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Lactose Assay Kit - Sequential/High Sensitivity

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00:04  Introduction
01:00  Principle
03:19   Reagent Preparation
04:23  Sample Preparation
05:37  Glucose Oxidase / Catalase Pre-Treatment
07:45  Procedure
11:08   Calculations

Lactose Assay Kit K-LOLAC Scheme
Product code: K-LOLAC

65 assays per kit

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Available for shipping

Content: 65 assays per kit
Shipping Temperature: Ambient
Storage Temperature: Short term stability: 2-8oC,
Long term stability: See individual component labels
Stability: > 2 years under recommended storage conditions
Analyte: Lactose
Assay Format: Spectrophotometer
Detection Method: Absorbance
Wavelength (nm): 340
Signal Response: Increase
Linear Range: 1 to 50 µg of lactose (or 0.50 to 25 µg of D-glucose)
Limit of Detection: 1.62 mg/L
Reaction Time (min): ~ 10 min

The K-LOLAC test kit offers a rapid, novel, sequential measurement of free-glucose and lactose in conventional, low-lactose and lactose-free dairy products. This sequential assay format reduces the manual input required by an analyst when compared to traditional lactose assay formats and therefore improves both accuracy and efficiency. When used in combination with the Megazyme Creep Calculator provided, the β-galactosidase employed in this kit allows for the selective measurement of lactose in the presence of galacto-oligosaccharides (GOS) which are commonly found in lactose-free dairy products. This constitutes a significant improvement over existing commercially available lactose assay kits which typically overestimate lactose content in lactose-free samples due to the unselective hydrolysis of GOS by β-galactosidase. Lastly, the sensitivity of the K-LOLAC assay kit has been doubled through the use of a cascade biochemical pathway, helping to significantly reduce the LOD and LOQ for the assay. British Patent Application No. 1710170.0.

We offer more monosaccharide and oligosaccharide assay kit products.

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View Product Poster Presentation - Single Lab Validation for K-LOLAC.

  • World’s first sequential assay for lactose, i.e. improves accuracy and efficiency 
  • Contains a specific β-galactosidase for the selective measurement of lactose in dairy products 
  • Efficient pre-treatment step allows for accurate measurement of lactose in “low-lactose” and “lactose-free” dairy products 
  • Lower limit of detection (LOD) than any other commercially available enzymatic lactose detection method. LOD at 1.62 mg/L 
  • Very competitive price (cost per test)
Certificate of Analysis
Safety Data Sheet
Booklet Data Calculator Supporting Information Validation Report
Megazyme publication

Determination of ethanol concentration in Kombucha beverages: Single-Laboratory Validation of an enzymatic method, First Action Method 2019.08.

Ivory, R., Delaney, E., Mangan & McCleary, B. V. (2020). Journal of AOAC International, qsaa122.

The Ethanol Assay Kit is an enzymatic test kit developed by Megazyme for the determination of ethanol in a variety of samples. The kit has been validated in a single laboratory for use with Kombucha fermented drinks, fruit juices and low-alcohol beer samples. The commercially available Ethanol Assay Kit (Megazyme catalogue no. K-ETOH) contains all components required for the analysis. Quantification is based on the oxidation of ethanol to acetaldehyde by alcohol dehydrogenase and further oxidation of acetaldehyde by acetaldehyde dehydrogenase with conversion of NAD+ to NADH. The single laboratory validation (SLV) outlined in this document was performed on a sample set of eight different commercial Kombucha products purchased in Ireland, a set of five Cerilliant aqueous ethanol solutions, two BCR low-alcohol beer reference materials, two alcohol-free beer samples and two fruit juice samples against SMPR 2016.001 (1). Parameters examined during the validation included Working range, Selectivity, Limit of Detection (LOD), Limit of Quantification (LOQ), Trueness (bias), Precision (reproducibility and repeatability), Robustness and Stability.

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Megazyme publication

A novel enzymatic method for the measurement of lactose in lactose‐free products.

Mangan, D., McCleary, B. V., Culleton, H., Cornaggia, C., Ivory, R., McKie, V. A., Delaney, E. & Kargelis, T. (2018). Journal of the Science of Food and Agriculture, 99, 947-956.

Background: In recent years there has been a surge in the number of commercially available lactose‐free variants of a wide variety of products. This presents an analytical challenge for the measurement of the residual lactose content in the presence of high levels of mono‐, di‐, and oligosaccharides. Results: In the current work, we describe the development of a novel enzymatic low‐lactose determination method termed LOLAC (low lactose), which is based on an optimized glucose removal pre‐treatment step followed by a sequential enzymatic assay that measures residual glucose and lactose in a single cuvette. Sensitivity was improved over existing enzymatic lactose assays through the extension of the typical glucose detection biochemical pathway to amplify the signal response. Selectivity for lactose in the presence of structurally similar oligosaccharides was provided by using a β-galactosidase with much improved selectivity over the analytical industry standards from Aspergillus oryzae and Escherichia coli (EcLacZ), coupled with a ‘creep’ calculation adjustment to account for any overestimation. The resulting enzymatic method was fully characterized in terms of its linear range (2.3-113 mg per 100 g), limit of detection (LOD) (0.13 mg per 100 g), limit of quantification (LOQ) (0.44 mg per 100 g) and reproducibility (≤ 3.2% coefficient of variation (CV)). A range of commercially available lactose‐free samples were analyzed with spiking experiments and excellent recoveries were obtained. Lactose quantitation in lactose‐free infant formula, a particularly challenging matrix, was carried out using the LOLAC method and the results compared favorably with those obtained from a United Kingdom Accreditation Service (UKAS) accredited laboratory employing quantitative high performance anion exchange chromatography - pulsed amperometric detection (HPAEC‐PAD) analysis. Conclusion: The LOLAC assay is the first reported enzymatic method that accurately quantitates lactose in lactose‐free samples.

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GRP78 regulates milk biosynthesis and the proliferation of bovinemammaryepithelial cells through the mTOR signaling pathway.

Liu, Y., Wang, X., Zhen, Z., Yu, Y., Qiu, Y. & Xiang, W. (2019). Cellular & molecular biology letters, 24(1), 1-12.

Methods: The expressions of GRP78 in BMECs stimulated with methionine, leucine, estrogen and prolactin were determined using western blotting and immunofluorescence assays. To explore the function of GRP78 in BMECs, the protein was overexpressed or knocked down, respectively using an overexpression vector or an siRNA mixture transfected into cells cultured in vitro. Flow cytometry was used to analyze cell proliferation and cell activity. The contents of lactose and triglyceride (TG) secreted from the treated BMECs were measured using lactose and TG assay kits, respectively. Western blotting analysis was used to measure the β-casein content and the protein levels of the signaling molecules known to be involved in milk biosynthesis and cell proliferation. Results: GRP78overexpression significantly stimulated milk protein and milk fat synthesis, enhanced cell proliferation, positively regulated the phosphorylation of mammalian target of rapamycin (mTOR), and increased the amount of protein of cyclinD1andsterol regulatory element-binding protein 1c (SREBP-1c). GRP78 knockdown after siRNA transfection had the opposite effects. We further found that GRP78 was located in the cytoplasm of BMECs, and that stimulating methionine, leucine, estrogen and prolactin expression led to a significant increase in the protein expression of GRP78 in BMECs. Conclusions: These data reveal that GRP78 is an important regulator of milk biosynthesis and the proliferation of BMECs through the mTOR signaling pathway.

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Comparative study of two lactases by K-Lolac enzymatic method in skimmed milk. 

Benbouziane, B., Bentahar, M. C., Takarly, H. & Benakriche, B. M. (2019). South Asian Journal of Experimental Biology, 9(1), 1-6.

Lactose absorption at the level of the small intestine depends on its hydrolysis by β-galactosidase. The activity of this enzyme, which gets to the peak at the beginning and halflife, decreases progressively after weaning. This activity loss (hypolactasie) is a physiological phenomenon observed in 70 to 75% of the world's population. Hypolactasy is transmitted according to an autosomal recessive mode to an incomplete penetrance and is linked to polymorphosis located in the promoter region of the gene coding the lactase. A solution is proposed regarding ingestion of dairy dislactosed products or products with unduly low lactose rates. In this study, two different enzymes were used, a β-galactosidase of Bifidobacterium [β-gal Bb] source and another β-galactosidase of Kluyveromyces lactis [β-gal Kl] source with different concentrations on lactose degradation in a preparation based on skimmed milk at 4°C during 18h with a 39 g/l lactose rate. Determining hydrolysis rate in lactose was achieved with an enzymatic method using a Megazyme K-lolac kit. The results demonstrated that β-gal Kl (Maxilat) in a 100 µl/L dose gives an optimal performance as compared to β-gal Bb (Nola fit) in residual lactose concentrations 1.85 g/L and 2.78 g/L respectively. However, in a dose that was superior to 1500 and 2000, the β-gal Bb was significantly more performing than β-gal Kl. To sum up, the enzymatic method used to define the residual lactose rate, the kit KLolac, gives very reliable results with a low threshold (LOD 1.62 mg/L).

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Lactose-free Yogurts do not Show any Benefits for Lactose-Intolerant Subjects, Compared with Lactose-Containing Yogurts. 

Ghio, B., Márquez, D., Peche, B., Peña, F. & Saavedra, F. (2019). Journal of Food & Nutritional Disorders, 8(3), 2.

Nowadays, there is constant increase of commercial lactose-free yogurts for lactose-intolerant individuals. However, the real interest of these yogurts is unclear considering that several clinical trials have shown that the living bacteria present in the yogurt improved lactose tolerance in hypolactasic subjects, due to their β-galactosidase activity that remains functional in the small intestine of these individuals. The aim of this study was to determine whether the intake of lactose-free yogurt (LFY) is beneficial for hypolactasic lactose-intolerant subjects compared with that of traditional, lactose-containing yogurt (LCY). Twenty-two subjects with auto-reported digestive symptoms after milk consumption carried out a hydrogen breath test (HBT) with 25g lactose to confirm their hypolactasic status. Fourteen subjects (63.6%) who exhibit a positive HBT accompanied by digestive symptoms were finally incorporated to the study. In two independent days, they have to ingest, in a double-blind and randomized form, 250g of LFY or LCY. These products brought 0.5g and 19.8g of lactose, respectively and both exhibited total counts of lactic acid bacteria higher than 107 CFU/g. Changes in breath H2 excretion and digestive symptoms were registered during 180 min. When the volunteers carried out the HBT with LFY and LCY, no differences were detected in H2 excretion or the intensity of digestive symptoms (individual or total). Accordingly, our results suggest than the intake of LFY that are more expensive than LCY, does not bring any supplementary detectable benefits for the lactose intolerant subjects.

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Influence of particle size on the physicochemical properties and stickiness of dairy powders.

O'Donoghue, L. T., Haque, M. K., Kennedy, D., Laffir, F. R., Hogan, S. A., O'Mahony, J. A. & Murphy, E. G. (2019). International Dairy Journal, 98, 54-63.

The compositional and physicochemical properties of different whey permeate (WPP), demineralised whey (DWP) and skim milk powder (SMP) size fractions were investigated. Bulk composition of WPP and DWP was significantly (P < 0.05) influenced by powder particle size; smaller particles had higher protein and lower lactose contents. Microscopic observations showed that WPP and DWP contained both larger lactose crystals and smaller amorphous particles. Bulk composition of SMP did not vary with particle size. Surface composition of the smallest SMP fraction (<75 µm) showed significantly lower protein (−9%) and higher fat (+5%) coverage compared with non-fractionated powders. For all powders, smaller particles were more susceptible to sticking. Hygroscopicity of SMP was not affected by particle size; hygroscopicity of semi-crystalline powders was inversely related to particle size. This study provides insights into differences between size fractions of dairy powders, which can potentially impact the sticking/caking behaviour of fine particles during processing.

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Accurate analysis of residual lactose in low-lactose milk: Comparing a variety of analytical techniques.

Churakova, E., Peri, K., Vis, J. S., Smith, D. W., Beam, J. M., Vijverberg, M. P., Stor, M. C. & Winter, R. T. (2019). International Dairy Journal, 96, 126-131.

To receive the designation “lactose-free”, milk should contain <0.01% (w/w) lactose. As the analysis of such low levels of lactose is often hampered by other saccharides present or formed during milk processing, methods are required that are highly sensitive, accurate and precise. Currently, there is no international standard analysis method for the determination of lactose in low- or lactose-free milk, despite such a need from the dairy industry. We validated the analysis of residual lactose in lactase-treated UHT milk using HPAEC-PAD on a CarboPac PA100 column and compared it with a variety of commonly used analytical techniques for measuring lactose, including HPLC-RI, NMR, enzymatic kits, cryoscopy, and lactose biosensors. The results show that only one analytical technique, namely the Biomilk300, an amperometric biosensor, has performance comparable with analysis by HPAEC-PAD, which remains one of the most accurate, precise and sensitive methods to assess low levels of lactose in milk.

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Safety Information
Symbol : GHS05, GHS07, GHS08
Signal Word : Danger
Hazard Statements : H302, H302+H332, H314, H334, H360
Precautionary Statements : P201, P202, P260, P261, P264, P270, P271, P280, P284, P301+P312, P301+P330+P331, P304+P340, P342+P311, P501
Safety Data Sheet
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