Food Biochemistry and Food Processing (2 edition)

BLBS102-c35 BLBS102-Simpson March 21, 2012 14:9 Trim: 276mm X 219mm Printer Name: Yet to Come

35

Biochemistry and Probiotics

Claude P. Champagne and Fatemeh Zare

Introduction

Biochemistry and Growth of Probiotic Cultures in Foods

Milk

Soy and Pulses

Prebiotics and Other Foods

Biochemistry and Stability During Storage in Foods

Protection Against Oxygen

Protection Against Acid

Biochemistry and Health Functionality

Survival to Gastric Acidity

Lactose Maldigestion

Blood Cholesterol Level

Gas Discomforts

Other Benefits

Conclusion

References

Abstract:The level of viable cells is essential to the functional-

ity of probiotic bacteria in foods. Many enzymatic activities have

been identified to be critical in the ability of probiotics cultures to

grow in food matrices, remain stable during storage, survive pas-

sage to the stomach and duodenum as well as to express activity in

the gastro-intestinal tract (GIT). The importance of the following

enzymatic activities on these functionalities will be addressed:α-

galactosidase for growth in soy and pulses as well as to help prevent

gas discomforts in the GIT,β-galactosidase for growth in milk as

well as to reduce lactose maldigestion problems in the GIT, pro-

teases for growth in milk and soy as well as to generate bioactive

peptides, oxidases and peroxidase to prevent oxygen toxicity during

fermentation and storage, proton-translocating ATPases for survival

to acid environments in foods and the GIT, bile salt hydrolase for

survival in the GIT and bioactivity toward cholesterol metabolism,

β-glucosidases for the release of bioactives (isoflavones, quercetin)

during fermentation.

INTRODUCTION

Probiotics are live microorganisms which, when administered

in sufficient quantity, confer a health benefit to the host (Araya

et al. 2002). Many health effects have been suggested: improved

carbohydrate digestion in the gastrointestinal (GI) tract, reduc-

tion of the incidence of diarrhoea, immune system enhancement,

blood cholesterol reduction (Shah 2000, Farnworth 2004). Of-

ficial recognition of these effects by regulatory agencies is be-

ginning (EFSA 2010). In light of these potential health benefits,

digestive health is considered as one of the ten key food trends

for 2010 (Mellentin 2010). As a result, the market for foods

which contain probiotic bacteria is in constant increase and is

predicted to reach US$30 billion by 2015 (Starling 2010).

From a technological and biochemical standpoint, this def-

inition of probiotics implies two important features: (1) the

cells must be viable, and (2) a certain quantity must be main-

tained. However, data suggest that, for some applications, non-

viable cells can present biological activity as well (Ouwehand

and Salminen 1998). The benefits of probiotics are increasingly

linked to specific biogenic metabolites (Stanton et al. 2005) that

may not necessarily require viable cells. In the current definition

of probiotics, fermented foods that carry bioactive compounds

but do not have viable cells are not considered to be as probi-

otics. If the functionality of the product is nevertheless directly

linked to some activity of the probiotic culture, then the concept

of “probioactive” may better apply to this health function. It

has been proposed that a probioactive be “a bioactive compound

influencing health that is synthesized by a probiotic culture or

that specifically results from the bioconversion of a food ma-

trix by a probiotic microorganism” (Farnworth and Champagne

2010). Exopolysaccharides, peptides, deconjugated metabolites

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.

675