Antioxidant potential of methanolic extracts and powders of some Cameroonian spices during accelerated storage of soybean oil

The efficacy of methanolic extracts and powders of 12 spices (Pimpinella anisum, Scorodophleuszenkeii, Xy- lopiaparviflora, Eugenia caryophyllus, Fagara leprieurii, Fagara macrophylla, Monodora myristica, Olax subscorpioidea, Xylopiaaethiopica, Allium sativum, Zinziber officinale and Cinnamomum zeylanicum) in stabilizing crude soyabean oil during accelerated storage was assessed. The phytochemical screening revealed the presence of phenols in all the spices except that of Allium sativum. Total phenolic content (TPC) and DPPH radical scavenging activity of the extracts varied significantly (p < 0.01) ranging from 1.34 to17.72 gGAE/100 gand 18.91% to 96.39% respectively. Extract of Zinziber officinale, Olax subscorpioidea, Fagaramacrophylla, Eugenia caryophyllus and Xylopia parviflora, which offered the highest TPC, exhibited superior antioxidant activity with regard to the DPPH. Furthermore, the antioxidant effectiveness of the extracts and powders was assessed using crude soyabean oil (CSO) as the oxidation substrate. CSO samples stabilized with extracts at a concentration of 500 ppm (w/w) and powders at a concentration of 1000 ppm were subjected to accelerated storage (65?C, oven heating, 24 days, 8 h heating cycle per day), and analyzed periodically for the extent of oxidative alterations following the measurement of iodine and peroxide value. CSO + BHT at 200 ppm served as standards besides the control. Results?reveal Zinziberofficinale, Cinnamomum zeylanicum, Scorodophleuszenkerii, Monodora myristica, Xylopiaaethiopica, Allium sativum, Fagara leprieurii extracts and powders and the powder of Pimpinella anisum to be potent antioxidants for stabilization of crude soyabean oil.

Lipid Oxidation of Catfish (<i>Arius maculatus</i>) after Cooking and Smoking by Different Methods Applied in Cameroon

The influence of different cooking and smoking methods (boiling, frying, frying + boiling, hot and cold smoking) on oxidation and fatty acid composition of catfish (Arius maculatus) commercialized on the Wouri river coast was evaluated including commonly used analytical indexes (peroxide and acid values)and physical analysis by Fourier transform infrared (FTIR) spectroscopy. The mean moisture, protein, ash and fat contents of raw fish were 75.88 ± 0.55;64.24 ± 0.14;10.98 ± 0.31 and 23.02 ± 0.88 respectively. All these treatments provoke the modification of the quality indexes. Lipid deterioration, thermolysis and lipid oxidation occurred throughout the treatment. Peroxide value decreased for all cooked and smoked catfish, while free fatty acids of smoked sample increased. The FTIR applied to evaluate lipid oxidation in extracted lipid clearly provided a better picture of the oxidation progress and led to a similar conclusion with chemical analysis. Boiled, bleaching hot and bleaching cold smoking were found to be the suitable treatment methods for catfish because they gave it a high nutritive value compared to other smoking methods.

Effects of Soursop flowers(Annona muricata L.)extract on chemical changes of refined palm olein stored at frying temperature

In this study,the antioxidant activity of soursop flowers extract in delaying palm olein oxidation at frying temperature was assessed.The oil was supplemented with the extract at concentrations 200–1800 ppm,and stored in the oven at 180◦C for 6 days(4 h heating per day).Palm olein containing butylated hydroxytoluene(BHT)served as positive control while the same oil without antioxidant(Control)served as negative one,in order to monitor changes in oils.After each two heating days,oil samples were collected,and their chemical indexes were determined.Peroxide,para-anisidine,TOTOX,thiobarbituric acid and iodine values were the parameters evaluated.Additionally,the evolution of the fatty acid composition of each oil sample during the storage was assessed by gas-chromatography using a flame ionization detector(GC/FID).Generally,palm olein samples containing the natural extract have exhibited the lowest rate of oxidation,and were efficient in limiting the destruction of unsaturated fatty acids in oil at frying temperature.The order of effectiveness in inhibiting oil oxidation was the following:PO+AnM1800ppm>PO+AnM1400ppm>PO+AnM1000ppm>PO+An.M600ppm>PO+An.M200ppm>PO+BHT200ppm=Control.From these results,it can be concluded that soursop flowers are a potent sources of natural antioxidants for stabilization of palm olein.