Megazyme Available Carbohydrates Assay Kit, 100 assays

The Available Carbohydrates Assay Kit method is suitable for the measurement of available carbohydrates (AVCHO) comprising *total digestible starch (TDS) plus maltodextrins, sucrose, D-glucose, D-fructose and lactose. This method is designed to simulate in vivo conditions in the human small intestine (i.e. a 4 h incubation time with PAA + AMG) in parallel with recent advances in Dietary Fiber (DF) methodology (K-RINTDF: AOAC Method 2017.16) and in accordance with the new (physiological based) definition of DF announced by Codex Alimentarius in 2009. Also, sucrose is hydrolysed with a specific “sucrase” enzyme which (unlike invertase which has been used traditionally for this reaction) has no action on fructo-oligosaccharides (FOS).

* Total digestible starch (TDS) is defined as starch that is digested in a 4 h period and is part of the carbohydrate that is available for digestion and absorption in the human small intestine.

For the measurement of available carbohydrates (total digestible starch plus maltodextrins, sucrose, D-glucose, D-fructose and the glucose component of lactose) in cereal products, foodstuffs, feeds and other materials; measured as D-glucose and D-fructose. 

Principle:
(PAA + AMG, pH 6.0, 37°C, 4 h)
(1) Digestible starch + H₂O → D-glucose

(sucrase)
(2) Sucrose → D-glucose + D-fructose

(β-galactosidase)
(3) Lactose → D-galactose + D-glucose 

(HK)
(4) D-Glucose + ATP → G-6-P + ADP

(HK)
(5) D-Fructose + ATP → F-6-P + ADP

(G-6-P DH)
(6) G-6-P + NADP⁺ → gluconate-6-phosphate + NADPH + H⁺

(PGI)
(7) F-6-P ↔ G-6-P

(GalDH/GalM)
(8) β-D-Galactose + NADP⁺ ↔ D-galactonate + NADPH + H⁺