Torger Børresen

Is trimethylamine oxide a reliable indicator for the marine origin of fish

Abstract 1. 1. The non-protein nitrogen fraction of four fish species from Lake Victoria was investigated. 2. 2. The presence of content of trimethylamine oxide (TMAO) was determined by the Conway microdiffusion assay and confirmed by 1 H and 13 C NMR spectroscopy and FAB mass spectrometry. 3. 3. Nile perch ( Lates niloticus ) and a Tilapia sp. contained exceptionally high levels of TMAO (150–200 mg/100 g) for freshwater fish species. 4. 4. TMAO was not present in the catfish Bagrus and Clarias from the same area. 5. 5. Concentrations of free amino acids were 2700–5000 μmol/100 g with taurine accounting for 50–75% of the free amino acids.

Inhibition of microsomal glucose 6-phosphatase by unsaturated aliphatic aldehydes and ketones.

Aldehydes and ketones with one double bond conjugated to the carbonyl group inhibited the enzyme glucose 6-phosphatase, which is embedded in the microsomal membrane. The Michaelis constant, Km and the maximal rate of reaction, V, were affected in a way dependent on the inhibitors chain-length: trans-2-pentenal and 1-penten-3-one increased Km linearly with concentration and had almost no effect on V, whereas trans-2-nonenal caused a large increase in V but only a small and non-linear change in Km. The effect of the short-chain aldehydes on the kinetic parameters increased with chain-length, but pentenone increased Km more than did trans-2-heptenal and conjugated dienals did not act as inhibitors. Therefore, sterical effects apparently are of importance. Washing the microsomes after incubation with hexenal or heptenal did not substantially decrease the inhibition, but with nonenal the inhibition was reduced by washing. Inhibition by the SH-group blocking reagent p-hydroxymercuribenzoate was competitive to inhibition by the alkenals. It is concluded that the alpha-beta unsaturated oxo-compounds inhibit glucose 6-phosphatase by binding covalently to an important mercapto group and that perturbation of the enzymes membrane environment also plays a part in the inhibition.

Concurrent Engineering and product models in seafood companies

Concurrent Engineering (CE) can provide an improved approach to product development for extending the lines of seafood products. Information technology (IT) support tools based on product models can provide an integrated and simultaneous approach for specifying new recipes. The seafood industry can benefit from the CE approach which can support product developers to provide concurrent specifications for raw materials, ingredients, packaging, and production methods. The approach involves the use of product models from which line extensions are more easily generated than by use of customary stepwise techniques. It is anticipated that other food industries can also benefit from the more simultaneous development approach.

Purification and characterization of elastase from the pyloric caeca of rainbow trout (Oncorhynchus mykiss)

Abstract 1. 1. An elastase-like enzyme was purified from the pyloric caeca of rainbow trout by hydrophobic interaction, cation exchange and gel-filtration chromatography. 2. 2. The approximate molecular weight of the elastase was 27 kDa and the isoelectric point was remarkably basic. 3. 3. The pH optimum of this enzyme was 8.0, when assayed with Succinyl-Ala-Ala-Ala- p -Nitroanilide. 4. 4. When assayed with Succinyl-Ala-Ala-Ala- p -Nitroanilide, the enzyme activity had a temperature optimum of 45°C, and the enzyme was stable up to this temperature. 5. 5. The trout elastase exhibited a higher specific activity than porcine elastase against Succinyl-Ala-Ala-Ala- p -Nitroanilide and elastin-orcein. 6. 6. The trout elastase was inhibited by elastatinal, PMSF, TPCK, SBTI and Bowman-Birk inhibitor.

Development of a product model for specifying new lines of seafood products

Abstract New product development in the seafood industries is increasingly based on extension of product lines. These must be tailored to the retailer and customer needs and be available with short lead-times. One possibility for seafood companies to meet this challenge is to utilise the benefits and prospects of an IT approach to product modelling. The approach used is developed for non-food specification tasks and coupled with the experience gained in a seafood company. IT application prototype that consisted mainly of earlier product solutions and knowledge related to the specification tasks was developed. Testing of the prototype has indicated possibilities for speeding up the specification process in the company and it is assumed that similar results can be obtained in other food product development processes.