Agriculture Reference
In-Depth Information
Wharton, Chapter
11;
Jones, Chapter
12;
and
Mikitzel, Chapter 14). Potato breeders must ac-
tively breed and select for genetic resistance to
those that impact yield and quality seriously in
the production regions for which they develop
new potato cultivars. In addition, they must en-
sure during the development of a new cultivar
that it has no greater susceptibility to lesser pests
and diseases than those cultivars currently used
by the industry. Agronomic characteristics such
as yield, tuber size distribution and dormancy,
starch content, sensory attributes, and process-
ing and storage characteristics (see Bethke,
Chapter
15,
this volume) must also meet indus-
try standards with respect to market class (see
Bond, Chapter
3,
this volume). Enhanced nutri-
tional value (biofortification) and flavor have
also come to the forefront in potato breeding,
with enhancement of these traits also being dis-
cussed in Chapter
18
(Navarre
et al
.) and Chap-
ter
19
(Taylor), this volume. Bradshaw (2007a)
provides a thorough review of resistance and
agronomic traits important in potato breeding,
with Simko
et al
. (2007) and van Eck (2007)
providing detailed analyses of the genetics of re-
sistance and morphological and tuber traits, re-
spectively. Rather than restate the well-written
summaries provided by the aforementioned au-
thors, this section will discuss the food safety,
disease, and sustainability issues of potato that
have most recently emerged as important breed-
ing objectives.
an understanding of the factors contributing to
acrylamide formation and strategies for its miti-
gation. The effects of acrylamide on human
health at the amounts found in food are not yet
clear, with no country having yet used regula-
tory action to set limits on the acrylamide con-
tent in foods or in the diet (Lineback
et al
., 2012).
However, acrylamide in foods is of concern, with
the US potato industry proactively seeking to re-
duce its levels in processed potato products sev-
eral years prior to the US Food and Drug Admin-
istration issuing draft guidance to the food industry
in November 2013 on approaches for reducing
the levels of acrylamide in certain foods.
Potato cultivars with low levels of reducing
sugars and/or free asparagine in tubers would
be a means of reducing acrylamide in processed
potato products (Vinci
et al
., 2012). For several
decades, potato breeders have bred for reduced
tuber sugar levels to facilitate the development
of processing cultivars having lighter fry or
chip color following frying. Fortuitously, breed-
ing for reduced sugar levels in potato has
also contributed to reducing acrylamide. How-
ever, efforts in reducing the concentration of as-
paragine in potato were not a breeding objective
until the recent elucidation of its role in acryl-
amide formation. In potato, asparagine concen-
trations are in excess compared to reducing
sugar content, with the conclusion being that
acrylamide formation will be determined largely
by reducing sugar levels (Vinci
et al
., 2012).
However, while the majority of published data
show stronger correlations between reducing
sugars and acrylamide formation than for as-
paragine, cold-induced sweetening in tubers
following storage can change the balance, with
reducing sugars no longer being limiting and
asparagine content now becoming critical in
acrylamide formation (Matsuura-Endo
et al
., 2006).
A combined breeding approach for reducing
acrylamide formation by lowering concentrations
of both tuber reducing sugars and free aspara-
gine appears warranted. Support for such an
approach was voiced by Shepherd
et al
. (2010),
with the authors making the following statement
based on data from their analysis of acrylamide
formation in a tetraploid breeding population
segregating for tuber sugars and asparagine: “In
conclusion our data indicate that conventional
breeding approaches need to select for both low
reducing sugar levels and low asparagine levels,
Acrylamide
Acrylamide is a chemical compound that is a
neurotoxin, a carcinogen in rodents, and a sus-
pected carcinogen in humans. In 2002, moder-
ate levels of acrylamide were reported in heated
protein-rich foods, with higher concentrations
found in carbohydrate-rich foods such as potato
and their fried products (Tareke
et al
., 2002).
Formation of acrylamide has subsequently been
shown to be a product of the Maillard reaction
and is primarily a consequence of a chemical re-
action occurring between the free amino acid,
asparagine (Asn), and reducing sugars (glucose/
fructose) at high temperatures. Recent reviews
of acrylamide formation in foods (Lineback
et al
.,
2012) and potato specifically (Vinci
et al
., 2012;
Bethke and Bussan, 2013) are recommended for
