Food Biochemistry and Food Processing (2 edition)

BLBS102-c27 BLBS102-Simpson March 21, 2012 13:25 Trim: 276mm X 219mm Printer Name: Yet to Come

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Biochemistry of Fruits

Gopinadhan Paliyath, Krishnaraj Tiwari, Carole Sitbon, and Bruce D. Whitaker

Introduction

Biochemical Composition of Fruits

Carbohydrates, Storage and Structural Components

Lipids and Biomembranes

Proteins

Organic Acids

Fruit Ripening and Softening

Carbohydrate Metabolism

Cell Wall Degradation

Starch Degradation

Glycolysis

Citric Acid Cycle

Gluconeogenesis

Anaerobic Respiration

Pentose Phosphate Pathway

Lipid Metabolism

Proteolysis and Structure Breakdown in Chloroplasts

Secondary Plant Products and Flavour Components

Isoprenoid Biosynthesis

Anthocyanin Biosynthesis

Ester Volatile Biosynthesis

General Reading

References

Abstract:Fruits are major ingredients of human diet and pro-

vide several nutritional ingredients including carbohydrates, vita-

mins and functional food ingredients such as soluble and insoluble

fibers, polyphenols and carotenoids. Biochemical changes during

fruit ripening make the fruit edible by making them soft, changing

the texture through the breakdown of cell wall, converting acids or

stored starch into sugars and causing the biosynthesis of pigments

and flavour components. Fruits are processed into several products

to preserve these qualities.

INTRODUCTION

Because of various health benefits associated with the consump-

tion of fruits and various products derived from fruits, these are

at the centre stage of human dietary choices in recent days. The

selection of trees that produce fruits with ideal edible quality

has been a common process throughout human history. Fruits

are developmental manifestations of the seed-bearing structures

in plants, the ovary. After fertilisation, the hormonal changes in-

duced in the ovary result in the development of the characteristic

fruit that may vary in ontogeny, form, structure and quality. Pome

fruits such as apple and pear are developed from the develop-

ment of the thalamus in the flower. Drupe fruits, such as cherry,

peach, plum, apricot and so on, are developed from the ovary

wall (mesocarp) enclosing a single seed. Berry fruits such as

tomato possess the seeds embedded in a jelly-like pectinaceous

matrix, with the ovary wall developing into the flesh of the fruit.

Cucumbers and melons develop from an inferior ovary. Citrus

fruits belong to the class hesperidium, where the ovary wall

develops as a protective structure surrounding the juice-filled

locules that become the edible part of the fruit. In strawberry,

the seeds are located outside the fruit, and it is the receptacle of

the ovary (central portion) that develops into the edible part. The

biological purpose of the fruit is to attract vectors that help in the

dispersal of the seeds. For this, the fruits have developed various

organoleptic (stimulatory to organs) characteristics that include

attractive colour, flavour and taste. The biochemical characteris-

tics and pathways in the fruits are developmentally structured to

achieve these goals. The nutritional and food qualities of fruits

arise as a result of the accumulation of components derived from

these intricate biochemical pathways. In terms of production and

Food Biochemistry and Food Processing, Second Edition. Edited by Benjamin K. Simpson, Leo M.L. Nollet, Fidel Toldr ́a, Soottawat Benjakul, Gopinadhan Paliyath and Y.H. Hui.

©C2012 John Wiley & Sons, Inc. Published 2012 by John Wiley & Sons, Inc.

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