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AssigneeHer Majesty the Queen in right of Canada, as represented by the National Research Council of Canada
InventorsJohn H. T. Luong, Keith B. Male, An L. Nguyen
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The present invention relates to a method for determining the degree of freshness of raw, frozen and processed edible fish by monitoring the degradation of adenine triphosphate to inosine monophosphate, inosine and hypoxanthine. This method comprises simultaneously determining, by use of a suitable amperometric electrode such as platinum vs. silver/silver chloride polarized at 0.7 V, the amount of uric acid and hydrogen peroxide resulting from the degradation of hypoxanthine by xanthine oxidase, the degradation of inosine by the combined action of nucleoside phosphorylase and xanthine oxidase and the degradation of inosine monophosphate by the combined action of nucleotidase, nucleoside phosphorylase and xanthine oxidase. Also within the scope of this invention is a method for the immobilization of nucleotidase on the walls of a polymeric tube such as polystyrene tube and the co-immobilization of nucleoside phosphorylase and xanthine oxidase on a porous polymeric membrane such as a nylon membrane.
A method for determining the degree of freshness of raw, frozen or processed edible fish by monitoring the autolytic degradation of adenosine triphosphate in fish muscles to inosine monophosphate, inosine and hypoxanthine, said method comprising:
An enzyme biosensor system for use in the determination of fish freshness from a fish extract obtained by breaking the cell membrane of said fish, the freshness of said fish being determined by monitoring the autolytic degradation of adenosine triphosphate in fish muscles to inosine monophosphate, inosine and hypoxanthine, said system including a biosensor comprising in combination an amperometric probe having thereon a porous membrane having the enzymes xanthine oxidase and nucleoside phosphorylase co-immobilized thereon to form an enzyme electrode and a polymeric support having the enzyme nucleotidase immobilized thereon, a first portion of said extract being contacted with said enzyme electrode to electrochemically measure a value d.sub.1 =[HxR]+[Hx] from the simultaneous determination of the amount of hydrogen peroxide and uric acid resulting from the degradation hypoxanthine and inosine in said first extract portion by said enzyme electrode enzymes wherein [HxR] is the concentration of inosine and [Hx] is the concentration of hypoxanthine, a second portion of said extract being contacted with said enzyme electrode and said polymeric support to electrochemically measure a value d.sub.2 =[IMP]+[HxR]+[Hx] from the simultaneous determination of the amount of hydrogen peroxide and uric acid resulting from the degradation of inosine monophosphate, inosine and hypoxanthine in said second extract portion by said enzyme electrode enzymes and said polymeric support enzyme, wherein [HxR] is the concentration of inosine, [Hx] is the concentration of hypoxanthine and [IMP] is the concentration of inosine monophosphate, whereby the index of freshness is determined from the formula K=d.sub.1 /d.sub.2, wherein K represents the index of freshness.
Dependencies are inferred from the claim text.