Agriculture Reference
In-Depth Information
are a current problem in human populations. It
has been proven that their content can be in-
creased through bioengineering without broadly
affecting plant biology. Startlingly little work has
been done to investigate vitamin content vari-
ation among potato germplasm for these and
most other vitamins. This leaves one to speculate
about what potential there is to enhance vita-
min B uptake by breeding or choosing different
extant cultivars. A reasonable approach would
be to generate detailed vitamin profiles in a wide
range of germplasm to understand the potential
of breeding efforts for enhancing their vitamin B
content. The efficiency of this approach has al-
ready been demonstrated for vitamins B
1
and B
6
,
but is missing for other B vitamins. It may also be
of interest for the industry to use this informa-
tion for consumers, to let them know that a spe-
cific consumed potato variety is very rich in
these beneficial vitamins and to help consumers
understand more fully the nutritional benefits of
potatoes.
Another poorly investigated aspect is to en-
gineer genetically the biosynthetic pathway of B
vitamins in potato or to establish proof-of-
concept that changing B-vitamin content in this
crop is possible. Such attempts would provide
critical knowledge about the potential advantages
and disadvantages of altered vitamin biosyn-
thesis in potato, verify the potential of biofortifi-
cation, and show how this affects plant development
and performance under normal and stressful
conditions. Given the current focus in Western
societies about “healthy foods”, providing more
detailed information about the B vitamins in po-
tato would be beneficial for the processing indus-
try as well as for consumers.
Like many antioxidants, vitamin C concentra-
tions in plants are subject to environmental control,
and perhaps consequently are quite variable.
Some genotypes have more consistent vitamin C
concentrations than others across multiple
years or when grown in different locations (Love
et al
., 2004). This study of
75
genotypes found
concentrations ranged from 11.5 to 29.8 mg
100
g
-
1
FW. Analysis of
33
cultivars grown in
three locations around Europe found
13-
30.8 mg
100
g
-
1
FW (Dale
et al
., 2003).
Vitamin C levels decrease rapidly during
cold storage of potatoes, and can decrease 60%
(Keijbets and Ebbenhorst-Seller, 1990). Vitamin
C in the cultivar Bintje decreased when stored at
7°C, but increased at
16
and 28°C (Linnemann
et al
., 1985). Conversely, in a more recent study,
levels decreased at the same rate in Ranger Rus-
set stored at
4
or 32°C, but decreased less rapidly
when stored under reduced oxygen (Blauer
et al
.,
2013). The decrease in cold storage varies by
genotype, from
20
to 60% among
33
genotypes,
leading authors to suggest that breeding efforts
to increase vitamin C should focus on post-
storage content more than on concentrations at
harvest (Dale
et al
., 2003). Another study exam-
ined the effect of cold storage on vitamin C con-
tent in
12
potato genotypes after
2,
4,
and
7 months (Kulen
et al
., 2013). All showed a sub-
stantial loss after 4 months. Interestingly, sev-
eral of the genotypes did not show a significant
loss after 2 months of cold storage. It would be of
interest to know whether those potatoes show-
ing no loss after 2 months would consistently
show no loss in repeated experiments from dif-
ferent years and locations, because a genotype
capable of showing no loss after months of stor-
age would be highly desirable.
Potatoes peeled, blanched, and then fried
lost only 10% of their vitamin C after 6 months
of storage at -18°C (Tosun and Yücecan, 2008).
Vitamin C losses during cooking can be substan-
tial, but need not be. Skin-on potatoes prepared
using microwaving, steaming, baking, and boil-
ing had a negligible loss of vitamin C (Navarre
et al
., 2010).
Wounding increases vitamin C levels. Pota-
toes stored for 2 days following slicing or bruis-
ing underwent a 400% increase in vitamin C in
sliced tubers, but a 350% decrease in bruised
tubers (Mondy and Leja, 1986). Vitamin C in-
creased in fresh-cut potatoes stored in air, but
18.5 Vitamin C
Potatoes may be best known nutritionally for pro-
viding high amounts of two nutrients, vitamin C
and potassium. The RDA for vitamin C is
75-
90
mg, and plants are the primary dietary source.
A red-skinned potato (
173
g) provides about 36%
of the RDA according to the USDA. Vitamin C de-
ficiency causes scurvy, which in severe cases is
typified by loss of teeth, liver spots, and bleeding.
Vitamin C is an important cellular antioxidant
and is a cofactor for numerous enzymes.
