Highly Sensitive Method for Urea Detection in Wine

Kodama, Seiichi; Suzuki, Tohru

doi:10.1111/j.1365-2621.1995.tb06300.x

Cited by 14 publications

(12 citation statements)

References 10 publications

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“…As the temperature rose by 5ЊC, K increased by 50%, and the required treatment period decreased by about 33%. Similar results were reported in table wines (Kodama, 1995). At 35ЊC, the urea content showed the sharpest decline.…”

Section: Temperature and Treatment Time Effectssupporting

confidence: 89%

“…It could, therefore, be separated from wine by filtration through nitrocellulose filters with a pore size Ͻ1.0 µm (Kodama, 1995). One unit of urease was defined as the amount of enzyme activity that released 1 µmol ammonia from urea (5000 mg/L)/min at 37ЊC and a pH of 4.0 (0.1 mol/L citrate) (Kodama, 1995).…”

Section: Acid Ureasementioning

confidence: 99%

“…Two kinds of urea determination methods were used: one, the urea/ammonia UV method using an enzymatic test kit (Boehringer Mannheim GmbH, Mannheim, Germany); and the other, highly sensitive urea detection method developed by Kodama and Suzuki (1995). The latter method was adopted when the urea content was Ͻ1.0 mg/L.…”

Section: Determination Of Urea In Winementioning

confidence: 99%

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Acid Urease: Reduction of Ethyl Carbamate Formation in Sherry under Simulated Baking Conditions

Kodama

Yotsuzuka

1996

Journal of Food Science

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Acid urease derived from Lactobacillus fermentum was applied to reduce ethyl carbamate (EC) formation in California sherry production. Commercial sherry and sherry base were treated with urease under different conditions. Amounts of urea were determined and EC amounts were monitored by gas chromatography. Urea removal by acid urease reduced EC formation during the baking process and effectively maintained EC concentrations below the target level (90 µg/L). However, complete prevention of EC was not achieved because of precursors other than urea.

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Section: Temperature and Treatment Time Effectssupporting

confidence: 89%

Section: Acid Ureasementioning

confidence: 99%

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Acid Urease: Reduction of Ethyl Carbamate Formation in Sherry under Simulated Baking Conditions

Kodama

Yotsuzuka

1996

Journal of Food Science

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“…Recent methods in the literature for determination of urea in wines are based on enzymic analysis and monitoring of the pH change using two capillary glass electrodes capable of quantifying changes of pH of 0.001 units produced in the hydrolysis by urease [6]; on HPLC with a previous derivatisation reaction for facilitating separation [7,8] or on derivatisation with 1-phenyl-propan-1,2-dione 2-oxime in ethanol and photometric monitoring at 540 nm [9].…”

Section: Introductionmentioning

confidence: 99%

Method for monitoring urea and ammonia in wine and must by flow injection–pervaporation

Pérez-Juan¹,

Castro

2002

Analytica Chimica Acta

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An easy to automate flow-injection-pervaporation method for monitoring urea and ammonia in must and wine was developed. The method is based on separation of the ammonia from the sample matrix by pervaporation followed by its reaction with salicylate, hypochlorite and nitroprusside to form a diazonium salt with maximum absorption at 647 nm. Conversion of urea into ammonia catalysed by urease was mandatory before pervaporation. After optimisation by either the univariate or multivariate approaches as required, the linear range was established (between 0 and 25 mg l -1 ) for both analytes. Then, the assessment of the proposed method versus a reference one for urea and ammonia was studied in terms of repeatability (0.52 mg l -1 and 0.43 mg l -1 , respectively), reproducibility (1.34 mg l -1 and 1.21 mg l -1 , respectively), detection and quantification limits (LOD=0.9 and 0.6 mg l -1 , LQ=1.02 and 0.67 mg l -1 , respectively) and traceability. The sample throughput was 16 samples h -1 . The method can be applied to the monitoring of the target analytes in must and young wine in order to control their contents, preventing formation of ethyl carbamate.

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“…Adsorption is not considered as an alternative removal method since urea does not show high affinity to common adsorbents [3]. Urea rejection by reverse osmosis membranes is also not efficient [4,5]. An attractive, alternative removal method is based on the hydrolysis of urea by urease immobilized on a suitable support material.…”

Section: Introductionmentioning

confidence: 99%

Catalytic performances of chemically immobilized urease under static and dynamic conditions: A comparative study

Yürekli

Altınkaya

2011

Journal of Molecular Catalysis B: Enzymatic

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a b s t r a c tImmobilized urease has been used for direct removal of urea from aqueous solution and as biological sensing material in the preparation of urea biosensors. The former application is carried out under dynamic condition using ultrafiltration membrane either in tubular form or in flat sheet, while the latter is used in static condition. In this study, the performance of chemically immobilized urease on poly(acrylonitrileco-sodium methallyl sulfonate) ultrafiltration membrane was determined under both static and dynamic conditions. Results reveal that the immobilization enhanced the thermal and storage stabilities of urease. The hydraulic permeability of urea solution was not influenced by the addition of enzyme layer. The maximum reaction rate measured under pressure in the ultrafiltration unit was found higher compared to the rate observed just under mixing without any pressure applied. The highest urea conversion was found at the lowest transmembrane pressure and the urea concentration in the feed solution. The catalytic activity of the membrane was completely preserved at the end of 450 min of filtration.

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Highly Sensitive Method for Urea Detection in Wine

Cited by 14 publications

References 10 publications

Acid Urease: Reduction of Ethyl Carbamate Formation in Sherry under Simulated Baking Conditions

Acid Urease: Reduction of Ethyl Carbamate Formation in Sherry under Simulated Baking Conditions

Method for monitoring urea and ammonia in wine and must by flow injection–pervaporation

Catalytic performances of chemically immobilized urease under static and dynamic conditions: A comparative study

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