Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

PURPOSE: The purpose of this study is to examine the effects of different types of carbohydrates on blood glucose response in collegiate soccer athletes at rest. This will help to determine the effectiveness of a carbohydrate supplement in providing sustained energy and maintained performance if ingested prior to a soccer match. METHODS: In a cross-over design, 10 female collegiate soccer players (n= 10, age 20.10 ± .99 years, height 65.55 ± 2.77 inches, weight 64.12 ± 8.36 kilograms) from the University of South Florida reported to the laboratory on five separate occasions after an overnight fast. Once a baseline blood glucose measurement was obtained, subjects ingested one of four different carbohydrate beverages (dextrose, maltodextrin, Vitargo®, and waxy maize) and a control (water). Each subject consumed 1 gram of carbohydrate per kilogram body weight in a 7% solution. Order of carbohydrate and control supplements was randomly assigned for each participant. After the subject ingested one of the test beverages blood glucose measurements were taken at the 30, 45, 60, 90, 120, and 180 minute time points (a total of three hours). The same procedures took place during each subject's visit. A series of one-way analysis of variance (ANOVA) were performed using SPSS 19 to determine differences in the blood glucose response at each time point between the carbohydrate supplements. RESULTS: No significant difference existed between treatments for blood glucose levels at baseline. At 30, 45, and 60 minutes, blood glucose concentrations following dextrose, maltodextrin, and Vitargo® ingestion were significantly higher as compared to the placebo ingestion. No significant difference was observed between waxy maize and placebo at these time points. At ninety minutes the blood glucose concentrations for dextrose and Vitargo® were significantly higher than placebo, and at 120 minutes only Vitargo® was significantly higher than the placebo. Finally, at 180 minutes, the blood glucose concentration for waxy maize was significantly higher than all other treatments. CONCLUSION: The main finding of this study was that waxy maize does not observe a sharp increase in blood glucose response following ingestion but maintains an elevated blood glucose concentration over an extended period of time. All other treatments (maltodextrin, dextrose, and Vitargo®) resulted in a significant rise in blood glucose within the first thirty minutes following ingestion.

Today, the focus lies on the state of the environment and how we can choose more sustainable alternatives to oil based materials. One material of interest is microfibrillated cellulose (MFC).The microfibril exhibits interesting properties, which one is its excellent barrier properties, that is expected to come in good use for the conversion to a more sustainable society. It is believed that the use of biobased barriers will increase with these new materials and MFC is showing promising results. But in order to develop the material to its full potential, it is important to investigate how MFC behaves in different situations, which can be examined with rheological measurements. The aim of the thesis is to examine how the rheological properties of suspensions containing MFC are affected by temperature and time storing and how the learning from this work can be used for influencing dispersion properties. Four samples were investigated, containing different amounts of MFC and modified waxy maize starch. The samples were analyzed with a dynamic rotational rheometer (Kinexus Pro +) with a splined cup and bob. The following steps were included in the method development used in this work: sample preparation, the repeatability, rest time and statistical analysis. An oscillatory shear and steady shear measurement was performed on the samples, and selected samples were studied with microscopy. The results show that the temperature has affected the samples. The shear viscosity of all samples decreased with increasing temperature and the samples followed the temperature dependence of Arrhenius' equation. For samples containing MFC, the structure was affected, and the initial viscosity was not recovered. The complex viscosity did also decrease at the beginning to then suggestively increase, creating a stronger network at higher temperatures. With the raised temperature the bonding between the fibrils became weaker, which in turn made the dispersion less viscous. Then, depending on the applied force, the shear viscosity and complex viscosity acted differently. To conclude, both the shear viscosity and the complex viscosity in these dispersions containing MFC are dependent on the temperature and time storing. By the learnings from this work, a method has been developed to understand how to use temperature and storing time to lower the shear viscosity and lower, or increase, the complex viscosity. / Idag ligger det ett stort fokus på miljöns tillstånd och hur vi kan välja mer hållbara alternativjämfört med oljebaserade material. Ett material av intresse är mikrofibrillerad cellulosa (MFC).Denna mikrofibrill besitter intressanta egenskaper, varav en är enastående barriäregenskaper,som förväntas komma till god användning i omställningen till ett mer hållbart samhälle. Det tros att biobaserade barriärer kommer att användas mer i dessa nya material och här visar MFC lovande resultat. Men för att kunna utveckla materialet till sin fulla potential är det viktigt att undersöka hur MFC beter sig i olika situationer, som kan undersökas genom reologiska mätningar. Syftet med arbetet är att undersöka hur de reologiska egenskaperna för suspensioner innehållande MFC påverkas av temperatur och lagringstid samt hur lärdomen från det här arbetet kan användas för att påverka dispersionsegenskaper. Fyra prover undersöktes,innehållande olika mängd MFC och modifierad majsstärkelse. Proverna analyserades med en dynamisk rotations reometer (Kinexus Pro +) med räfflad kopp och bob. Följande steg ingick i metodutvecklingen som användes i detta arbete: provberedning, repeterbarhet, vilotid och statistisk analys. En oscillerande skjuvning och jämn skjuvmätning utfördes på de olika proverna samt att utvalda prover studerades med mikroskopi. Resultatet visade att temperaturen hade påverkat proverna. Skjuvviskositeten för alla prover minskade med en ökande temperatur och proverna följde temperaturberoendet av Arrhenius ekvation. För prover innehållande MFC påverkades strukturen och startviskositeten återficks inte. Den komplexa viskositeten minskade också till en början för att sedan suggestivt öka, vilket skapade ett starkare nätverk vid högre temperaturer. Med en högre temperatur blev bindningarna mellan fibrillerna svagare, vilket bidrog att dispersionerna blev mindre viskösa. Beroende på den applicerade kraften, verkade skjuvviskositeten och den komplexa viskositeten olika. Slutsatsen var att både skjuvviskositeten och den komplexa viskositeten i dessa prover innehållande MFC beroende av temperaturen och lagringstid. Från lärdomen av arbetet har en metod tagits fram för att kunna använda temperatur och lagringstid för att sänka skjuvviskositeten och sänka, eller öka, den komplexa viskositeten.