产品货号:ZZK-K-ACHDF
产品品名:可吸收糖类和膳食纤维检测试剂盒
英文品名:Available Carbohydrates/Dietary Fibre Assay Kit
规格型号:100 assays of each component
An integrated procedure for the measurement of available carbohydratesand dietary fibre in cereal products, fruit and vegetables and food products.
INTRODUCTION:
A need for information on the carbohydrate composition of foods fordiabetics prompted McCance and Lawrence1 to attempt to measure this togain results that would be of biological significance. They divided thecarbohydrates in foods into two broad groups, ‘available’ and‘unavailable’. The available carbohydrates, that is sugar plus starch,were defined as those that are digested and absorbed by the human smallintestine and which are glucogenic. The unavailable carbohydrates weredefined as those that are not digested by the endogenous secretions ofthe human digestive tract. These are now generally referred to asdietary fibre.
The concept of ‘available’ and ‘unavailable’ carbohydrates drewattention to the fact that some carbohydrates are not digested andabsorbed in the small intestine but rather reach the large bowel wherethey are fermented. In the FAO/WHO report on “Carbohydrates in HumanNutrition”2, it was stated that these terms can be misleading since theso-called ‘unavailable’ carbohydrate can, in fact, provide energy to thebody through fermentation. This committee recommended use of the term‘glycemic’ (i.e. providing carbohydrate for metabolism) to replace‘available’. However, this term has not gained widespread acceptance,possibly because there is some confusion with the well recognised term‘glycemic index’. For this reason, we have decided to continue using theterm ‘available carbohydrates’ for carbohydrates that are digested andabsorbed by the human small intestine; these include D-glucose,
D-fructose, sucrose, maltodextrins, non-resistant starch and the
D-glucose component of lactose; all measured as D-glucose plus
D-fructose following enzymic hydrolysis.
Dietary fibre is a mixture of complex organic substances including arange of hydrophilic compounds such as soluble and insolublepolysaccharides and non-digestable oligosaccharides as well asnon-swellable, more or less hydrophobic compounds such as cutins,suberins and lignins. The procedures for the determination of totaldietary fibre as outlined in this booklet are based on the methods ofLee et al.3 and Prosky et al.4 (AOAC Official Method 991.43, AACC Method32-07). These methods do not measure non-digestible oligosaccharides, asthese remain soluble in the ethanolic solution used to precipitate highmolecular weight dietary fibre components.
KITS:
Kits suitable for performing 100 assays of each are available fromMegazyme. The kits contain the full assay method plus:
Bottle 1: Buffer (11 mL, pH 7.6) plus sodium azide(0.02% w/v) as apreservative.Stable for > 3 years at 4°C.
Bottle 2: NADP+ plus ATP.Stable for> 5 years at -20°C.
Bottle 3: Thermostable α-amylase (6 mL, 3,000 U/mL)(no. E-BLAAM).Stablefor > 3 years at 4°C.
Bottle 4: Protease (10 mL, ~ 350 U/mL)(no. E-BSPRT).Stable for > 3years at -20°C.
Bottle 5: Amyloglucosidase (20 mL, ~ 3,300 U/mL)(no. E-AMGDF).Stablefor > 3 years at 4°C.
Bottle 6: Sucrase plus β-galactosidase, freeze-dried powder.Stable for> 3 years at -20°C.
Bottle 7: Hexokinase plus glucose-6-phosphate dehydrogenase suspension,2.25 mL.Stable for> 3 years at 4°C.
Bottle 8: Phosphoglucose isomerase suspension (2.25 mL). Stable for> 3 years at 4°C.
Bottle 9: D-Glucose plus D-fructose standard solution(5 mL, 0.2 mg/mLof each sugar).Stable for > 3 years at room temperature.
EQUIPMENT (RECOMMENDED):
1. Duran? bottles (250 mL volume).
2. Fritted crucible, Corning No. 36060 Büchner, fritted disk, Pyrex
60 mL, pore size, coarse, ASTM 40-60 μm, or equivalent. Prepare as follows:
a. Ash overnight at 525°C in muffle furnace.
b. Remove Celite and ash material by using a vacuum.
c. Soak in 2% (v/v) Micro cleaning solution (reagent 6) at roomtemperature for 1 h.
d. Rinse crucibles with water and then deionised water.
e. For final rinse, use 15 mL acetone and air dry.
f. Add approximately 1.0 g Celite to dried crucibles and dry at 130°Cto constant weight.
g. Cool crucible in desiccator for approximately 1 h and record weightof crucible containing Celite.
3. Filtering flask, heavy-walled, with 1-L side arm.
4. Rubber ring adaptors for use on filtering flasks.
5. Vacuum source: vacuum pump or aspirator with regulator capable ofregulating vacuum.
6. Water bath, shaking, large-capacity (20-24 L) with covers; capableof maintaining temperature of 100°C; equipped with automatic timers foron-off operation.
7. Balance, 0.1 mg accuracy.
8. Ovens, two, mechanical convection, set at 103 ± 2°C and
130 ± 3°C.
9. Desiccator, airtight, with SiO2 or equivalent desiccant. Desiccantdried biweekly overnight in 130°C oven.
10. pH meter.
11. Pipettors and tips, 50-200 μL and 5 mL capacity.
12. Dispensers
a. 15 ± 0.5 mL for 78% (v/v) EtOH, 95% ethanol, and acetone.
b. 40 ± 0.5 mL for buffer.
13. Measuring cylinder, 500 mL.
14. Magnetic stirrers and stirring bars.
15. Rubber spatulas.
16. Muffle furnace, 525 ± 5°C.
17. Microfuge, capable of 12,000 g.
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