Antioxidant Effect of Plants Aqueous Extract on Lipid Stability of <i>Oreochromis niloticus</i>during Traditional Sun and Smoke Drying in Far-North Cameroon

Fishes are suitable for sun drying and smoking. But their high contains of unsaturated fatty acids make them very prone to lipid oxidation. However, some plants are rich in natural antioxidants and have been shown to be potent inhibitors of lipid oxidation during processing of meat. The effect of three aqueous plants extracts on lipid stability of Oreochromis niloticus collected in Far-North Cameroon during processing was evaluated. Results show the high nutritious of these fish with high levels of proteins, lipid and ash (71.02%, 13.71% and 10.65%, respectively). It has been observed that oleic acid (C18:1), followed by palmitic acid (C16:0) and linoleic acid (C18:2) are the most dominant fatty acids present in Oreochromis niloticus lipids. Their lipid also showed a much higher content of omega-3 polyunsaturated fatty acids (PUFA) compared to omega 6 PUFA. The total phenolic contents (TPC) of the three plants ranged from 12,150 to 16,050 mg/100 g. The leaves of Moringa oleifera exhibited the higher content of TPC. The results of iodine, peroxide value and thiobarbituric acids test were revealed that the aqueous extracts of the tree plants had antioxidant properties. These plants extracts inhibit lipid oxidation of Oreochromis niloticus during processing. Increasing of the concentration of plant extracts enhanced their antioxidant activities and the highest oxidation inhibitor was obtained at 30 g/l. Moringa oleifera leaves inhibit highly the lipid oxidation of Oreochromis niloticus.

Influence of stir-frying on the lipid stability and flavor substances in oat flour during storage using HS-SPME-GC-MS and electronic nose

Objectives:We used stir-fried oat flour as experimental material and raw oat flour as a control to explore the influence of stir-frying on the storagequalityofoatflour.Materials and Methods:The HS-SPME-GC-MS method combined with electronic nose technology was used to understand the lipid stability and analyze the changes in the flavor of the substances during the entire storage period.Results:It was observed that during the storage period,stir-fried oat flour contained less water than raw oat flavor.The former was characterized by a lower fatty acid value,lower acid value,and lower linoleic acid content,but higher oleic acid content and palmitic acid content compared to the latter.With the passage of storage time,the palmitic acid content significantly increased,and the linoleic acid content significantly decreased in raw and stir-fried oats flour(P<o.05).The sulfur and methyl contents in the stir-fried oat flour were higher than those in the raw flour,while nitrogen oxide content in the former was lower than that in the latter.Stir-fried oat flour possessed a total of 78 identified flavor substances.The process of stir-frying boosts the oxidation decomposition of unsaturated fatty acids aldehydes and heterocyclic compounds produced by the Maillard reaction,so the flavor substances of stir-fried oat flour are richer.Conclusions:Stir-fried oat flour,containing diverse types of flavor substances,experienced more obvious flavor changes throughout the storage period than raw oat flour.