Extraction of protein from the wastewater of fish meal production plant by isoelectric precipitation method and evaluation of its functional properties

Fishmeal factories produce a large amount of wastewater during the production process, which contains protein. The aim of this study was to recover protein from the effluent of fishmeal factory by isoelectric method and investigate the functional properties of recycled protein. The effluent sample was obtained from fishmeal production plant in the Konarak city and proximate composition analysis of the effluent sample was investigated. The protein in the effluent was recycled using the isoelectric precipitation method and pH changing. The functional properties of the recovered protein including solubility, oil and water holding capacity, emulsifying index and emulsion stability, foam formation and foam stability were measured using standard methods procedures. The results showed that the amount of protein in the treated sample has no any significant differences under the effluent effects (p >0.05). The highest and lowest solubility were obtained at pH 2 and pH 6, respectively. The water and oil holding capacity of recycled protein was 0.45 and 0.4 ml/g, respectively. The highest emulsion activity was observed at pH 10 and the highest foam formation capacity at pH 2. The highest emulsion stability was observed at pH 2 and the highest foam stability was observed at pH 2 and 10. Recycled protein showed good functional properties and changed with pH, but not all properties followed a specific trend.