Formulation of Fish Feed for Aquaculture using Olive Pomace Extract as an Antioxidant
- Authors: Koza, Nondumiso Norma
- Date: 2024-12
- Subjects: Fishes -- Feeding and feeds , Fishes -- Ecology , Sustainable aquaculture
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/69318 , vital:77205
- Description: Olive pomace is a significant by-product of the olive oil extraction process and is an environmental issue in olive-producing countries. This project aimed to add extracts from olive pomace as an antioxidant to a fish feed formulation without compromising growth performance and meat quality, thereby contributing to the aquaculture industry. To produce the olive pomace extracts, Coratina cultivar olives were collected from a farm near Oudtshoorn, and the fresh pomace was immediately frozen at -22oC for preservation. The extracts were obtained using a large-scale extraction method using a solvent blend of n-heptane, ethanol, and water. A pressure filtration and centrifuge method were then applied to separate any residue from the extracts. An HPLC method was developed to characterise the extracts' content, identifying various bioactive compounds such as squalene, α-tocopherol, and water-soluble polyphenols like oleuropein, hydroxytyrosol, and tyrosol. In a fish feeding trial it was concluded that the fish fed with the feed without olive pomace gained more weight than those fed the feed with the added pomace extract. Overall, the results indicate that fish sustained on the feed without the olive pomace extract ate more food, consuming more energy to support weight gain but that this did not necessarily translate to an improved feed conversion ratio. The morphometric variables suggest that fish used in the trial remained healthy, implying that there may be a taste or palatability difference between feeds that could explain why less of the feed with olive pomace extract was eaten. Overall, the observed feed conversion ratio values were somewhat lower than the expected values for tilapia (FCR: 1.5-2.0). The peroxide value of fish feed with an addition of 0.3% olive pomace extract was lower than that of the feed without olive pomace extract after 12 weeks of stability testing at room temperature. The results showed a value of 1.48 MeqO2/kg for the feed containing olive pomace extract compared to the peroxide value for the fish feed without olive pomace extract, which was 2.75 MeqO2/kg. This indicates that the nutritional content of the feed was preserved. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-12
- Authors: Koza, Nondumiso Norma
- Date: 2024-12
- Subjects: Fishes -- Feeding and feeds , Fishes -- Ecology , Sustainable aquaculture
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/69318 , vital:77205
- Description: Olive pomace is a significant by-product of the olive oil extraction process and is an environmental issue in olive-producing countries. This project aimed to add extracts from olive pomace as an antioxidant to a fish feed formulation without compromising growth performance and meat quality, thereby contributing to the aquaculture industry. To produce the olive pomace extracts, Coratina cultivar olives were collected from a farm near Oudtshoorn, and the fresh pomace was immediately frozen at -22oC for preservation. The extracts were obtained using a large-scale extraction method using a solvent blend of n-heptane, ethanol, and water. A pressure filtration and centrifuge method were then applied to separate any residue from the extracts. An HPLC method was developed to characterise the extracts' content, identifying various bioactive compounds such as squalene, α-tocopherol, and water-soluble polyphenols like oleuropein, hydroxytyrosol, and tyrosol. In a fish feeding trial it was concluded that the fish fed with the feed without olive pomace gained more weight than those fed the feed with the added pomace extract. Overall, the results indicate that fish sustained on the feed without the olive pomace extract ate more food, consuming more energy to support weight gain but that this did not necessarily translate to an improved feed conversion ratio. The morphometric variables suggest that fish used in the trial remained healthy, implying that there may be a taste or palatability difference between feeds that could explain why less of the feed with olive pomace extract was eaten. Overall, the observed feed conversion ratio values were somewhat lower than the expected values for tilapia (FCR: 1.5-2.0). The peroxide value of fish feed with an addition of 0.3% olive pomace extract was lower than that of the feed without olive pomace extract after 12 weeks of stability testing at room temperature. The results showed a value of 1.48 MeqO2/kg for the feed containing olive pomace extract compared to the peroxide value for the fish feed without olive pomace extract, which was 2.75 MeqO2/kg. This indicates that the nutritional content of the feed was preserved. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-12
Formulation of Fish Feed from Supermarket Food Waste
- Authors: Vundisa, Noluyolo
- Date: 2024
- Subjects: Food waste , Aquafeed , Retail sector , Sustainable aquaculture , Resource recovery , Specific growth rate
- Language: English
- Identifier: http://hdl.handle.net/11260/13401 , vital:78701
- Description: Food waste (FW) represents a significant anthropogenic burden, driving economic losses, environmental degradation, and social disparities. This study aimed to elucidate the seasonal variability and compositional heterogeneity of FW generated within the retail sector, specifically focusing on its potential as a novel aqua-feed resource. A comprehensive 12-month sampling protocol was implemented across four retail departments, followed by a detailed proximate chemical analysis of processed FW. Three experimental diets were formulated, incorporating 0%, 25%, and 50% FW, and evaluated in a six-week feeding trial using tilapia. Seasonal analysis revealed a consistent dominance of vegetable waste, with peak contributions reaching 65.7% in spring and a notable contribution from fruit waste. Conversely, bakery and grain waste constituted minor fractions of the overall FW stream. Diet 1 exhibited the highest overall specific growth rate, reaching 1.54±0.12, surpassing diet 3 (0.86±0.57) and diet 2 (0.74±0.62). Specific growth rate analysis demonstrated a statistically significant advantage for the control diet, highlighting the need for further nutritional optimization of FW-based diets. This research quantifies the substantial daily FW generation within retail environments, emphasizing the critical need for targeted waste mitigation strategies. Moreover, it establishes the potential for sustainable FW repurposes within aquaculture, offering a viable alternative to conventional feed ingredients. Future investigations should prioritize optimizing FW processing techniques, rigorous safety assessments, and developing nutritionally balanced feed formulations to enhance digestibility and promote sustainable aquaculture practices. , Thesis (Doctoral)
- Full Text:
- Date Issued: 2024
- Authors: Vundisa, Noluyolo
- Date: 2024
- Subjects: Food waste , Aquafeed , Retail sector , Sustainable aquaculture , Resource recovery , Specific growth rate
- Language: English
- Identifier: http://hdl.handle.net/11260/13401 , vital:78701
- Description: Food waste (FW) represents a significant anthropogenic burden, driving economic losses, environmental degradation, and social disparities. This study aimed to elucidate the seasonal variability and compositional heterogeneity of FW generated within the retail sector, specifically focusing on its potential as a novel aqua-feed resource. A comprehensive 12-month sampling protocol was implemented across four retail departments, followed by a detailed proximate chemical analysis of processed FW. Three experimental diets were formulated, incorporating 0%, 25%, and 50% FW, and evaluated in a six-week feeding trial using tilapia. Seasonal analysis revealed a consistent dominance of vegetable waste, with peak contributions reaching 65.7% in spring and a notable contribution from fruit waste. Conversely, bakery and grain waste constituted minor fractions of the overall FW stream. Diet 1 exhibited the highest overall specific growth rate, reaching 1.54±0.12, surpassing diet 3 (0.86±0.57) and diet 2 (0.74±0.62). Specific growth rate analysis demonstrated a statistically significant advantage for the control diet, highlighting the need for further nutritional optimization of FW-based diets. This research quantifies the substantial daily FW generation within retail environments, emphasizing the critical need for targeted waste mitigation strategies. Moreover, it establishes the potential for sustainable FW repurposes within aquaculture, offering a viable alternative to conventional feed ingredients. Future investigations should prioritize optimizing FW processing techniques, rigorous safety assessments, and developing nutritionally balanced feed formulations to enhance digestibility and promote sustainable aquaculture practices. , Thesis (Doctoral)
- Full Text:
- Date Issued: 2024
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