110 mL of prepared reagent (e.g. 500 assays of 0.22 mL)
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|Content:||110 mL of prepared reagent (e.g. 500 assays of 0.22 mL)|
Short term stability: 2-8oC,
Long term stability: See individual component labels
|Stability:||> 2 years under recommended storage conditions|
|Limit of Detection:||~ 10 mg/L|
|Reaction Time (min):||8 min at 25oC or 5 min at 37oC|
|Application examples:||Wine, beer, fruit and fruit juices, soft drinks, vinegar, vegetables, pickles, dairy products (e.g. cheese), meat, fish, bread, bakery products (and baking agents), ketchup, soy sauce, mayonnaise, dressings, paper (and cardboard), tea, pharmaceuticals (e.g. infusion solutions), feed and other materials (e.g. biological cultures, samples, etc.).|
|Method recognition:||Improved method|
The Acetic Acid GK format test kit is for use with auto-analysers and is suitable for the specific measurement and analysis of acetic acid (acetate) especially in wines, fruit juices, beverages and food products.
As part of Megazyme’s overall commitment to providing the highest quality products, we have developed this acetic acid kit that provides a specific and rapid assay for use with auto-analysers. The kit assay is based on the conversion of NAD+ to NADH and therefore provides a positive reaction (increase in absorbance) which offers a more robust assay.
The reagents, as supplied, are stable for a minimum of 2 years and the prepared reagents are stable for a minimum of 1 week (on-board stability). In addition, the prepared reagents can be stored frozen for longer term stability (see K-ACETGK Booklet for more details).
- Excellent reagent stability
- > 7 days at 4oC or > 2 years below -10oC when prepared for auto-analyser applications
- > 2 years as supplied
- Very rapid reaction (~ 5 min at 37oC)
- Linear calibration (R2 ~ 0.997 up to 1.8 g/L sample)
Megazyme “advanced” wine test kits general characteristics and validation.
Charnock, S. J., McCleary, B. V., Daverede, C. & Gallant, P. (2006). Reveue des Oenologues, 120, 1-5.
Many of the enzymatic test kits are official methods of prestigious organisations such as the Association of Official Analytical Chemicals (AOAC) and the American Association of Cereal Chemists (AACC) in response to the interest from oenologists. Megazyme decided to use its long history of enzymatic bio-analysis to make a significant contribution to the wine industry, by the development of a range of advanced enzymatic test kits. This task has now been successfully completed through the strategic and comprehensive process of identifying limitations of existing enzymatic bio-analysis test kits where they occurred, and then using advanced techniques, such as molecular biology (photo 1), to rapidly overcome them. Novel test kits have also been developed for analytes of emerging interest to the oenologist, such as yeast available nitrogen (YAN; see pages 2-3 of issue 117 article), or where previously enzymes were simply either not available, or were too expensive to employ, such as for D-mannitol analysis.Hide Abstract
Grape and wine analysis: Oenologists to exploit advanced test kits.
Charnock, S. C. & McCleary, B. V. (2005). Revue des Enology, 117, 1-5.
It is without doubt that testing plays a pivotal role throughout the whole of the vinification process. To produce the best possible quality wine and to minimise process problems such as “stuck” fermentation or troublesome infections, it is now recognised that if possible testing should begin prior to harvesting of the grapes and continue through to bottling. Traditional methods of wine analysis are often expensive, time consuming, require either elaborate equipment or specialist expertise and frequently lack accuracy. However, enzymatic bio-analysis enables the accurate measurement of the vast majority of analytes of interest to the wine maker, using just one piece of apparatus, the spectrophotometer (see previous issue No. 116 for a detailed technical review). Grape juice and wine are amenable to enzymatic testing as being liquids they are homogenous, easy to manipulate, and can generally be analysed without any sample preparation.Hide Abstract
Guerrini, L., Angeloni, G., Masella, P., Calamai, L. & Parenti, A. (2018). Food and Bioprocess Technology, 11(6), 1259-1266.
During the production of fermented alcoholic beverages, such as wine or beer, the loss of aroma active compounds (AACs) has a significant impact on the overall product aroma. This paper presents the results of an experimental technique in which a condenser was placed on the top of the fermenter in order to reduce such losses. AAC concentrations in beers produced in this way were compared with a control produced without a condenser. There were two main findings: (i) some AACs could be recovered during fermentation and (ii) the technique stimulated the de novo synthesis of esters from carboxylic acids and alcohols. In particular, the production of ethyl esters from the reaction between ethanol and organic acids and the production of acetates from the reaction between acetic acid and alcohols were demonstrated. Consequently, the addition of the condenser changed the final aroma of the beverage. The effect was confirmed by a panel test and AAC quantitation using HS-SPME-GC-MS. The technique could be used by brewers as a tool to modulate the flavor and aroma of beer.Hide Abstract
Amabebe, E., Reynolds, S., Stern, V., Stafford, G., Paley, M. & Anumba, D. O. (2016). Frontiers in Medicine, 3, 48.
Changes in vaginal microbiota that is associated with preterm birth (PTB) leave specific metabolite fingerprints that can be detected in the cervicovaginal fluid (CVF) using metabolomics techniques. In this study, we characterize and validate the CVF metabolite profile of pregnant women presenting with symptoms of threatened preterm labor (PTL) by both 1H-nuclear magnetic resonance spectroscopy (NMR) and enzyme-based spectrophotometry. We also determine their predictive capacity for PTB, singly, and in combination, with current clinical screening tools – cervicovaginal fetal fibronectin (FFN) and ultrasound cervical length (CL). CVF was obtained by high-vaginal swabs from 82 pregnant women with intact fetal membranes presenting between 24 and 36 weeks gestation with symptoms of threatened, but not established, PTL. Dissolved CVF samples were scanned with a 400 MHz NMR spectrometer. Acetate and other metabolites were identified in the NMR spectrum, integrated for peak area, and normalized to the total spectrum integral. To confirm and validate our observations, acetate concentrations (AceConc) were also determined from a randomly-selected subset of the same samples (n = 57), by spectrophotometric absorption of NADH using an acetic acid assay kit. CVF FFN level, transvaginal ultrasound CL, and vaginal pH were also ascertained. Acetate normalized integral and AceConc were significantly higher in the women who delivered preterm compared to their term counterparts (P = 0.002 and P = 0.006, respectively). The 1H NMR-derived acetate integrals were strongly correlated with the AceConc estimated by spectrophotometry (r = 0.69; P < 0.0001). Both methods were equally predictive of PTB <37 weeks (acetate integral: AUC = 0.75, 95% CI = 0.60-0.91; AceConc: AUC = 0.74, 95% CI = 0.57-0.90, optimal predictive cutoff of >0.53 g/l), and of delivery within 2 weeks of the index assessment (acetate integral: AUC = 0.77, 95% CI = 0.58-0.96; AceConc: AUC = 0.68, 95% CI = 0.5-0.9). The predictive accuracy of CVF acetate was similar to CL and FFN. The combination of CVF acetate, FFN, and ultrasound CL in a binary logistic regression model improved the prediction of PTB compared to the three markers individually, but CVF acetate offered no predictive improvement over ultrasound CL combined with CVF FFN. Elevated CVF acetate in women with symptoms of PTL appears predictive of preterm delivery, as well as delivery within 2 weeks of presentation. An assay of acetate in CVF may prove of clinical utility for predicting PTB.Hide Abstract