1100 assays (microplate) / 1100 assays (auto-analyser)
Prices exclude VAT
Available for shipping
|Content:||1100 assays (microplate) / 1100 assays (auto-analyser)|
Short term stability: 2-8oC,
Long term stability: See individual component labels
|Stability:||> 2 years under recommended storage conditions|
|Assay Format:||Spectrophotometer, Auto-analyser|
|Linear Range:||0.5 to 14 μg of L-malic acid per assay|
|Limit of Detection:||166 mg/L|
|Reaction Time (min):||~ 3 min|
|Application examples:||Wine, beer, fruit juices, soft drinks, candies, fruit and vegetables, bread, cosmetics, pharmaceuticals and other materials (e.g. biological cultures, samples, etc.).|
|Method recognition:||Methods based on this principle have been accepted by AOAC, EEC, EN, NF, NEN, DIN, GOST, OIV, IFU, AIJN, NBN, ISO and MEBAK|
The L-Malic Acid (Liquid Ready) test kit is a rapid, simple, reliable and accurate method for the specific measurement and analysis of L-malic acid in wine, beverages, foodstuffs and other materials. Supplied as a “ready to use” liquid stable formulation that is suitable for auto-analyser and microplate formats.
Browse more test kit products in our organic acid assay kits list.
- PVP incorporated to prevent tannin inhibition
- “Ready to use” liquid stable formulation
- Very competitive price (cost per test)
- All reagents stable for > 18 Months
- Very rapid reaction (~ 3 min)
- Standard included
- Suitable for microplate and auto-analyser formats
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
Above- and below-ground resource acquisition strategies determine plant species responses to nitrogen enrichment.
Zhang, D., Peng, Y., Li, F., Yang, G., Wang, J., Yu, J., Zhou, G. & Yang, Y. (2021). Annals of Botany, 20, 1-14.
Background and aims: Knowledge of plant resource acquisition strategies is crucial for understanding the mechanisms mediating the responses of ecosystems to external nitrogen (N) input. However, few studies have considered the joint effects of above-ground (light) and below-ground (nutrient) resource acquisition strategies in regulating plant species responses to N enrichment. Here, we quantified the effects of light and non-N nutrient acquisition capacities on species relative abundance in the case of extra N input. Methods: Based on an N-manipulation experiment in a Tibetan alpine steppe, we determined the responses of species relative abundances and light and nutrient acquisition capacities to N enrichment for two species with different resource acquisition strategies (the taller Stipa purpurea, which is colonized by arbuscular mycorrhizal fungi, and the shorter Carex stenophylloides, which has cluster roots). Structural equation models were developed to explore the relative effects of light and nutrient acquisition on species relative abundance along the N addition gradient. Key results: We found that the relative abundance of taller S. purpurea increased with the improved light acquisition along the N addition gradient. In contrast, the shorter C. stenophylloides, with cluster roots, excelled in acquiring phosphorus (P) so as to elevate its leaf P concentration under N enrichment by producing large amounts of carboxylate exudates that mobilized moderately labile and recalcitrant soil P forms. The increased leaf P concentration of C. stenophylloides enhanced its light use efficiency and promoted its relative abundance even in the shade of taller competitors. Conclusions: Our findings highlight that the combined effects of above-ground (light) and below-ground (nutrient) resources rather than light alone (the prevailing perspective) determine the responses of grassland community structure to N enrichment.Hide Abstract
Chemical Composition of Sour Beer Resulting from Supplementation the Fermentation Medium with Magnesium and Zinc Ions.
Ciosek, A., Fulara, K., Hrabia, O., Satora, P. & Poreda, A. (2020). Biomolecules, 10(12), 1599.
The bioavailability of minerals, such as zinc and magnesium, has a significant impact on the fermentation process. These metal ions are known to influence the growth and metabolic activity of yeast, but there are few reports on their effects on lactic acid bacteria (LAB) metabolism during sour brewing. This study aimed to evaluate the influence of magnesium and zinc ions on the metabolism of Lactobacillus brevis WLP672 during the fermentation of brewers’ wort. We carried out lactic acid fermentations using wort with different mineral compositions: without supplementation; supplemented with magnesium at 60 mg/L and 120 mg/L; and supplemented with zinc at 0.4 mg/L and 2 mg/L. The concentration of organic acids, pH of the wort and carbohydrate use was determined during fermentation, while aroma compounds, real extract and ethanol were measured after the mixed fermentation. The addition of magnesium ions resulted in the pH of the fermenting wort decreasing more quickly, an increase in the level of L-lactic acid (after 48 h of fermentation) and increased concentrations of some volatile compounds. While zinc supplementation had a negative impact on the L. brevis strain, resulting in a decrease in the L-lactic acid content and a higher pH in the beer. We conclude that zinc supplementation is not recommended in sour beer production using L. brevis WLP672.Hide Abstract
Technological characterisation of potential malolactic starters from Rioja Alavesa winemaking region.
Diez-Ozaeta, I., Lavilla, M. & Amárita, F. (2020). LWT, 134, 109916.
Technological characterisation of 22 strains of lactic acid bacteria belonging to Oenococcus oeni, Lactobacillus mali and Lactobacillus plantarum species has been carried out in order to elucidate their oenological potential as malolactic starters. After analysing their behaviour against typical harsh conditions found in wine as well as their malolactic fermentation vigour, the better suitability of O. oeni strains was confirmed. These O. oeni strains were further characterised for multiple enzyme activities. Both molecular and phenotypical methods confirmed citrate catabolising ability of all strains. Glycosidase (α-glucosidase, β-glucosidase, β-xylosidase and α-arabinosidase) and esterase activities under different pH and ethanol concentration combinations were also quantified. All strains exhibited α-glucosidase, β-glucosidase and esterase activity. Conversely, only few strains showed β-xylosidase and α-arabinosidase activity. A synergistic negative effect of pH and ethanol on enzyme activity was observed under the most extreme conditions, in that way, when ethanol concentration was more aggressive, a sift to lower pH was traduced on significant enzyme activity decline. However, many strains still retained detectable activities. These results encourage the potential use of many of the characterised autochthonous O. oeni strains as an effective strategy to perform a reliable MLF and to enhance wine aroma complexity in Rioja Alavesa region.Hide Abstract
Deletion of Voltage-Dependent Anion Channel 1 knocks mitochondria down triggering metabolic rewiring in yeast.
Magri, A., Di Rosa, M. C., Orlandi, I., Guarino, F., Reina, S., Guarnaccia, M., Morello, G., Spampinato, A., Cavallaro, S., Messina, A., Vai, M. & De Pinto, V. (2020). Cellular and Molecular Life Sciences, 77(16), 3195-3213.
The Voltage-Dependent Anion-selective Channel (VDAC) is the pore-forming protein of mitochondrial outer membrane, allowing metabolites and ions exchanges. In Saccharomyces cerevisiae, inactivation of POR1, encoding VDAC1, produces defective growth in the presence of non-fermentable carbon source. Here, we characterized the whole-genome expression pattern of a VDAC1-null strain (Δpor1) by microarray analysis, discovering that the expression of mitochondrial genes was completely abolished, as consequence of the dramatic reduction of mtDNA. To overcome organelle dysfunction, Δpor1 cells do not activate the rescue signaling retrograde response, as ρ0 cells, and rather carry out complete metabolic rewiring. The TCA cycle works in a “branched” fashion, shunting intermediates towards mitochondrial pyruvate generation via malic enzyme, and the glycolysis-derived pyruvate is pushed towards cytosolic utilization by PDH bypass rather than the canonical mitochondrial uptake. Overall, Δpor1 cells enhance phospholipid biosynthesis, accumulate lipid droplets, increase vacuoles and cell size, overproduce and excrete inositol. Such unexpected re-arrangement of whole metabolism suggests a regulatory role of VDAC1 in cell bioenergetics.Hide Abstract