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Rat brain acyl‐CoA hydrolase enzymes which hydrolyse C2, C4, C8 and C16 derivatives were localized primarily in the soluble, 144,000 g, supernatant fluid. With octanoyl‐CoA as substrate, long‐chain acyl‐CoA hydrolase activity was greater in the pons, medulla and midbrain than in the cerebral cortex and caudate nucleus. The long‐chain acyl‐CoA hydrolase enzyme was purified from bovine brain stems to a specific activity of 4‐61 n mol of palmitoyl‐CoA hydrolysed per min per mg protein. The Km values for palmitoyl‐CoA and octanoyl‐CoA were 5 μm and 14 μ/m, respectively. Activity of the enzyme was inhibited by bovine serum albumin and ρ‐chloromercuribenzoate. The partially purified enzyme protein was found to have approximately eight titratable sulphydryl residues per 105 g of protein. Studies of the molecular weight of the enzyme indicated the presence of associated and dissociated forms with molecular weights of approximately 96,000 and 46,000 respectively.

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Superpositioning principles were applied twice to model temperature (25 to 125 Њ Њ Њ Њ ЊC) and concentration (0.005 to 0.040% w/w) effects on skim milk and carrageenan solutions. Samples were analyzed using a controlled stress rheometer equipped with a pressurized sealed cell, permitting measurements well above standard boiling conditions. Individual samples were sheared between 10 and 160 s -1 , and predictive equations were developed to predict Newtonian viscosity as a function of temperature and carrageenan concentration. The superpositioning technique coupled with advancements in rheological instrumentation permits high temperature measurements and offers a strategy for viscosity determination for thermal processing unit operations.

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