Handbook of Dietary Fiber

Susan Sungsoo Cho

• Publisher: CRC Press
• Year: 2001
• eBook ISBN: 9781135569600
• Topic: Medicine
• Subtopic: Nutrition, Dietics & Bariatrics

Presents the latest research on the analysis, metabolism, function, and physicochemical properties of fiber, fiber concentrates, and bioactive isolates--exploring the effect of fiber on chronic disease, cardiovascular health, cancer, and diabetes. Examines food applications and the efficacy and safety of psyllium, sugar beet fiber, pectin, alginate, gum arabic, and rice bran.

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Food Uses of Fiber

Janette Gelroth and Gur S. Ranhotra

American Institute of Baking, Manhattan, Kansas

I. INTRODUCTION

Epidemiological and clinical studies, especially those reported by British researchers a few decades ago, have linked the inadequacy of fiber in the Western diet with the higher incidence of chronic diseases among us. Numerous aspects of this relationship have been investigated and expanded, including the definition of dietary fiber and its constituents and the correct methods by which to measure them.

As a result of these investigations, fiber’s health benefits have become increasingly recognized. This has led to the marketing of a plethora of new fiber-containing food products. Many of these are highly successful, but others have failed. New laws have been enacted to regulate the labeling of fiber in fiber sources and fiber-containing foods, and restrictions have also been placed regarding health claims that can and cannot be made on food labels and in advertising.

Over the years, various fiber sources have fallen into and out of acceptance by the food industry and consumers alike. However, the use of fiber in foods has continued to grow and expand, with an ever-increasing number of fiber sources becoming available for food applications. In addition, functional characteristics of fiber sources have also been recognized and developed. This chapter discusses various aspects of fiber ingredients and their use in foods.

II. SOURCES OF FIBER

Fiber is found only in foods of plant origin—cereal grains, legumes, fruits, vegetables, nuts, and seeds. In many Western countries, including the United States, fiber has traditionally been obtained by consumption of plant-based foods. Over the years, however, food-consumption patterns, which increasingly included more animal-based than plant-based foods, have shown a significant decline in fiber intake; currently, fiber intake in the United States averages only 10–15 g per day.

Increasing awareness of the health benefits of fiber has led to various dietary recommendations, which suggest that we increase our fiber intake substantially (1). A daily intake of 25 g is now widely suggested—i.e., a doubling of the current intake. Toward this goal, an increasing number of fiber ingredients for food use have been developed from a variety of different sources. Table 1 lists many of these sources and an approximate range of fiber contents in ingredients derived from them (2, 3, 4, 5, 6). As is evident from Table 1, different sources of fiber can yield products that differ greatly in fiber content.

Table 1 Selected Sources of Fiber for Use in Food Applications

Source	Total dietary fiber^a (%)
Grains
Amaranth	NA
Barley	35–70
Corn	50–95
Oats	15–95
Rice	30–80
Rye	NA
Wheat	10–65
Legumes
Soy	45–75
Peas	50–95
Peanuts	50–55
Sweet lupin	60–95
Vegetables
Carob	45–50
Cocoa	55–75
Potato pectin	50–55
Sugar beet	60–80
Sugar cane	72–86
Tomato	45–65
Tapioca	70
Fruits
Apple	43–60
Black currant	43
Citrus^b	25–70
Cranberry	6–8
Date	44–52
Fig	12–64
Peach	10
Pear	13–14
Prune	16–57
Raisin	6–8
Raspberry	2–5
Nuts and seeds
Almond	2–12
Cottonseed	NA
Flaxseed	30–40
Hazelnut	3
Mustard	NA
Pecan	2–3
Psyllium	NA
Sunflower	NA
Cellulose and cellulose derivatives^c	75–100
Gums
Agar	75–85
Carrageenan	85–90
Guar	85–90
Gum arabic	80–90
Locust bean	90
Pectin	100
Tragacanth	80
Xanthan	75
Others
oligosaccharides	NA
Polydextrose	NA
Resistant starch	30–40

NA = Not available

^aRange values of processed sources (not of raw materials).

^be.g., grapefruit, lemon, lime, and orange.

^ce.g., cellulose, methylcellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose.

Source: Refs. 2, 3, 4, 5, 6.

For all practical purposes, fiber is viewed as total dietary fiber (TDF) and not as crude fiber—a term now rarely used, primarily because the method involved grossly underestimates fiber in most foods. For health and nutrition labeling purposes, TDF is broadly classified into insoluble fiber (IF) and soluble fiber (SF).

III. PROCESSING AND CONCENTRATING FIBER

A variety of processing techniques are employed in the production of fiber ingredients for use in food. These techniques include such things as various milling processes, simple extraction and drying procedures, and enzyme and additive treatments, to name a few. Using these techniques, fiber ingredients can be isolated from raw materials and concentrated or otherwise modified to serve a particular function within a food system. Fiber ingredients can even be produced from sources that might otherwise be considered waste products. For example, wheat straw, soy hulls, oat hulls, peanut and almond skins, corn stalks and cobs, spent brewer’s grains, and waste portions of fruits and vegetables processed in large quantities (7, 8, 9, 10) can be converted into fiber ingredients, which may be highly functional in certain food applications.

The extent or degree of processing used in the manufacture of fiber ingredients can have a substantial impact on characteristics of the finished products. Often this accounts for the wide range of TDF contents observed for fiber ingredients from various sources (Table 1). For cereal grains, TDF content would also differ greatly based on the portion of the grain (e.g., whole grain, bran, or hull) utilized as the starting material. For example, oat groats, which are produced by removal of the outer layer (hulls) of whole oats, contain about 10% TDF. Additional milling and fractionating of the groats produce oat bran. Cleaning, bleaching, and grinding of the hulls removed in the initial step result in an additional fiber product (Table 2) (11).

Modified fiber ingredients are products that are subjected to additional processing to yield an altered product, which may have a higher fiber content, different functional characteristics, or other attributes useful when incorporating the ingredients into food products. In one study, for example, fine grinding followed by air classification of a wheat bran formed a fraction containing 10% more fiber (51% vs. 61% TDF) (12). In another study, an alcoholic extraction process followed ...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Preface
• Table of Contents
• Contributors
• I. Dietary Fiber in Health and Disease
• II. Physicochemical Properties
• III. Chemistry and Analysis
• IV. Functional Dietary Fiber Ingredients
• V. Worldwide Dietary Fiber Intake and Regulations of Dietary Fiber Foods
• Index