Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
fructans. Historically, levans of grasses are often named phleins, after Phleum pratense
L., from where fructans were first isolated.
Grain fructans are of the levan type (see Chapter 1) with b(2Æ6)-linked fructofuranosyl
residues and a terminal glucosyl residue. Their polymerization starts
primarily from 1-kestose; however, additionally, a significant percentage of 6-kestose
is found. Wheat and rye fructans dominantly (50 to 70%) have DPs over 10. As
high-molecular-weight fructans become increasingly branched (mixed-type fructans),
the DPs increase.
13.4.9 ASPARAGACEAE
Sprouts of Asperagaceae species, in particular Asparagus officinalis L. (asparagus),
are popular vegetables worldwide. Dry matter contents range from 40 to 50%,
depending on cultivar and cultivation conditions, with 10–15% being glucose and
fructose and 1–2% sucrose. Fructan contents are similar to those of onion (25 to
30%), with a rather homogeneous distribution of low- and high-molecular-weight
fructans (Table 13.2). Fructans are of the mixed type, and include the neo-kestose
series similar to that in Liliaceae.
13.4.10 AMARYLLIDACEAE
The most important species from the Amaryllidaceae family is banana, in particular
flour banana (Musacea paradiiaca L.) and fruit banana (Musacea sapentium L.),
which are used as vegetable and fruit. Besides starch, glucose, fructose, and sucrose,
fruit bananas contain more than 5% fructans, which corresponds to ca. 1.4% fresh
weight at a dry matter content of ca. 26%.
13.4.11 AGAVACEAE
The family Agavaceae grows in Mediterranean and hot climates and needs
ferrous and calcareous soil for optimum development of plant organelles. More than
200 species are known worldwide, with ca. 120 located in Mexico. A few varieties
are used to grow raw material for food and for fermentation for tequila production.
Tequila is a liquor from fermented agaves dominantly produced in Mexico. Today,
ca. 120 tequila brands of different quality levels are offered by 17 producers. The
preferred raw material is the Agavaceae species Agave tequila Weber L. var. azul.
Blue agave is cultivated in specific plantations, with up to 3000 vegetative plant
seedlings/ha, and it is harvested 6 to 8 years before blooming, which guarantees
maximum carbohydrate content. Trunk weight is ca. 240 t/ha.
Dry matter contents of the trunk range from 30 to 32% if harvested after a dry
period. Total carbohydrate content is 22–24%, with fructan contents of ca. 20–23%.
The amount of FOSs (3 < DP > 10) is 8–10%, and is identical with the amount of
midrange-DP fructans (11 < DP > 30), and 4–8% of fructans have DPs between 20
and 50. Agave fructans are of the mixed type with b(2Æ1)- and b(2Æ6) linkages
and a basic backbone of b-D-(2Æ1)-linked fructofuranosyl residues. Short branches
having two or three fructofuranosyl residues are b-D-(2Æ6) linked. The terminal
segment either is a a-D-glucopyranosyl-residue or a b(2Æ6) linked to a glucose