Food Chemistry

700 15 Cereals and Cereal Products

Table 15.26.Reduced (GSH), oxidized (GSSG) and protein-boundglutathione (PSSG), total glutathione (GSS)
as well as cysteine (CSH) and CSSa

Wheat cultivar Ash (wt. %) Concentration (nmol/gflour)

GSH GSSG PSSG GSS CSH CSS

DNS 0. 78 100 n.a. n.a. 279 13 159
Maris Huntsman 0. 68 81 n.a. n.a. 232 9 145
Kanzler 0. 62 35 n.a. n.a. 180 8 118
Frescob n.a. 31 24 131 210 n.a. n.a.
Normanb n.a. 74 15 73 177 n.a. n.a.
Merciab n.a. 74 27 102 230 n.a. n.a.
Havenb n.a. 18 20 89 147 n.a. n.a.

aCSS consists of free cysteine, cystine and cysteine, which is linked with wheat proteins only via disulfide bridges

but not via peptide bonds.
bDegree of grinding 64–68%.

n.a.: not analyzed.

Table 15.27.Glutathione concentration as a function of
the degree of grinding

Wheat Ash Glutathionea
cultivar (w/w%)
GSH Totalb

CWRSc 0. 54 16 172
0. 71 35 348

1. 44 60 575
   DNSc 0. 59 41 175


2. 78 110 345


3. 57 215 657
   Maris 0. 55 20 185
   Huntsman 0. 68 94 273


4. 73 210 435

aCalculated as GSH in nmol/g based on the dry

weight.
bSum of GSH, GSSG, and GSSP.
cMarks of origin: Canadian Western Red Spring

(CWRS), Dark Northern Spring (DNS).

urements of flour/water dough show the effect of
GSH (Fig. 15.16). At 124 nmol/g, the concen-
tration of GSH in the sample of flour is rela-
tively high. The strength of the dough decreases
with the addition of 100 nmol/g GSH. GSSG is
also active but not as much as GSH (Fig. 15.16)
because it first has to be reduced to GSH, e. g.,
by proteins with free SH groups (PSH, cf. For-
mula 15.5), before it can depolymerize aggre-
gated gluten proteins as shown in Formula 15.4.

GSSG+PSHGSSP+GSH (15.5)

Cysteine is also rheologically active and cystine

after disulfide exchange, e. g., with PSH. To

identify the disulfide bonds in gluten proteins,

which are cleaved by endogenous GSH by disul-

fide exchange, flour was kneaded with added

[^35 S]-GSH. The use of high specific radioactivity

allowed the additive to be kept very low in com-

parison to the GSH present in flour. The disulfide

bonds labelled by [^35 S]-GSH are cleaved by the

endogenous GSH according to the reaction given

Fig. 15.16.Influence of reduced (GSH) and oxidized

glutathione (GSSG) on the rheological properties of

wheat dough (according toHahnandGrosch, 1998).

Tensile tests with dough made of 10 g of DNS flour

(0.76% ash, 15.5% protein, 124 nmol/gGSH),water,

2% NaCl and the following additives (nnol/l flour):

GSH (100;◦–◦), GSSG (50;•–•), control without addi-

tive (—). F: force, L: distance