Examensarbeten på grundnivå // Basic Level Theses
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- PostAnalysis of avenanthramides in oats with Ultra High Performance Liquid Chromatography(2016) Astner, Martin; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological EngineeringAvenanthramides have been shown to have beneficial properties such as strong antioxidant activity and anti-inflammatory effects in humans, and are a key defence molecule for oats. The goal of this project was to create and validate a method for quantification of avenanthramides in oats that would take less than 20 minutes. A new extraction method and new liquid chromatography method were tested, as well as the introduction of an internal standard to improve quantification. We found that the internal standard selected was not stable during extraction and that it was necessary to use an external standard curve. We found that the liquid chromatography method was reproducible for standard compounds and that we could get separation of the three main avenathramides in oats for a total run time of 15 minutes. The extraction component of the method requires further work to improve recovery and stability before this method can be used for quantification of avenanthramides in oats.
- PostOptimering av en gaskromatografisk tandem-masspektrometrisk metabolomikmetod för cerebrospinalvästska med tillämpning relaterat till Alzheimers sjukdom(2016) Vänerlöv, Xuan; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological EngineeringI detta experiment har gaskromatografi använts för att separera analyterna i cerebrospinalvätska och sedan har masspektrometri används innehållande en trippel kvadrupol som körts i MRM-läge parallellt med fullt skanningsläge. För att Multiple Reaction Monitoring MRM skulle kunna användas var parametrar tvungna att optimeras från de standarderna som sedan skulle analyseras i provet. Standarderna som optimerades var ett urval metaboliter till en metod relaterat till diabetes samt hjärnans signalsubstanser dopamin, serotonin, epinefrin, gamma-aminobutyric acid (GABA) och acetylkolin. Metoden som användes var en befintlig metod utformad för plasmaprover som modifierades för att passa cerebrospinalvätska. Den modifierade metoden med de tillagda substanserna testades och utvärderades sedan. Dopamin, serotonin, GABA och epinefrin kunde optimeras för MRM-läge och dopamin och GABA kunde ses i cerebrospinalvätska. Vid utvärdering av metoden hade majoriteten av metaboliterna tillräckligt hög reproducerbarhet för att inkluderas i metoden. Slutsatsen som drogs var att gaskromatografi med en masspektrometer innehållande en trippel kvadrupol var lämplig till metoden för cerebrospinalvätska. Metoden kan appliceras vid undersökning av olika sjukdomar som till exempel Alzheimers sjukdom och tas därför upp som ett omfattande kapitel i rapporten.
- PostUndersökning av variabler vid optimering av syrningsprocessen för framställning av cottage cheese(2019) Hansson, Björn; Chalmers tekniska högskola / Institutionen för biologi och bioteknik; Chalmers University of Technology / Department of Biology and Biological EngineeringArla Foods dairy in Falkenberg produces cottage cheese and under the fall of 2018, they had some problems with an uneven acidification, which gave their product an uneven quality. Those problems are now solved but in the continued work their product technicians always work to find methods for a more reliable and stable acidification process, for a product with more even quality. In the work for a more reliable and stable process, two projects have been done. The acidification project performed to examine which conditions that were most optimal regarding the temperature, the percentage of protein in the milk and the amount of starter culture used. The other project, the vat and cooling towers project, was done to examine the change in dry matter content in the cheese curd when there are delays in the production line, i.e. when the cheese curd has to lie in the vat longer than usual and how that affects the curds dry matter content, and how long the curd has to lie in the cooling towers to reach normal dry matter content limits. Both projects were done in laboratory scale. In the acidification project the rate of the acidification were assessed by measuring the pH of the sample every fifteen minutes. The times down to pH 5.7 (when rennet is added) and pH 4.7 (when the coagulum is cut) were measured and used to calculate the results using a 2 sided 95 % confidence interval. The temperature, the percentage of the milk and their factor interaction were significant for the rate of acidification down to pH 5.7. For the acidification rate down to pH 4.7, all the factors and factor interactions were significant except for the three-way factor interaction. A higher temperature made the acidification rate increase while a higher percentage of protein in the milk decreased the acidification rate. In the vat and cooling towers project whey and cheese curd were stirred and heated at 60 ℃ in a beaker, with samples of the curd taken out after 0, 30, 60 and 90 minutes. At these times cheese curd was transferred to a stirred and cooled beaker with 4 ℃ water in them, with samples of the curd taken out after 2, 4 and 6 hours. The dry matter of the cheese curd was then measured with a Milkoscan FT1. Because of the different chemical compositions of the cheese curd taken out from different vats the results were not comparable but a significant drop in dry matter could be seen from all runs after two hours of cooling.