Wine Chemistry and Biochemistry

442 M. Monagas and B. Bartolom ́e

O

OH

HO

OH

+O

OR

OH

R 1

HO R 2

OH

OH

+O

OR

OH

R 1

HO

OH

R 2

+O

OR

OH

R 1

HO

OH

R 2

O

OH

HO

OH

OH

OH

CH 3 -CH

O

OR

OH

R 1

HO

OH

R 2

O

OH

O

OH

OH

OH

+O

OR

OH

R 1

HO R

2

O

R (^3) OH
R 4
+O
OR
OH
R 1
HO
OH
R 2
O
OR
HO
OH
R 2
OH
CH 3 -CH R^1
OH
+O
OR
OH
R 1
HO R
2
O
COOH
+O
OR
OH
R 1
HO R
2
O
+O
OR
OH
R 1
HO R 2
O
OH
O
OH
HO
OH
OH
OH
R 5
+O
OR
OH
R 1
HO R 2
O
+O
OR
OH
R 1
HO R 2
O
OH
HO
OH
OH
OH
R 5
O
+O
OR
OH
R 1
HO
OH
R 2
OH
OH
HCO C
CO O H
COOH
O
HCOH
(h)
flavanols,
acetaldehyde
vinylflavanols
O
OH
HO
OH
+O
OR
OH
R 1
HO R 2
OH
OH
+O
OR
OH
R 1
HO
OH
R 2
+O
OR
OH
R 1
HO
OH
R 2
O
OH
HO
OH
OH
OH
CH 3 -CH
O
OR
OH
R 1
HO
OH
R 2
O
OH
O
OH
OH
OH
+O
OR
OH
R 1
HO R
2
O
R (^3) OH
R 4
+O
OR
OH
R 1
HO
OH
R 2
O
OR
HO
OH
R 2
OH
CH 3 -CH R^1
OH
+O
OR
OH
R 1
HO R
2
O
COOH
+O
OR
OH
R 1
HO R
2
O
+O
OR
OH
R 1
HO R 2
O
OH
Flavanol-anthocyanin
adducts
Anthocyanin-flavanol
adducts
flavanols
Anthocyanin-ethyl-
anthocyanin dimers
Flavanol-ethyl-
anthocyanin adducts
Flavanyl-pyranoanthocyanins
acetaldehyde
Vitisin B-pyranoanthocyanins
Vitisin A-
pyranoanthocyanins
vinylflavanols vinylphenols
Flavanyl-vinylpyranoanthocyanins
(Portisins)
Hydroxyphenyl-
vinylpyranoanthocyanins
vinylphenols or pyruvic acid
hydroxycinnamic acids
Hydroxyphenyl-
pyranoanthocyanins
o-quinones of
caftaric acid (CA)
CA-anthocyanin adducts
O
OH
HO
OH
OH
OH
R 5
+O
OR
OH
R 1
HO R 2
O
O
OH
HO
OH
OH
OH
R 5
+O
OR
OH
R 1
HO R 2
O
+O
OR
OH
R 1
HO R 2
O
OH
HO
OH
OH
OH
R 5
O
+O
OR
OH
R 1
HO R 2
O
OH
HO
OH
OH
OH
R 5
O
(c) (b) (d) (e)
+O
OR
OH
R 1
HO
OH
R 2
OH
OH
HCO C
CO O H
COOH
O
HCOH
+O
OR
OH
R 1
HO
OH
R 2
OH
OH
HCO C
CO O H
COOH
O
HCOOHH
(a)
(f)
(j) (k)
(i)
(g)
(h)
Fig. 9A.2Anthocyanin equilibrium forms and bleaching reaction with bisulfite
an aromatic residue linked to the pigment (intramolecular copigmentation). Through
this interaction, the nucleophilic attack of water at C-2 is partially reduced. The color
properties of anthocyanins in wine are described in detail in Chapter 9B.
9A.2 Chemical Reactions of Anthocyanins During Winemaking:
Main Anthocyanin-Derived Compounds
Main chemical reactions involving anthocyanins during winemaking include reac-
tions with enzymatically generatedo-quinones, direct andacetaldehyde-mediated
anthocyanin-flavanol and anthocyanin-anthocyanin condensation reactions and reac-
tions leading to pyranoanthocyanin formation (Fig. 9A.3). For each of these reac-
tions, the precursors, mechanism, products obtained in model solution and identified
in wine, are provided. Evidence of factors affecting these reactions, such as the con-
centration of the reactants, pH, temperature, metal ions and oxygen, among others,
are also reported. Since flavanols and other phenolic compounds are also involved
in many of these reactions, they are also described in Chapters 9B and 9C. The