Browsing by Author "Chove, Bernard"
Now showing 1 - 5 of 5
- Results Per Page
- Sort Options
Item Effect of clove (Syzygium aromaticum) and seaweed (Kappaphycus alvarezii) water extracts pretreatment on lipid oxidation in sun‐dried sardines (Rastrineobola argentea) from Lake Victoria, Tanzania(Food Science & Nutrition published by Wiley Periodicals, Inc., 2019) Chaula, Davis; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Jacobsen, Charlotte; Hyldig, GretheSmall indigenous fish species play a significant role in food and nutritional security of poor communities in developing countries. Sardines (Rastrineobola argentea) are fish species of Lake Victoria known to be a good source of health‐promoting omega‐3 fatty acids. Open sun drying is a common and traditional sardine processing and preservation method. Sun‐dried products suffer from characteristic off‐flavor due to lipid oxidation which discourage product consumption and limit diversification. This study investigated the use of clove (Syzygium aromaticum) and seaweed (Kappaphycus alvarezii) water extracts as natural antioxidants to impede lipid oxidation in sun‐dried sardines. Lipid oxidation was assessed by peroxide value, volatile secondary oxida- tion products, and fatty acid profiles. The antioxidant capacity of extracts was evalu- ated by total phenolic content, 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, and iron (Fe 2+ ) chelating ability. Results showed that 5, 10, and 20 g/L clove extracts significantly reduced peroxidation in sun‐dried sardines by 38.7%, 54.6%, and 56%, respectively. Clove extracts resulted in higher retention of omega‐3 fatty acids and lower concentrations of secondary lipid oxidation products as op- posed to seaweed counterpart. This research has demonstrated feasibility of pre- treating whole, omega‐3‐rich small sardines with natural antioxidants to avert lipid oxidation during sun drying.Item Fatty acid profiles and lipid oxidation status of sun dried, deep fried, and smoked sardine (Rastrineobola argentea) from Lake Victoria, Tanzania(Taylor & Francis, 2019) Chaula, Davis; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheFreshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constitut- ing 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 μmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.Item Natural antioxidants from clove for protecting omega-3 fatty acids in sardines (Rastrineobola argentea) during deep frying process.(Sokoine University of Agriculture, 2019-04-11) Chaula, Davis; Jacobsen, Charlotte; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheSardines (Rastrineobola argentea), popularly known as “dagaa” is one of the leading commercial fish species of Lake Victoria. The fatty fish species are attracting great attention because they are good source of omega-3 polyunsaturated fatty acids which are vital for a wide range of biological functions and are implicated in the prevention of numerous diseases. While nutritionally valued omega-3 fatty acids are highly susceptible to oxidation during fish processing due to their unsaturated nature. Oxidation reactions result in loss of omega-3 fatty acids and production of undesired off-flavours which discourage consumption and limit diversification of sardine products.Synthetic antioxidants may be used to prevent lipid oxidation but have been claimed to be carcinogenic at higher levels. The replacement of synthetic antioxidants with ones of natural origin is now in demand. In this study, natural antioxidants rich extracts from clove buds were applied on sardines in a bid to impede lipid oxidation during deep frying process. Lipid oxidation was assessed by peroxide value (PV), volatile compounds and fatty acid profiles using Gas chromatograph (GC-MS and GC-FID).The results showed that natural antioxidants from clove buds reduced peroxidation and protected highly unsaturated omega-3 fatty acids from oxidation during deep frying process. Total polyunsaturated fatty acids amounted 7.30 % in pre-treated deep fried sardines.Retention of omega-3 fatty acids was 0.70 % more in pre-treated than untreated fish. Significantly lower amounts of representative volatile compounds were produced in sardines pre-treated with clove extracts. The study demonstrated feasibility to pre-treat sardines with natural antioxidants for protecting omega-3 fatty acids against oxidation during deep frying.Item Protection against oxidation of Omega-3 Fatty Acids with natural antioxidants in clove (szygium aromaticum) water extracts during storage of sun dried sardines (Ratrineobola Argentea)(Fortune Journals, 2019) Chaula, Davis; Jacobsen, Charlotte; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheOmega-3 fatty acids are a family of polyunsaturated fatty acids (PUFAs) with beneficial health effects to humans if consumed in required amounts. Fatty fish species are known to be rich in marine-based omega-3 fatty acids, eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and docosapentaenoic acid (DPA, C22:5n-3). Sardines (Rastrineobola argentea) from Lake Victoria are a good source of health promoting omega-3 fatty acids. Open sun drying is a common and traditional sardine processing and preservation method. Due to their chemical instability omega-3 fatty acids in sun dried sardines are prone to lipid oxidation during processing and subsequent storage. This study investigated the use of clove (Syzygium aromaticum) water extracts as natural antioxidants to protect omega-3 fatty acids against oxidative damage during storage of sun dried sardines. Lipid oxidation was assessed by peroxide value, volatile secondary oxidation products and fatty acid profiles. The antioxidant capacity of extracts was evaluated by total phenolic content, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and iron (Fe 2+ ) chelating ability. Clove extracts resulted into significantly higher retention of total PUFAs, DHA, EPA and DPA at the end of 30 days storage period and lower concentrations of secondary lipid oxidation products. This is an evidence of their enhanced oxidative stability in the real food system due to presence of natural clove antioxidants.Item Similarities in functional attributes and nutritional effects of magadi soda and bean debris-ash used in cooking African traditional dishes(African Journal of Biotechnology, 2011) Mamiro, Peter; Nyagaya, Martha; Kimani, Paul; Mamiro, Delphina; Jumbe, Theresia; Macha, Joyce; Chove, BernardMagadi soda and bean debris-ash have been used as condiments for a long time by various ethnic groups in East and Central Africa in cooking traditional dishes. The aim of the study was to investigate whether magadi soda and bean debris-ash had similar effects and functional attributes when added to traditional dishes during cooking. Reason for the addition of the two condiments has not been revealed by researchers. Mineral content, in-vitro bioavailability studies and pH of non-ashed and ashed magadi soda and bean debris were evaluated. The results indicated that high concentrations of sodium ions (30.2%) and potassium ions (64.2%) were observed in magadi soda and bean debris-ash, respectively. In-vitro iron and zinc bioavailability decreased significantly with the addition of magadi soda and bean debris-ash in maize, beans and sorghum. Equally, the cooking time was significantly reduced. The mean pH for both magadi soda (9.66) and bean debris-ash (9.75) were not significantly different indicating that both aqueous solutions had alkaline properties. The similarity in properties especially in mineral profile, alkalinity, decreased cooking time and lowered mineral uptake by magadi soda and bean debris-ash explain similar functionality in foods they are added to during cooking. Despite the similarities observed, communities should be informed of the negative nutritional effects of these condiments so as to diversify their meal patterns accordingly.