Determination Of Fish Freshness Research Articles

Amperometric detection of uric acid and hypoxanthine with Xanthine oxidase immobilized and carbon based screen-printed electrode. Application for fish freshness determination

Carbon-based screen-printed electrodes are suitable for uric acid detection. Xanthine oxidase (XO) was immobilized either directly on the surface of the electrode or in a reactor with CPG aminopropylsilane in a FIA assembly. Higher reproducibility and lifetime was obtained with the reactor. Optimum conditions were found for the determination of Hypoxanthine (Hx), Inosine (HxR) and Inosine monophosphate (IMP). Calibration curves for IMP, HxR and Hx are linear up to 50 μM with detection limit of 1 μM for 50 μl injection. One assay is completed within 30 s. The reproducibility of 20 μM of Hx was obtained with CV 2%.

A sensitive xanthine oxidase electrode with silk net for estimating fish freshness

AbstractAn enzyme biosensor was constructed using a plate platinum electrode and immobilized xanthine oxidase (XOD). Only a very small quantity of enzyme was chemically immobilized on a special silk net. Hydrogen peroxide released during the enzymatic reaction was detected by the electrode at +0.65 V (vs. Ag/AgCl). The electrode was very sensitive to hypoxanthine and its detection limit was 1×10–7 mol/L. When it was applied to the determination of fish freshness, the results agreed well with those obtained by traditional methods‐determination of total volatile basic nitrogen (TVB‐N) and microbial count. A range for estimating the freshness of river fish was suggested.

Development of screen-printed enzyme electrodes for the estimation of fish quality

Enzyme electrodes for the determination of biogenic amines have been developed using monoamine oxidase (MAO) from Aspergillus niger and putrescine oxidase (PO) from Micrococcus rubens. Determination is based on the electrochemical oxidation of enzymatically produced H 2O 2 at screen-printed platinum electrodes. The enzymes are immobilized on silanized electrodes by cross-linking with glutaraldehyde. Compositions of the immobilization mixtures are optimized with respect to stability, sensitivity and selectivity of the sensors. The electrodes using MAO as the biochemical component respond to several amines including histamine, an important amine in the determination of fish freshness. The PO electrodes show a significant response not only to putrescine and its homologue cadaverine but also to tyramine, an electrochemically active amine. The optimal buffer for both types of amine oxidase electrodes is Clark and Lubs (C+L) buffer pH 8.5. Simultaneous determination of the substrates of both enzymes can be accomplished by immobilizing PO and MAO onto different working electrodes of the same sensor. The sensors have been used to monitor the freshness of mackerel and codfish in storage. As expected, sensor signals increase with storage time of the fish, indicating the production of biogenic amines. During storage of mackerel, mainly histamine is produced, which leads to an increase in the signals obtained with the MAO electrodes. On the other hand, the putrefaction process of codfish during storage is detected mainly by the PO electrodes. All results are confirmed by comparison with HPLC data.

Amperometric Determination of Fish Freshness by a Hypoxanthine Biosensor

The traditional determination of fish freshness is to detect total volatile basic nitrogen, microbial load or hypoxanthine. These methods are complex and expensive. A hypoxanthine biosensor was constructed by using immobilised xanthine oxidase and a platinum electrode. The enzyme was immobilised on a silk membrane. The electrode detected the hydrogen peroxide released during the enzymatic reaction. A linear range from 0·05 to 100×10−6 M of hypoxanthine was observed. When the method was applied to fish samples, the results obtained agreed well with those obtained by the conventional total volatile basic nitrogen and microbial load. This biosensor provides a reliable, simple, rapid and economical method for the measurement of fish freshness.

Amperometric Determination of Fish Freshness by a Hypoxanthine Biosensor

Amperometric Determination of Fish Freshness by a Hypoxanthine Biosensor

Enzyme sensors for determination of fish freshness

A simple and rapid procedure for the determination of fish freshness was developed and applied to the determination of the K 1 parameter (freshness indicator): K 1 = ([HXR] + [HX])/([IMP] + [HXR] + [HX]) × 100, where [IMP], [HXR] and [HX] are inosine monophosphate, inosine and hypoxanthine concentrations, respectively. A platinum electrode is used to detect hydrogen peroxide produced by the enzymatic reaction catalysed by xanthine oxidase immobilised on the electrode surface. The determination of inosine and inosine monophosphate was performed by the addition of nucleoside phosphorylase, 5′-nucleotidase or alkaline phosphatase to the buffer solution. Parameters such as type of buffer, amount of enzymes and sample treatment were optimised. With this procedure a linear response was obtained in the concentration range 1 × 10 −6−2 × 10 −5mol 1 −1 for hypoxanthine, inosine and inosine monophosphate. The detection limit was 5 × 10 −7 mol 1 −1.

Selective detection of aroma components by acoustic wave sensors coated with conducting polymer films

Eight conducting polymer films of polypyrrole and its derivatives were used as sensitive and selective coatings for thickness-shear mode (TSM) acoustic wave sensors. They were applied to the detection of volatile alcohols and carbonyl compounds, which are important fish freshness determinants. The conducting polymers were synthesized and coated on TSM devices by electrochemical oxidation. The exposure of the coated TSM sensors to four compounds (pent-1-en-3-ol, oct-1-en-3-ol, nona-3,6-dien-1-ol and nona-2,6-dienal) was investigated, and a linear response with concentration found for the different aroma components. The sensor response was also found to be proportional to the film thickness. The response patterns obtained by grouping the data from the individual sensors are characteristic for each aroma molecule, and were investigated using both cluster and principal components analysis. The results demonstrate the feasibility of fish freshness determination through the use of a TSM sensor array combined with pattern recognition techniques.

Thin-film polyamine biosensor: substrate specificity and application to fish freshness determination

A polyamine biosensor was developed by immobilizing putrescine oxidase on micro planar thin-film hydrogen peroxide electrodes. The sensor showed a rapid response to putrescine (90% response: 40 s) and the relationship between putrescine concentration and output current was linear between 0.03 and 3 μM under the optimum reaction conditions (pH 8.0, 30°C). The substrate specificity of the polyamine sensor was determined using a flow-injection analysis system. In addition to the main substrate putrescine, the sensor also converted cadaverine (46%), spermidine (45%), agmatine (13%), 1,6-diaminohexane (3%), 1,7-diaminoheptane (2%) and tyramine (13%, non-enzymatic response). These conversion rates were high compared with those of soluble putrescine oxidase. This is probably due to broadening of the enzyme's active centre during the immobilization procedure. The sensor was applied to fish freshness determination during a fish storage experiment. The sensor response obtained in fish extracts increased with increasing storage time and agreed with liquid chromatographic amine determinations.

Development of a system with double enzyme reactors for the determination of fish freshness

A continous system for the determination of fish freshness with double enzyme reactors was developed and applied to the determination of the freshness indicator ( K i=[(HxR + Hx)/(IMP + Hx)/IMP + Hxr + Hx)]× 100) in many types of fish, where IMP, HxR and Hx are inosine monophosphate, inosine and hypoxanthine, respectively. The system was prepared from two combinations of oxygen electrodes and reactors. One reactor for the determination of the total amount of HxR and Hx was packed with nucleoside phosphorylase (NP) and xanthine oxidase (XOD) immobilized simultaneously on chitosan porous beads. Similarly, another reactor for IMP, HxR and Hx was packed with 5-nucleotidase (NT), NP and XOD immobilized simultaneously on chitosan beads. The system was prepared from two combinations of oxygen electrodes and reactors. One assay could be completed within 5 min. The system for the determination of fish freshness was reproducible within 2.1% ( n=30). The immobilized enzymes were sufficiently stable for at least 7 months at 4°C. More than 200 samples could be analysed in about 1 month by using these enzyme reactors. The results for fish meat (13 types) correlated satisfactorily with those obtained by liquid chromatography ( r=0.989, n==253) and ion-exchange column chromatography ( r=0.973, n=50). These results suggest that the proposed sensor system provides a simple, rapid and economical method for the determination of fish freshness ( K i ).

魚介類鮮度計測用ｐＨセンサシステムの試作

A pH sensor system, by which β-buffer capacity in fish muscle is determined continuously, was prepared from a pH electrode, a flow cell, a peristaltic pump, and a recorder. The optimum conditions for the proposed system were established, and then β-buffer capacity in fish muscles was determined by the the sensor system and a conventional method. Good correlation were obtained between β-buffffer capacities obtained by the output of the sensor and the conventional method. The results obtained by the system were also in good correlation with the K values. From these results, the possibility of determination of fish freshness with the proposed sensor system was suggested. The conditions for the determination of the buffer capacity in fish muscles were as follows: pH of buffer 7.0, flow rate 1.4 ml/min, and sample volume 50μl.

Feasibility Study on the Determination of Fish Freshness by Trimethylamine Headspace Analysis

ABSTRACTTrimethylamine (TMA) concentration in fish tissue is an accepted measure of deterioration. In this preliminary study a direct relation was demonstrated between TMA in the tissue and in the headspace above the fish flesh. A relatively simple but precise procedure was developed for measuring TMA headspace concentration, based on air sampling with Carbotrap or Tenax sorbent tubes and subsequent thermal desorption and gas chromatographic (GC) analysis. Sampling and analysis are completed in less than 5 min. Fish freshness determined by TMA headspace analysis was consistent with grading estimated by sensory tests, but the instrumental method provided a more objective and quantitative assessment of quality and an estimation of postmortem age of the fish.

Microbial Sensors for the Detection of Fish Freshness

ABSTRACTA microbial sensor system consisting of immobilized living spoilage‐causing bacterium, Alteromonas putrefaciens, and an oxygen electrode was prepared and applied to the continuous determination of fish freshness. Fish freshness was expressed as a ratio of A/B, where A is the current decrease of the microbial sensor obtained by the application of l0–50 μL fish extract and B is the current decrease by the equivalent volume of culture medium. Freshness of bluefin tuna and yellowtail meats stored in ice for up to 2 weeks was determined by both the proposed and the conventional K value enzyme sensor method. Good comparative results were obtained. One assay could be completed within 13 min.

Determination of fish freshness with a multielectrode enzyme sensor system.

Amultielectrode enzyme sensor system was applied to determine the freshness indicator [KI={(HxR+Hx)/(IMP+HxR+Hx)}×100]in some fish and the display of freshness pattemwas studied by a computer. Moreover, the exudate obtained by the heat and press-treatment ofthe fish muscle was examined to determine zhe freshness of the fish. The apparatus used in this study consisted of multielectrode enzyme sensor, relay controller, A/D converter, microcomputer, floppy disk, monitor and printer. The output current of thesensor was read by the computer and converted to digital signals every s sec. This data wasstored in the floppy disk. The amounts of hypoxanthine(Hx), inosine(HxR), inosine mono-phosphate(IMP)and KI value were calculated by the computer on the basis of this data. Fresh-ness of fish was expressed as foillows; very fresh: KI<10, fresh: KI<40, not fresh:KI>40. Fresh-ness pattern was depicted on the display screen in the shape of a triangle, the apexes were C1/C0, C2/C0 and C3/C0, where C1, C2 and C3 are the concentration of Hx, HxR and IMP, respectively.C0 is the total amount of C1, C2 and C3. In order to avoid the tedious extraction procedure for the preparation of samples, fish muscleswere heated at 80°C for 5-10min and press-treated to obtain the exudates. The KI values of the exudates were in fair agreement with those of the extracts which were prepared by the con-ventional extraction method. One assay including the preparation of sample required about15min.

Determination of fish freshness with an enzyme sensor system

Principe et mise en oeuvre d'un detecteur enzymatique multifonctionnel permettant d'evaluer simultanement trois composes, l'inosine 5'-phosphate, l'inosine et l'hypoxanthine