RI-ERP-FINALACTION-Recommendations

H ALL : J OURNAL OF AOAC I NTERNATIONAL V OL . 92, N O . 1, 2009 45

Table 2. Results for determinations of free glucose and starch + maltooligosaccharides corrected for free glucose in food and feed samples (dry matter basis)

Extension of AOAC 996.11

Hot water

Acetate buffer

DM, % a

b

Sample

Mean

s r

Mean

s r

Mean

s r

Free glucose

Alfalfa silage

90.0

0.12

0.00

0.14

0.00

0.12

0.01

Corn grain, ensiled

93.5

0.44

0.00

0.38

0.00

0.18

0.00

Corn silage

91.1

0.05

0.00

0.07

0.00

0.07

0.00

Rice

90.4

0.18

0.01

0.20

0.01

0.02

0.02

Soybean meal

92.2

0.08

0.00

0.04

0.00

0.05

0.00

Split peas

91.4

0.07

0.00

0.04

0.00

0.02

0.02

Wheat flour

90.9

0.17

0.02

0.13

0.00

0.05

0.02

Starch + maltooligosaccharides corrected for free glucose

Alfalfa silage

90.0

1.5

0.1

1.6

0.0

1.4

0.0

Corn grain, ensiled

93.5

69.0

0.1

75.6

0.8

70.4

0.2

Corn silage

91.1

7.3

0.8

37.1

0.4

34.2

0.9

Rice

90.4

82.0

0.4

83.3

1.3

82.4

0.1

Soybean meal

92.2

1.4

0.0

0.8

0.0

0.9

0.0

Split peas

91.4

48.4

0.3

50.1

0.7

48.1

0.1

Wheat flour

90.9

74.3

0.5

79.6

0.2

74.8

0.1

Average of feed/food samples

Mean

40.6

46.9

44.6

s r

0.31

0.48

0.20

CV, % c

2.57

1.55

0.78

a DM = Dry matter. b s r

= Standard deviation of replicates.

c CV = Coefficient of variation (s r

/mean).

to 4.5 with 1 M NaOH solution. Dilute to 1 L with water. ( 2 ) 100 mM, pH 5.0 .—Same procedure as for ( a )( 1 ), except pH is adjusted to 5.0. ( b ) Heat-stable -amylase solution. —Heat-stable -amylase, ca 20 000 liquefon units/g, specific gravity 1.25 (Product Multifect AA 21L, Genencor International, Rochester, NY; origin: Bacillus licheniformis ; pH optima, 5.5–5.8). ( c ) Amyloglucosidase solution. —( 1 ) 7 U/8 mL.— Pipet 0.067 mL concentrated amyloglucosidase and dilute to 250 mL with 100 mM sodium acetate buffer, ( a )( 1 ) . ( 2 ) 100 U/mL .—Dilute 0.77 mL concentrated amyloglucosidase with 100 mM sodium acetate buffer, ( a )( 2 ) , to 25 mL (concentrated amyloglucosidase, 3260 U/mL, Product E-AMGDF, Megazyme International Ireland, Ltd, Bray Co., Wicklow, Ireland; origin: Aspergillus niger ; optimum pH, 4.0; stable pH, 4.0–5.5). ( d ) Glucose oxidase–peroxidase–aminoantipyrine buffer mixture. —Mixture of glucose oxidase, 7000 U/L; peroxidase, 7000 U/L; and 4-aminoantipyrine, 0.74 mM. Prepare by dissolving 9.1 g Na 2 HPO 4 and 5.0 g KH 2 PO 4 in ca 300 mL

distilled water in a volumetric flask. Use distilled water to rinse chemicals into bulb of flask. Swirl flask to dissolve completely. Add 1.0 g phenol (ACS grade) and 0.15 g 4-aminoantipyrine. Use distilled water to rinse chemicals into bulb of flask. Swirl flask to dissolve completely. Add glucose oxidase (7000 U) and peroxidase (7000 U), rinse enzymes into flask with distilled water, and gently swirl flask to dissolve contents without causing excessive foaming. Dilute to 1 L with distilled water. Seal flask and invert repeatedly to mix. Filter solution through a glass fiber filter with 1.6 m retention. Store in a sealed amber bottle at ca 4 C. Determine standard curve for the reagent, using a 4-point standard curve with distilled water and ( e ), according to Preparation of Reagent Blanks and Standard Curves , ( b )( 1 ). ( e ) Glucose standard solutions. —40, 60, and 80 g/mL. Determine the dry matter of powdered crystalline glucose (purity 99.5%). Weigh approximately 20, 30, and 40 mg glucose, and record weight to 0.0001 g. Dissolve each portion separately in distilled water. Dilute each solution to 500 mL to obtain 3 independent glucose standard solutions. Multiply the weight of glucose by the percentage of dry matter, and divide

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