Saccharomyces cerevisiae C8-5 and Candida tropicalis F0-5 isolated from traditional sorghum beer were tested for kinetic parameters on barley malt extract, YPD (863 medium) and for alcohol production. The results showed that C. tropicalis has the highest maximum growth rate and the lowest doubling time. Values were 0.22 and 0.32 h −1 for maximum growth rate, 3 h 09 min and 2 h 09 min for doubling time respectively on barley malt extract and YPD. On contrary, glucose consumption was the fastest with S. cerevisiae (−0.36 and −0.722 g/l/h respectively on barley malt extract and YPD). When these two yeasts were used as starters in pure culture and co-culture at proportion of 1:1 and 2:1 (cell/cell) for barley malt extract fermentation, we noticed that maltose content increased first from 12.12 g/l to 13.62-16.46 g/l and then decreased. The highest increase was obtained with starter C. tropicalis + S. cerevisiae 2:1. On contrary, glucose content decreased throughout all the fermentation process. For all the starters used, the major part of the ethanol was produced at 16 h of fermentation. Values obtained in the final beers were 11.4, 11.6, 10.4 and 10.9 g/l for fermentation conducted with S. cerevisiae, C. tropicalis, C. tropicalis + S. cerevisiae 1:1 and C. tropicalis + S. cerevisiae 2:1. Cell viability measurement during the fermentation by using flow cytometry revealed that the lowest mean channel fluorescence for FL3 (yeast rate of death) was obtained with C. tropicalis + S. cerevisiae 2:1 after 48 h of fermentation.

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Fresh mackerel heads were submitted to enzymatic hydrolysis using Alcalase 2.4L (60°C, 2h). The centrifugation of the slurry displayed three lipid fractions. Chemical characteristics of these fractions showed significant differences for protein, lipid and ash contents. The rate of oil released after enzymatic extraction accounted for 19.20% and 21% for 3% E/S and 5% E/S respectively with no significant difference (p< 0.05). Lipids released after enzymatic processes, lipids from emulsified fraction displayed similar lipid classes level amounted to 95-98% for triglycerides (TG) and 2-5% for phospholipids (PL). As for heavy fraction, there were 42% of TG and 58 % of PL. Lipids released by enzymatic hydrolysis and lipids of emulsified fraction displayed similar content of PUFA and were compared to lipids extracted by solvent. The main PUFA were EPA (6.99 to 7.56%) and DHA (from 11.26 to 15.86%). The lipid of the heavy fraction, which contained the most abundant amount of the DHA accounted for 26.11% and a high amount of EPA (7.73%).