EFFECT OF DRYING AND DESOLVENTIZING ON THE FUNCTIONAL 

 PROPERTIES OF FISH PROTEIN CONCENTRATE (FPCJ 



David L. Dubrow' 



ABSTRACT 



Experiments were performed to determine the effects of drying and steam desolventizing 

 on the functional properties of fish protein concentrate (FPC). The FPC's were pro- 

 duced by a room temperature extraction of either red hake or menhaden with azeotropic 

 isopropyl alcohol. FPC's thus produced contained about 36% soluble protein and, when 

 dried at ambient temperature and pressure, showed very little loss in protein solubility. 

 Drying the extracted wet solids at 40° to 50°, 60° to 70°, 90° to 100°, or 140° to 150°C 

 for 30 or 120 min produced decreased protein solubility, i.e., 30.7% (40° to 50°C) to 12.5% 

 (100° to 120°C). Emulsion stability of an FPC-water-oil system was satisfactory with 

 all samples except those dried at 140° to 150°C. 



Desolventizing dry solids or alcohol wet solids by steam stripping produced a dramatic 

 loss in soluble protein and emulsion stability. There was also a significant darkening in 

 color of the FPC's desolventized as wet solids as compared to FPC's desolventized as 

 dry solids. 



Food protein additives are used because of their 

 nutritional and/or functional properties. Func- 

 tional properties include solubility, dispersibility, 

 water holding capacity, and emulsifying capacity 

 (Johnson, 1969, 1970). FPC (fish protein con- 

 centrate) can have a range of functional proper- 

 ties depending upon the processing methods 

 used. It is necessary, however, to control certain 

 processing parameters in order to retain func- 

 tionality. 



Extraction of fish with IP A (isopropyl alco- 

 hol) at 20° to 30°C produces an FPC with better 

 functional properties than extraction at 50°C 

 (Dubrow, 1971). Similar results have been ob- 

 tained by extracting chicken protein with IPA 

 (Toledo, 1970).^ Although low temperature ex- 

 tracted FPC retains a certain degree of protein 

 solubility and emulsifying capacity, these prop- 



' College Park Fishery Products Technology Labora- 

 tory, National Marine Fisheries Service, NOAA, College 

 Park, MD 20740. 



' Toledo, R. T. 1970. Design data for a low tem- 

 perature continuous countercurrent extraction process 

 for protein concentrate production. Paper presented at 

 the Institute of Food Technologists, 30th Annual Meet- 

 ing, San Francisco, Calif. 



Manuscript accepted July 1972. 



FISHERY BULLETIN: VOL. 71, NO. 1, 1973. 



erties may be lost during subsequent drying and 

 desolventizing of the wet solids. Drying and 

 desolventizing is necessary to reduce the residual 

 IPA to 250 ppm to meet FDA (Food and Drug 

 Administration) regulations (Federal Register, 

 1967). The purpose of the present studies, 

 therefore, was to determine the effect of time 

 and temperature of drying and desolventizing 

 on the functional properties of FPC. 



EXPERIMENT I: EFFECT OF TIME 



AND TEMPERATURE OF DRYING ON 



FUNCTIONAL PROPERTIES 



MATERIALS AND METHODS 



Preparation of Samples 



Whole red hake {Urophycis chuss) were ob- 

 tained from Block Island off the coast of Pt. 

 Judith, R.I. They were iced on board the fish- 

 ing vessel and then frozen at dockside. The ex- 

 traction process consisted of a five-stage cross- 

 current batch extraction at 22° to 27°C. The 

 solvent to raw fish ratio was 2:1 w/w. Each 



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