DK1908_CH13

8/3/2019 DK1908_CH13

1/13

13

Applications of Oxidoreductases in Foods

Colja LaaneDSM Food Specialties, Delft, The Netherlands

Yvonne BruggemanUnilever Research, Vlaardingen, The Netherlands

Chris WinkelQuest International, Naarden, The Netherlands

I. INTRODUCTION

Oxidative and reductive processes play an important

role in foods. They influence not only the taste but also

the texture, appearance, shelf life, nutritional value,

and process tolerance of food products. Both enzy-

matic and nonenzymatic redox processes are involved.

In some cases redox processes lead to undesirable

effects such as off-flavor, reduced shelf life, or texturalproblems. In other cases, they contribute in a positive

way to the final aroma, an improved texture, a more

desirable appearance, or an increased shelf life.

Controlling the redox behavior in food systems during

all stages of processing and storage is therefore of

utmost importance.

Up until now redox reactions in foods were con-

trolled mainly by carefully selecting raw materials, by

adapting process conditions, by adding chemicals or

antioxidants, or by designing air-tight packaging mate-

rials. As yet, little attention has been paid to tailor

redox reactions in foods by the addition of oxidore-ductases or by changing the profile or content of oxi-

doreductases in food raw materials by genetic tools.

Presumably, the major bottleneck for the application

of oxidoreductases to foods is that economically effi-

cient enzyme production is, with a few exceptions, still

not feasible. In addition, public concerns about the us

of recombinant enzymes in food products is slowing

down their market introduction.

In this chapter the current and potential usage o

oxidoreductases in controlling the taste, texture

appearance (i.e., color), shelf life, and the nutritiona

value of food products will be discussed. Increasingly

redox enzymes are being used for biosensor applica

tions in food systems. This topic will not be discussedin this chapter, however. Table 1 lists the most impor

tant redox enzymes and their functions in food sys

tems. Most attention will be paid to the marke

segments bakery, beverages, and dairy and to oxidases

since relatively little is known about role and applica

tions of reductases in food systems. Furthermore, th

emphasis will be on added enzymes and not o

enzymes already present in the food product constitu

ents. For detailed information on the properties of th

individual oxidoreductases the reader is referred to in

Sec. IIA of this book.

II. TASTE

Many oxidoreductases play a role by influencing th

taste profile of food products. They are involved in th

in vivo/in situ biogenesis of desirable aroma compo

yright 2003 by Marcel Dekker, Inc. All Rights Reserved.

8/3/2019 DK1908_CH13

2/13

Table 1 Overview of the Main (Potential) Applications of Oxidoreductases in Food Products

Enzymes Taste Texture Appearance Shelf life

Lipoxygenases (LOX) In situ and in vitro

(off)-flavor

production

Dough extensibility

and strength

Flour bleaching

Alcohol oxidases and

dehydrogenases

(AO, ADH)

In situ and in vitro

flavor production

(ILOX)

AO plus catala

removal

Sulfhydryl oxidases

(SOX)

Removal of cooked

flavor in UHT-milk

Dough strengthening in

combination with

POX

Peroxidases (POX,

LPO)

In vitro flavor

production and

debittering

Crosslinking

biopolymers

Assisting PPO in color

formation

LPO, antimicr

(Poly)phenol oxidases

(PPO)

Debittering of coffee,

cacao, and olives

(Dis)coloration; in vitro

production of colors

Laccase, O2 re

Carbohydrate oxidases

(GOX, HOX,

PYROX)

GOX, mild acid

production

Dough strengthening

via H2O2; thickening

agent

GOX plus cata

removal

Ascorbic acid oxidase

(AAO)

Browning AAO plus cata

removal

Xanthine oxidases (XO) Antimicrobial

Superoxide dismutases

(SOD)

Removal react

species with

Catalases Removal exces

Cholesterol

oxidoreductases


8/3/2019 DK1908_CH13

3/13

nents, in the in vitro production of flavoring topnotes,

and in the endogenous formation of off-flavors. The

main redox enzymes are discussed below.

A. Lipoxygenases

Lipoxygenase (LOX, EC 1.13.11.12; see Chapter 43,

for detailed information), formerly known as lipoxi-dase or carotene oxidase, is an iron-containing

dioxygenase which catalyzes the oxidation of polyun-

saturated fatty acids containing cis, cis-1, 4-pentadiene

groups (linoleic, linolenic, and arachidonic acids) to

the corresponding conjugated cis, trans dienoic mono-

hydroperoxides. In addition LOX also accepts a rela-

tively broad range of phenolic compounds as

substrates (1) and is capable of oxidizing other sub-

strates than the actual substrate. This process is

known as co-oxidation and includes compounds like

carotenoids and polyphenols (2).

LOX is one of those endogenous enzymes that playan important role in both flavor generation and off-

flavor formation in virtually all food products derived

from plant raw materials. Depending on the final con-

centration and the type of food product the same fla-

vor component can be a desired aroma component or

an off-flavor at higher concentrations. For example,

C6-aldehydes and alcohols derived by the LOX-cata-

lyzed oxidation of (poly)unsaturated fatty acids have,

in most cases, a positive effect on the aroma profile

(e.g., wines and juices), but in other beverages, have

an undesired flavor effect (e.g., beer). Likewise, endo-

genous LOX is known to generate carbonyl com-pounds in dough systems and hence influences bread

flavor (3).

The formation of C6 compounds requires the

sequential action of four enzymes of which two are

redox enzymes, namely an acylhydrolase, a lipoxygen-

ase, a hydroperoxide lyase, and a yeast-derived alcohol

dehydrogenase (4). Typically, off-flavor formation is

prevented by using crop variants deficient in LOX iso-

enzymes, either by screening or by genetic tools (5) or

by controlling the oxygen levels during processing (6),

as well as by removing the malodorous oxidation pro-

ducts afterwards. The deodorization of off-flavors canbe achieved by physical techniques such as adsorption,

or enzymatically by converting the undesired alde-

hydes (e.g., with aldehyde dehydrogenase/oxidase), or

alcohols (e.g., with alcohol oxidase) into their corre-

sponding less flavorful carboxylic acid. The use of

redox enzymes for this purpose has been claimed for

several products such as margarine, cream, fish oil,

noodles, cooked rice, and soybean products (7, 8).

LOX is also used for the in vitro production o

several natural topnote flavors, which are mainl

added to beverages and dairy products to tailor the

flavor profile (9, 10). Typical examples include the con

version of polyunsaturated fatty acids into variou

short to medium-chain aldehydes/alcohols (13), o

into S(-)--decalactone (butter flavor; 12). Well

known fatty acidderived flavoring aldehydes/alcoholinclude the above mentioned C5 and C6 compounds

as well as (E2, E6)-nonadienal (cucumber), 1-octen-3

one (field mushroom), (Z5)-octadien-3-one (geranium

leaves), (E3, E5)-undecatriene (blasamic), and (E3, Z5

Z8)-undecatetraene (seaweed). Depending on th

degree of unsaturation and the regioselectivity of th

lipoxygenase, different hydroperoxy compounds ar

formed, from which the above-mentioned compound

can be derived by subsequent enzymatic reactions. Fo

(Z3)-hexenol, linolenic acid is used as a substrate, whil

for most of the other aldehydes/alcohols higher unsa

turated fatty acids are required. The production o(Z3)-hexenol has recently been commercialized usin

plant homogenates (e.g., alfalfa sprouts, green pep

pers) which are relatively rich in hydroperoxide lyase

the enzyme required to split the hydroperoxide fatt

acid into smaller fragments. The generated (Z3)-hexe

nal was converted into (Z3)-hexenol using the reduc

tive enzymatic power of bakers yeast (13). A ver

elegant approach has been taken recently b

Givaudan-Roure. To unify all three enzymes involved

in the formation of (Z3)-hexenol, they have cloned and

overexpressed both soybean LOX and the hydroper

oxide lyase from banana in bakers yeast. In this waythey have developed a single-step process which pro

duces (Z3)-hexenol in relatively high yield (14).

For the production of lactones a different strategy

has to be followed after the formation of the linolei

acid hydroperoxide. It involves the fermentative -oxi

dation of the hydroperoxide intermediate by the yeas

Pichia etchellsii, and the subsequent cyclization of 5

hydroxydecanoic acid to the corresponding S(-)--dec

alactone (10).

As shown by Quest International (1), lipoxygenase

also accept a relatively broad spectrum of phenoli

compounds as substrates. Of interest to the flavoindustry are the LOX-catalyzed conversions of isoeu

genol and coniferyl benzoate from Siam resin int

vanillin. At present the commercialization of these bio

transformations is hampered by the fact that isoeu

genol is not readily available and that conifery

benzoate is difficult to handle in a reactor.

Other well-known reactions of LOX include the co

oxidation reaction of carotenoids to yield, amon

http://dk1908_ch43.pdf/http://dk1908_ch43.pdf/

8/3/2019 DK1908_CH13

4/13

others, -ionone (2, 15). More recently is the genera-

tion of a toasted or cookie-like flavor in starchy mate-

rials by a combination of LOX and an -amylase (16).

B. Alcohol Oxidases and Dehydrogenases

In general, aldehydes are more potent flavor com-pounds than their alcoholic counterparts. Hence, alco-

hol oxidases are interesting enzymes for the in vitro

production of flavoring preparations which, among

others, can be applied in beverages. Typical examples

include the use of methanol oxidase from Pichia,

Hansenula, and Candida (17) for the production of

natural acetaldehyde from ethanol. This enzyme is

induced during growth on methanol. At the end of

the logarithmic growth phase cells are harvested and

incubated with ethanol. In this way concentrations of

$ 1:5% natural acetaldehyde can be achieved, which

can be concentrated further to the desired applicationlevel. From yeast to yeast the substrate specificity of

the alcohol oxidase is different. Hence, this procedure

can also be used to convert other alcohols, such as

hexenol and other long-chain alcohols, to their corre-

sponding aldehyde (10, 18).

As alternatives to alcohol oxidases the correspond-

ing dehydrogenases could in principle be used (19). A

severe drawback, however, is that these dehydro-

genases require the expensive cofactor NAD(P)

instead of (cheap) oxygen as an electron acceptor.

Although various sophisticated NAD(P) cofactor

regenerating systems have been designed and substan-tial cost reductions have been realized in this way, it is

evident that in commercial applications oxidases are

preferred over their dehydrogenase counterparts. The

use of dehydrogenases for food purposes seems to be

restricted to whole-cell conversions.

Vanillyl alcohol oxidase (VAO) from Penicillium

simplicissimum is a special type of alcohol oxidase.

Recently, it has been shown that this stable, flavin-

containing enzyme has a very broad substrate specifi-

city and readily converts para-substituted phenols into

interesting flavor precursors or flavoring compounds

(2022). Apart from natural vanillin and coniferylalcohol, different vinylphenols (e.g., para-vinylguaia-

col) and allylphenols can be produced from cheap

raw materials and oxygen as an electron acceptor.

VAO can also be used for generation of flavor building

blocks. To that end a natural mix of phenolic com-

pounds could be treated with VAO to enrich foods

or flavor preparations with a range of vinylic/allylic

and aldehydic substances.

C. Sulfhydryl Oxidases

Sulfhydryl oxidase (SOX, no EC number assigned

Chapter 41 for more details) catalyzes the formatio

disulfide bonds from (protein) thiols. SOX is an Fe

containing glycoprotein and has been detected

bovine, human, goat, pig, rabbit, and rat milks (

The enzyme is capable of oxidizing the sulfhygroups of cysteine and glutathione, as well as milk

teins to their corresponding disulfides using molec

oxygen as electron acceptor (24). In practical app

tions bovine milk SOX may be added to UHT mi

reduce cooked flavors. Patents (see Refs. in 24) for

application have been issued. The enzyme has

immobilized on porous glass, and its effectivene

ameliorating the cooked flavor has been demonstr

on a pilot scale using immobilized enzyme column

D. Peroxidases

Peroxidases (POX, EC 1.11.1.7; see Chapters 28 an

for more details) occur widely in nature and is

general name for a group of both highly specific

nonspecific enzymes which use hydrogen pero

instead of oxygen as an electron accep

Peroxidases, especially the heme-containing ones,

catalyze a large number of different reactions inclu

sulfoxidation, N-demethylation, oxidation, and hy

xylation and hence are of potential interest in the

duction of specific flavoring topnotes. A re

example involves the demethylation of methy

methylanthranilate (ex Citrus) to monomethylantnilate (25). The latter compound is an important

note flavor in Concord grapes. Soybean, horserad

and microperoxidases were found to be convenient

alysts for this reaction. In addition POX gives rise

fresh flavor profile when added to tomato paste (2

E. Polyphenol Oxidases

Polyphenol oxidases (PPO) are a group of sev

enzymes. Different activities can be found within

group: tyrosinase (monophenol monooxygenase,

1.14.18.1; see Chapter 39) converting a phenol incatechol group; 1,2-diphenol oxidase or catechol

dase (EC 1.10.3.1) converting catechol into an o-

none, and laccase (EC 1.10.3.2; see Chapter

converting a 1,4-diphenol into p-quinone. Usually

first two activities are linked, as catechol is much m

readily oxidized than a phenol. Most enzymes

catalyze 1,4-diphenol oxidation also act on 1,2-di

nols.

http://dk1908_ch41.pdf/http://dk1908_ch28.pdf/http://dk1908_ch39.pdf/http://dk1908_ch40.pdf/http://dk1908_ch40.pdf/http://dk1908_ch39.pdf/http://dk1908_ch28.pdf/http://dk1908_ch41.pdf/

8/3/2019 DK1908_CH13

5/13

The bitter taste in many food products is often the

result of the presence of polyphenolic compounds such

as guaiacols. PPOs are capable of oxidizing these com-

pounds and hence can be applied to reduce bitterness.

At present the debittering of coffee beans (27), Adzuki

beans (28), and cacao beans (29) by PPOs have been

claimed. Another application involves the use of laccase

to debittering olives by treating stoned, chopped olivesin the presence of air at increased temperatures (30).

III. TEXTURE

The use of oxidoreductases in texturizing food is based

on their ability to crosslink proteins and/or polysac-

charides. This property is of particular interest to

improve the texture of dough and paste products (soft-

ness, volume, elasticity, crunchiness) or dairy products

(mouth feel, appearance), and of fish and meat pastes.

Basically, enzymatic crosslinking can occur via tworoutes:

1. Indirect via enzymatically produced hydrogen

peroxide (e.g., glucose oxidase, hexose oxidase, ascor-

bic acid oxidase), or via the enzymatic production of

radicals (e.g., peroxidase, lipoxygenase).

2. Direct via the oxidation of functional groups in

the protein. Examples include the linkage of tyrosine

and ferulic acid residues by tyrosinase and laccases,

linkages of lysine residues by lysyl oxidase, or the for-

mation of disulfide bridges by sulfhydryl oxidase.

An alternative, nonredox procedure for direct cross-

linking is being explored using transglutaminases (seeChapter 51).

These enzymatic routes are being explored to re-

place chemical oxidizers, such as dehydroascorbic

acid and potassium bromate. Replacement of the non-

specific chemical compounds by redox enzymes could

have the benefit of more specific and better-controlled

oxidation processes. Other disadvantages of the chemi-

cal substances are related to safety and labeling issues.

One of the major challenges in the baking industry is to

find a good replacer for potassium bromate, which is a

difficult task since bromate is still more effective and

cheaper than the enzymatic alternative. The mostimportant texturizing redox enzymes will be discussed

below.

A. Lipoxygenases

A rich source of LOX is soybeans. Soybean LOX con-

tains three distinct lipoxygenase isoenzymes, desig-

nated as L1, L2, and L3. These isoenzymes have

been isolated from seeds of commercial cultivars and

have been well characterized (31, 32). Recent studie

indicate that L2 has the greatest effect among LOX

isoenzymes on dough extensibility and strength (33

and is also mostly responsible for the production o

undesirable aroma compounds in bread doughs (34

see Sec. II, Chapter 43). For L3 an increase in foamin

activity has been reported, as well as an overaimprovement in breadmaking quality of wheat flou

(35). The bakery yeast Saccharomyces cerevisiae also

contains LOX. Recently, this enzyme was partiall

purified (36), but its potential, if any, on breadmakin

remains to be established.

Nowadays, it is feasible to change the profile and

content of LOX (iso)enzymes in plants either by clas

sical means (5), or potentially by genetic modification

For example, by appropriate crosses, near-isogeni

soybean seeds have been developed that lack eithe

isoenzymes L1 and L3, or isoenzymes L2 and L3

These LOX-minus mutants still grow well in the field(37). In principle, transgenic plants lacking or overex

pressing one or more LOX isoenzymes could be con

structed and tailored to specific applications (38). To

that end the heterologous expression of one or more

soybean LOX isoenzymes in wheat could be of interest

B. Sulfhydryl Oxidases

The action of SOX (see Sec. II, Chapter 41, for genera

information) may be the same as those of chemica

oxidizing agents, provided the formation of disulfid

bonds is the primary mode by which these agents function. In extensive testing (39, 40) it was found tha

SOX alone has no influence on loaf volume, doug

strength, or mixing tolerance. Also, relatively high con

centrations using recombinant SOX from Aspergillu

awamori did not have any significant positive effec

(40). One reason could be that SOX has only a limited

affinity for thiol groups in gluten proteins and as

result its application in the food industry seems to b

limited to the removal of small off-flavor molecule

(see Sec. II, Chapter 41).

C. Peroxidases

For detailed information about POX see Section II

Chapters 28 and 29. Wheat flour contains a peroxidas

that can crosslink phenolic constituents such as feruli

acid and vanillic acid. However, the pH optimum o

the wheat enzyme is 4.5, and in the pH range of 56 o

wheat doughs the activity is considerably lower than a

pH 4.5 (41). Although the dough-improving effect o

http://dk1908_c051.pdf/http://dk1908_ch43.pdf/http://dk1908_ch41.pdf/http://dk1908_ch41.pdf/http://dk1908_ch28.pdf/http://dk1908_ch29.pdf/http://dk1908_ch29.pdf/http://dk1908_ch28.pdf/http://dk1908_ch41.pdf/http://dk1908_ch41.pdf/http://dk1908_ch43.pdf/http://dk1908_c051.pdf/

8/3/2019 DK1908_CH13

6/13

peroxidase is well documented, the reactions involved

in the dough are only poorly understood.

Model studies with peroxidase, glutathione, and

cysteine indicate that sulfhydryl and/or lysyl groups

may be involved (42). Peroxidase-catalyzed reactions

result in a decreased amount of lysine recovered from

proteins after acid hydrolysis. Peroxidases, or the qui-

nones formed by the enzyme, oxidatively deaminatelysyl residues to form lysylaldehydes, resulting in the

formation of protein polymers, as was revealed by gel

filtration. These aggregates could not be dissociated by

detergents, which indicates that covalent bonds were

formed. In addition, the dough-strengthening effect of

peroxidases is also ascribed to the crosslinking of car-

bohydrates and the coupling of carbohydrates to pro-

teins. The gelation of wheat pentosans is due to the

oxidative dimerization of ferulic acid moieties, which

are covalently linked to pentosans (43).

Recently, a study has been described showing the

effect of different peroxidases on the baking perfor-mance of German Kaiser rolls (41). Deliberately

sticky doughs were prepared in order to demonstrate

the effects of added peroxidases. Especially the addi-

tion of soybean POX led to strengthening of wheat

doughs as determined by the stability of the dough

after shaking the dough for 1 min in a laboratory

shaker. This improving effect was observed at both

short and long fermentation times. Dough volume

increased after application of these peroxidases.

Compared with (GOX), the results of peroxidases are

better or at least equal in terms of stability and volume.

In bread dough, peroxidases seem to act without theextra addition of hydrogen peroxide in spite of their

peroxide dependence. This may indicate that peroxide

is present in dough at sufficient amounts, or that it is

generated as a result of the peroxidase reaction. In this

way, substrate radicals formed by peroxidase can react

with oxygen to form hydrogen peroxide. When this

reaction is occurring, catalytic amounts of peroxide

present in dough are sufficient to get the cycle started,

and may explain why no hydrogen peroxide has to be

added together with a peroxidase. An alternative

explanation is that wheat contains endogenous oxi-

dases, which are active enough to produce some hydro-gen peroxide in situ. Indeed, the addition of hydrogen

peroxideproducing enzymes such as GOX has a ben-

eficial effect on baking (4446).

In other systems than doughs, POX has been

claimed as a thickening and stabilizing agent in, for

example, ice creams, deserts, sauces, and jams and jel-

lies (47). There is also a recent patent application (48)

on the POX-catalyzed gelling of hemicelluloses to form

gels or viscous media for application as fat or gel

replacer, as well as for flavor delivery, coating, or g

ing.

D. Glucose Oxidases

Glucose oxidase (GOX, EC 1.1.3.4; see Chapter 30

detailed information) catalyzes the conversion of cose into the mild-tasting gluconic acid via glucon

lactone and hydrogen peroxide. GOX complies

the FAO/WHO and GRAS requirements for

grade enzymes and is one of the few commerc

available oxidases from Aspergillus niger

Penicillium strains at relatively low costs. Especi

the generation of hydrogen peroxide is believe

give the antiweakening effect in bread doughs

In a recent study by Hilhorst et al. (49) the effec

GOX on Dutch rusk dough was dough stiffening

a clear loss in extensibility. This made the overall e

quite undesirable. For comparison, they also teperoxidase (see Sec. III.C above). This enzyme ga

dough-stiffening effect without loss in extensib

The authors explain the difference by the fact

hydrogen peroxide from the GOX-catalyzed reac

oxidizes randomly and links the gluten network

the arabinoxylan network, whereas the peroxidase

increases the amount of crosslinks in the arabinox

fraction without affecting the gluten network or

coupling between the networks.

It has been found that synergistic effects occur w

using a combination of oxidative enzymes like

combination of GOX and SOX (50). Furthermthe dough has an increased stability.

E. Hexose Oxidases

A newcomer in the field of redox enzymes for ba

products is hexose oxidase (HOX, EC 1.1.3.5) from

seaweeds. This glycosylated flavoprotein is relate

GOX but has a broader substrate specificity tow

hexose sugars, including oligomers. Like GOX

acts on the C1-position of the sugar moiety

Recently, the enzyme from Chondrus crispus has isolated, cloned, and overexpressed in several reco

nant organisms such as Pichia pastoris, Saccharom

cerevisiae, and E. coli (51, 52). However, the pro

tion levels of active enzyme are still poor at

moment and have to be improved. For this rea

and because C. crispus has a long standing tradi

as an edible organism, efforts have been mad

develop a large-scale production method with the


8/3/2019 DK1908_CH13

7/13

of carrageenase, which reduces the viscosity of the

crude extract (51).

For HOX similar applications can be envisaged as

for GOX (see above). In particular, its application in

bakery products is foreseen (53), since HOX is able to

generate more H2O2 owing to its broader substrate

specificity, and hence should be more effective than

GOX in dough strengthening. Likewise, combinationsof HOX and H2O2-consuming enzymes, such as POX,

may be envisaged.

Another enzyme with similar properties as HOX,

isolated from Acremonium strictum T1, has been

reported in the literature (54). The enzyme is called

an oligosaccharide oxidase and is able to oxidize sev-

eral di- and oligosaccharides at the anomeric site,

yielding the corresponding di- and oligobionic acids.

A detailed comparison between HOX and oligosac-

charide oxidase performance in dough applications

has not been made yet.

F. Pyranose Oxidases

Pyranose oxidase (PYROX, EC 1.1.3.10; see Refs.

5557, 59 for more detailed information) catalyzes

the oxidation of several monosaccharides at the C2-

position and is therefore different from GOX, which

oxidizes glucose at the C1-position. While GOX is very

specific, PYROX is able to catalyze other substrates

such as maltose and pentoses (e.g., xylose). As a result,

the PYROX oxidation product of glucose is 2-keto-

glucose and not gluconic acid. At present, this enzyme

has been purified from several white rot fungi and aBacidiomycetous fungus (5557). PYROX has also

been reported to show significant activity toward D-

glucono-1,5-lactone, which is produced by the GOX-

catalyzed oxidation of glucose (58). So if PYROX is

combined with GOX, there will be more substrate

available for PYROX, thereby prolonging the activity

of PYROX and enhancing the total amount of hydro-

gen peroxide produced (59). The claimed effects in

baking are gluten strengthening, reduced dough sticki-

ness, and increased volume and crumb structure for

bread (59).

IV. APPEARANCE/COLOR

Apart from texture, the appearance of food products is

determined to a large extent by their color. Several

redox enzymes are known to influence the color of

foodstuffs. The most important ones will be discussed

below.

A. Lipoxygenases

It is interesting to note that the use of soybean lipox

ygenase was described in the 1930s as a means t

bleach the flour in preparation of white bread. Mor

recent experiments have shown that carotenoids pre

sent in wheat flour are destroyed by co-oxidation

Wheat flour itself contains little LOX activity, buLOX is abundantly present in, for example, soybeans

To that end wheat flour is often fortified with up to

0.5% enzyme-active soy flour (34, 60). Other applica

tions of LOX include the bleaching of noodles, whey

products, rice, and wheat bran (6164).

B. (Poly)phenol Oxidases and Peroxidases

PPOs (see Sec. II, Chapter 39 for general information

play an important role in the browning of fresh fruit

and vegetables (65, 66), in the coloring and flavoring o

tea (67, 68), and in improving the quality of coffee (69)A major concern in the food industry is to preven

the development of enzymatic browning prior to th

processing of fruits and vegetables (70). This is accom

plished by removing oxygen or by inhibiting PPO

activity using inhibitors such as metal chelating agents

inorganic ions (e.g., halide anions), benzoic acid and

some substituted cinnamic acids, reducing agents (e.g

L-cysteine, glutathione, sulfite, SO2, ascorbic acid)

small natural peptides, and combinations thereo

(68). In contrast, during the fermentation of black

tea PPO is used to initiate browning by oxidation o

polyphenolic substances such as catechins to theaflavins.

The quality of tea, based on sensory evaluation o

color and bitterness, has been correlated with tota

theaflavin content (71). Theaflavins, thearubigins, and

caffeine are all essential ingredients in high-qualit

teas. The addition of microbial laccases and/or perox

idases to green tea has shown that no higher theaflavin

levels can be obtained than with endogenous PPO

Addition of exogenous laccase/peroxidase to black

tea, however, did yield a very significant increase in

the color intensity of the tea (72).

Polyphenol oxidases also play an important role incoffee processing (69). The activity of PPO in green

coffee beans has been consistently related to the qualit

of the coffee beverage. The exact role of PPO in coco

beans is less well understood. There are, however, indi

cations that it plays a role in browning during th

curing of the cocoa beans (73).

In cereals, PPO is responsible for the darkening o

the breadcrumb, particularly in whole-grain and ry


8/3/2019 DK1908_CH13

8/13

breads. The rate of browning is greatest in sourdough

baking. Excessive discoloration can be prevented by

the addition of sodium metabisulfite or ascorbic acid

(41). Exogenous PPO is also reported to have a posi-

tive influence on the rheological properties of bread

(74).

PPO can also be used for the in vitro production of

colors. For example, Pruidze (75) reported the produc-tion of a whole range of natural colors by treating

waste streams of beet and tea with PPO.

Furthermore, it was claimed that safflower pigments

become darker red when safflower petals were sprayed

with a dilute laccase solution (76).

The role of endogenous POX in (dis)coloration is

not fully understood. It seems that the oxidative role of

peroxidases is useful in assisting PPOs in oxidizing the

polyphenols and ultimately contributing toward the

color and flavor of tea. The same seems to be true

for coffee and cocoa.

C. Ascorbic Acid Oxidases

Ascorbic acid oxidase (E.C.1.10.3.3; see Ref. 77 for

detailed information) plays a role in beverages such

as lemon and grapefruit juices, where it is responsible

for the initiation of browning and loss of vitamin C

activity during storage (77). The extent of browning

can be minimized by steam blanching or by the exclu-

sion of oxygen. The rate of ascorbic acid oxidation

increases markedly in the presence of metallic ions,

especially copper and iron. Hence, food processed in

tin cans and processing equipment should be copperfree. While the loss of ascorbic acid cannot be pre-

vented completely, it can be reduced to a minimal

level during processing.

V. SHELF LIFE

The application of redox enzymes for improving the

shelf life of food products includes mainly enzymes

which are capable of removing oxygen or reactive oxy-

gen species (e.g., H2O2 and superoxide anion), as well

as enzymes that are able to generate antimicrobialagents. In this way the stability of foods can be

increased significantly with respect to taste, appear-

ance, and microbial spoilage.

A. Lactoperoxidases

Lactoperoxidase (LPO; see Ref. 78 and Chapters 19

and 20 for detailed information) is the most prominent

enzyme in bovine milk, where it is found in concen

tions around 30 mg/L. It is a glycoprotein with a sin

covalently bound heme group (78). Lactoperoxi

requires hydrogen peroxide and thiocyanate (SC

for antibacterial activity. All three components

referred to as the LP system. The growth inhibi

effect of the LP system is mediated by the genera

of SCN

oxidation products, mainly hypothiocyaions (OSCN), which attack sulfhydryl groups of

metabolic enzymes of the microorgani

Mammalian cells are not affected by the LP sys

Only 1020 ppm of lactoperoxidase is required fo

effective system. The cofactor requirements are

very low: 1025 ppm for thiocyanate and 1015

for H2O2. Without the enzyme H2O2 is also bacte

dal, but at much higher concentrations: 300900

(79). Therefore LPO is often applied in combina

with H2O2-generating enzymes. From a toxicolog

point of view, the levels of the cofactors in the

system as well as the oxidation products are repoto be harmless.

The envisaged applications of the LP system

food products (e.g., liquid milk, cheese, meat,

and poultry products, and functional foods),

and veterinarian products (e.g., milk replacers,

antidiarrhea and antimastitis preparations), and de

products (7880). Typically, applications have

claimed for Lactobacillus fermented milk prod

(81), pickled foods (82), fish products (LPO in com

nation with GOX; 83), and white mold cheeses suc

Camembert (84). Also of interest is the effect of L

on yogurt. By adding LPO to yogurt the excessive production of lactic acid bacteria in the yogurt is

pressed (85). These applications are becoming wi

reach now that it is possible to isolate lactoperoxi

from milk with high purity on an industrial scale

Currently, LPO is already commercially availab

relatively low costs.

B. Xanthine Oxidases

Xanthine oxidase (XO, EC 1.2.3.2; see Chapter

and 42 for detailed information) is widely distrib

in animals, plants, and microorganisms. It catathe oxidation of hypoxanthine to xanthine

xanthine into uric acid. In addition XO is able to

dize a wide range of purines, aldehydes, and pterid

with concomitant reduction of O2 to H2O2. U

certain conditions XO also produces the highly r

tive superoxide anion. Bovine milk is very rich in

($ 35mg=L; 86). XO has been implicated in the ox

tive deterioration of milk and dairy products via

http://dk1908_ch19.pdf/http://dk1908_ch20.pdf/http://dk1908_ch19.pdf/http://dk1908_ch42.pdf/http://dk1908_ch42.pdf/http://dk1908_ch19.pdf/http://dk1908_ch20.pdf/http://dk1908_ch19.pdf/

8/3/2019 DK1908_CH13

9/13

production of superoxide anion during oxidation of its

substrates (87). However, Bruder et al. (88) found no

evidence to support a role for native bovine milk XO in

lipid oxidation. The results of Weihrauch (89) seem to

indicate that in the presence of purines, XO activity

generates H2O2 for the lactoperoxidase system in

milk, making it a bactericidal or bacteriostatic agent

in milk (23).

C. Superoxide Dismutases and Catalases

Superoxide dismutase (SOD; EC 1.15.1.1) and catalase

(EC 1.11.1.6; see Chapters 27 and 38 for detailed infor-

mation) are present in milk and are able to remove

reactive oxygen species generated by other (bio)chem-

ical processes (90). SOD catalyzes the reduction of

superoxide anion, as produced, for example, by XO,

to H2O2 and O2. In turn, catalase is able to neutralize

H2O2 to water and oxygen. A low level of exogenousSOD, coupled with catalase, is a very effective antiox-

idant in dairy products (91).

Recently, SOD has been shown to protect beer

against free radical damage (92). Obviously, the

commercial feasibility of SOD as an antioxidant

depends on cost, particularly compared to chemical

antioxidants, if permitted. As far as is known, SOD is

not used commercially as an antioxidant in food

systems.

Catalase is used for the cold-sterilization of milk in

regions lacking refrigeration and could in principle be

applied in developed countries for the treatment ofcheese milk (90). Good sources for catalase are beef,

liver, Aspergillus niger, and sweet potato. There is

also interest in using immobilized catalase reactors

for milk pasteurization or for glucose oxidasecata-

lase reactions (93). Besides the removal of reactive

oxygen species by SOD and catalase, other enzymes

can be applied to remove the less but still reactive

oxygen. Typical examples include glucose oxidase,

D-amino acid oxidase, alcohol oxidase, and ascorbic

acid oxidase. The disadvantage of these oxidases is

that they produce H2O2, which by itself is a powerful

oxidant. Catalase can be added to remove H2O2, butthen oxygen is produced again. More recently, poly-

phenol oxidases such as laccase have been proposed

as a deoxygenation tool for beer (94) and juices (95,

96). These enzymes have the advantage that they do

not produce H2O2, and thus the combination with

catalase is not necessary. As a result PPOs allow a

more efficient oxygen removal.

VI. NUTRITIONAL VALUE

Redox enzymes can have both pro- as well as antinu

tritional effects. For example, lipoxygenase, apart from

all its other functions in food products (see Table 1), i

involved in the oxidative destruction of liposolubl

vitamins (provitamin A) and essential fatty acids (3)

Likewise, ascorbic acid oxidase has an antinutritionaeffect since it oxidizes vitamin C (97).

Increasingly, redox enzymes are being claimed t

improve the healthiness of especially beverages

For example, peroxidase and catalase have been

claimed for the removal of unhealthy hydrogen per

oxide in coffee and tea (98). Other examples includ

the use of cholesterol oxidase, epicholesterol dehydro

genase and cholesterol reductase to lower the choles

terol level in foods such as meat, fish, milk, and egg

products (99101).

VII. CONCLUDING REMARKS

Compared to the usage of hydrolytic enzymes such a

proteases, carbohydrates, and lipases, the application

of oxidoreductases as a tool to improve the processa

bility and quality of food products is still in its infancy

Like hydrolytic enzymes, oxidoreductases are capabl

of tailoring the taste, texture, appearance, shelf life

nutritional value, and process tolerance of foods and

the properties of all major food constituents (e.g., pro

teins, carbohydrates, oils, fats, flavors; see Table 1). In

both cases, they can exert a positive as well as a negative effect on the food quality parameters, which can

be reduced or eliminated by careful selection of the raw

materials, by properly controlling the process condi

tion, by the addition of counteracting ingredients

and by genetic tools. Likewise, hydrolytic and redox

active enzymes often have more than one effect. A

typical redox example is the multifunctional enzym

lipoxygenase, which can be applied to influence eithe

taste, texture, appearance, and/or nutritional value o

food products. The key difference resides in the type

of reactions they catalyze. As a result, redox enzyme

can be combined with hydrolytic enzymes in a varietyof food products to create improved or even new func

tionalities, which cannot be realized by either one o

them.

At present, major bottlenecks for the large-scal

application of oxidoreductases include their limited

availability, their safety status (not GRAS), their sta

bility, and the fact that they often initiate radical reac

http://dk1908_ch27.pdf/http://dk1908_ch38.pdf/http://dk1908_ch38.pdf/http://dk1908_ch27.pdf/

8/3/2019 DK1908_CH13

10/13

tions, which propagate via redox-active food constitu-

ents such as metal ions and quinones and hence are

difficult to control. In addition, many oxidoreductases

require expensive cofactors for catalysis. Despite these

disadvantages over hydrolytic enzymes, certain oxidor-

eductases are increasingly finding a home in food pro-

cessing. The first generation (see Table 1) includes

enzymes which are cofactor independent and thriveon oxygen (e.g., oxidases) and hydrogen peroxide

(e.g., peroxidases). Owing to advances in recombinant

DNA technology the low-cost, large-scale production

of these enzymes in GRAS host microorganisms is

becoming within reach, and the tools are ready to tai-

lor redox enzymes to specific needs by site-directed

mutagenesis and directed evolution. Also feasible will

be the in planta overexpression of desired redox

enzymes in food raw materials and the deletion of

undesirable redox traits. The usage of cofactor-depen-

dent oxidative enzymes seems tentatively to be con-

fined to whole-cell systems, in which the cofactor canbe regenerated, and hence to the in vitro as well as the

in situ production of functional food ingredients such

as flavors. The same seems to be true for reductases,

since most if not all require reducing equivalents in the

form of a small protein, hydrogen, and/or NAD(P)H.

Clearly, the usage of oxidoreductases in food pro-

cessing is emerging. The benefits and limitations are

becoming known, which allows a promising and

focused search for new opportunities.

REFERENCES

1. PA Markus, ALJ Peters, R Roos. Enzymatic process

for preparation of phenylacetaldehyde compounds

especially vanillin by conversion of starting com-

pounds in the presence of lipoxidase. Patent

EP542348, 1991.

2. D Waldman, P Schreier. Stereochemical studies of

epoxides formed by lipoxygenase-catalyzed co-oxida-

tion of retinol, beta-ionone and 4-hydroxy-beta-

ionone. J Agric Food Chem 43:626630, 1995.

3. M Martnez-Anaya. Enzymes and bread flavor. J

Agric Food Chem 44:24692480, 1996.4. J Crouzet, M Nicolas, J Molina, G Valentin. Enzymes

occurring in the formation of 6-carbon aldehydes and

alcohols in grapes. In: J Adda, ed. Progress in Flavour

Research. Amsterdam: Elsevier Science Publishers,

1985, pp 401408.

5. DS Robinson, Z Wu, C Domoney, R Casey.

Lipoxygenases and the quality of foods. Food Chem

54:3343, 1995.

6. TE Mathiasen. Improving the storage stability of

by fermenting wort into beer and adding a lacca

the fermented beer. Patent WO9521240.

7. RL Antrim, JB Taylor. Deodorization of a wate

oil emulsion containing fish oil using pure alcoho

aldehyde oxidases/dehydrogenase in combina

with a cofactor. Patent US4961939, 1990.

8. Y Nomura, N Shiomi. Production of a powd

acidic acid bacteria that produce aldehyde oxiPatent JP10108671, 1998.

9. IM Whitehead, BL Muller, C Dean. Industrial u

soybean lipoxygenase for the production of na

green note flavour compounds. Cereal Foods W

40:193197, 1995.

10. C Laane, I Rietjens, H Haaker, W van Be

Generation of taste through (redox) biocatalysi

KAD Swift, ed. Flavours and Fragra

Proceedings of the 1997 RSC/SCI Internat

Conference on Flavours and Fragrances, R

Society of Chemistry, Special Publication No.

1197, pp 137152.

11. JC Villettaz, D Dubourdieu. Enzymes in winemaIn: PE Fox, ed. Food Enzymology, Vol 1. Lon

Elsevier Science Publishers, 1991, pp 427454.

12. PSJ Cheetham. The use of biotransformations fo

production of flavours and fragrances. Tib

11:478488, 1993.

13. P Brunerie (Pernod Ricard). Synthesis ofcis-3-hex

from unsaturated aliphatic acidusing comb

action of natural enzyme system and yeast. P

EP481147, 1991.

14. A Muheim, A Ha usler, B Schilling, K Lerch.

impact of recombinant DNA-technology on th

vour and fragrance industry. In: KAD Swift

Flavours and Fragrances. Proceedings of the RSC/SCI International Conference on Flavours

Fragrances, Royal Society of Chemists, Sp

Publication No. 214, 1997, pp 1120.

15. M Jaren-Galan, MI Minquez-Mosquera. Beta-

tene and capsanthin co-oxidation by lipoxyge

kinetic and thermodynamic aspects of the reacti

Agric Food Chem 45:48144820, 1997.

16. JJ Desjardins, P Duby, P Dupart, RD Woo

Zurcher. Producing of starchy material with -

lase and lipoxygenase to produce a toasted or co

like flavor. Patent EP772980, 1997.

17. H Stam, M Hoogland, C Laane. Food flavours

yeast. In: BJB Wood, ed. Microbiology of FermeFoods, 2nd ed, part 2. London: Chapman and

1998, pp 505543.

18. WD Murray, SJB Duff. Bio-oxidation of aliphatic

aromatic high molecular weight alcohols by P

pastoris alcohol oxidase. Appl Microbiol Biotec

33:202205, 1990.

19. IEM Deutz, LC Fraysse, HTWM van der Hi

Manipulation of the aroma profile of tomato


8/3/2019 DK1908_CH13

11/13

ductscomprises adding alcohol dehydrogenase and

a cofactor, electron donor or electron acceptor to

tomato pieces. Patent WO9857533A1, 1998.

20. WJH van Berkel, MW Fraaije, E de Jong. Process of

producing 4-hydroxycinnamyl alcohols. Patent

EP0710289B1, 1997.

21. HH van den Heuvel, MW Fraaije, C Laane, WJH van

Berkel. Regio- and stereospecific conversion of 4-

alkylphenols by the covalent flavoprotein vanillyl-alcohol oxidase. J Bacteriol 180:56465651, 1998.

22. A Mattevi, MW Fraaije, A Mozzarelli, L Olivi, A

Coda, WJH van Berkel. Crystal structure and inhibi-

tor binding in the octameric flavoenzyme vanillyl-

alcohol oxidase. Structure 5:907920, 1997.

23. NY Farkye. Indigenous enzymes in milk: other

enzymes. In: PF Fox, ed. Food Enzymology, Vol 1.

New York: Elsevier Science Publishers, 1991, pp 107

130.

24. VG Janolino, HE Swaisgood. Isolation and character-

ization of sulfhydryl oxidase from bovine milk. J Biol

Chem 250:25322538, 1975.

25. MJH van Haandel, FCE Sarabe` r, MG Boersma, CLaane, Y Fleming, H Weenen, IMCM Rietjens.

Characterization of different commercial soybean per-

oxidase preparations and use of the enzyme for N-

demethylation of methyl-N-methylanthranilate to

produce the food flavor methylanthranilate. J Agric

Food Chem 48:19491954, 2000.

26. P Wilding, EM Woolner. Treatment of tomato with

peroxidase to achieve a fresh flavour profile. Patent

WO9738591, 1997.

27. LE Small, TN Asquith. Process for treating coffee

beans with enzyme-containing solution under pressure

to reduce bitterness. Patent EP337541, 1989.

28. S Okazawa, M Hashimoto, Y Hatsutori. Treatmentof adzuki bean with enzymes. Patent JP05244889,

1993.

29. T Takemori, Y Ito, M Ito, M Yoshama. Flavor and

taste improvement of cacao nib by enzymatic treat-

ment. Patent JP04126037, 1992.

30. NOVO Nordisk. Debittering and darkening of olives

by laccase treatment. Research Enclosure No. 37828,

1995, p 676.

31. JJ Rackis, DJ Sessa, DH Honig. Lipoxygenase and

peroxidase activities of soybeans as related to the fla-

vor profile during maturation. J Am Oil Chem 56:262

271, 1979.

32. B Axelrod, TM Cheesbrough, S Laakso.Lipoxygenases in soybean. Methods Enzymol

71:441451, 1981.

33. B Cumbee, DF Hildebrand, K Addo. Soybean flour

lipoxygenase isoenzymes effects on wheat flour dough

rheological and breadmaking properties. J Food Sci

62:281283, 294, 1997.

34. K Addo, D Burton, MR Stuart, HR Burton, DF

Hildebrand. Soybean flour lipoxygenase isoenzyme

mutant effects on bread dough volatiles. J Food Sc

58:583585, 608, 1993.

35. K Shiiba, Y Negishi, K Okada, S Nagao. Purificatio

and characterization of lipoxygenase isoenzymes from

wheat germ. Cereal Chem 68:115122, 1991.

36. B Bisakowski, S Kermasha, C Schuepp. Partia

purification and some properties of lipoxygenas

from Saccharomyces cerevisiae. World J Micro

Biotechnol 11:494496, 1995.37. TW Pfeiffer, DF Hildebrand, DM TeKrony

Agronomic performance of soybean lipoxygenase iso

lines. Crop Sci 32:357362, 1992.

38. D Shibata. Peroxidation of plant lipids and gen

manipulation of plant lipoxygenases. J Am O

Chem Soc 41:741744, 1992.

39. SP Kaufman, O Fennema. Evaluation of sulfhydry

oxidase as a strengthening agent for wheat flou

dough. Cereal Chem 64:172176, 1987.

40. J Maat, W Musters, H Stam, PJ Schaap, PJ van de

Vonderwoort, J Visser, JM Verbakel. Cloning an

expression of DNA encoding of ripening form of

polypeptide having sulfhydryl oxidase activityPatent EP565172, 1993.

41. M van Oort. Oxidases in baking. Int Food Ingredient

4:4247, 1996.

42. G Matheis, JR Whitaker. Peroxidase catalyzed cross

linking of proteins. J Protein Chem 3:3548, 1987.

43. T Geissmann, H Neukom. Comparison of the water

soluble wheat flour pentosans and their oxidative gela

tion. Lebensm Wiss Techn 6:5962, 1973.

44. J Maat, M Roza. Novel formulation in combinatio

with cellulase for structure, volume, appearanc

improvement of bread. Patent CA2012723, 1990.

45. M Roza, GHE Pieters. Bread-improving storag

stable enzyme solutions. Patent EP669082, 1995.46. PM Nielsen, P Wagner. Bread- or dough-improvin

composition. Patent WO9800029, 1998.

47. G Budolfsen, HP Heldt-Hansen. Oxidase promote

gelling of phenolic polymers. Patent WO9603440

1994.

48. CS Fitchett. Production of vegetable gels. Paten

WO9822513, 1997.

49. R Hilhorst, H Gruppen, R Orsel, C Laane, HA

Schols, AGJ Voragen. On the mechanism of actio

of peroxidase in wheat dough. Proceeding

Oxidation in Foods, Viborg, Denmark, p 2729.

50. F van Welie, B Poldermans. Enzymen gaan broodver

beteraars domineren. Voedingsmiddelen Techno24:5557, 1998.

51. JP van der Lugt. Evaluation of methods for chemica

and biological carbohydrate oxidation. PhD disserta

tion, Delft University, Delft, Netherlands, 1998.

52. OC Hansen, P Sougaard. Hexose oxidase from the re

alga Chondrus crispus: purification, molecular cloning

and expression in Pichia pastoris. J Biol Chem

272:1158111587, 1997.


8/3/2019 DK1908_CH13

12/13

53. P Stougaard, OC Hansen. Recombinant hexose oxi-

dase: a method of producing same and use of such

enzyme. Patent WO9640935, 1996.

54. SF Lin, TY Yang, T Inukai, M Yamasaki, YC Tsai.

Purification and characterization of a novel gluco-oli-

gosaccharide oxidase from Acremonium strictum T1.

Biochim Biophys Acta 1118:4147, 1991.

55. J Volc, K-E Eriksson. Pyranose 2-oxidase from

Phanerochaete chrysosporium. Methods Enzymol161:316322, 1988.

56. Y Izumi, Y Furaya, H Yamada. Purification and

properties of pyranose oxidase from basidiomycetous

fungus No. 52. Agric Biol Chem 54:13931400, 1990.

57. H-J Danneel, E Ro ssner, A Zeeck, F Giffhorn.

Purification and characterization of a pyranose oxi-

dase from basidiomycete Peniophora gigantea and che-

mical analyses of its reaction products. Eur J Biochem

214:795802, 1993.

58. L Olsson, CF Mandenius. Immobilization of pyranose

oxidase (Phanerochaete chrysosporium): characteriza-

tion of the enzymic properties. Enzyme Microb

Technol 13:755759, 1991.59. P Wagner, JQ Si. Use of pyranose oxidase in baking.

Patent WO9722257, 1997.

60. HW Gardner. Lipoxygenase pathway in cereals. In: Y

Pomeranz, ed. Advances in Cereal Science and

Technology, Vol IX. St. Paul, MN: American

Association Cereal Chemistry, 1988, pp 161215.

61. K Kikuchi, M Enjo, S Ikeda, K Akimoto, M

Imamura. Noodles containing soybean lipoxidase.

Patent JP53062846, 1978.

62. SK Meiji. Improving colour, taste and flavour of pro-

cessed flour foodsby adding lipoxidase and lipase.

Patent JP55153549, 1980.

63. Y Isao. Production of storable noodle with good lus-ter and color. Patent JP56131358, 1981.

64. H Fukui, D Hosokawa, H Matsuda, M Nagahama, H

Morita. Bakery products and confectioneries and their

manufacture using lipoxygenase-containing soybean

meal as bleaching agent. Patent JP63254939, 1988.

65. G Matheis, JR Whitaker. A review: enzymatic cross-

linking of proteins applicable to foods. J Food

Biochem 11:309327, 1987.

66. AM Mayer, E Harel. Phenoloxidases and their signif-

icance in fruit and vegetables. In: PF Fox, ed. Food

Enzymology, Vol 1. London: Elsevier Science

Publishers, 1991, pp 373394.

67. MR Ullah. Tea. In: PF Fox, ed. Food Enzymology,Vol 2. London: Elsevier Science Publishers, 1991, pp

163188.

68. J Zawistowski, CG Billaderis, NAM Eskin. Phenol

oxidase. In: DS Robinson, NAM Eskins, eds.

Oxidative Enzymes in Foods. New York: Elsevier

Applied Science, 1991, pp 217276.

69. HV Amorim, M Melo. Significance of enzymes in cof-

fee. In: PF Fox, ed. Food Enzymology, Vol 2.

London: Elsevier Science Publishers, 1991, pp

210.

70. NAM Eskin. Biochemistry of Foods. New Y

Academic Press, 1990.

71. PJ Hilton, RT Ellis. Estimation of the market val

Central African tea by theaflavin analysis. J Sci F

Agric 23:227232, 1972.

72. ECM Bouwens, K Trivedi, C van Vliet, C Wi

Enhancing colour of tea-based products. PEP760213, 1996.

73. AS Lopez, PS Dimick. Enzymes involved in c

curing. In: PF Fox, ed. Food Enzymology, V

London: Elsevier Science Publishers, 1991, pp

236.

74. JQ Si. Laccase enzyme in bread-, dough- or p

improvers to give improved gluten strength, increa

specific volume index and crustiness. P

WO9428728, 1994.

75. GN Pruidze. Stable natural food-dyes of phenolic

gin. Proceedings of XVth International Confe

Polyphenols. Strasbourg, France: Bull. Gr

Polyphenols, 1990, pp 15, 136139.76. T Aso, N Sakota. Deepening of the red pigme

safflower as food colouring by spraying a dilute

case solution on safflower petal. Patent JP08214

1996.

77. NAM Eskin. Biotechnology: enzymes in the

industry. In: NAM Eskin, ed. Biochemistr

Foods. New York: Academic Press, 1976, pp.

539.

78. IM Kooter, AJ Pierik, M Merkx, BA Averil

Moguilevsky, A Bollen, R Wever. Difference Fo

transform infrared evidence for ester bonds linkin

heme group in myeloperoxidase, lactoperoxidase

eosinophil peroxidase. J Am Chem Soc 119:1111543, 1997.

79. K Kussendrager. Lactoferrin and lactoperoxi

bio-active milk proteins. Int Food Ingredients 6

21, 1993.

80. SA Farrag, EH Marth. E. coli 0157 H7, Y. ente

litica and their control in milk by the LP syste

review. Lebensm Wiss Technol 25:201211, 1992

81. H Kawamoto, O Ashibe. Lactobacillus-ferme

foods. Patent JP62228224, 1987.

82. T Suguri, M Hirano, T Uchida, K Tatsum

Nakajima, Y Ichiro. Preservatives for pickled ve

bles. Patent JP09271319, 1997.

83. L. Bernard. Control of bacteria in fish, shellfishseafood by using lactoperoxidase system. P

FR2750575, 1998.

84. M Hirano, T Suguri, K Tatsumi. Lactoperoxidas

manufacturing white mold cheese. Patent JP1021

85. M Nakada, S Dosako, R Hirano, M Oook

Nakajima. Lactoperoxidase suppresses acid pro

tion in yoghurt during storage under refrigera

Int Dairy J 6:3342, 1996.


8/3/2019 DK1908_CH13

13/13

86. P Walstra, R Jenness. In: Dairy Chemistry and

Physics. New York: John Wiley & Sons, 1984, p 128.

87. LW Aurand, NH Boone, GG Giddings. Superoxide

and singlet oxygen in milk lipid peroxidation. J Dairy

Sci 60:363369, 1977.

88. G Bruder, H Heid, E-D Jorasch, TW Keenan, IH

Mather. Characteristics of membrane-bound and

soluble forms of xanthine oxidase from milk and

endothelial cells of capillaries. Biochim Biophys Acta701:357369, 1982.

89. JL Weihrauch. In: NP Wong, R Jenness, M Keeney,

EH Marth, eds. Fundamentals of Dairy Chemistry.

New York: Van Nostrand Reinhold, 1988, pp 244

245.

90. PF Fox, MB Grufferty. Exogenous enzymes in dairy

technology. In: PF Fox, ed. Food Enzymology, Vol 1.

London: Elsevier Science Publishers, 1991, pp 219270.

91. CL Hicks. Occurrence and consequence of superoxide

dismutase in milk products: a review. J Dairy Sci

63:11991204, 1980.

92. G Yao, G Chen, J Fu. Technique for brewing beer

containing SOD, hedgehog polysaccharide and thea-flavin. Patent CH1145404, 1987.

93. HD Chu, JG Leeder, SG Gilbert. Immobilized cata-

lase reactor for use in peroxide sterilization of dairy

products. J Food Sci 40:641643, 1975.

94. TE Mathiasen. Laccase and beer storage. Paten

WO9521240, 1994.

95. BR Petersen, TE Mathiasen. Deoxygenation of a foo

item using a laccase. Patent WO9631133, 1995.

96. G Ritter, H Dietrich. The influence of modern proces

sing techniques on the content of important plant phe

nols in apple juice. Fluss Obst 63:256263, 1996.

97. GJC Bauw, MW Davey, J Ostergaard, MCE va

Montagu. Production of ascorbic acid in plantsPatent WOg850558, 1998.

98. Y Suwa, T Kobayashi, N Kiyota, S Komatsubara, H

Yoshizumi. Agent for inactivating the mutagenicity o

coffee. Patent EP128333, 1984.

99. C Saito, H Senda, Y Yokoo. Reduction of cholestero

level by enzyme producing bacteria. Paten

WO9325702, 1993.

100. DC Beitz, JW Young, SS Dehal. Plant cholestero

reductase to convert cholesterol in foods of anima

origin. Patent US4921710, 1990.

101. C Aitoh, H Kumazawa, K Aisaka, T Mizakami, R

Katsumata, K Ando, K Chiai, K Ouchi. Process fo

preparing a cholesterol-lowering compound. PatenWO9820150, 1998.

DK1908_CH13

Documents

Transcript of DK1908_CH13