MFR PAPER 1034 vents, u ually isopropyl alcohol, a nd several pilot plants and a few full -scale indu tria l pl ants have been constructed An enzymatic FPC process could (Ern t. 197 1). By olve nt e\.traction make profitable use of some of our FPC can be produced that is a bland. underutilized or latent resources . nearl y odorless. li ghtl y-colo red. water­ insoluble. but hi ghl y nutritive powder. FPC's pre pared by biological proce­ dures are usuall y mo re Aavorful and may have desira bl e functional proper­ Using Enzymes to Make ties. In ge neral the bi ologica l proce­ dures have not advanced beyond the Fish Protein Concentrates labo ratory o r small pilot plant stage. THE BIOLOGICAL METHOD The wo rk described in this paper MALCOLM B. HALE has been called the '" Bi ological Meth od " within the fish protein con­ centrate (FPC) program of the ation­ ABSTRACT a l Ma rine Fisheries Service. Biological proces ing st udies at the Coll ege Park Fish proTein CO ll cellTraT es having desirable JuncTional properTies call be pre­ Fishery Products Technology Labora­ pared by using selecTed enzy/ll es TO solubili::.e prOTein and release lipids. All en­ tory have been concentrated on the u e ::'Y IiUlTi c FPC process could /IIak e profiTable use oj sOlli e oj our IIl1denllili::.ed or of proteolytic enzymes to prepare 01- Im ellT resollrces. ubl e hydrolysates of fish protein. Th e relaTive aCTiviTies oj 23 cO lllll1 ercially ([I'ailab le proTeolYTi c enZY lll e prepar­ Fish proteins are complex molecules aTiollS aCTing 0 11 a fish proTein slibsTraT e were m easured. Pallcrea Tin , pepsin, lind consisting of chains of simpler mole­ papain had highes T aCTiviTy per UlliT COS T oJ ell <..Y lll e. cu les call ed amino acids lin ked togeth­ Soluble hydrolysaTes were prepared from red hake (Urophycis chuss) II sillg a er by peptide bonds. Proteolytic en­ l'arieTy oj en::.yme and digesTioll condiTions. ConcellTraTions oj Th e alllillo acids zy mes are also proteins and are struc­ Tr ypT ophan and hisTidin e ill Th e soluble producTs \I'ere criTical nliTriTioll ally and tured in such a way that they act as varied wiTh Th e pH oj hydrolysis. A soluble FPC ha ving a proTeill eJficiency raTio catalysts in the breakage of peptide equal TO ThaT oJ casein was prepared wiTh an alkalille baCTerial ell <..Y lll e aT pH 8.5. bonds by a process call ed hydrolysis. Pr odu c Ti on COS TS ha ve been eSTimaT ed Jor a soluble producT prepared Jro/ll Most of the shorter amino acid chains II'hole fish and a parTially soluble produ cT prepared frOIll presscake Through Th e broken off from the fish protein are lise oj ell zym es. water-soluble. Fish li pids (fat) are also released from the tissue during hydrolysis and can be physicall y sep­ INTRODUCTION FPC's may be produced by vari ous arated by cent ri fugation. processes to give products with differ­ Fish protein concentrates (FPC's) The enzyme systems employed in ent cost a nd properties. thus differe nt are made by processes which concen­ fish protein hydrolysis may be either appli cations. Most of th ese processes trate fi h protei n into a more stable the natural enzymes contained in the are described in a rece ntl y compiled form. As a form of animal protein, fis h (a uto lysis). purified commercial bibliography published by the Libra ry FPC's can supplement vegetable pro­ preparati o ns from variou biological of Congress (1970) . Most of the pro­ teins very effectively. Added in low sources (vegetable. animal. or micro­ ces ing method can be cl assifi ed as concentrations they can markedly im­ bial). or the enzymes supplied b, living chemical (solvent extractio n) o r bio­ prove the nutritive value of bread and cultures of microorgani ms. logical (enzymatic a nd microbi al) pro­ many other common foods by supply­ Development of a biological pro­ cedures. During recent years most ing certain essential amino acids defi­ cess was pursued because ( I) the efforts have involved the use of sol- cient in vegetable proteins. Produced product can have special properties from species of fish not normally used MaJcolm B. Hale is a member of (e.g.. olubility) w hi ch make it more as food , they are an inexpensive source the staff of the College Park suitable for certain appli cations than Fishery Products Technology is the o lvent extracted F PC. (2) it ma) of animal protein and could provide a Laboratory, National Marine profitable use for some of our presently Fisheries Service, NOAA, Col­ be possi ble to produce an acceptable underuti Iized or latent resources. lege Park, MD 20740. protein concentrate more cheapl, 15 hecau,c of thc addcd c ff cct o f na tive It, h c n /)- IllC, I hc rei at l v c effect IVl:nc.,\ o f pl: p' ln. fo r In , tance. wa., 10'" Wi th ACID ",holc fi,h hccau,c thl: nat lll: l:n / jlllc\ BASE arc not act lvc at p H 2 ",h lc h 1\ o ptl ­ IllUIll for pl:r'>ln Over a rerlod of time. Illany rroducl'> "'ere prl:ran;d In ~­ HYDROLYSIS VESSEL Itter hatchl:'" (I Igurl: I) U'>lng di ff erent en/) me, and rroce,,,ng condition., \erclgc ) leld, of dry ,oluhlc rroduct \\Ith each t\ pc or Cnl) mc arc li'll:d in T ahle I. Amino aCid anal),e, and BONES & SCALES Table 1 - Average Yi elds o f dry so lids from red hake so lubilIZ e d by proteolytiC enzymes Y'e d dry l OIL SO u bles/ Ne Number fish °0 - Sid Enzyme(s 01 runs de'w'lallon UNDIGESTED SOLIDS AutolYSIS 100 + 0 4 PepSin 1 109 Papain 5 113., 0 8 BPN 4 117 +010 Bromelin FICin 3 123·03 Rhozyme P-ll 3 12 5 - 075 Pancreal n 7 138= 13 Alkaline pro eases 5 143- 10 SPRAY DRY PRODUCT, DRYER SOLUBLE FPC llmlteJ feeJlng 'tuJle Indicated that h)drol)\" at p H , ~I\lth an al~altne rrt1 teu..,e 01 8m illill IIIhlilil re,ulteJ fn Figure 1.-Basic process ou tline for enzymatic hydrolysis of fish . the he,t nutritlle lalue a\ Ilell a\ the hlghe ... t ) lelJ of product. pol) peptide~. and ~ome Iree amino through biological means than through HYDROLYSIS CONDITIONS acids. An alternate product. ea,tI) dl,­ solvent extraction. and (3) a biological AND AMINO ACIDS method with proper controls ",ould be per,iblc but onl) part lall) ,oluble. I, more suitable for u e on shipboard or prepared by elimina ting the centrifuga­ RaIl fl,h i~ h) Jrol) zed ~o that the for use in remote areas. tion step. Either product could be ~old actll It) of nat" e enz) me.., i cOlllblned A process has been developed for as a concentrated paste Illth elimina­ I\ith that of aJded enz)llle . In initial the preparation of a nutritious. totally tion of the dry i ng ~tep. ru ns the ti h 1\ a~ coo~eJ a.' a control Illea ure rrior to hydrol)~i~. Both water-soluble concentrate deri \ ed SELECTION OF ENZYMES from fish protein", hich may be u~ed ) ielJ and nutritive lalue \\ ere poor. to advantage in foods such as soups In early research the relati\e prote- n e'l.perlment shO\\ed that the degree a nd beverages. Although proc es~ing 01) tic activities of 23 commerciall) )f solubilization ach ie l ed \\ ith ral\ costs have been considered throu gho ut available enz) me preparations I\ere ha ke coulJ be obtained 1\ it h cooked the work. the major concern has been compared. A speciall) prepared fish hake onl) if si 'l. times as much com­ for improvement of the amino acid protein ub trate was used in sta ndard mercial e n z) me "'ere a dded . pattern and nutritive value of the sol­ hydrolysis tests of I-ho u r a nd 2.+- hour Solu ble h ydrolysates pre pa red fro m uble product. durations . Fici n was m ost active for a cooked ha ke ha d low nutritil e values The basic bi ologica l process is de­ I-hour period. O ver the lo nger h ydroly­ as the sole source of prote in in feeding picted in Figure 1. Enzymatic diges­ sis period the e nzymes pepsin. papain . studies w ith ra ts. The co ncentra ti o n o f tion of a whole fis h slurry with control and panc reatin ra nked hi ghest o n th e the essentia l a mino acid try ptopha n of p H and temperature is followed by basis of acti vity per unit cos!. These was quite lo w in the e pro ducts , Treat­ screening to remove bones and scales. results were de ta il ed in a previo us pu b­ ing ra w h ake unde r sli ghtl y alkaline Insoluble solids are separated by cen­ li cation (H ale. 1969). conditi o ns gave a good yie ld of pro ­ tr ifugation and a c larified hydrolysate When who le red ha ke ( Uropliycis duct conta inin g adequa te try ptopha n . is spray-dried (Figure 2) to yie ld a cllllss) was used the re la ti ve effecti ve­ The positi ve co rrela ti o n between the soluble p rodu ct consisting of peptides.