Rotating pressure cookers

Seal blubber tends to be pure homogeneous fat and like the fish liver oils can be rendered quite simply. Whale blubber on the other hand contains tough connective tissue and fibres and is now rendered in rotating Kvaerner cookers under high pressure steam. As recently as 1955, world production figures (xlOOO metric tons) for marine oils were whale, 378 sperm, 91 seal, 6.5 fish body, 310 aquatic animal liver, 73 (presumably including whale liver oils as a source of vitamins A and D). By 1989 the figures (xlOOO) were marine mammal oil production, 1 fish liver oil, 32 fish oils, 1593 (Bimbo and Crowther, 1992). 

The raw material mixed with sulfuric acid is introduced through a manhole, and after closing the latter, rotation of the cooker and passage of steam to give 153 C are applied for 5 hours. The temperature of 153 °C was imposed by the pressure rating of the available cookers. After trying various materials, QUAKER OATS ended up lining the cookers with carbon bricks sealed by an acid-proof cement. This is the process as it is still used today. 

Cooking.—Starch is completely pastified by cooking under pressure. In order to maintain semi-continuous operation this is accomplished in three cookers used cyclically at intervals of an hour. That is, cooking of each distinct batch consumes three hours, but each hour another cooker in rotation has completed its batch and commences with a fresh one. A scheme of this operation is shown in Figure 32, p. 125. 

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