Food Chemistry

16.2 Individual Constituents 761

Fig. 16.3.Biosynthesis of cyanogenic glucosides

Fig. 16.4.Lima beans: linamarin degradation, resulting in a release of hydrocyanic acid

Table 16.23.Amount of glycoside-bound hydrocyanic
acid in food

Food HCN
(mg/100 g)

Lima beana 210–310
Bitter almond 280–310
Sorghum sp. 250
Cassava 110
Pea 2. 3
Bean 2. 0
Chick pea 0. 8
aIn the United States new cultivars have been devel-

oped that contain only 10 mg HCN/100 g seed.

rived from phenylalanine or tyrosine, but not lina-
marin.

As shown in Fig. 16.4,β-glucosidase hydrolysis

produces an unstable hydroxynitrile which slowly

degrades into the corresponding carbonyl com-

pound and HCN. However, most legume seeds

contain a hydroxynitrile lyase which accelerates

this reaction.

16.2.7 Lipids∗

With the exception of soybeans and peanuts,

the lipid content of most legumes is so low

(cf. Table 16.2) that they can not be considered

∗The composition of soy and peanut lipids is covered

in Chapters 3 and 14.