Agriculture Reference
In-Depth Information
correlate with the amount of browning ob-
served in fresh-cut potatoes (Cantos
et al
., 2002).
Another study using a quantitative trait locus
(QTL) approach found no correlation (correl-
ation coefficient 0.13) between browning and
chlorogenic acid (Werij
et al
., 2007). An associ-
ation genetics analysis found correlation be-
tween enzymatic browning and unexpected
traits including specific gravity and a class III lip-
ase (Urbany
et al
., 2011). Chlorogenic acid and
other phenolics interact non-enzymatically with
iron to cause ACD (Hughes and Evans, 1969;
Wang-Pruski, 2007). However, other tuber
compounds mediate this reaction and organic
acids like citrate ameliorate the reaction, as does
vitamin C and phosphate (Silva
et al
., 1991). Dip
treatments such as EDTA or sodium acid sulfate
also reduce ACD (Calder
et al
., 2012). Other
minerals including P, S, and Ca may influence
the severity of ACD (LeRiche
et al
., 2009).
Given the health benefits of polyphenols, it
is strongly desired to have cultivars that provide
generous amounts of these compounds. This
may be particularly important for potatoes, given
the negative view of some nutritionists. More-
over, the major tuber phenylpropanoid, chloro-
genic acid, has been implicated in reducing the
risk of diabetes, obesity, and hypertension, some
of the things for which potatoes have been criti-
cized. Red and purple potatoes not only contain
higher amounts of polyphenols but also are less
affected by discoloration than white potatoes, be-
cause their natural color would mask browning.
Moreover, key roles of polyphenols in potatoes in-
clude improving the plant's resistance to biotic
and abiotic stresses. Decreasing these com-
pounds could require increased use of pesticides.
A strategy to reduce discoloration by decreasing
polyphenols may be short-sighted. A preferable
approach is to minimize discoloration by other
methods, focusing on other genetic and environ-
mental factors that influence discoloration.
advantages. Evidence is accumulating that they
have higher amounts of phytonutrients than ma-
ture potatoes, including B1 as mentioned above.
Tuber development has a strong effect on phenyl-
propanoid metabolism and various other phyto-
nutrients (Navarre
et al
., 2013). Swelling stolons
and developing tubers had higher concentrations
of carotenoids than in mature tubers (Morris
et al.
, 2004). Folate in tuber flesh and anthocya-
nins in tuber periderm decreased during tuber de-
velopment, as did vitamin C (Hung
et al
., 1997;
Goyer and Navarre, 2009; Blauer
et al
., 2013).
Products of both early and late phenylpropanoid
pathways decreased in field-grown tubers har-
vested at intervals throughout the season, start-
ing about 60 days after planting. The magnitude
of the phenylpropanoid decrease between imma-
ture and mature potatoes varied by genotype, but
in some cases was up to threefold. CGA was
higher in immature tubers, as was expression of
various genes involved in early phenylpropanoid
metabolism. Late phenylpropanoid pathways
were also affected, with total anthocyanins de-
creasing from
10
mg g
-
1
DW to 6.3 mg g
-
1
D W,
and
dihydroflavonol reductase
(
DFR
) expression de-
creased almost 70% (Payyavula
et al
., 2013). Su-
crose, fructose, and glucose concentrations were
highest earlier in tuber maturation, as was ex-
pression of key genes and enzymes in the glyco-
lytic and shikimate pathways, suggesting sugars
may modulate tuber phenylpropanoids. The
strong correlation between sucrose and total phe-
nolics during development (r = 0.91 in Russet
Burbank) and the higher expression of
sucrose
synthase
(
SUSY
) was consistent with a role for
sugars in modulating phenylpropanoid synthesis.
Historically, baby potatoes command a
price premium because consumers perceive
them to have superior taste. Potato products that
appeal to people with more disposable income
are an important need for the potato industry,
which is seeing declining consumption in much
of the developed world. Reasons for the decline
are complex and multifaceted, but economics,
nutritional perception, and a decrease in the
number of sit-down, home-cooked meals likely
contribute. In the USA, potato consumption has
particularly decreased among the demographic
with more disposable income, including much
of the middle class. Surveys have found that
some consumers regard potatoes as “boring” or
Baby potatoes
Baby potatoes, also referred to as new potatoes or
gourmet potatoes, are immature potatoes har-
vested from young plants, typically
60-
80 days
after planting. Baby potatoes could be important
for the potato industry because they have unique
