Food Biochemistry and Food Processing (2 edition)

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Biochemistry of Beer Fermentation

Ronnie Willaert

Introduction

The Beer Brewing Process

Carbohydrate Metabolism—Ethanol Production

Wort Carbohydrates Uptake and Metabolism

Maltose and Maltotriose Metabolism

Glycogen and Trehalose 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 Sulfide

Acetaldehyde

Development of Flavor Fullness

Beer Fermentation Using Immobilized Cell Technology

Carrier Materials

Applications of 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

Acknowledgments

References

Abstract:The carbohydrate metabolism and flavor formation dur-

ing yeast primary and secondary fermentation (maturation) is re-

viewed. Carbohydrate metabolism and ethanol production during

the primary fermentation is discussed firstly. Next, the metabolism

of the bioflavoring by-product formation, that is, higher alcohols,

esters, organic acids, and vicinal diketones, is elaborated. The next

step of the fermentation process is the maturation process where

the vicinal diketones, acetaldehyde, and hydrogen sulfide concen-

tration needs to be reduced to acceptable levels. The chapter is

concluded with a discussion about the use of immobilized cell tech-

nology to intensify the fermentation process and its impact on flavor

production.

INTRODUCTION

The production of alcoholic beverages is as old as history.

Wine may have an archeological record going back more than

7500 years, with the early suspected wine residues dating from

early to mid-fifth millenniumbc(McGovern et al. 1996). Clear

evidence of intentional winemaking first appears in the repre-

sentations 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 thousands of years before early thinking man devel-

oped beer brewing and, probably coincidentally, bread baking

(Hardwick 1995). The oldest historical evidence of formal brew-

ing dates back to about 6000bcin ancient Babylonia is a piece

of pottery found there, which shows workers either stirring or

skimming a brewing vat.

Nowadays, alcoholic beverage production represents a sig-

nificant contribution to the economies of many countries. The

most important beverages today are beer, wine, distilled spir-

its, cider, sake, and liqueurs (Lea and Piggott 1995). In Bel-

gium (“the beer paradise”), beer is the most important alcoholic

beverage, although the beer consumption declined in the last

40 years: from 11,096,717 hL in 1965 to 9,703,000 hL in 2004

(NN 2005). In this time frame, wine consumption doubled from

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

crease in waters and soft drinks consumption (from 5,215,056 to

26,395,000 hL).

In this chapter, the biochemistry and fermentation of beer is

reviewed. First, the carbohydrate metabolism in brewer’s yeast

is discussed. The maltose metabolism is of major importance in

beer brewing, since this sugar is in a high concentration present in

wort. For the production of a high-quality beer, a well-controlled

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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