Food Biochemistry and Food Processing

29

Biochemistry and Fermentation of

Beer*

R. Willaert

659

Introduction

The Beer Brewing Process

Carbohydrate Metabolism—Ethanol Production

Carbohydrate Uptake

Maltose and Maltotriose Metabolism

Wort Fermentation

Metabolism of Bioflavoring By-products

Biosynthesis of Higher Alcohols

Biosynthesis of Esters

Biosynthesis of Organic Acids

Biosynthesis of Vicinal Diketones

Secondary Fermentation

Vicinal Diketones

Hydrogen Sulphide

Acetaldehyde

Development of Flavor Fullness

Beer Fermentation Using Immobilized Cell Technology

Carrier Materials

Applications of Immobilized Cell Technology (ICT) in

the Brewing Industry

Flavor Maturation of Green Beer

Production of Alcohol-Free or Low-Alcohol Beer

Production of Acidified Wort Using Immobilized

Lactic Acid Bacteria

Continuous Main Fermentation

References

INTRODUCTION

The production of alcoholic beverages is as old has

history. Wine may have an archeological record

going back more than 7500 years, with the early sus-

pected wine residues dating from early to mid-fifth

millennium BC (McGovern et al. 1996). Clear evi-

dence of intentional wine making first appears in the

representations of wine presses that date back to the

reign of Udimu in Egypt, some 5000 years ago. The

direct fermentation of fruit juices, such as that of

grape, had doubtlessly taken place for many thou-

sands of years before early thinking man developed

beer brewing and, probably coincidentally, bread

baking (Hardwick 1995). The oldest historical evi-

dence of formal brewing dates back to about 6000

BC in ancient Babylonia: a piece of pottery found

there shows workers either stirring or skimming a

brewing vat.

Nowadays, alcoholic beverage production repre-

sents a significant contribution to the economies of

many countries. The most important beverages

today are beer, wine, distilled spirits, cider, sake,

and liqueurs (Lea and Piggott 1995). In Belgium

(“the beer paradise”), beer is the most important al-

coholic beverage, although the beer consumption

has declined in the last 40 years: from 11,096,717

hL in 1965 to 10,059,513 hL in 2001 (N.N. 2002).

In this time frame, wine consumption doubled from

1,059,964 to 2,215,579 hL. Another trend is the

spectacular increase in water and soft drink con-

sumption (from 5,215,056 hL to 24,628,781 hL).

In this chapter, the biochemistry and fermentation

of beer is reviewed. Firstly, the carbohydrate metab-

olism in brewer’s yeast is discussed. The maltose

metabolism is of major importance in beer brewing

since this sugar is present in a high concentration in

*The information in this chapter has been derived from
“Beer,” in Alcoholic Beverages Manual,©2004 by
Ronnie Willaert. Used with permission.

Food Biochemistry and Food Processing

Edited by Y. H. Hui

Copyright © 2006 by Blackwell Publishing