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- All Subjects: Degradation
- Creators: An, Keju
- Creators: Cahill, Thomas
Description
Capsaicin and dihydrocapsaicin account for 90% of capsaicinoids when it comes to the pungency of peppers. Capsaicin stability was investigated through a cooking and storage parameter where three different tests were done; cooking duration, cooking temperature, and storage stability. The concentration of capsaicinoids was quantified through gas chromatography-mass spectrometry where those values were then used to determine the total Scoville heat units (SHU). Furthermore, half-life was determined by finding the decay rate during cooking and storage. Results showed that there was an increase in degradation of capsaicinoids concentration when peppers were cooked for a long period of time. Degradation rate increases with increasing temperatures as would be expected by the Arrhenius equation. Hence, if a maximum pungency is wanted, it is best to cook the least time as possible or add the peppers towards the end of the culinary technique. This would help by cooking the peppers for a short period of time while not being exposed to the high temperature long enough before significant degradation occurs. Lastly, the storage stability results interpreted that a maximum potency of the peppers can be retained in a freezer or refrigerator opposed to an open room temperature environment or exposure from the sun. Furthermore, the stability of peppers has a long shelf life with even that the worse storage condition's half-life value was 113.5 months (9.5 years). Thus, peppers do not need to be bought frequently because its potency will last for several years.
ContributorsBustamante, Krista Gisselle (Author) / Cahill, Thomas (Thesis director) / Sweat, Ken (Committee member) / Armendariz Guajardo, Jose (Committee member) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
TiO2 has been studied in the degradation of ethanol for indoor application. A dynamic flowing non-loop system was utilized. The reactor was a quartz tube filled with the TiO2 catalyst with glass wool on the ends. The analytical equipment used were Vernier's ethanol and CO2 sensors with a two-point calibration performed on the ethanol sensor. The purpose of the calibration was to create a known standard to establish accurate readings. The experimental procedure followed the scheme of bypassing the reactor, flowing into the reactor without the UV lights on for a small period, turning the UV lights on for five minutes, and then going back to the bypass. A CFD simulation using ANSYS Fluent was done to determine the optimal inlet and outlet positions of the biochamber that housed the sensors. The objective of the simulation was to determine which inlet and outlet locations provided the best fluid flow for sensor contact and mixing. Sensitivity analysis of varying parameters were tested to determine the optimal settings in producing accurate results to fulfill the simulation goals. It was determined that a vertical position biochamber with an inlet centered on the top face and the outlet on the bottom of a side face was ideal. The main experimental results showed that ethanol of both low and high concentrations were completely or almost fully degraded into carbon-products. The results showed that there was CO2 consumption and it was most likely due to a combination of sensor inaccuracy and accumulation onto the catalyst surface. However, the sensor inaccuracy would not account for the entirely of the CO2 consumption and previous studies have shown that carbon-products do form on the catalyst surface. Therefore, it can be asserted that CO2 has accumulated on the catalyst and the inclusion of water may have caused catalyst deactivation. Having the light on the photoreactor the whole time rather than waiting to turn on the light has shown to decrease the period of degradation but has no effect on the amount of degradation. Research from Nimlos, Muggli, etc., have determined that intermediate products such as acetaldehyde, acetic acid, formaldehyde, and formic acid form during ethanol degradation and this can be assumed to have occurred in this research as well. These intermediate products were not analyzed for this study, but has been included in the go-forward for future works. For indoor applications, TiO2 catalyst have already been implemented into consumer and commercialized air purifiers, but there is tremendous potential for HVAC systems. There are concerns with HVAC application as discussed, but if implemented correctly, it can be a useful tool for indoor air purification.
ContributorsNguyen, Jeremy Franklin (Author) / Andino, Jean (Thesis director) / An, Keju (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05