Phytonutritional Improvement of Crops by Noureddine Benkeblia

Author:Noureddine Benkeblia
Language: eng
Format: epub
ISBN: 9781119079989
Publisher: John Wiley & Sons, Inc.
Published: 2017-07-24T00:00:00+00:00

Chapter 7

Carotenoids: Biotechnological Improvements for Human Health and Sustainable Development

George G. Khachatourians

College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, Canada

7.1 Introduction

Availability of quality foods for consumption is a fundamental prerequisite for life and maintenance of optimal health. In addition to their natural attributes, there are other ways of improving the appearance and nutritional quality of foods. Improving food constituents and ingredients is one of the high priority areas of food research worldwide. Carotene, was first isolated and crystallised from carrot roots some 185 years ago. Just over that number of structurally distinct carotenoids and their glycosides had been chemically characterised. This makes carotenoids the second most abundant pigment in nature, behind only chlorophyll. They are orange-red pigments found in chloroplasts and chromoplasts of plants, algae, bacteria, and fungi. Carotenoids also accumulate in flowers, fruits, and storage roots as well as animal species, for example, crustaceans, insects, fish, and birds. In the animal species their presence is through food intake. In chemical terms, the common term ‘carotene’ refers to a hydrocarbon carotenoid, and xanthophyll denotes the same as a derivative with one or more oxygen-containing functional groups. Most carotenoid pigments are C40 polyenes and all are derived from phytoene, a 40-carbon intermediate in the biosynthesis of carotenoids. The synthesis of phytoene is the first committed step in plants, produced from two molecules of geranylgeranyl pyrophosphate (GGPP) by the action of the enzyme phytoene synthase. The two GGPP molecules are condensed together followed by removal of diphosphate and proton shift leading to the formation of phytoene. They are essential components of the photosynthetic machinery, where they are involved in the assembly of the photosystems and play a role in light harvesting, where they absorb light in a broader range of the blue spectrum than chlorophyll and then transfer the energy to chlorophyll. Carotenoids also have a critical role as photo-protective compounds by quenching triplet chlorophyll and singlet oxygen derived from excess light energy, thus limiting membrane damage.

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