Browsing by Subject "CMC"
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Item Antistaling properties of amylases, wheat gluten and CMC on corn tortilla(Texas A&M University, 2004-09-30) Bueso Ucles, Francisco JavierAntistaling properties of enzymes (xylanase, bacterial maltogenic and conventional a-amylases), CMC and vital wheat gluten on corn tortillas were evaluated during storage for up to 21 days. Effect of storage time (0-21 days) and temperature (-40, -20, 3, 10 and 21 oC) on tortilla staling was evaluated with or without additives. Addition of 275-1650 AU of ICS maltogenic amylase effectively reduced amylopectin retrogradation without reducing tortilla yields, but did not improve tortilla flexibility. The combination of 825 AU of ICS amylase (to interfere with intra-granular amylopectin re-crystallization) and 0.25% CMC (to create a more flexible inter-granular matrix than retrograded amylose) produced less stiff, equally flexible and less chewy tortillas than 0.5% CMC. Corn tortilla staling followed the basic laws that control aging in starch-based semi-crystalline systems such as starch gels, bread and other baked products. Amylopectin re-crystallization was the driving force behind the staling of corn tortillas. Increasing levels of re-crystallized amylopectin measured by DSC correlated significantly with increased tortilla stiffness and reduction in tortilla rollability, pliability and rupture distance during storage. Re-crystallization of amylopectin in fresh tortillas was not detected. It increased rapidly during the first 24 hr reaching a plateau after 7 days storage. The level of amylopectin re-crystallization on tortillas showed a bell-shaped trend along the evaluated storage temperature range with a maximum around 7 oC. However, a negative linear relationship of peak pasting viscosity with storage temperature of tortilla extracts without additives after 21 days suggests other compounds besides amylopectin affect tortilla staling. Thus, interfering with amylopectin re-crystallization is not the only way to retard staling. Further research is required to optimize the addition of maltogenic amylases in continuous processing lines that use fresh masa instead of nixtamalized corn flour, to determine how these amylases interfere with amylopectin re-crystallization and to elucidate if amylose retrogradation continues during storage and plays a role in tortilla staling.Item Effects of barley flour and beta-glucans in corn tortillas(Texas A&M University, 2004-09-30) Silva, LauraThe effects of b-glucan on corn tortilla texture were evaluated. Barley flour (9.7% b-glucan) was substituted at 2.5, 5 and 10% for dry masa flour in corn tortillas. Texture was evaluated after 4 hr and up to 7 d storage at 4?C. Substitution of 2.5-10% barley flour significantly improved tortilla texture. Combined effects of barley flour (0-2.5%), maltogenic amylase (0-1650MAU) and carboxymethylcellulose (0-0.5%) were evaluated using surface response methodology. Barley flour increased rollability, pliability, energy dissipated and reduced rupture force and final stiffness. Overall, maltogenic amylase decreased rupture force and Young's modulus but decreased rupture distance, rollability and pliability at levels above 825 MAU. CMC improved rollability, pliability, and rupture distance. The best response was found using barley flour and CMC with 825 MAU, where rollability, pliability, rupture distance and energy dissipated increased while rupture force, Young's modulus and final stiffness decreased. A 70% barley b-glucan concentrate combined with amylase (550 MAU) or CMC (0-0.5%) was evaluated in corn tortillas. Amylase combined with b-glucan did not improve texture. Tortillas with b-glucan and CMC had significantly improved pliability, rollability, final stiffness and energy dissipated. Texture measurements analysis showed that depending on the stage of storage, objective and subjective methods correlate differently. Subjective and objective measurements of texture were not correlated at 4 hr storage. At the end of storage, pliability had significant correlations with stress relaxation measurements, but rollability had higher correlation coefficients with extensibility measurements. Pliability had higher R2 and lower coefficients of variation compared to rollability. Sensory evaluation was conducted using reheated 14-day-old tortillas of control, 825 MAU with 0.25% CMC, 0.12% b-glucans, 0.18% b-glucan with 0.375% CMC, and 0.24% b-glucan with 0.25% CMC. All tortillas had similar appearance, flexibility, gumminess, flavor and overall quality. Softness and chewiness of treatments with 0.12% b-glucan or 0.24% b-glucan with 0.25% CMC were similar to control. Other tortillas were significantly tougher and chewier. b-glucan may be the active ingredient in barley flour that modifies firming of corn tortillas during storage. Barley flour is inexpensive and effectively improves texture of corn tortillas.Item The influence of stigma of mental illnesses on decoding and encodting of verbal and nonverbal messages(2013-05) Imai, Tatsuya; Dailey, René M.Stigmas associated with depression and schizophrenia have been found to negatively impact the communication those with mental illness have with others in face-to-face interactions (e.g., Lysaker, Roe, & Yanos, 2007; Nicholson & Sacco, 1999). This study attempted to specifically examine how stigma affects cognitions, emotions, and behaviors of interactants without a mental illness toward those with a mental illness in online interactions. In this experimental study, 412 participants interacted with a hypothetical target on Facebook, who was believed to have depression, schizophrenia, or a cavity (i.e., the control group). They were asked to read a profile of the target on Facebook, respond to a message from the target, and complete measurements assessing perceived positive and negative face threats in the target's message, perceived facial expressions of the target, induced affect, predicted outcome value, and rejecting attitudes towards the target. Results revealed that the target labeled as schizophrenic was rejected more and perceived to have lower outcome value than the target without a mental illness or labeled as depressive. However, there were no significant differences in any outcomes between the depression and control groups. The mixed results were discussed in relation to methodological limitations and possible modifications of previous theoretical arguments. Theoretical and practical contributions were considered and suggestions for future research were offered.Item Noticing in text-based computer-mediated communication: a study of a task-based telecommunication between native and nonnative English speakers(2009-05-15) Chen, Wen-ChunThis dissertation investigated the occurrence and the effect of incidental noticing in a text-based Computer-Mediated Communication (CMC) environment on enhancing second language learning. Learning proficiency was also examined as a possible intervening variable. This was a quasi-experimental study of sixteen nonnative English speakers from a four-year college in Taiwan, collaborating with sixteen native speaking peers in Texas, via chat agents in order to complete two communicative learning tasks over a two-month period of time. Two posttests were customized for each Nonnative English Speaker (NNES) in order to assess his/her second language learning outcomes. In addition, Language- Related Episode?s (LRE?s) characteristics were expected to serve as powerful predictors of NNES? correct language learning outcomes. In order to unveil the possible impact of the learner?s language proficiency level and its effect on noticing, eight low- intermediate and eight high- intermediate NNESs were included in the study. The findings revealed that CMC context and native and nonnative English speaking task-based peer interactions promoted learner?s noticing and affected the learning performance of NNESs of different levels. The posttest performance showed that incidental noticing facilitated learner?s linguistic knowledge intake and memory retention. Text-based CMC created a visual and collaborative context which allowed NES peers to offer NNESs of different levels personalized feedback. Among LRE?s characteristics, successful uptake, as a powerful predictor, constantly entered all the models generated by logistic regression analysis, which underpinned the importance of quality uptake during the two-way communication for second language learning. In addition, directness (explicit feedback) and response (elicitation) also appeared in regression models of the subsets of LRE data, which indicated the particular type of feedback needed by learners, especially lower proficiency level ones. In addition, NESs? involvement also facilitated NNESs? noticing; NES peers applied elicitation techniques to redirect learner?s attention to the problematic utterances and initiated meaning negotiation. The findings reveal that incidental noticing is beneficial to learning, especially when learners are provided with explicit feedback and incorporate the targeted linguistic items into their language production.Item Perceptions and Expressions of Social Presence During Conversations on Twitter(2012-02-14) Pritchett, KellyComputer-mediated environments such as social media create new social climates that impact communication interactions in un-mediated environments. This study examined social variables during conversations on Twitter through a qualitative document analysis that coded messages into affective, interactive or cohesive categories. Perceived social presence, participant satisfaction, and relationships between social presence and satisfaction among Twitter users during streaming conversations were examined through an online questionnaire that was created using qualtrics.com and made available to respondents over a one-week period. The researcher concluded that most social variables in the Twitter conversations of this study fall into the interactive social presence category. In addition, each category of responses functions in a different way to foster social presence. Two groups of survey respondents agreed with 10 out of 21 and 13 out of 21 statements about social presence and 10 out of 13 and 12 out of 13 statements about satisfaction. Findings indicated that positive and negative relationships exist between social presence and satisfaction. Both conversations in this study appeared to be successful. Therefore, agricultural communicators should feel comfortable using CMC more frequently to circulate agricultural information among populations across the globe. It was recommended that further research be conducted to examine social presence among new topics, populations, and other forms of CMC.Item Performing in the virtual organization(2010-12) Sinclair, Caroline Louise, 1971-; Stephens, Keri K.; Browning, LarryThis qualitative study examined fifteen organizational members across four international technology companies to discover how they behave and manage daily interactions in a virtual environment within a geographically distributed team. Using a grounded theory methodology, an extensive analysis of the interview data was conducted. Three core themes emerged that focus on the individuals’ attempts to manage impressions in an environment that demands multicommunication. The themes of time stacking, participation predications and performance are discussed in detail using the theoretical lens of impression management.Item Situating Korean EFL teacher education in a CMC environment : online exchanges between preservice English teachers and elementary school students(2011-12) Chun, Sun Young, 1976-; Schallert, Diane L.; Horwitz, Elaine K.; Palmer, Deborah K.; Wilson, Jennifer C.; Svinicki, Marilla D.; French, Karen D.The purpose of this study was to gain insight into the characteristics of student-teacher interactions between Korean EFL preservice teachers and elementary school students during online exchanges and of the preservice teachers’ overall impressions and perceptions of teaching English to elementary school students and interacting with them online. The participants in this study were 31 Korean preservice elementary school teachers and 10 Korean elementary school students who were learning English as a foreign language. Ten groups with an average of three preservice teachers were paired with one child partner per group and engaged in one-on-one email exchanges, mostly using English, in discussing English books. Data came from multiple sources, including transcripts of the online exchanges between the preservice teachers and the child partner, preservice teachers’ collaborative dialogue scripts, their responses to questionnaires, their group reflection journals, individual final reflection papers, and researcher field notes. These data were analyzed using a combination of inductive and deductive data analysis methods. Through inductive analysis using the constant comparative analysis method (Glaser & Strauss, 1967; Lincoln & Guba, 1985), I derived themes that captured the experience of online interactions and the strategies that the preservice teachers used to maintain the exchange. Through deductive analysis, I identified groups that were more and less successful and described their experiences. Results indicated that the online exchanges with elementary students provided Korean EFL preservice teachers opportunities to practice teaching skills, as well as to develop close personal and social relationships with their child partners. Also, how the preservice teachers approached the exchanges and their specific online “actions” seemed to make a difference in their child partners’ responses, thereby yielding results in which some groups were more successful and others less successful. The preservice teachers reported that their participation in the project was beneficial for them as future elementary teachers of English and that they enjoyed interacting with their child partners online. Finally, the participation in the project appeared to have many benefits for the preservice teachers’ professional development, including newly-gained insights into the benefits of using technology as a valuable instructional tool in their future teaching practices as well as an increase in their confidence in using English to teach English to elementary students.Item Student performance on computer chats and in classroom discussions : same or different?(2000) Deveny Oestreich, Tina Marie; Wright, David Allan; Swaffar, Janet K.This thesis explores the concept of learner interaction in the context of an advanced Business German language course at The University of Texas at Austin to evaluate classroom communication in an advanced level, content oriented foreign language course. The goal of this study was to investigate the quantitative differences between intermediate to advanced foreign language learner discourse in both face-to-face classroom and computer mediated communication (CMC) discussions by focusing on the percentages of turns and the length of student utterances in each environment. The questions addressed by this study stem from a growing body of research suggesting that the integration of CMC into the L2 classroom has pedagogical benefits that can be qualitatively and quantitatively measured. Studies focusing specifically on the use of synchronous CMC, which allows participants to communicate in real-time via networked computers, have recognized that learners interacting in a synchronous CMC environment are not bound to the same turn-taking conventions found in oral conversations. Some researchers and educators claim that synchronous CMC might be an environment that can allow for more equal exchanges than that found in comparable oral classroom conversations. Findings indicate that communication was far from equal in both of the oral environments, and that although the CMC environment produced more equal communication than the oral activities, it was still far from equally distributed. Furthermore, there were very few instances of negotiation in the CMC environment.Item The effect of enzymes and hydrocolloids on the texture of tortillas from fresh nixtamalized masa and nixtamalized corn flour(Texas A&M University, 2004-09-30) Gutierrez de Velasco, Arturo CarlosThe texture of tortillas was improved by the addition of maltogenic amylase and carboxymethylcellulose (CMC) and guar gum to fresh masa from ground nixtamal (FNM) and nixtamalized corn flour (NCF) masa. Differences in the performance of additives in tortillas held under refrigeration or ambient storage were documented. For NCF tortillas, significant improvements were obtained in objective and subjective texture measurements by two treatments. Tortilla texture was improved by a treatment with a high enzyme level (170 mg/kg of maltogenic ?-amylase, 0.14% CMC, 0.85% guar) as measured by objective tests and by a treatment with low enzyme level (60 mg/kg of maltogenic ?-amylase, 0.43% CMC, 0.57% guar) as measured by subjective tests. The addition of maltogenic ?-amylase (70 mg/kg) and CMC (0.35%) to FNM tortillas at levels similar to the low enzyme NCF treatment but with lower guar level (0.12%) improved tortilla texture. The maltogenic ?-amylase softened tortillas by trimming the starch structure. This allowed the guar to interfere with amylopectin re-crystallization inside gelatinized starch granules. The CMC created a more flexible intergranular matrix that helped maintain the disrupted tortilla structure. Guar was ineffective in refrigerated tortillas, whereas, maltodextrins effectively improved refrigerated tortillas. The sequence of partial starch hydrolysis, warm holding condition, and time for guar to associate with starch and CMC was necessary to improve tortilla texture. Thus, different additives may be required for cold versus room temperature storage. Sugars increased in enzyme-treated tortillas during storage. This suggests that maltogenic ?-amylase was only partially inactivated during baking of corn tortillas. Tortillas with more enzyme had lower and later pasting viscosity as measured by a Rapid Viscoanalyzer. Tortillas prepared from FNM also had lower and later pasting viscosity compared to NCF tortillas. Pasting viscosity of tortillas revealed intrinsic starch polymer characteristics and interactions. Results of this study provide commercially applicable information about desired levels for the extent of starch hydrolysis, the type and amount of gums and starches, and product microstructure to delay staling of corn tortillas.Item Virtually speaking : comparing foreign language speaking performances in distance education and face to face classes(2010-08) Volle, Lisa Marie; Abrams, Zsuzsanna; Horwitz, Elaine K.; Moore, Zena T.; Resta, Paul E.; Schallert, Diane L.The purpose of this study was to investigate the performances on speaking assessments in a first semester Spanish course to determine if there are differences among four sections based on required speaking tasks and mode of class delivery. Two of the classes were conducted online in a distance education delivery mode and two of the classes were conducted in the classroom. One section of delivery mode was required to fulfill speaking tasks throughout the semester while the alternate sections were offered the same speaking tasks as optional activities. Furthermore, the study investigated testing items repeated prompts versus new prompts to determine if there were differences in performance. Finally, the study investigated student performance confidence and beliefs about course materials. The data were collected through quantitative methods (oral rubric scores) and qualitative methods (open-ended questions). A total of 64 students participated in the study. Eight students completed the distance education course with optional speaking tasks. Thirteen students completed the distance education course with required speaking. Eighteen students completed the classroom course with optional speaking, and 24 students completed the classroom course with required speaking. In general, all classes made improvement between the first assessment and the second assessment. However, the mean performance scores for three of the four speaking prompts did not show significant difference among the four classes. In addition, there were no significant differences in mean scores of performances at the introduction of the two new speaking tasks on the final assessment. Only with one speaking repeated measure was there a significant difference. The significant difference was between the classroom with required speaking section and the distance education with optional speaking section. With an analysis of the Target Language Use, it was determined that the differences were due to lexical complexity and morphological complexity. In general, the self-report of confidence levels on the final oral assessment showed no significant differences among the four classes. There was a significant drop in confidence on one of the two new assessment prompts for all classes. Student comments indicated that there were frustrations with cognitive overload and dealing with ambiguity.Item We like people who are easy to read : the influence of processing fluency in impression formation(2013-08) Merola, Nicholas Aaron; McGlone, Matthew S., 1966-Processing fluency describes the assessment of how easy a stimulus is to cognitively process, an assessment which can be mistakenly applied to judgments of other aspects of the stimulus. This dissertation introduces a novel approach to understanding the development of impressions from online profiles by incorporating the role of processing fluency in interpersonal judgments based on a social networking profile. 195 participants (155 females) were asked to view the "about me" section of a social networking profile, which had been manipulated according to one of three fluency conditions to be harder or easier to process. Participants completed scales assessing liking, similarity, trust, and compatibility, and their disclosure was measured in an open-response item. Confirming expectations based on the processing fluency literature, each of these variables was increased in the high fluency profile condition. No differences in these variables were found between the low fluency conditions and a control condition, and analysis revealed that the manipulations intended to lower fluency may have been too salient to participants. Broadly, this study shows that processing fluency can influence impression formation from online profiles across a number of meaningful relational variables. Enhancing processing ease may allow online interactants a relational "jump-start," increasing liking, perceptions of similarity, trust, compatibility, and disclosure. These findings hold important implications for the role of processing fluency in computer-mediated communication and for models of online relationship development.