ORIGINAL ARTICLE

Individual Sugars, Soluble, and Insoluble Dietary Fiber

Contents of 70 High Consumption Foods

Betty W. Li*

,1

, Karen W. Andrewsw

,2

, and Pamela R. Pehrssonw

*Food Composition Laboratory, Beltsville Human Nutrition Research Center, ARS, USDA, U.S.A.; and

The U.S. Department of Agriculture (USDA) publishes representative nutrient data

for foods in their Standard Reference Data Base, available on the internet and on

To whom correspondence and reprint requests should be addressed. Tel.: +1-301-504-8466. Fax: +1-

301-504-8314. E-mail: [email protected]

and reported for all foods. Total dietary fiber (TDF) data are provided for most

foods. The Nutrient Data Laboratory, ARS, USDA has been updating and

expanding the carbohydrate data in Standard Reference since TDF values were

first published by Human Nutrition Information Service (Matthews and Pehrsson,

1988). Data have generally been determined using AOAC-approved methods of

analysis. Individual and total sugar values were first published in the Home

Economics Research Report Number 48 (Matthews et al., 1987). Since then, more

values from USDA-sponsored contracts have been added to the database. In

response to many inquiries and requests for soluble and insoluble dietary fiber

values (obtained as separate fractions in analytical procedures) in the early 1990s, a

American diet. The top 100 foods on this list represented 74% of the TDF

consumed in this country. According to the latest CSFII (USDA, 1998), all these

foods are still major contributors, with the exception of those listed under

legumes and fruits, at least half of which remained on the list. Approximately 70

foods from this list, chosen because they contain both sugars and TDF were

procured, prepared and analyzed by a commercial laboratory according to a

detailed work plan written into a USDA contract. Foods included 14 baked

products, 10 cereal grains and pastas, 19 fruits, seven legumes, 10 cooked vegetables,

analyzed both raw and cooked.

A simple sampling plan was determined for each food based on Nielsen data from

market share information (Nielsen, 1988). Foods were purchased in the Wilson,

North Carolina area. For most of the foods (especially the legumes, baked products

and cereal grains/pasta), the two top national brands were purchased. In cases where

one brand dominated (i.e., Quaker Oats), then only that brand was used, but it was

acquired from two major grocery chains. When market data indicated that store

brands represented a major market share (i.e., hamburger/hotdog rolls), a major

store brand was purchased and composited with the top national brand. For the

removed before further sample preparation. No salt, oil or butter/margarine was

added to any food during cooking. Vegetables were cooked until fork tender. All

which was boiled, and potatoes which were either baked or boiled. Cereals and pasta

were cooked according to package instructions, except no salt or fat was added.

Following preparation, the foods were composited. Equal weight portions of the

same food from two different stores or two different brands were composited and

blended to a homogenous mixture. Following the removal of a portion from each

-h, the

remainder of the mixture was freeze-dried, ground to 30 mesh, and stored at 201C.

Freeze-dried, frozen samples were further dried in a 601C vacuum oven for 3

-h just

18

Sep-Pak

cartridge and then filtered through a 0.45 mm nylon disc. Separation and

quantitation were carried out on an amino-bonded column with a mobile phase of

CH

Samples were analyzed for soluble and insoluble dietary fiber fractions according to

AOAC Method 991.43, an enzymatic-gravimetric procedure (Lee et al., 1992).

washing were mixed with 4  volume of 95% ethanol to precipitate materials that

were soluble in the digestates. After 1 h, precipitates were filtered through tared

fritted glass crucibles. One of each set of duplicate insoluble fiber residues and

soluble fiber residues was ashed in a muffle furnace at 5251C for 5 h. Another set of

residues was used to determine protein as Kjeldahl nitrogen  6.25. Soluble or

insoluble dietary fiber residues (% original sample weight) minus % ash and % crude

protein found in the residues were taken to be the values for the respective dietary

fiber fraction. Total dietary fiber was calculated as the sum of soluble and insoluble

dietary fiber.

All data shown in Table 1 were obtained through a USDA contract with a

commercial laboratory, and are arranged according to food groups and expressed as

g/100 g (as eaten).

glucose, and/or maltose; total sugar content varied between none detected for

cornstarch and 0.78 for cooked instant oatmeal. All of the 19 fruits (except both

varieties of avocado) contained fructose, glucose, and sucrose; six contained maltose.

Total sugar content varied between 0.16 for avocado (California Haas variety) to

59.15 for seedless raisins. All seven legumes contained sucrose; only two contained

fructose and glucose. None of the legumes contained maltose and total sugar content

varied between 0.39 for dry, cooked, drained lentils and 4.92 for canned beans with

contained fructose, seven contained glucose and one contained maltose; total sugar

content varied between 0.44 for French fries and 7.37 for microwaved carrots. Of the

and 12.72 for guava. Legumes contained the highest amount of dietary fiber (mostly

as IDF); SDF ranging from 0.09 to 1.38, and IDF ranging from 4.02 to 10.56. TDF

content varying between 4.53 for canned cowpeas and 10.65 for cooked split peas.

For cooked vegetables, SDF ranged from 0.13 to 1.85 and IDF ranged from 1.06 to

4.21; TDF content varied between 2.05 for boiled white potato and 5.23 for cooked

lima beans. Vegetables, which are eaten raw, have a lower TDF content when

compared to their cooked counterpart or cooked vegetables in general. The SDF for

raw vegetables ranged from 0.10 to 0.77 and IDF ranged from 0.88 to 3.06; TDF

Mongeau and Brassard (1989) conducted studies comparing two or three dietary

fiber methods for the analysis of a variety of foods. They concluded that enzymatic-

gravimetric methods (e.g., AOAC method 991.43) generate higher fiber values than

enzymatic-chemical methods (e.g., AOAC method 994.13). For this study, we chose

AOAC Method 991.43 because it is a method that was adopted for nutrition labeling

of dietary fiber by the U.S. Food and Drug Administration (USDHHS, 1993).

Food Composition Laboratory, ARS, USDA for individual sugars and total dietary

were comparable to those from direct analysis using the method described in their

collaborative study. Table 2 gives the squared correlation coefficient for different

methods by each food group. Good agreement was found among total sugar values

obtained in two analytical laboratories using different methods (r

for baked products to 0.98 for fruits). Greater variations were found for TDF values

(r

2

sucrose than those eaten raw. Overall, fruits contain the most total sugar and cereal

grains/pasta the least.

Of the 70 foods tested, only six had TDF less than 1 g/100 g (as eaten). Therefore,

the remaining 64 foods may be considered good sources of dietary fiber. The

proportion of SDF to IDF varied across the food groups and even within each food

rather than developing generalizations on the relative proportions of fiber fractions

according to food groups.

TABLE 2

Squared correlation coefficient (r

Baked products 0.89 0.95

Cereal grains and pasta 0.90 0.64

Fruits 0.98 0.97

Legumes 0.97 0.78

Vegetables, cooked 0.93 0.76

Vegetables, raw 0.97 0.91

HPLC versus GC.

AOAC method 991.43 versus single enzyme method.

The authors wish to thank Zhenkun Zhao for her analysis of the samples in the Food Composition

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