Conversion of Scallop Viscera Wastes to Valuable Compounds using Sub-Critical Water

The large amounts of seafood wastes discharge from related industries have become a serious problem since dumping of these kinds of wastes has been banned by the London treaty in 1996. Since these wastes contain high concentration of nutrients such as proteins and fat, incinerating method which became common procedure recently did not only result to enable recovery of useful materials, but also was very expensive. In this work, the sub-critical water hydrolysis of scallop viscera wastes has been studied in a batch-type reactor and temperature range of 443-653 K, and time 1-50 min. The experimental results demonstrated that this method produced valuable materials such as amino acids, organic acids, soluble proteins and peptides by hydrolysis reaction. Fat and oil extracted also contained wide variety of fatty acids. At 513 K and 50 min, the maximum total amounts of amino acids (0.15 kg/kg dry scallop waste) were obtained. The total amounts of organic acids were found maximum at 553 K and 40 min (0.08 kg/kg dry scallop waste). The temperature, which showed the maximum yields of amino and organic acids were close to the temperature at which ion product of water is maximum. Among amino acids glycine showed maximum yield, where in organic acids pyroglutamic acid was maximum. On the viewpoint of overall waste recovery, material balance resulted to at least 74 % conversion. The obtained experimental results showed that the method employed in this work is important due to not only energy saving, environmental friendly and cost effectiveness but also produce many useful materials in the road toward zero emission.