半乳甘露聚糖检测试剂盒 Galactomannan Assay Kit 货号：K-GALM Megazyme中文站

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半乳甘露聚糖检测试剂盒

英文名：Galactomannan Assay Kit

货号：K-GALM

规格：100 Assays per kit

分析物意义：许多豆科植物的储备糖 

Megazyme检测试剂盒优点：只有试剂盒可用，试剂稳定，功能强大。AOAC方法2002.02；AACC方法32-40. 

The Galactomannon test kit is suitable for the measurement and analysis of Galactomannan in food and plant products.

UV-method for the determination of Galactomannan in legume
seeds, foodstuffs and plant products

Principle:
(β-mannanase)
(1) Galactomannan + H2O → galactomanno-oligomers

(β-mannanase + α-galactosidase)
(2) Galactomanno-oligomers + H2O → D-galactose +
manno-oligomers

(β-galactose dehydrogenase)
(3) D-Galactose + NAD+ → D-galactonic acid + NADH + H+

Kit size:                            100 assays
Method:                            Spectrophotometric at 340 nm
Total assay time:              ~ 80 min
Detection limit:                 1-100% of sample weight
Application examples: 
Seeds, milling fractions and food ingredients
Method recognition:          Novel method

Advantages

  • Galactose dehydrogenase now included in the kit
  • Very cost effective
  • All reagents stable for > 2 years after preparation
  • Only enzymatic kit available
  • Simple format
  • Mega-Calc™ software tool is available from our website for hassle-free raw data processing
  • Standard included

Q1. Should the pH of the sample be adjusted even for samples in acidic media?

The pH of the assay solution after the sample is added should be the same as that of the assay buffer that is supplied with the kit.
Low sample volumes (e.g. 0.1 mL) are not likely to affect the pH of the assay solution and therefore may not require pH adjustment.
Samples above 0.1 mL are more likely to affect the pH of the assay solution and therefore the pH of these samples should be adjusted as described in the data booklet, prior to addition to the assay.

Q2. Sometimes a negative absorbance change is obtained for the blank samples, is this normal? Should the real value (negative absorbance change) or “0” be used in the calculation of results?

Sometimes the addition of the last assay component can cause a small negative absorbance change in the blank samples due to a dilution effect and in such cases it is recommended that the real absorbance values be used in the calculation of results.

Q3. Is your Galactomannan Assay Kit only suitable for the galactomannan in carob or guar, or can it be used for any type of galactomannan?

The kit can be used for any type of galactomannan.  However, to calculate the galactomannan content, you will need to know the galactose/mannose ratio of the galactomannan.

Q4. Concerning your Galactomannan Assay Kit (K-GALM), are there any differences in the assay procedure for carob and guar?

Carob and Guar galactomannan can be measured using essentially the same procedure.

Q5. There is an issue with the performance of the kit; the results are not as expected.

If you suspect that the Megazyme test kit is not performing as expected such that expected results are not obtained please do the following:

  1. Ensure that you have tested the standard sample that is supplied with the Megazyme test kit.
  2. Send the results of the kit standard, blank samples and the results obtained for your sample, in the relevant MegaCalc spreadsheet (if available) to Megazyme (cs@megazyme.com). Where available the relevant MegaCalc spreadsheet can be downloaded from where the product appears on the Megazyme website.
  3. State the kit lot number being used (this is found on the outside of the kit box).
  4. State which assay format was used (refer to the relevant page in the kit booklet if necessary).
  5. State exact details of any modifications to the standard procedure that is provided by Megazyme.
  6. State the sample type and describe the sample preparation steps if applicable.

Q6. The Galactomannan Assay Procedure (GLM 8/98) gives the galactose:mannose ratio for carob. I was wondering if you are aware of any similar data on guar gum, i.e. is there any similar galactose:mannose ratio published for guar gum?

Yes, we did a lot of work on guar gum from numerous samples, and the value we found for it was 38% +/- 1% galactose. 

Q7. I am attempting to quantitate Guar Gum or Guaran in baked products. The level of guar in the product is approx. 0.32%. Can the Megazyme Galactomannan Kit be used to measure this?

The Megazyme Galactomannan Kit measures guar and carob galactomannans.  The method is based on hydrolysis of galactomannan to galactose and manno-oligosaccharides and the galactose is measured with galactose dehydrogenase.  The method could be adapted for levels of 0.3%.

Q8. What is a suitable NAD preparation to use for the Galactomannan Kit?

Megazyme product C-NAD25 is suitable.

Q9. Is there an alternative galactose dehydrogenase product which can be used for the Galactomannan assay method?

Sigma product N-7004 is a suitable alternative to Boehringer Mannheim 662046 and can be used at the same volume per test.

Q10. Can you tell me is it accurate to calculate the total content of galactomannans based on the mannose/galactose ratio, assuming the latter is known? Also, can this ratio vary as a function not only of guar cultivar but also of seasonal variety, etc.?

Yes, we believe that it is possible to accurately measure the galactomannan content based on the known galactose/mannose ratio.  In studies we performed many years ago, we found that there was little difference in the ratio of galactomannans extracted from a wide range of carob seed varieties or of guar seed varieties; please refer to the papers cited below:
McCleary, B. V. (1981).  Galactomannan quantitation in guar varieties and seed fractions.  Lebensm. – Wiss. Technol., 14, 188-191.
McCleary, B. V., Dea, I. C. M., Clark, A. H. and Rees, D. A. (1985).  The fine structures of guar and carob galactomannans.  Carbohydrate Research, 139, 237-260.