Phytochemicals present in plant food residues

The main groups of plant secondary metabolites that are suitable for use in nutraceuticals or as functional food ingredients are the terpenoids, the polyphenols and the organosulphur compounds.

The terpenoids (Fig. 17.1) are biosynthesised by the acetate-mevalonate pathway and constitute a group of lipophilic compounds with a wide range of molecular weights, biological properties and potential uses (Bartley and Scolnik, 1995). The monoterpenes (10 carbon atoms) are generally volatile compounds that are constituents of the essential oils (i.e. limonene) and are key compounds in the flavour of some fruits. Some of them have relevant biological properties. The sesquiterpenes and diterpenes (15 and 20 carbon atoms, respectively) are less relevant in food, while the triterpenes (30 carbon atoms) are relevant phytosterols (ergosterol, campesterol, sitosterol, etc.) and the tetraterpenes (40 carbon atoms) include carotenoid pigments with interesting biological properties (lycopene, P-carotene, P-cryptoxanthin, etc.).

Polyphenols (Fig. 17.2) constitute a very large group of secondary metabolites characterised by the presence of phenolic hydroxyls in the molecule. They are biosynthesised from acetate by the shikimate pathway

Lycopene (tomato)

Lycopene (tomato)

Beta carotene (carrot)

Beta carotene (carrot)

HO1'

Lactucaxantin (lettuce)

Lactucaxantin (lettuce)

HO1'

Limonene (citrus)

Limonene (citrus)

Fig. 17.1 Terpenoids from plant food wastes.

(Dixon and Paiva, 1995). They can be as simple as hydroxyl-benzoic acid and as complex as large procyanidin polymers with molecular weights of several thousand mass units. Their chemical and biological properties are also very wide. Some of them are water soluble (some anthocyanins), while others are highly lipophilic (the citrus flavone tangeretin and the stilbenoid resveratrol). They have been classified as flavonoids (C6-C3-C6) and non-flavonoid compounds. Flavonoids include anthocyanins, flavones, flavanones, chalcones, isoflavones and procyanidins (flavan-3-ols). Non-flavonoid compounds include benzoic acid derivatives, hydroxycinnamates, ellagic acid derivatives and ellagitannins, and stilbenoids.

Organosulphur compounds (Fig. 17.3) are biosynthesised from sulphur amino acids and include the compounds of the Alliaceae (alliin and allicin) and those of the Brassicaceae (glucosinolates).

Flavonol (quercetin)

Flavonol (quercetin)

OH

Isoflavone (genistein)

HO O

HO O

OH O

OH O

OH Anthocyanin O J (cyanin)

HO O

HO O

Flavan-3-ol (catechin)

OH OH

OH OH

Phenylpropanoids (chlorogenic)

Phenolic acids (ellagic acid) O

Phenolic acids (ellagic acid) O

Procyanidins Resveratrol

Stilbenoids (resveratrol)

Fig. 17.2 Polyphenols from plant food residues.

Alliaceae

CH2-CH2-C VN

OSO3

H Glucosinolates

Fig. 17.3 Organosulphur compounds from plant food residues (glc) glucose.

Was this article helpful?

0 0
Going Green Foods

Going Green Foods

What Is The First Essential Step For Going Green With Food? Get Everything You Need To Know To Get Started With Helping The Earth And Going Green With Food. This Book Is One Of The Most Valuable Resources In The World When It Comes To Everything You Need To Know About Green Agriculture.

Get My Free Ebook


Post a comment