Plant-Based Biogas Production for Improved Nutrient Management ...

nomenclature. However, nowadays Beta vulgaris L. subsp. vulgaris (Garden
beet group) is the preferred form.
Beetroot varieties are divided into four groups depending on root shape:
circular, conical, cylindrical and flat (Balvoll, 1999; p 113).
1.5.2 History, use and health aspects
Beta vulgaris was initially valued for its leaves and for the fleshy elongated leaf
midribs that characterise chard. Leaf beets have been popular food plants in
Europe, North Africa and the Middle East since the start of recorded
history. Beta vulgaris is described in Greek texts from 400-300 BC. The
Greeks ate the leaves but the roots were used medically. The Romans were
the first people to become interested in the root of Beta vulgaris, both as a
medicine and as a food, and were the first to cultivate beetroot. By 300 AD
the first recipes for preparing the root had appeared. At that time, the roots
of beet were black or white, long, thin and roughly turnip-shaped. By the
end of the 15 th Century cultivated forms of Beta vulgaris could be found
throughout Europe. In contrast to the Romans, who also primarily took the
root medically, from the 16 th Century onwards people consumed beetroot
mainly as a vegetable. In the 16th Century a beet type with red roots began
to be described. For example, a shorter thicker form of beetroot described
by an Italian source in 1586 is generally recognised as the forerunner of the
modern beetroot. When this beet type spread to France, Germany and
England it was called Roman beet. During the 16 th and 17 th Century Roman
beet and possibly other early long-root types became variable in leaf and
root morphology due to hybridisation with leaf beets, chards and other
beetroot cultivars. By the 19 th Century, a wide range of cylindrical, flat and
globular varieties had been introduced to growers, particularly in Northern
Europe (Nottingham, 2004; chapter 2 & 6).
As mentioned above, beetroot has long been considered a medicinal
plant. In the Roman era it was used to treat fever, constipation and other
ailments. More recently, it has been considered interesting because of its
high content of the antioxidant betalain, which is the characteristic pigment
in beetroot. Betalain has been identified as being a dietary antioxidant.
Many other health aspects of beetroot are described by Nottingham (2004;
chapter 6).
Beetroot has one of the highest nitrate concentrations recorded in
- -1
vegetables. Contents above 2500 mg NO kg are common and maximum
3
levels in commercial beetroot range from 3000 to 4500 mg NO 3 kg -1
countries with limits on nitrate level in beetroot (Santamaria, 2006).
Although recent reports show that the blood pressure lowering effect of
50
in