Table 14. — Material balances for the processing of red 

 hake by three digestion methods. 



Enzyme : Pancreatin Alcalase Autolysis 

 Run No.: II-PC-2 II-A-E II-Aut-2 



Total . . 



Percent ^ Supemate 

 recovery i- Sludge . . 

 lipids J Bones . . . 



Total . . 



Percent "| Supemate 

 recovery /-Sludge . . 

 ash' J Bones . . . 



Total . . 



95.8 



92.3 



118.3 



' Based on ash content of fish plus ash added during pH 

 adjustment and control. 



A flow diagram with more detailed material 

 balance information for preparation of a totally- 

 soluble hydrolysate using pancreatin, Run No. 

 II-PC-2, is shown in Figure 11. 



Hydrolysis of alewife. — Material balances for 

 one run by each of the three processes employed 

 with alewife are summarized in Table 15. Dry 

 solids recoveries of about 80 ^r were obtained 

 when the various supernates were spray-dried. 

 Recoveries nearer to 95 '^r would be expected in 

 a continuous operation with a secondary bag 

 collector. Therefore, product yields calculated 

 were based on dry solids contents of the super- 

 nates. 



More detailed material balance information 

 is shown for runs yielding a soluble product from 

 raw alewife (Figure 12) and a partially soluble 

 product from press cake (Figure 13). 



SUGGESTED PROCESS OUTLINES 



Raw Fish 



Fatty fish — The processing of raw, fatty 

 fish for the production of a dry soluble concen- 

 trate and/or fish paste is outlined in Figure 14. 

 Raw fish are chosen because the active autolytic 

 enzymes are required in combination with an 

 added commercial proteolytic enzyme in order 

 to obtain economically the desired degree of sol- 

 ubilization. Water equal in weight to the fish 

 is metered in during comminution. 



PANCREATIN 

 28b 



pN CONTROL 



WATER: 3000 g 

 HAKE: 2796 g 



PROTEIN 462 2 

 LIPID ■ 86 7 

 ASH 76 3 



NAOH 24 g 

 CA|0Hl2 15g 

 H2SO4 42 g 

 H2O 117g 



LOSSES: 196 g 



5HRS 

 pH 8 5 

 45°C 

 DIGESTER 



ANTIOXIDANT 



TENOX 2. 3g 

 IPA. 2.2 g 



SCREEN 



-BONES + SCALES: 193 g 



r CENTRIFUGE 



SLUDGE 939 g 



SUPERNATANT 4672 g 



Figure 11. — Material balance, Run No. II-PC-2: totally- 

 soluble product from red hake. 



Table 15. — Material balances for the processing of ale- 

 wife (river herring) by three digestion methods. 



' Digestion of press cake; recoveries based on weight of 

 fish to cooker. 



' Fat and oil fraction removed by centrifugation. 



^ Free oil separated by pressing of cooked fish. 



' Based on ash content of fish plus ash added during pH 

 adjustment and control. 



22 



