|  | Maltotriose Mattresses is a trisaccharide consisting of three glucose molecules linked with alpha-1,4 bonds. It is present in beer and sweet beverages. |  |

|  | Hemicelluloses Hemicelluloses are polysaccharides consisting of many different sugar monomers (50-200) other than glucose, such as xylose, mannose, galactose, rhamnose, and arabinose. Hemicelluloses are embedded in the cell walls of plants. Hemicelluloses cannot be digested by intestinal enzymes, and are part of the dietary fibre fraction. |  |

|  | Glycogen Glycogen is a highly branched polymer of glucose, consisting of about 60,000 glucose residues. It is found to a limited extent in meats. The glucose units are linked by alpha-1,4 and alpha-1,6 bounds*. Because of these alpha bounds, intestinal enzymes can digest glycogen. The structure is similar to amylopectin. However glycogen contains more branches as compared to amylopectin. *see glossary: glucosidic bound |  |

|  | Fructooligosaccharides (FOS) Fructooligosaccharides (FOS), sometimes called oligofructose or oligofructan, are a class of oligosaccharides used as an artificial or alternative sweetener. FOS can be produced by degradation of Inulin, a polymer of D-fructose residues linked by β(2-1) bonds with a terminal α(1-2) linked D-glucose. This process also occurs to some extent in nature, and these oligosaccharides can be found in a large number of plants, especially in artichoke and chicory. Inuline may be regarded as dietary fibre. |  |

|  | Amylopectin Amylopectin is a polymer of glucose units found in plants. It is made up of straight chains (alpha- 1,4 linkages*) and highly branched chains of glucose (alpha-1,6 linkage*). The average degree of polymerization is in the thousands. The most common cereal starches, such as maize, potatoes, rice, and wheat contain approximately 70-80% amylopectin. However, some starches from maize, rice, sorghum and barley are even higher in amylopectin and are known as ‘waxy’. Amylopectin can be digested by intestinal enzymes. *see glossary: glucosidic bound |  |

|  | Stachyose Stachyose consists of 4 monosaccharide units. It is present in vegetables mainly pulses, such as peas, beans and lentils. Stachyose is not digested in the small intestine by human gastrointestinal enzymes. It enters the large intestine where it is fermented by intestinal micro flora with the production of gas, the reason why the consumption of beans produces flatulence. |  |

|  | Pectins Pectins are water-soluble polymers of galacturonic acids which are present in the cell walls and intracellular tissues of fruit and vegetables. Pectins are soluble in hot water and then form gels on cooling. They are widely used as gelling and thickening agents in foods such as jams and jellies. Although fruits contain the most pectins, they also represent 15-20% of the dietary fibre in vegetables, legumes and nuts. The carboxyl groups are to a variable extent esterified with methanol. The main pectin chain also contains small amounts of other sugars such as rhamnose. Pectin is a constituent of dietary fibre. In human digestion, pectin passes through the small intestine more or less intact. |  |

|  | Lignins Lignins are insoluble polyphenolic components of the plant cell wall. They are not polysaccharides, but they are chemically bound to hemicellulose in the plant cell wall. They are present in foods with a ‘woody’ component and in the outer layers of cereal grains. Lignins are a constituent of dietary fibre. |  |

|  | Amylose Amylose is a starch constituent of plants comprising mainly linear chains of glucose units (alpha - 1,4 linkage*) which tend to coil up into a helix. Because of these alpha linkages, intestinal enzymes (amylases) are able to digest amylose. The average degree of polymerisation is approximately 1000 or less. Most common cereal starches, such as maize, potatoes, rice, wheat, and barley contain 20-30% of amylose. However, the amylose content depends on the source (e.g. the amylose content is 70% in high amylose maize, but less than 1% in waxy maize). *see glossary: glucosidic bound |  |

|  | Cellulose Cellulose consists of an unbranched (linear) chain of up to 10,000 glucose units per molecule (beta -1,4 linkage*). The linear molecules are packed closely together as long fibres in a very water-insoluble structure. Cellulose is the major structural component of plant cell walls and is therefore present in fruits, vegetables and cereals. Cellulose forms about one quarter of the dietary fibre in grains and fruit and one third in vegetables and nuts. Intestinal enzymes are not able to break down the linkages between glucose in the beta position. Therefore, cellulose is part of the dietary fibre fraction. *see glossary: glucosidic bound |  |

|  | Glucose Glucose (also called dextrose) is as 70-80% as sweet as sucrose. Glucose is present in varying amounts in honey, fruits, and vegetables. Glucose is often formed from the hydrolysis* of sucrose, as in honey, maple sugar, and invert sugar** . Furthermore, glucose is present in processed foods, such as soft drinks, confectionery, and bakery products. These products contain ingredients originating from the hydrolysis and conversion of starch such as corn syrups. *see glossary: hydrolysis **see glossary: invert sugar |  |

|  | Lactose Lactose (also known as milk sugar) is composed of glucose and galactose. Lactose is also found in foods containing dairy products, such as baked foods, and in foods containing whey, such as sausages. |  |

|  | Galactose Galactose occurs naturally as a free single sugar in only a few foods. The disaccharide lactose is formed in a condensation* reaction where galactose is combined with glucose. *see glossary: condensation |  |

|  | Maltose Maltose (also known as malt sugar) is composed of two glucose molecules. Maltose is only a minor constituent of a few foods, especially in barley. Furthermore, maltose is produced when starch is broken down. This occurs in humans during carbohydrate digestion and also occurs in the fermentation process that yields alcohol. |  |

|  | Fructose Fructose has the same chemical formula as glucose (C 6 H 12 O 6), but its structure is different: it forms a 5-ring instead of a 6-ring. Fructose is 140% sweeter than sucrose. Fructose is present in honey, maple sugar, fruits, and vegetables. It is often formed from the hydrolysis* of sucrose and corn starch (corn syrup). Furthermore, fructose is present in processed foods, such as soft drinks, bakery products, and candies. *see glossary: hydrolysis |  |

|  | Sucrose Sucrose or saccharose (also known as table sugar, beet sugar or cane sugar) is composed of glucose and fructose. Sucrose is present in honey, maple sugar, fruits and vegetables. Furthermore, sucrose is an important ingredient in baked foods, desserts, ice cream, confectionery, and soft drinks. To make table sugar, sucrose is refined from the juices of sugarcane and sugar beets. The extent to which it is refined, determines whether the product becomes brown, white or powdered sugar. |  |

|  | Xylitol Xylitol is a reduced form of sugar (sugar alcohol) and occurs naturally in many fruits and vegetables. It is also prepared commercially from hardwood trees. Xylitol is widely used as a sweetener in chewing gum. One of the advantages of this kind of sweeteners over sucrose as sweetener is that they are not metabolised by bacteria in the mouth and therefore do not cause caries. Xylitol approaches the sweetness of sucrose. |  |

|  | Sorbitol Sorbitol is a reduced form of sugar (sugar alcohol) and occurs naturally in several fruits, such as cherries. Sorbitol is used as sweetener and as moistener in many types of products. One of the advantages of this kind of sweeteners over sucrose is that they are not metabolised by bacteria in the mouth and therefore do not cause caries. Sorbitol is about 60 percent as sweet as sucrose with one-third fewer calories. High intake of sorbitol may have laxative effects, due to lower digestibility of sorbitol. |  |

Title of page

Here you see several food components. Most are (nutritional important) carbohydrates, others are not carbohydrates at all.

Drag all carbohydrates to the appropriate boxes. Non-carbohydrates should not be placed in the boxes!

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Not completely right. Glucose, Galactose and Fructose are monosaccharides. If you look at the structure of the formulas of these sugars you will notice that they consist of one unit. These three sugars are nutritional important monosaccharides.

Not completely right. Lactose, maltose and sucrose are disaccharides. Take a look at the structural formulas of these sugars to see that they consist of two monosaccharide units.

Not completely right. Sorbitol and Xylitol are both reduced forms of sugar, the so-called sugar alcohols.

Not completely right. If you take time to read the information on Stachyose, FOS and Maltotriose carefully, you will discover that these are oligosaccharides because they consist of 3 till 9 monosaccharide units.

Not completely right. It is very important to realize that Lignin is not a carbohydrate because it does not consist of sugar units. Therefore it should NOT be placed in any of the boxes. However Lignin is an important constituent of the plant cell wall. For this reason Lignin will be included into fibre values although it is not a carbohydrate. More information about the definition and analysis of fibre will be given in the last part of this case.

Not completely right. It is important to realize that starch consist of polymers of only glucose units. These glucose units are linked by alpha glucosidic bounds (see glossary: glucosidic bounds) and not by beta glucosidic bounds. Starch can be digested in the human intestinal system because the human body contains enzymes being able to break down alpha linkage (but not beta linkages). If you take a careful look at the information about Amylose and Amylopectin you will discover both are starches. Glycogen is not considered as starch because it does not originate from plants but from animals. However, sometimes glycogen is called ‘animal starch’ because the structure of glycogen is similar to the structure of Amylopectin.

Not completely right. Non starch polysaccharides are mainly those polysaccharides present in the plant cell wall. This are Pectin, Cellulose and Hemicellulose. It is very important to realize that Lignin is not a carbohydrate because it does not consist of sugar units. Therefore it should NOT be placed in any of the boxes. However Lignin is an important constituent of the plant cell wall. For this reason Lignin will be include into fibre values although it is not a carbohydrate. More information about the definition and analysis of fibre will be given in the last part of this case.

Not completely right. Glycogen is the only polysaccharide in this exercise not belonging to the (plant) starches or to NSP (or fibre). Glycogen is not considered as starch because it does not originates from plants but from animals. However, sometimes Glycogen is called animal starch because the structure of Glycogen is similar to the structure of Amylopectin. Therefore Glycogen should be placed in the group ‘other polysaccharides’. Furthermore, realize that lignin is not a carbohydrate because it does not consist of sugar units. Therefore Lignin should NOT be placed in any of the boxes.

Right! Now this scheme gives you an overview of the classification of the nutritional important carbohydrates. (Realize that lignin is not a carbohydrate because it does not consist of sugar units. Therefore Lignin should NOT be placed in any of the boxes.)

In the next question you will learn in which foods you can find those nutritional important carbohydrates.