Biotransformation of the fish waste by fermentation

Abstract

Fish waste (viscera, backbones, heads and tails) was recovered fish merchants and ground. 50 kg of the ground fish was mixed with 10 kg of molasses and incubated in 200 kg barrels in closed plastic in a
room where the ambient temperature varies between 30 and 33°C. Stumps of lactic bacteria and yeasts were used to inoculate the mixture. There was a decrease of pH from the third day which stabilized at 4.2 and a remarkable change of the number of bacteria between the initial and the finished products. The total aerobic mesophilic flora increased from 2.4 x 106 to 4.58 x 107 cfu and yeasts from 1.30 x 103 to 1.59 x 105. As for the anaerobic sulfur-reducing (ASR) bacteria, their number reduced from 1.65 x 103 to 2 x 102, the fecal coliforms were eliminated completely even though their initial number was 1.20 x 103., Also, total coliforms went from 1.9 x 104 to zero. At the end this fermentation, the fishy smell was concealed by products of fermentation. There was total absence of nematodes and the useful products (proteins, lipids, mineral elements) can be exploited in the fertilization of soil or used as ingredient to balance the food ration of the animals especially during the periods of drought. The obtained results
confirm the efficiency of our isolated inoculum and a fast, simple and less expensive fermentation process.