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Tropical roots and tubers generally contain mucilage. These mucilages exhibit unique rheological properties with considerable potential as a food thickener and stabilizer. A one-step extraction procedure was used to isolate starch free mucilage and associated proteins from a number of taro (Colocasia esculenta) varieties. The monosaccharide and amino acid composition, the structural and flow properties were investigated. The results showed that yield of mucilage fraction varied from 30 to 190 g.kg(-1). A negative correlation (r = -0.87; p < 0.05) was observed between the crude protein level and the yield. The monosaccharide profiles revealed that galactose, mannose and arabinose were the main monosaccharides in the hydrolysate of the mucilage. From the 17 amino acids analyzed, aspartic acid/asparagine (14.4-17.2%) and glutamic acid/glutamine (10.3-13.6%) were prominent in the mucilage as well as the flour. No significant differences were observed in the FT-IR spectra and in the viscosity behavior of the mucilage dispersions. The greatest difference in the mucilage is based on its monosaccharide profile while the protein composition, which reflects that of the flour, is relatively stable.

The effect of essential oils from Syzygium aromaticum and Cymbopogon citratus on the lipid oxidation and microbial growth in beef patties was investigated in the present study. Essential oils were incorporated into the beef patties at 0.1% and 0.2% (w/w). The beef patties were then inoculated with cultures of E. coli and S. aureus and stored at 4˚C. The control patties were processed without essential oil but inoculated with E. coli or S. aureus. The proximate composition, lipid oxidation and microbial counts were carried out after 7, 14, 21 and 28 days. Results showed that the incorporation of essential oils in beef patties did not significantly (P < 0.05) influenced the chemical composition of the beef patties but significantly (P < 0.05) reduced the TBA (Thiobarbituric acid) during storage period. The incorporation of the essential oil of S. aromaticum at 0.2% reduced the E. coli growth by 1.48 log CFU/g and that of S. aureus by 6.52 log CFU/g while the incorporation of C. citratus at 0.2% reduced the E. coli growth by 1.21 log CFU/g and that of S. aureus by 1.4 log CFU/g after 28 days of storage. The pH measurement during the storage period showed a slight drop during the first 7 days of storage and an increase during the last 21 days in all samples. The sensory test of the beef patties showed that the consumers accepted patties formulated with the two * Corresponding author. F. B. Siewe et al. 375 essential oils. But the one made with 0.1% essential oil of S. aromaticum was the most accepted. The analysis of the color of beef patties between 0 and 28 days of storage revealed that the incorporation of essential oils retarded the degradation of the color of patties. Results obtained in the present study indicate the possibility of exploiting Syzygium aromaticum and Cymbopogon citratus essential oils to protect beef patties against lipid oxidation and microbial growth.

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The aim of the present study was to investigate the essential oil of Cinnamomum zeylanicum from Cameroon for its chemical composition, antiradical and antifungal activities against some common fungi causing spoilage of stored food product. The essential oil, obtained by hydrodistillation of fresh leaves, was analysed by GC and GC/MS. The oil contains 11 components among which eugenol (89.1%), linalool (4.3%), benzoate benzyl (3.1%) and cinnamaldehyde (1.5%) were the main components. Determination of antiradical activity of the oil was studied by the DPPH (diphenyl picryl hydrazyl) method. The antiradical activity of Cinnamomum essential oil (SC 50 = 4.5 mg/L) was higher than that of butylated hydroxy toluene (BHT), which was used as the reference compound (SC 50 = 7 mg/L). The growth inhibitory effect of C. zeylanicumn essential oil on Aspergillus flavus and Fusarium moniliforme was determined on potato dextrose agar. After 9 days of incubation on essential oil-supplemented medium, the growth of A. flavus and Fusarium was totally inhibited by 500 ppm of Cinnamommum zeylanicum oil. Results obtained in the present study indicate the possibility of exploiting C. zeylanicum essential oil to prevent diseases such as diabetes and cancer, to slow down ageing, and also to combat strains of A. flavus and Fusarium moniliforme responsible for biodeterioration of stored food products.

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