SPSFAM ERP

Removal of these oligosaccharides is achieved by incubating the sample extract with α -galactosidase at pH 4.5, before incubation with the sucrase/amylase mixture. In this step, the galactosyl-sucrose oligosaccharides are hydrolyzed to galactose and sucrose by α -galactosidase, with subsequent hydrolysis of sucrose to glucose and fructose by sucrase. Interference by sucrose, wheat starch, maltodextrins, α -cellulose, β -glucan and galactosyl-sucrose oligosaccharides is shown in Table 2. Each of the samples was analyzed using the full Fructan Assay Kit (K-FRUC) procedure. Clearly, starch, maltodextrins, α -cellulose and β -glucan do not interfere with the assay.

Table 2. Interference of α - and β -glucans, maltodextrins and galactosyl-sucrose oligosaccharides on fructan determination using the Fructan Assay Kit (K-FRUC)

method. Sample

Sample weight analyzed 400 mg 400 mg 400 mg 200 mg 400 mg 7.5 mg 7.5 mg 400 mg

Apparent “fructan” content % w/w (“as is”)

Sucrose/cellulose control (8.9% sucrose)

0.13 – 0.14 0.03 – 0.05 0.08 – 0.10 0.05 – 0.06 0.01 – 0.02 7.5 – 7.7 0.11 – 0.13 2.85 – 3.05

Wheat starch

Maltodextrins (Matsutani Chemical Co.) β -Glucan (Megazyme cat. no. P-BGBM)

α -Cellulose

Raffinose (galactosyl-sucrose)

Raffinose – pre-treated with α -galactosidase a Mung beans (containing 3.05% of galactosyl- sucrose oligosaccharides) Mung beans (3.05% galactosyl-sucrose oligosaccharides) plus α -galactosidase a

400 mg

0.10 – 0.11

a Sample (0.2 mL) was incubated with 0.05 mL of α -galactosidase solution (20 U) in 50 mM sodium acetate buffer (pH 4.5) for 30 min at 40 o C.

6.2.4 Recovery For accurate measurement of fructan and FOS, the sucrase/amylase mixture must give near complete hydrolysis of sucrose with essentially no hydrolysis of fructan or FOS. The recovery of kestose, the smallest and most sensitive native fructooligosaccharide, in the K-FRUC assay procedure is shown in Table 3. Assays were performed according to the standard procedure, and also with the non-inclusion of the sucrase/amylase incubation step.

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