chapter  6
Peptides
Pages 42

Dolores Gonza´lez de Llano Centro Nacional de Biotecnologı´a (CSIC), Madrid, Spain

Toma´s Herraiz and M. Carmen Polo Instituto de Fermentaciones Industriales (CSIC), Madrid, Spain

I. INTRODUCTION

Peptides are present naturally in foods, arising mainly

from the partial degradation of protein polypeptide

chains. Some peptides, like the dipeptides carnosine,

anserine, and balenine in vertebrate muscle or gluta-

thione in fruits, are nonproteinic in origin. In other

cases, peptides are present in foods because they

are used as additives (sweeteners, flavor enhancers,

bulking agents in light drinks, etc.). Enzymatic hydrolysis of food proteins yields pep-

tides that are of great interest to the food industry

and are utilized for various purposes, e.g., improving the

functional properties of foods, flavoring agents, in

dietetic food, parenteral feeding (casein hydrolyzates),

or milk protein substitutes in cases of intolerance. The multiple functions of peptides in foods (anti-

oxidants, antimicrobial agents, interfacial agents) and

their role in the development of characteristic flavors

(sweetness, bitterness), as well as the information they

can provide about the genuineness of foods, make

peptide analysis a necessity. Both producers and government laboratories

have considerable interest in the study of peptides,

both for research purposes and for the control of raw

materials or manufactured foods. For this reason,

substantial attention is now being focussed on the

development of analytical techniques designed to

separate, characterize, and quantify peptides.