Food security in South Africa ranks as one of the top ten priorities in the country. Potato
is a fundamental staple food crop in South Africa, providing essential nutrition. While
there are several cultivars currently in production for the potato market, there is a need
to explore cultivars that are available, but not utilised within the country. Pigmented
potatoes are not regarded as high value on the South African market; however, yield
prospects as well as health-promoting benefits could have a positive contribution on the
South African Gross Domestic Product (GDP) and on the population’s health. Potato
cultivar (cv.) Salad blue (SB) seems to be a drought-tolerant crop with the ability to
produce reasonable yields under severe environmental condition
s. In order to promote
cv. SB as a possible food security option for South Africa, there is a critical need for
empirical information, describing some basic horticultural as well as biochemical
information and vitamin C presence. This study investigated the potential of pigmented
potato SB tubers as an alternative to high yielding white potato for the South African
market. Tubers of
Solanum tuberosum
cv. BP1 and SB, were used for this research. The
high amounts in phenolic compounds in SB can be considered to be health-promoting
phytochemicals. Anticarcinogenic, antibacterial, antiviral properties have been reported.
A greenhouse, bag trial with virus-free plantlets of BP1 and SB cultivars was conducted
using three water and nutrient levels and favourable root zone temperature (100%
without heat, 100% heated, 50% heated, 25% heated) all grown in coco peat. Cultivar
SB showed nearly two-fold yield compared to the control BP1. Methanol extracts of the
tubers were assessed for their total polyphenolic, flavanol, and flavonol contents as well
as 1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, ferric reducing antioxidant
power (FRAP), Trolox equivalence antioxidant capacity (TEAC), anthocyanin and
L
-ascorbic
acid assays. The aqueous extract of the SB tubers was found to contain higher
level of total polyphenols (320 mg GAE/g), and flavonol (85 mg QE/g) than the extract
of the BP1 tubers with values of 173 mg GAE/g (total polyphenol), and 67 mg QE/g
(flavonol). Similarly, the methanol extract of the tuber skins also exhibited higher DPPH
(818,86 IC
50 mg/mL), FRAP (18,19
μmol AAE/g), and TEAC (911,12
μmol TE/g) than
the extract of the BP1 with DPPH (595,99 IC
50 mg/mL), FRAP (10,86
μmol AAE/g) and
TEAC (435,44
μmol TE/g). The present study provides useful information for farmers
and health professionals in respect to increased yield and health-promoting benefits of
an underutilized potato variety.
