Theses and Dissertations- Doctor of Philosophy

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Browsing Theses and Dissertations- Doctor of Philosophy by Subject "application of natural antioxidant in crude sesame oil stability"

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    Crude sesame (sesame indicum l.) Oil quality assurance through hazard analysis critical control points and application of natural antioxidant in crude sesame oil stability: the case of the small - scale processing plants in Western Tigray, Ethiopia
    (Egerton University, 2024-09) Gebremeskel, Abrehet Fisseha
    Sesame (Sesame indicum) is a significant crop for the Ethiopian economy, but improper handling causes 22–35% of the seed to be lost along the value chain. The study aimed to reduce post-harvest losses in the sesame value chain in western Tigray, Ethiopia by implementing a Hazard Analysis Critical Control Point (HACCP). To better understand the sesame value chain, a questionnaire survey conducted to 332 actors. Crude sesame oil (CSO) was extracted using a cold press mechanical extraction method. Sesame seeds' proximate composition and CSO physico-chemical quality were determined using the corresponding AOAC standard methods. Microbial quality assessment, chemical (Aflatoxin levels, pesticides, oxidation) and physical hazards analysis was conducted. The moisture content of sesame seed and CSO was found to be 3.36 and 0.37 percent, respectively. Sesame seeds were found to have 50.9% oil, of which 83.15% was made up of unsaturated fatty acids. Three critical control points (CCPs) identified were during sesame roasting, conditioning while pressing, and packaging of CSO. Potential hazards during roasting were fungi and mycotoxins; hazards during extraction were staphylococcus aureus, and aerobic plate bacteria; and hazards during packaging were staphylococcus aureus, aerobic plate bacteria, and oxidative metabolites during the filling process, to be carefully controlled for safe CSO production. The peroxide value of CSO from raw and roasted sesame seeds was 8.23 and 5.98 meq O2/kg oil after 35 days of storage at room temperature. However, after 35 days of storage at 65 oC, the raw and roasted sesame seeds' respective CSO peroxide values were 20.92 and 81.01 meq O2/kg. Meanwhile, oxidation was reduced when basil was added. Accordingly, during ambient condition storage, the peroxide values of CSO for raw and roasted seeds were 0.42 - 0.55 meq O2/kg, and during accelerated storage, they were 2.62 - 10.13 meq O2/kg, respectively. The total aflatoxin level in sesame seeds was found to be 14.98 μm/kg whose B1 (AFB1) component was 0.51 μg/kg. CSO total aflatoxin level was 8.5 μm/kg with the B1 component being 0.37 μm/kg. Because it lacks a refining procedure and hazards detected, the CSO shelf life was calculated to be no longer than two months based on the available data. The small and medium-scale food processing industries hold significant role in the community and yet lacks attention. As a result, periodic training and restricts regulatory on value addition, hygienic practices, and application of organic preservatives promote safe food production and improve the economic value. Though, spices such as sweet basil have been utilized as flavour enhancer and yet the preservatives effect in semi-packed and packed food is not well utilized.