Food Biochemistry and Food Processing (2 edition)

BLBS102-c23 BLBS102-Simpson March 21, 2012 13:44 Trim: 276mm X 219mm Printer Name: Yet to Come

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Dairy Products

Terri D. Boylston

Introduction

Biochemistry of Cultured Dairy Products

Composition of Milk

Lactic Acid Bacteria

Key Processing Steps in Cultured Dairy Products

Lactic Acid Fermentation

Coagulation of Milk Proteins

Homogenization

Pasteurization

Cooling

Processing of Cultured Dairy Products

Cheese

Natural Cheeses

Standardization of the Milk

Coagulation of the Milk Proteins

Cutting the Coagulum

Shaping and Pressing

Salting

Ripening

Processed Cheese

Butter

Buttermilk

Sour Cream

Yogurt

Acidophilus Milk

The Future—Cultured Dairy Products with Therapeutic

Benefits

Acknowledgments

Further Reading

References

Abstract:This chapter provides an overview of the biochemistry

and processing of cultured dairy products. The role of lactic acid

bacteria in developing cultured dairy products and coagulation of the

milk proteins through either enzyme addition or acid production is

emphasized. The biochemistry involved in the processing of natural

and processed cheeses, butter, buttermilk, sour cream, yogurt, and

acidophilus milk is discussed.

INTRODUCTION

Cultured dairy products were originally developed as a means

to preserve milk through the production of lactic acid. However,

these products are also recognized because of their desirable

sensory characteristics and nutritional value. The term, cultured

dairy products, is currently used to indicate that these products

are prepared using lactic acid bacteria starter cultures and con-

trolled fermentation. The lactic acid bacteria utilize the nutrients

in the milk to support their growth. The production of lactic acid

reduces the pH of these products to inhibit the growth of many

pathogenic and spoilage microorganisms. In addition, the fer-

mentation process develops a wide range of dairy products with

a diversity of flavor and textural attributes, including cheese,

yogurt, buttermilk, butter, acidophilus milk, and sour cream.

Chapters 24 and 25 provide detailed information on the bio-

chemistry and processing of milk and milk products. This chap-

ter will focus on the biochemistry and processing involved in the

production of cultured dairy products. This chapter will include

a general discussion of the biochemistry and processing of cul-

tured dairy products, followed by a discussion of the processing

of the individual dairy products.

BIOCHEMISTRY OF CULTURED DAIRY

PRODUCTS

Composition of Milk

The quality of the cultured dairy products is influenced by the

composition and quality of the raw milk. Species, breed, nutri-

tional status, health, and stage of lactation of the cow can have

an impact on the fat, protein, and calcium content and over-

all composition and quality of the milk. On the average, cows’

milk consists of 3.7% fat, 3.4% protein, 4.8% lactose, 0.7% ash,

and has a pH of 6.6 (Fox et al. 2000). Good microbiological

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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