ABSTRACT
A number of sweet natural organic compounds have been found. They belong to families of proteins, terpenoids, steroids, dihydroisocoumarins, and flavanoids. Some of them are being currently used in the human diet as sweetening or flavoring agents.
Except for a limited number of sweet proteins, high-molecular-weight substances do not stimulate taste cells. Up to this point, six sweet proteins have been known: thaumatin, composed of 207 amino acid chains (~22 kDa) (24.1); its aluminium salt, talin (24.2); monellin, with two 45 to 50 amino acid chains (~11 kDa) (24.3); mabinlin, having two 33 and 72 amino acid chains, respectively (~12.4 kDa) (24.4); pentadin, consisting of a 54 amino acid chain (~12 kDa) (24.5); and brazzein, with the same number of amino acids in the chain but of ~6 kDa. (24.6) (Table 24.1). Some proteins such as miraculin and curculin, although tasteless, are used as tastemodifiers. All these proteins can be used as harmless low-calorie sweeteners and are helpful in reducing the sugar intake. Table 24.1 lists selected physical and functional properties of sweet proteins as well as their occurrence.
