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Lactose Assay Kit - Sequential/High Sensitivity

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 - Sequential/High Sensitivity
Lactose Assay Kit K-LOLAC
   
Product code: K-LOLAC
€291.00

65 assays per kit

Prices exclude VAT

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.

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Advantages
  • 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)
Documents
Certificate of Analysis
Safety Data Sheet
Booklet Data Calculator Supporting Information Validation Report
Publications
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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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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