfelli G. , Carpi G. , Galassi S.
Published: March 2007

The effects of high hydrostatic pressure treatment (HHP) and the use of glucose oxidase-catalase enzymes on the color stability of a white grape juice were studied. The cold-prepared grape juice was stored for three weeks at 5 °C and evaluated for color and non-flavonoid phenolic content. The HHP treatments at 600 and 900 MPa slowed the degradation of non-flavonoid phenolics and reduced the rate of the browning during storage. No significant effect on the color was observed using 300 MPa. Further color stabilization was obtained using glucose oxidase-catalase enzymes and by setting the initial temperature of water inside the pressure vessel at 50 °C prior to HHP treatment. The sensory analyses indicated that enzymes and HHP improved the aroma and taste of juices; by contrast, oper ating the HHP process at an initial temperature of 50 °C showed no significant effect.
Linear and non-linear viscoelasticity of low-in-cholesterol mayonnaise / Viscoelasticidad lineal y no lineal de mayonesas con bajo contenido en colesterol
Authors: Guerrero A. , Partal P. , Gallegos C.
Published: March 2007

Five different mayonnaise products were prepared with constant composition except for the type of egg product used. The linear viscoelastic functions were superposed using a time-temperature su perposition method and the shift-factor showed an Arrhenius-like temperature dependence. The ther mal susceptibility was found to be higher for processed-egg-containing mayonnaise and when egg yolk was used instead of whole egg as the emulsifier. Transient flow curves always showed a stress overshoot, but a stress undershoot was found for whole-egg-containing emulsions at high shear rates. Processed yolk gave rise to higher storage modulus values than did native yolk. This effect lost sig nificance when yolk was diluted by native egg white. Mayonnaise made from egg yolk was always more viscous and did not show a stress undershoot in transient flow. The non-linear relaxation modulus was factorized as the product of the linear relaxation modulus and the damping function. Hence, the Wagner model was able to predict the transient flow of these emulsions fairly well. However, this model failed at low shear rates. This fact may be explained on the basis of wall-slip phenomena.
Lubricated squeezing flow viscometry for dulce de leche (milk sweet) Viscometría de extensión biaxial sin fricción de dulce de leche
Authors: Corradini M.G. , Peleg M.
Published: March 2007

Commercial samples of dulce de leche (milk sweet, caramel jam) of two types, made by two different manufacturers were squeezed between two parallel Teflon® plates, 64 mm in diameter. The initial height of the samples was about 8 mm and they were compressed to 0.4 mm at rates of 0.1, 0.2, 0.3 and 0.4 mm/s. After the samples had reached the final height, they were allowed to relax for about 3 min. The force-height relationships, when plotted on logarithmic coordinates, had a clearly discern ible linear region, with slope in the range of -1.1 to -1.5. The apparent stress at pre-selected heights was used as a measure of the product consistency. The experimental scatter of these stresses was in the order of the 10%, small enough to detect differences between the different brands and monitor rate effects. The latter did not conform to theoretical predictions based on the power law model, most probably because of the products' considerable apparent yield stress on the experimental time scale. An empirical formula to describe the rate effect was developed and found to be appropriate for all the products tested. The yield stress itself was manifested in the magnitude of the residual stress after relaxation. It could also be used as a measure of consistency which provided the same ranking of the samples as the apparent stress at a fixed height.
Review: Technological and organoleptic issues pertaining to cheeses with denomination of origin manufactured in the Iberian Peninsula from ovine and caprine milks Revisión: Aspectos tecnológicos y sensoriales de quesos con denominación de origen elaborados en la Península Ibérica con leche de oveja y de cabra
Authors: Freitas A.C. , Macedo A.C. , Malcata F.X.
Published: March 2007

A few European countries have created Appélations d'Origine Protegée (AOP) in order to support legal protection and hence promote enforcement of high-quality standards of selected food products. This paper comprehensively reviews and updates fundamental and applied aspects encompassing tech nological and organoleptic characteristics of AOP traditional cheeses manufactured in the Iberian Peninsula, from ovine and/or caprine milks. Those cheeses from Portugal and Spain can be divided into four distinctive groups, based on milk source and rennet type: ( i) Azeitão, Castelo Branco, Évora, Nisa, Serpa, Serra da Estrela and La Serena cheeses, manufactured with raw ovine milk and coagulated via plant rennet; ( ii) Terrincho, Idiazábal, Manchego, Roncal and Zamorano cheeses, elaborated with raw ovine milk and coagulated via animal rennet; ( iii) Cabra Transmontano and Majorero cheeses, manufac tured with raw caprine milk and coagulated via animal rennet; and ( iv) Amarelo da Beira Baixa, Picante da Beira Baixa and Rabaçal cheeses, manufactured with mixtures of raw ovine and caprine milks and coagulated via animal rennet. Considerable differences between Portuguese and Spanish AOP cheeses exist; the former are, in general, characterized by softer consistencies and similarities to one another in terms of manufacturing protocols (usually encompassing coagulation of plain raw milk followed by slow draining of the curd), whereas the latter are, in general, larger and firmer.
Calcium and phosphorus bioavailability in rats consuming oil from either raw sardines or sardines fried in olive oil Biodisponibilidad de calcio y fósforo en ratas alimentadas con grasa de sardina cruda o frita con aceite de oliva
Authors: Pérez-Granados A.M. , Vaquero M.P. , Navarro M.P.
Published: March 2007

Three diets were prepared containing 8% olive oil (OO), fresh sardine ( Clupea pilchardus) oil (SO), and oil from sardines fried in olive oil (FSO), respectively. After in vitro digestion, soluble (dialyzed and nondialyzed) and insoluble Ca and P fractions were determined. In vitro Ca availability tended to be higher with SO, and even more so with FSO, than with OO, while that of P increased only slightly with FSO. Growing rats consumed the diets for 28 days. Food intake and body weight increased with FSO more than with OO, but decreased markedly with SO, due to an imbalance in the n-3/n-6 fatty acid ratio. Absorption efficiencies of Ca and P were higher with SO than with the other diets during days 5-12. Because urinary Ca excretion was also greater with SO, apparent retention of both Ca and P was lower with this diet. With SO, carcass content of Ca and P was low but their concentrations were high. Apparent retention of these minerals and their carcass content were similar or higher with FSO than with OO. Therefore, although availability of Ca and P from raw and fried sardine oil diets was sufficient in vitro, consumption of raw sardine oil as the only dietary fat produced changes in calcium and phosphorus bioavailability, an effect of sardine oil which disappeared after frying in olive oil.
In vitro digestibility study of thermal oxidized palm oleins Estudio de la digestibilidad in vitro de oleínas de palma termooxidadas
Authors: Sánchez-Muniz F.J. , Arroyo R. , Sánchez-Montero J.M. , Cuesta C.
Published: March 2007

Information on digestibility and absorption of oils and fats used for frying is under debate. To get knowledge on this, unused palm olein (9.27 ± 0.10% w/w polar content), used frying palm olein with a moderate degree of alteration (14.81 ± 0.90% w/w polar content) and highly altered used frying palm olein (26.36 ± 0.30% w/w polar content) and their respective nonpolar and polar fractions were studied. Samples were analyzed by high-performance size-exclusion chromatography before and after a 20-min in vitro incubation with pancreatic lipase. Formation of monoacylglycerols and free fatty acids reflected no relevant differences between unused and moderately altered oleins, whereas the most altered olein was hydrolyzed to a much lesser degree. The presence of oligomers (dimers and polymers of triacylglycerols) negatively affected the hydrolysis of triacylglycerol monomers in whole oleins. The hydrolysis of these monomers in the isolated nonpolar and polar fractions ranked between 60.2% and 78.5%. Oligomers were efficiently hydrolyzed by pancreatic lipase in whole un used and moderately altered oleins but not in the most altered one. Polymers from isolated polar fractions were poorly hydrolyzed or not hydrolyzed at all. These data suggest that whole oleins contained some compounds that increase susceptibility of oligomers to enzymatic hydrolysis and that such compounds were not present in the polar fraction.
Review : Instrumentation for the rheological characterization of foods/Instrumentación para la caracterización reológica de alimentos
Authors: Ma L. , Barbosa-Canovas G.V.
Published: March 2007

The rheometer, which measures the associated torque at controlled deformation, or, alternately, the associated deformation at controllable known torque, is an essential tool in food rheological studies. The modern rheometer consists of three main components: a measuring geometry, a torque transducer, and an angular displacement device. The geometry is very important; it is used to generate a particular deformation of a food material. In rheological measurements, the geometry is usually interchangeable and can be selected according to the physical state of the testing material. Thus, the selection of a measuring geometry (i.e., cone-plate, parallel plate, concentric cylinder, or capillary geometry) is critical if reliable and accurate rheological data are required.

In this review, the basic concepts of rheological properties (viscosity and viscoelasticity) are summarized; working equations of several commonly used geometries are presented; nonideality of geometries (i.e., end effect, slippage, viscous heating, etc.) are discussed; working equations of standard geometries are given; and, finally, the design philosophy of newly developed features of several commercial rheometers are addressed.
Parámetros de color del jugo de granadilla (Passiflora edulis Sims): influencia de la época de cosecha de la fruta/ Color parameters of passion fruit juice (Passiflora edulis Sims): influence of harvest season
Authors: Sepúlveda E. , Sáenz C. , Navarrete A. , Rustom A.
Published: March 2007

This study covers the evolution of color parameters (L*, a*, b*) of passion fruit juice from 2 different seasons (winter and summer) and its relation with carotenoid content and also the sensory evaluation of juices. Three different harvests were made during the two seasons, every 15-20 days. Soluble solids/acidity ratio was used as a maturity index. Winter maturity index was 3.5 and summer index was 6.6: The carotenoids content for winter fruit was higher than that for summer fruit (2.6 and 1.7 mg β-carotene/100ml respectively). Color differences between harvest seasons were observed; a* value for winter juices was higher than for summer juices (7.4 and 4.3 respectively). Furthermore, an increment of a* value was observed in the winter harvest rising from 5.0 to 10.3. A color difference was also detected through the sensory evaluation; the judges ranked the third harvest from winter with the highest degree. This sample had the highest carotenoid content (3.2 mg β-carotene/100 ml).
Note. Effect of a cryoprotectant agent (sodium tripolyphosphate) on hake slices preserved in modified atmosphere packaging/Nota. Efecto de un crioprotector (tripolyphosphate sódico) sobre merluza en rodajas envasada en atmósfera modificada
Authors: Alvarez J.A. , Pozo R. , Pastoriza L.
Published: March 2007

Fresh hake slices packed in a modified atmosphere with a cryoprotectant agent (sodium tripolyphosphate) and under chilling conditions showed a reduction of exudate production. However, no improvement was achieved in microbiological and chemical parameters used as quality control factors compared with those packed only in a modified atmosphere (MAP). Thus final results concluded that the shelf-life of fresh hake slices packed using MAP and sodium tripolyphosphate was shorter than the shelf-life of fresh hake slices packed using only MAP.
Effects of processing conditions on the caseinolytic activity of crude extracts of Cynara cardunculus L/Efectos de las condiciones de extracción sobre la actividad caseinolítica de los extractos de Cynara cardunculus L
Authors: Sousa M.J. , Malcata F.X.
Published: March 2007

Four processing parameters (time of grinding, pH of buffer, salt concentration of buffer, and homogenization time) involved in the liquid extraction of proteinases from flowers of the wild thistle ( Cynara cardunculus), were studied for their effects on final caseinolytic activity by a surface response method. The caseinolytic activity was assayed spectrophotometrically using o-phthal dialdehyde. An empirical quadratic model was applied to experimental data pertaining to the average enzymatic activity and equations describing the optimal conditions were obtained. Simultaneous solution of these equations for the local maxima indicated that, within the range tested, the maximum (estimated) specific caseinolytic activity (around 9.5 μmol of equivalent leucine/min.g of thistle flower) was obtained by grinding the flowers for 36 s, using an extrac tion buffer with a pH of 5.9 and a salt content of 0% (w/w), and homogenizing the ground flower/buffer suspension for 15 min. These data are of use in the optimization of extraction proce dures, which are of relevance to the production of standardized plant rennets suitable for the large scale manufacture of ewe's milk cheese.
Efecto de la dieta de cerdos ibéricos sobre la composición en ácidos grasos de la grasa intramuscular e intermuscular de jamones / Effect of diet on the fatty acid composition of intramuscular and intermuscular fat in Iberian pig cured hams
Authors: de la Hoz L. , López M.O. , Hierro E. , Cambero M.I. , Ordóñez J.A.
Published: March 2007

The fatty acid composition of total, apolar and polar lipid fractions from intra- and intermuscular fat of Iberian pig cured hams was determined. Animals were fed with diets of pasture and acorns ( montanera), acorns and cereals ( recebo) or cereals ( cebo). The major fatty acids from the total and apolar lipid fraction of Iberian pig cured ham muscular tissue were C18:1 (45-54%), C16:0 (22-26%) and C18:1 (10-13%). The same fatty acids were the major components in the total and apolar lipids from intermuscular fat of Iberian pig cured hams, with values ranging from 44 to 53% for C18:1, from 21 to 27% for C16:0 and from 10 to 14% for C18:0. In the total lipid fraction from intramus cular fat significant differences ( p ≤ 0.05) were found between all three batches in the composi tion of C18:1 and C 18:2, and between montanera and the other two batches in the fatty acids C14:0 and C16:0. For intermuscular fat, significant differences ( p ≤ 0.05) were observed between all three batches for the fatty acids C14:0, C16:0, C18:1 , C18:2 and C18:3. Although significant differences in the composition of some fatty acids of the total lipid fraction from intra- and intermuscular fat were due to the feeding system, a 100% partition among the three different diets was not obtained when stepwise discriminant analysis was applied. The results were not improved when the apolar lipid fraction was analysed.
Rheological and functional characterization of a biopolymer obtained from Beijerinckia sp. / Caracterización reológica y funcional de un biopolímero obtenido de Beijerinckia sp
Authors: Martínez-Padilla L.P. , Cabada-Celis N.
Published: March 2007

An exopolysaccharide producer, Beijerinckia sp. was isolated and identified from a sample of soil. A sample of 10.3 g (dry weight) of polysaccharide/L was obtained by fermentation on liquid Czapek culture media supplemented with yeast extract. The functionality of the biopolymer was characterized for its potential use by the food industry. It showed shear thinning behaviour (pseudoplastic). The effects of concentration, temperature and pH were evaluated; almost all of the salts had no effect on rheological parameters of the power law model. There was a linear rela tionship between the percent of remaining emulsion after centrifugation and the polysaccharide biopolymer concentration, demonstrating the stabilizing effect of biopolymer on the emulsion. In contrast, the biopolymer was not able to form a gel under various pH and temperature condi tions, or with the addition of ions.
Utilización de cultivos iniciadores en la elaboración de chorizo y su influencia en las propiedades sensoriales / Use of starter cultures in dry-fermented sausage (chorizo) and their influence on the sensory properties
Authors: González-Fernández C. , Santos E.M. , Jaime I. , Rovira J.
Published: March 2007

The influence of different starter cultures on the sensory properties of chorizo, especially on texture, was studied. This work focused on the differences observed between the use of the commercial lactic acid bacteria Lactobacillus sake (Lc) and Pediococcus sp (Pc), as well as on the differences between these commercial strains and another Lactobacillus sake (A216) isolated from traditional chorizo. Three batches of chorizo were processed, each batch made up of four different types that contained or lacked one of the three starter cultures. Concerning capacity of acidification, the results indicated that there were no differences between the use of Lactobacillics sake or Pediococcus sp when 0.1% glucose is used. Furthermore, there were no differences in the sensory properties of the final product. Sausage processed with noncommercial Lactobacillus sake (A216) had a more intense flavour and was preferred by consumers because of its texture and overall characteristics. The use of starter culture had a favourable influence on sausage processing, reducing its manu facture time and improving some sensory properties of the final product.
Dietary approaches to alleviation of lactose maldigestion / Efectos de la dieta sobre la digestión de la lactosa
Authors: Renner E.
Published: March 2007

Because dairy products are a significant source of essential nutrients, elimination of all dairy foods in the diet would be nutritionally unwise and is usually not necessary in the case of lactose maldigestion. About 250 ml milk/d can generally be taken without adverse effects. If milk is taken in combination with solid foods, lactose malabsorption may be reduced by about 50%, probably due to a slower rate of colonic fermentation which may lower gastrointestinal symptoms in lactose malabsorbers. It is well established that, in lactase-deficient subjects, yoghurt is better tolerated than milk. This is only to some extent related to the fact that the lactose content of the products is reduced during fermentation, but is mainly attributed to the fact that the culture organisms- by virtue of being rich in lactase - are able to participate in the hydrolysis of ingested lactose. Up to 20 g of lactose in yoghurt is tolerated well by lactase-deficient persons. The enhanced absorp tion of lactose in yoghurt is explained as a result of the intestinal release of lactase from the yoghurt organisms. Ripened cheese is also tolerated very well by lactose-intolerant persons since virtually all of the lactose present is decomposed to lactic acid and other metabolites.
Tecnología del almidón resistente / Technology of resistant starch
Authors: Escarpa A. , González M.C.
Published: March 2007

In recent years the discovery of the starch fraction called resistant starch (RS) has lead to numerous investigations. The nature of this fraction is very heterogeneous, and it comprises different types of resistant starches. From a technological point of view, RS type III or retrograded starch is the most important fraction. This resistant starch is formed after heating and cooling processes which therefore may occur in numerous fresh foods and foodstuffs. This brief review describes the gela tinization and retrogradation, which occur during heating and cooling, involved in the formation of resistant starch. The influence on RS formation of technological processes used in the manu facture of cereals has been studied as well as the influence of certain treatments used in legumes. In addition, the interactions between starch and nutrients such as proteins, lipids and sugars have also been studied. Recently, a high pressure autoclave has been used in a gelatinization system, which allows a better technological control and an increase in RS yields in comparison to conven tional systems.
A proposal for a method to measure the colour of red wines by measuring transmittance at three wavelengths / Propuesta de un método de medida del color de vinos tintos mediante la lectura de las transmitancia a tres longitudes de onda
Authors: Juárez M.C. , Echávarri J.F. , Negueruela A.I.
Published: March 2007

Characteristic vectors analysis has been used to reconstitute the transmittance spectrum of red wines measured in 0.2 cm path-length cells. We have verified that an accurate reconstitution of the spectrum is obtained with the mean vector and the first three characteristic vectors. Applying the outputs obtained to the colour calculation, tristimulus values are obtained as a function of transmittance measured at 420, 520 and 620 nm. The errors involved, measured in colour differ ences, are less than 3 CIELAB units in 97% of the cases.
Nota. Cinética de pardeamiento no enzimático de zumo de pera concentrado Note./ Non-enzymatic browning kinetics of concentrated pear juice
Authors: Ibarz A. , Martín O. , Barbosa-Cánovas G.V.
Published: March 2007

Non-enzymatic browning kinetics of concentrated juice for three pear varieties (Alexandrine Douillard, Flor de Invierno and Blanquilla) was evaluated at three temperatures (90, 80 and 70 °C) and different soluble solid contents (52, 62 and 72 °Brix). The evolution of absorbance at 420 nm is described by zero order kinetics, but the formation of 5-hydroxymethyl-2 furfuraldehyde (HMF) and the reduction in formol index followed first order kinetics. The Alexandrine Douillard juices showed non-enzymatic browning which was less pronounced than in Flor de Invierno and Blanquilla juices.
Kinetics of forced convective air drying of potato and squash slabs / Cinética del secado de rodajas de patatas y calabacin con corriente de aire
Authors: Rovedo C.O. , Suárez C. , Viollaz P.E.
Published: March 2007

Moisture content, temperature, and surface area variations of potato and squash slabs were measured during forced convective air drying; the effect of the initial moisture content on drying behaviour was also investigated. A mathematical model that numerically integrated the diffusion equation and the thermal balance for a three-dimensional shrinking slab was used to simulate the drying process. The parameters of the model (surface area, heat transfer coefficient and dry solid density) were experimentally determined. Fitting parameters (activation energy and pre- exponential coefficient in the Arrhenius equation) were found by comparing experimental and predicted drying curves. Good agreement was obtained down to a moisture level of 0.4 kg water/kg dry solid. Diffusion coefficients were independent of their moisture content within the range studied for both products. The activation energies for potato and squash were 2.09 x 104 kJ/kg mol and 3.76 x 10 4 kJ/kg mol, respectively. Changes in the rates of drying and heating curves for potato took place at moisture levels around 0.4 kg water/kg dry solid, but this was not the case for squash. The differences were mainly attributed to the different shapes of the sorp tion isotherms.
Modelling of lactic fermentation of carrot slices in salted brines / Modelo de fermentación de rodajas de zanahorias en salmuera
Authors: Nabais R.M. , Malcata F.X.
Published: March 2007

Increases in suspended biomass and variation in the concentrations of reducing sugars, salt, and lactic acid in brine containing sliced carrots were followed for a period of several days. A tentative unstructured, unsegregated model for the metabolism of suspended Lactobacillus plan tarum coupled with Fick's second law of diffusion for the transport of solutes within the carrot material was postulated. This general model was fitted by non-linear multiresponse regression analysis to an extensive set of experimental data encompassing several processing temperatures and initial brine concentrations. Maximum specific growth rates decreased with initial sodium chloride (NaCl) concentration and were maximal at ca 30°C leading to a peak concentration of reducing sugars in the brine. The lag phase of microbial growth in the brine is apparently disguised by the lag phase of sugar leaching from the carrots into the brine. Lactic acid was confirmed to be a growth-associated product. Intrinsic diffusivities of the various compounds considered ranged up to ca 10-11 m2/s, and varied with temperature according to the Arrhenius law; the maximum activation energy was at ca 8% (w/v) NaCl. The work developed is useful for the simulation and eventual optimization of pickled carrot manufacture.