Handbook of Hydrocolloids

Glyn O. Phillips, Peter A. Williams

• Publisher: Woodhead Publishing
• Year: 2009
• ISBN:
  9781845695873
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Hydrocolloids are among the most widely used ingredients in the food industry. They function as thickening and gelling agents, texturizers, stabilisers and emulsifiers and in addition have application in areas such as edible coatings and flavour release. Products reformulated for fat reduction are particularly dependent on hydrocolloids for satisfactory sensory quality. They now also find increasing applications in the health area as dietary fibre of low calorific value.

The first edition of Handbook of Hydrocolloids provided professionals in the food industry with relevant practical information about the range of hydrocolloid ingredients readily and at the same time authoritatively. It was exceptionally well received and has subsequently been used as the substantive reference on these food ingredients. Extensively revised and expanded and containing eight new chapters, this major new edition strengthens that reputation.

Edited by two leading international authorities in the field, the second edition reviews over twenty-five hydrocolloids, covering structure and properties, processing, functionality, applications and regulatory status. Since there is now greater emphasis on the protein hydrocolloids, new chapters on vegetable proteins and egg protein have been added. Coverage of microbial polysaccharides has also been increased and the developing role of the exudate gums recognised, with a new chapter on Gum Ghatti. Protein-polysaccharide complexes are finding increased application in food products and a new chapter on this topic as been added. Two additional chapters reviewing the role of hydrocolloids in emulsification and their role as dietary fibre and subsequent health benefits are also included.

The second edition of Handbook of hydrocolloids is an essential reference for post-graduate students, research scientists and food manufacturers.

• Extensively revised and expanded second edition edited by two leading international authorities
• Provides an introduction to food hydrocolliods considering regulatory aspects and thickening characteristics
• Comprehensively examines the manufacture, structure, function and applications of over twenty five hydrocolloids

1

Introduction to food hydrocolloids

P.A. Williams; G.O. Phillips Glyndwr University, UK

Abstract

This introductory chapter provides an overview of the source, market, functional characteristics and regulatory aspects of hydrocolloids used in foods. Examples of a number of different food products are given and the role of the hydrocolloids in controlling their texture and properties is discussed. A brief introduction to the rheological properties of the various types of hydrocolloids is provided and comparisons of the viscosity and viscoelastic behaviour are given. Many hydrocolloids are able to form gels in response to changes in temperature and/or in the presence of ions. The various mechanisms by which gelation occurs are summarised. The interactions that occur in systems containing mixtures of hydrocolloids are considered and combinations demonstrating synergistic behaviour are highlighted. The role of hydrocolloids as dietary fibre is an area of increasing importance because of the associated benefits for health and this area is briefly reviewed.

Key words

source of hydrocolloids

hydrocolloids

market

regulatory aspects

rheological properties

viscosity

storage and loss moduli

food products

dietary fibre

health benefits

1.1 Introduction

The term ‘hydrocolloids’ is commonly used to describe a range of polysaccharides and proteins that are nowadays widely used in a variety of industrial sectors to perform a number of functions including thickening and gelling aqueous solutions, stabilising foams, emulsions and dispersions, inhibiting ice and sugar crystal formation and the controlled release of flavours, etc. The commercially important hydrocolloids and their origins are given in Table 1.1.

Table 1.1

Source of commercially important hydrocolloids

Botanical trees cellulose tree gum exudates gum arabic, gum karaya, gum ghatti, gum tragacanth plants starch, pectin, cellulose seeds guar gum, locust bean gum, tara gum, tamarind gum tubers konjac mannan

Algal red seaweeds agar, carrageenan brown seaweeds alginate

Microbial xanthan gum, curdlan, dextran, gellan gum, cellulose

Animal Gelatin, caseinate, whey protein, soy protein, egg white protein, chitosan

The food industry, in particular, has seen a large increase in the use of these materials in recent years. Even though they are often present only at concentrations of less than 1% they can have a significant influence on the textural and organoleptic properties of food products. Some typical examples of foods containing hydrocolloids are shown in Fig. 1.1, clearly demonstrating the widespread application of these materials. The specific hydrocolloids used in the production of the individual products shown are:

Fig. 1.1 Examples of food products containing hydrocolloids.

• baked beans contain modified corn starch as a thickener

• hoi-sin sauce contains modified corn starch as a thickener

• sweet and sour sauce contains guar gum as a thickener

• Sunny Delight fruit drink contains modified starch as an emulsifier with carboxymethyl cellulose (CMC) and xanthan gum as thickeners

• the Italian dressing includes xanthan gum as a thickener

• ‘light’ mayonnaise contains guar gum and xanthan gum as fat replacers to enhance viscosity

• the yoghurt incorporates gelatin as a thickener rather than a gelling agent

• the mousse contains modified maize starch as a thickener with guar gum, carrageenan and pectin present as ‘stabilisers’

• the Bramley apple pies contain modified maize starch with sodium alginate as gelling agent

• the fruit pie bars contain gellan gum and the blackcurrant preserve and redcurrant jelly contain pectin as gelling agents

• the trifle contains xanthan gum, sodium alginate and locust bean gum as ‘stabilisers’, modified maize starch as a thickener and pectin as a gelling agent.

The changes in modern lifestyle, the ever growing awareness of the link between diet and health and new processing technologies have led to a rapid rise in the consumption of ready-made meals, functional foods and the development of high fibre and low-fat food products. In particular, numerous hydrocolloid products have been developed specifically for use as fat replacers in food. This has consequently led to an increased demand for hydrocolloids. The world hydrocolloids market is valued at around $4.4 billion p.a. with a total volume of about 260,000 tonnes. The market has been growing at the rate of 2–3% in recent years.

Hydrocolloid selection is dictated by the functional characteristics required but is inevitably influenced by price and security of supply. It is for these reasons that starches (costing typically < US$1/kg) are the most commonly used thickening agents. It is interesting to note here, however, that xanthan gum (~ US$12/kg) is becoming the thickener of choice in many applications. This is because xanthan gum has unique rheological behaviour and its increased use has led to strong competition between supplier companies ensuring that the price has remained at reduced levels. Xanthan gum forms highly viscous, highly shear thinning solutions at very low concentrations and the viscosity is not influenced to any great extent by changes in pH, the presence of salts and temperature. The high viscosity at low shear enables the gum to prevent particle sedimentation and droplet creaming and the shear thinning characteristics ensure that the product readily flows from the bottle after shaking. This explains its widespread application in sauces and salad dressings.

Gelatin is by far the most widely used gelling agent, although with the increasing demand for non-animal products and in particular the Bovine Spongiform Encephalopathy (BSE) outbreak in the UK, prices have increased significantly over recent years. There is currently considerable interest in alternative sources of gelatine, nota...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• Contributor contact details
• Preface
• 1: Introduction to food hydrocolloids
• 2: Hydrocolloids and emulsion stability
• 3: The health aspects of hydrocolloids
• 4: Agar
• 5: Starch*
• 6: Gelatin
• 7: Carrageenan and furcellaran
• 8: Xanthan gum
• 9: Gellan gum
• 10: Galactomannans
• 11: Gum arabic
• 12: Pectins
• 13: Milk proteins
• 14: Egg proteins
• 15: Vegetable protein isolates
• 16: Protein–polysaccharide complexes and coacervates
• 17: Gum ghatti
• 18: Other exudates: tragancanth, karaya, mesquite gum and larchwood arabinogalactan
• 19: Xyloglucan
• 20: Curdlan
• 21: Other microbial polysaccharides: pullulan, scleroglucan, elsinan, levan, alternant, dextran
• 22: Cereal β-glucans
• 23: Arabinoxylans
• 24: Soluble soybean polysaccharide
• 25: Cellulosics
• 26: Bacterial cellulose
• 27: Microcrystalline cellulose
• 28: Hydrocolloids for coatings and adhesives
• 29: Alginates
• 30: Inulin
• 31: Chitin and chitosan hydrogels
• 32: Konjac mannan
• Index